While most lichenicolous fungi belong to the Ascomycota, c. 5% of them are members of the Basidiomycota. Among these, the poorly known genus Crittendenia in the Pucciniomycotina has recently been described for lichenicolous fungi with minuscule needle-like synnematous basidiomata. Although only two species were hitherto known, the wide observed host-spectrum suggested a larger number of mainly host-specific species. A classical revision using morphological characters alone proved to be virtually impossible, because of the large variability of the material from each host genus, and the scant morphological differences between hypothetically distinct species from different hosts. We studied over sixty specimens and made a large number of measurements of the available morphological characters. We additionally generated 18 ITS and 21 nuLSU rDNA sequences and conducted maximum likelihood and Bayesian analyses. We also performed one species delimitation analysis (bPTP-ML). By combining sometimes subtle morphological differences, host choice and phylogenetic results, we were able to accept eighteen morphologically and/or genetically distinct species, all confined to a single host genus or to several closely related host genera. Two further putative species are left unnamed, as richer material is needed and molecular data are missing. Sixteen new species are described: Crittendenia absistentis (on Bacidia absistens), C. bacidinae (on Bacidina apiahica), C. bryostigmatis (on Bryostigma muscigenum), C. byssolomatis (on Byssoloma maderense), C. crassitunicata (on Melanohalea ushuaiensis), C. heterodermiae (on Heterodermia comosa), C. hypotrachynae (on Hypotrachyna), C. kakouettae (on ‘Byssoloma’ kakouettae), C. lecanorae (on Lecanora), C. lecidellae (on Lecidella elaeochroma), C. lopadii (on Lopadium disciforme), C. parvispora (on Bacidia), C. physciiphila (on Phaeophyscia, Physcia and Physciella), C. physconiae (on Physconia distorta), C. stictae (on Sticta fuliginosa) and C. teloschistis (on Teloschistes). Further, a ML analysis of the Agaricostilbomycetes using ITS and nuLSU sequences suggested that Crittendenia cannot be included in any known family, and the new family Crittendeniaceae is therefore described for the genus.
Lichenicolous fungi are a very successful biological group specialized in having symbiotic or parasitic relationships with lichenized fungi. Diederich et al. (2018) presented a catalogue of the 2000 species known at that time, and new species are regularly being added. While most of them belong to the ascomycetes, c. 100 basidiomycetous species are known, most belonging to the Tremellomycetes. Just two genera with four species were reported from the Pucciniomycotina, one of them being the genus Chionosphaera D.E.Cox, of which the lichenicolous species have recently been transferred to the new genus Crittendenia Diederich et al., based on molecular phylogenetic evidence (Millanes et al. 2021).
From a historical point of view, Cox (1976) was the first to study “a new homobasidiomycete with anomalous basidia,” with tiny, synnemata-like basidiocarps, aseptate 7-spored apobasidia lacking basal clamps, developing over dead branches of trees, that he described as the new genus and species Chionosphaera apobasidialis Cox. Oberwinkler & Bandoni (1982) later introduced the new family Chionosphaeraceae Oberw. & Bandoni that also included the genus Stilbum Tode ex Mérat, within the new order Atractiellales Oberw. & Bandoni, described for “heterobasidiomycetous species with gasteroid meiosporangia of the auricularioid or holobasidiate types.” A first lichenicolous species, Chionosphaera lichenicola Alstrup, Sutton & Tønsberg, collected by T. Tønsberg on corticolous Micarea prasina, was described from Norway (Alstrup 1993). In his revision of lichenicolous heterobasidiomycetes, Diederich (1996) studied three similar specimens collected by J. Etayo on the thallus of Lecidella elaeochroma, Parmelina quercina and Teloschistes flavicans; despite some morphological variability in this material, he did not find any convincing arguments to distinguish these specimens as distinct species and called them provisionally Chionosphaera cf. apobasidialis, awaiting the discovery of more and richer specimens on these and other host lichens. Roberts (1997) studied a rich Scottish specimen on Melanelixia glabrata, differing from C. apobasidialis and C. lichenicola by the 4-spored basidia with basal clamps, that he described as the new Chionosphaera coppinsii P.Roberts; a further Scottish specimen on Lecidella elaeochroma studied by him had shorter, 4–6-spored basidia and was provisionally included in C. coppinsii. Kirschner et al. (2001) described the new Chionosphaera cuniculicola R.Kirschner, D.Begerow & Oberw. growing in galleries of bark beetles on conifers in Central Europe, presented a first phylogenetic analysis including C. apobasidialis and C. cuniculicola, combined Fibulostilbum phylaciicola Seifert & Bandoni in Chionosphaera, restudied the type of C. lichenicola and found that basidia possess basal clamps, and concluded that Roberts’ specimen on Lecidella belongs to C. lichenicola. Kirschner & Chen (2008) further combined the poorly known Stilbum erythrinae Hansf. in Chionosphaera.
Millanes et al. (2021) obtained ITS and nuLSU sequences from Chionosphaera coppinsii and seven unidentified lichenicolous Chionosphaera specimens from diverse hosts. Their phylogenetic results suggested that all lichenicolous species formed a clade that was only distantly related to the type of Chionosphaera, and they consequently described the new genus Crittendenia for the lichenicolous taxa. They also obtained Crittendenia coppinsii sequences from host thalli devoid of basidiomata, but growing together with infected thalli, showing that the fungus may be present asymptomatically within the host thallus.
Most Crittendenia species are extraordinarily rare or overlooked, and many lichenologists interested in lichenicolous fungi had never collected them. Further, basidiomata in many species are so small that they are difficult to detect, even under a binocular microscope with a high magnification. On some well-known and common hosts, their rarity is striking. For example, from Physcia adscendens, with almost 44,000 results in the GBIF database ( www.gbif.org; 23 Nov. 2021), only two infected specimens are known, collected by the same person (P. Pinault) in two neighboring localities. Hunting in the field for Crittendenia species is therefore much like searching for the proverbial needle in the haystack, the slender, synnemata-like basidiomata with an enlarged capitulum strongly resembling a pinhead needle.
The aim of this paper was to prepare a taxonomic revision of the species of Crittendenia, using molecular phylogenies and morphological characters. Preliminary studies have shown that Crittendenia specimens from the same host may be morphologically particularly variable. On the other hand, specimens from different host species or genera may be extremely similar, the small differences observed possibly just resulting from the limited sampling. To revise these species with classical morphological methods therefore rapidly proved to be virtually impossible. By combining molecular phylogenetic results, morphological data combined with statistical analyses, and the host choice, we have succeeded in proposing a taxonomic treatment and a key that should allow the identification of most specimens, even when sequences are not available, and at the same time allow collectors to recognize which specimens are likely to represent undescribed species, and those for which DNA data should be obtained.
Material and Methods
Morphological studies. The material examined is deposited in bg, br, c, e, g, k (incl. former imi), li, lpb, maf, ny, po, pra, trh, ubc and wis, and in the private collections of W. von Brackel, M. Eichler & R. Cezanne, J. Etayo, P. van den Boom and E. Zimmermann. Dry herbarium specimens were examined and measured under a binocular microscope Leica MZ 7.5. Macroscopic photographs were done using a Canon 6D camera with Nikon BD Plan 10× or Nikon BD Plan 60× ELWD microscope objectives, StackShot (Cognisys) and Helicon Focus (HeliconSoft) for increasing the depth of field. For microscopical examination, squash preparations and rarely vertical sections of all specimens were examined in 5% KOH + phloxine B, of some specimens also in water, 5% KOH, ammoniacal Congo red and Melzer's reagent. Microscopic photographs were prepared using a Leica DMLB microscope with DIC optics and a Leica EC3 camera, and Helicon Focus for increasing the depth of field. Measurements of microscopical characters were done in 5% KOH + phloxine B.
Measurements from a specimen are given as (min)x-sd – x+sd(max), where x represents the mean, sd the standard deviation, min the smallest value and max the largest value observed, followed by the number of measurements n. This represents the 69% probability interval, thus excluding the smallest and the largest 15.5%. Measurements from a species are given as (min)[min x-sd]x-sd –x+sd[max x+sd](max), where ‘min x-sd’ represents the smallest ‘x-sd’ value obtained within the specimens examined and ‘max x+sd’ the largest ‘x+sd’ value obtained within these specimens. For example, if the basidial length from three specimens is (27)30–60(68) µm, (23)40–50(62) µm and (34)40–70(91) µm, and that of the species (including the three specimens) is (23)35–60(91) µm, then the resulting measurements will be given as (23)[30]35–60[70](91) µm. Values between square brackets will be omitted when a species is known from a single specimen. In the identification key, extreme values between parentheses are omitted. The following abbreviations are used: StH (stipe height, including capitulum), StD (stipe diameter), CaD (capitulum diameter), these three measured under a binocular microscope, BaL (basidial length), BaD (basidial diameter, at the middle of the basidium), BaApD (broadest basidial diameter, close to the apex), SpL (spore length) and SpB (spore breadth).
DNA extraction, amplification and sequencing. DNA was extracted from either recently collected or dried herbarium material (Table 1). From each specimen, between three and ten fruiting bodies were carefully separated from the lichen thallus with a scalpel and tweezers to minimize the lichen material in the DNA extraction. Total DNA was extracted using the Qiagen DNeasy Plant Mini Kit (Qiagen, Venlo, the Netherlands), according to the manufacturer's instructions. We amplified two molecular markers: the internal transcribed spacer (ITS) and the large subunit (nuLSU) of the nuclear ribosomal DNA.
Table 1.
Sequences of taxa in the Agaricostilbomycetes included in this study, either newly produced (all from Crittendenia, in bold font) or retrieved from GenBank. Host, specimen data and DNA extraction code are given for Crittendenia samples. A (T) next to the species name indicates a type specimen. A hash symbol indicates a sequence of Crittendenia coppinsii obtained from an asymptomatic lichen specimen. An asterisk next to an nuLSU GenBank accession number indicates a short sequence obtained using the reverse primer ChioLSU3-3.
Table 1.
Continued.
We used the specific primers Cc-F1, Cc-R1 and ChioLSU 3-3, designed to selectively amplify the DNA of Crittendenia, avoiding that of other basidiomycetes and of the lichenized host (Millanes et al. 2021). These, in combination with general fungal primers, viz. ITS1F (Gardes & Bruns 1993), ITS4 (White et al. 1990), LR0R (Rehner & Samuels 1994), LR3 (Vilgalys & Hester 1990), were combined to amplify the ITS and a fragment of c. 600 bp of the nuLSU in the nuclear ribosomal DNA. Amplification reactions were performed using IllustraTM Hot Start PCR beads (GE Healthcare Life Sciences, Pittsburg, California, U.S.A.), according to the manufacturer's instructions, for a 25 µL final volume. PCR amplifications followed protocols described in Millanes et al. (2021). Nested PCR was used when samples did not amplify at a first instance—or when very faint bands were obtained—by direct PCR. For the nested protocol we ran an initial PCR using the general primer combinations ITS1F/LR3. One mL of the amplicons obtained in that first PCR was used as DNA template for the second PCR. Settings for the second (nested) PCR are the same as the ones previously described in Millanes et al. (2021) for direct PCR. We often obtained multiple amplicons—both using direct or nested PCR—and in those cases bands of the appropriate size were selected, and gel extracted using the Qiagen MinElute Gel Extraction kit. Gel extraction was tested in a new gel before sequencing. Single PCR products not gel extracted were purified with Exo-sap-ITTM (USB Corporation, Cleveland, Ohio, U.S.A.). The purified samples were sequenced by Macrogen Inc. (in Amsterdam, the Netherlands, or in Madrid, Spain).
Multiple sequence alignment, and phylogenetic and species delimitation analyses. Newly produced sequences were assembled and edited using Geneious Prime ®2021.0.3. ( https://www.geneious.com). We produced two data matrices for subsequent phylogenetic analyses, using two loci (ITS and nuLSU). The first (dataset 1) included all sequenced Crittendenia specimens, and a sequence of Ruinenia rubra (Ruineniaceae, Agaricostilbales) was used as outgroup, based on previous phylogenies (Millanes et al. 2021). The second (dataset 2) included only one Crittendenia representative per species, representatives of the five accepted families in the Agaricostilbomycetes (i.e., Agaricostilbaceae, Chionosphaeraceae, Jianyuniaceae, Kondoaceae and Ruineniaceae: Li et al. 2020; Wang et al. 2016). Phyllozyma dimmenae was used as outgroup, based on Wang et al. (2016). We assembled this second dataset to 1) further test the monophyly of Crittendenia—including all newly described species in an expanded sampling in the Agaricostilbomycetes, and 2) to test the possible family assignment of the genus. In dataset 2, large parts of the ITS were unable to align and were therefore excluded from the matrix. Species names, voucher information, and GenBank Accession numbers are given in Table 1.
For phylogenetic analyses, sequences were aligned using MAFFT version 7 (Katoh et al. 2019) with the Q-INS-i algorithm. The alignments were trimmed to exclude ambiguously aligned regions using GBlocks (Castresana 2000), following the relaxed conditions described by Talavera & Castresana (2007), and manually checked, before and after trimming, using Mesquite 3.7 (Maddison & Maddison 2021). We considered four independent partitions, ITS1, 5.8S, ITS2 and nuLSU, in analyses. Each partition was analysed individually by maximum likelihood ultrafast bootstrap in IQTree (Hoang et al. 2018) to assess for conflicts. Phylogenetic relationships were reconstructed using maximum likelihood (ML) and Bayesian approaches. Maximum likelihood analyses were carried out in IQTree (Nguyen et al. 2015). Model selection for each partition was achieved using ModelFinder in IQTree (Kalyaanamoorthy et al. 2017), with the corrected Akaike information criterion (AICc). For dataset 1, the TIM3 + F + Γ4 was selected for the ITS1, the KP2 + I for the 5.8S, the GTR + F+ Γ4 for the ITS2, and the TN+F+I + G for the nuclear LSU. For dataset 2, the GTR + F +I+ Γ4 was selected for the ITS1, the KP2 + Γ for the 5.8S, the TVMe + Γ4 for the ITS2, and the TIM+F+I + Γ4 for the nuclear LSU. We assessed node support by standard bootstrap using 1000 bootstrap pseudoreplicates. Bayesian analyses were performed by Markov chain Monte Carlo (MCMC) sampling as implemented in the software MrBayes 3.2.7a (Ronquist et al. 2012) on the CIPRES Web Portal (Miller et al. 2015). As not all models tested by ModelFinder in IQTree can be directly implemented in MrBayes, for the Bayesian analyses we selected among a subsample of substitution models using the corrected Akaike information criterion (AICc) as implemented in jModelTest 2 (Darriba et al. 2012), allowing only 3 substitution schemes, using full likelihood optimization and four discrete gamma categories. For dataset 1, the GTR + Γ was selected for the ITS1, the JC for the 5.8S, the GTR + Γ for the ITS2, and the HKY + Γ for the nuclear LSU rDNA. For dataset 2, the JC + Γ model was selected for the ITS1, the JC for the 5.8S, the K80 + Γ for the ITS2, and the GTR + I + Γ for the nuclear LSU rDNA. The combined analyses treated the different regions as separate partitions with topology linked across partitions but separate model parameter values and proportional rates across partitions. For each combined dataset, two parallel runs were performed, each with four chains, three of which were incrementally heated with a temperature of 0.15. The analyses were diagnosed for convergence every 100,000 generations and were set to halt automatically when the average standard deviation of splits across runs in the last half of the analysis descended below 0.01. Every 100th tree was saved. The first 50% of each run was discarded as burn-in. The alignments for this study have been submitted to TreeBASE with accessions numbers 29494 and 29495.
To test our species delimitation hypotheses, we used the Poisson tree process model (PTP) (Zhang et al. 2013), which considers the number of substitutions between sequences. PTP detects the transition points between inter- and intraspecific branching events, considering that the number of substitutions between species is significantly higher than that within species. PTP neither requires an ultrametric tree nor a sequence similarity threshold as input. The best ML tree from the phylogenetic IQTree analysis of dataset 1, excluding the outgroup, was used as input for the bPTP-ML analysis as implemented at https://species.h-its.org/.
Results and Discussion
Phylogeny and species delimitation. We generated 39 new sequences (18 ITS and 21 nuLSU rDNA) that were aligned together with sequences already available in GenBank (Table 1). No incongruence was detected among partitions in any of the datasets. The combined matrix corresponding to dataset 1 contained 1264 aligned characters (ITS1, 1–393; 5.8S, 394–511; ITS2, 512–731; nuLSU, 732–1264). The combined matrix corresponding to dataset 2 contained 1000 aligned characters (ITS1, 1–93; 5.8S, 94–195; ITS2, 196–350; nuLSU, 351–1000).
The best trees obtained from the ML analyses had lnLikelihood values of –6039.788 for dataset 1 and –8753.626 for dataset 2. The Bayesian analyses halted after 500,000 generations both in analyses of dataset 1, and in analyses of dataset 2, when the average standard deviation of split frequencies across runs was <0.01, indicating that the three runs had converged (<0.01). In all analyses, Potential Scale Reduction Factor (PSRF) values for all model parameters as well as all branch lengths were close to 1. A majority-rule consensus tree was constructed from the 5,000 trees of the stationary tree sample in each case. There was no incongruence between the ML and Bayesian trees in any of the two analysed datasets. Therefore, only the ML trees corresponding to datasets 1 and 2 are shown in Figs. 1 and 2, respectively, with information on Bayesian posterior probability values added. Nodes with values for maximum likelihood bootstrap support (ML-BS) ≥70 and Bayesian posterior probability (BPP) values ≥0.95 were considered to be phylogenetically supported. Phylogenetic trees were visualized using FigTree v.1.4.4 (Rambaut 2019).
Figure 1.
Maximum likelihood best tree from the combined analysis including ITS and nuLSU and representing Crittendenia. Black dots indicate branches supported by both ML and Bayesian analyses. Grey and white dots indicate branches supported only by ML or Bayesian analyses, respectively. ML-BS values ≥70 and BPP values ≥0.95 are indicated above and below branches, respectively. Type specimens are indicated with ‘(T)’. Species within Crittendenia are indicated to the right. Species delimitation obtained in the bPTP-ML analysis is indicated in the right margin as grey rectangles. Two white squares indicate two putative species within Crittendenia lichenicola, inferred by bPTP-ML. Branch lengths are scaled to the expected number of substitutions per site.
Figure 2.
Maximum likelihood best tree from the combined analysis including ITS and nuLSU and representing the Agaricostilbomycetes. Black dots indicate branches supported by both ML and Bayesian analyses. White dots indicate branches supported only by Bayesian analyses. ML-BS values ≥70 and BPP values ≥0.95 are indicated above and below branches, respectively. Family assignments are indicated in the right margin. Branch lengths are scaled to the expected number of substitutions per site.
Our analyses revealed 14–15 independently evolving lineages—putative species—within Crittendenia (Fig. 1), understood either as monophyletic supported groups, or as putative species or operational taxonomical units (OTUs) by bPTP-ML. There are only two cases in which Bayesian and ML phylogenetic analyses and bPTP-ML analysis were not consistent: 1) C. physciiphila forms a group with ML-BS <70 and BPP <0.95 but is conservatively considered a single species based on bPTP-ML results; 2) C. lichenicola forms a monophyletic supported group, but it is split in two OTUs by bPTP-ML. We nevertheless tentatively consider it as a single species until more samples can be included in phylogenetic studies. Both C. physciiphila and C. lichenicola could, however, represent species complexes, according to our molecular results.
The genus Crittendenia is monophyletic, and it is not included in any of the existing families in the Agaricostilbomycetes (Fig. 2). At an early stage of the study, we considered that proposing a new family for Crittendenia based on an ITS and nuLSU phylogeny could be premature. We unfortunately could not obtain sequences of other genes (nuSSU, RPB1, RPB2, TEF1-alpha, and CYTb) that would have allowed us to include Crittendenia in previously existing multigene phylogenies to further test the family assignment of the genus (Wang et al. 2016). However, even if the relationships between the different families are not supported by ITS and LSU, all families in Agaricostilbomycetes (depicted in Fig. 2) have already been confirmed by multigene phylogenies (Wang et al. 2016). Our results show that Crittendenia does not belong to any of these families in the Agaricostilbales, and we could only include the genus Crittendenia in a family if we considered Agaricostilbales as a single family (which is not acceptable in the light of the most recent taxonomic treatment of the group; see Wang et al. 2016). We therefore propose the new family Crittendeniaceae to accommodate the genus Crittendenia.
Morphology, biology and diversity. Basidioma development.—Basidiomatal initials are formed inside the lichen thallus and are made of the same elongated, cylindrical cells that later form the stipe of mature basidiomata (Fig. 3A). When emerging from the thallus, they are entirely surrounded by a transparent, gelatinous layer that eventually disappears while the basidiomatal stipe elongates (Fig. 3B). The stipe is entirely composed of hyaline, cylindrical, subparallel, elongated cells, without any specialized external layer (Fig. 3C). Primary septa are relatively thick and have clamp connections, while thin secondary septa may be devoid of clamps (Fig. 3D–E). Apical, almost identical cells later function as basidia (Fig. 3F). These typically have a basal clamp, able to proliferate to produce further basidia (Fig. 3G). In some species, multiple proliferations result in fascicles composed of a large number of basidia, all originating from the same hypha of the stipe (Fig. 3H), and this explains why the capitulum is generally much broader than the stipe.
Figure 3.
Basidioma and basidium development in Crittendenia species, and yeast cells. A–B. Section through a thallus of Lopadium disciforme, showing two young basidiomata; the own thalli of Crittendenia in A are immersed and not yet stained; the young basidioma in B is surrounded by a hyaline gelatinous layer. C. Squash preparation of a mature basidioma, showing the subparallel, cylindrical hyphae of the stipe, the hymenium and a few basidiospores. D. Thick-walled stipe hypha with clamped septa (arrows); presence of a basidiospore. E. Stipe hypha with a thin, non-clamped secondary septum. F. Young basidium with basal clamp, arising from stipe hypha. G. Proliferating basidia arising from one hypha. H. Fascicle of numerous basidia originating from one hypha. I. Putative Crittendenia yeast cells observed near the base of a stipe. A–B: Crittendenia lopadii, Tønsberg 15250, C: C. lopadii, Hilmo, D: C. physciiphila, Pinault, Cournols, on Physcia adscendens, E: C. coppinsii, Coppins 22784, F: C. physciiphila, Pinault, on Phaeophyscia orbicularis, G: C. crassitunicatum, holotype, H: C. lichenicola, holotype, I: C. coppinsii, Westberg (ups f-805352). A–B, H, in ammoniacal Congo Red. C–G, I in KOH + phloxine. Scale bars: A, C = 20 µm, B = 10 µm, D–I = 5 µm.
Crittendenia basidiomata are extremely tiny. The smallest measured by us was observed in the holotype of C. bacidinae and was just 35 µm tall, with a stipe of 17 µm and a capitulum of 20 µm in diameter, which may represent the smallest basidioma ever observed. If we exclude the stipe, the fertile part of this basidioma (i.e., the capitulum), considered as subspherical, would then have a volume of c. 4000 µm3.
Sporogenesis.—Mature basidia bear at their apex a crown of minuscule sterigmata that are clearly visible in some specimens, but obscure in most others, probably depending on the degree of maturity (Figs. 7D, 12D, 22E). Basidia in some species almost constantly produce (5–)7–8 sterigmata, while in others basidia with (3–)4 sterigmata dominate (Fig. 10E). In the case of eight basidiospores, the basidial crown is too small to accommodate them all, and then one of them moves to the center and is surrounded by the seven other spores. All together, they resemble, when viewed from above, a daisy flower with seven petals (or less, when some spores do not reach maturity) (Figs. 7E, 13I, 16H–I, 17D, 18G). Independent of being produced in groups of four or eight, basidiospores often detach together as a cluster of more or less equally sized spores. Basidiospores are not apiculate (although often basally slightly truncate), not borne obliquely on the sterigmata and not forcibly discharged, and represent therefore apobasidia, as defined by Rogers (1947). Mature basidiospores often remain deposited over older basidiomata (Figs. 6D, 8B, 16D, 22C), and are probably dispersed by wind or arthropods.
Figure 7.
Crittendenia bryostigmatis, holotype. A. Basidiomata on the thallus of Bryostigma muscigenum (arrows point at host ascomata). B. Squash preparation of basidioma. C. Stipe hyphae with clamps and basidia. D. Mature basidia having produced basidiospores, one (arrow) with basidiospores still attached. E. Groups of basidiospores, each from one basidium. B, in KOH + phloxine, C–E, in Melzer's reagent. Scale bars: A = 100 µm, B = 20 µm, C = 10 µm, D–E = 5 µm.
Figure 12.
Crittendenia hypotrachynae. A. Basidiomata on the soredia of Hypotrachyna endochlora. B. Basidiomata on the thallus of H. laevigata. C. Squash preparation of basidioma. D. Mature basidia. E. Basidiospores with a perisporal sac. F. Basidiospores without a perisporal sac. A, C–F: holotype, B: Diederich 4913. C–F in KOH + phloxine. Scale bars: A–B = 200 µm, C = 20 µm, D = 10 µm, E–F = 5 µm.
Figure 22.
Crittendenia teloschistis, holotype. A–B. Basidiomata on the thallus of Teloschistes flavicans; arrows point to gall-like, swollen own thalli of Crittendenia. C. Squash preparation of basidioma, showing an own, non-lichenized thallus of Crittendenia (CrTh), developing over the host thallus (HTh). D–E. Immature and mature basidia. F. Basidiospores, the lower ones representing a partial group arising from one basidium (some spores are missing in a squash preparation). G. Numerous basidiospores deposited over basidia. C–G, in KOH + phloxine. Scale bars: A–B = 100 µm, C = 20 µm, D–E, G = 10 µm, F = 5 µm.
Figure 10.
Crittendenia crassitunicata, holotype. A–B. Basidiomata on the thallus of Melanohalea ushuaiensis. C. Squash preparation of basidiomata. D–E. Mature basidia, some with attached basidiospores. F. Thick-walled basidiospores. C–E, in KOH + phloxine, F, in ammoniacal Congo Red. Scale bars: A–B = 200 µm, C = 50 µm, D–E = 10 µm, F = 5 µm.
Figure 13.
Crittendenia kakouettae. A–C. Basidiomata on the thallus of ‘Byssoloma’ kakouettae. D. Basidiomata of C. aff. kakouettae on the thallus of Fellhanera bouteillei. E. Squash preparation of basidioma. F. Thick-walled stipe hyphae. G. Mature basidia. H. Young basidium with basal clamp, and apex of mature basidium with basidiospores. I. Basidiospores. A, E–H: holotype, B, I: van den Boom 58880, C, Diederich 16490, D, van den Boom 56901. E–I in KOH + phloxine. Scale bars: A–D = 200 µm, E = 20 µm, F–G = 10 µm, H–I = 5 µm.
Figure 16.
Crittendenia lichenicola. A. Basidiomata on the thallus of Micarea prasina s.l. B. Idem, at a higher magnification, showing groups of basidiospores produced each from one basidium, covering the capitulum, with some attached to the stipe. C. Basidiomata on the thallus of M. micrococca. D. Squash preparation of basidiomata covered by groups of basidiospores. E. Mature basidia. F. Basidia originating from a single stipe hypha, proliferating at the original basal clamp. G. Mature basidia with basidiospores. H–I. Groups of 7–8 basidiospores originating from individual basidia, each group with one spore moved to the centre. A–B, D–I: holotype, C: Coppins 21517. D–E, I in KOH + phloxine, F–H in ammoniacal Congo Red. Scale bars: A = 100 µm, B = 20 µm, C = 200 µm, D = 20 µm, E–G = 10 µm, H–I = 5 µm.
Figure 17.
Crittendenia lopadii. A. Basidiomata on the thallus of Lopadium disciforme. B. Squash preparation of a basidioma. C. Mature basidia. D. Groups of 7 thick-walled basidiospores, some with a perisporal sac. A–B, D: Hilmo, C: holotype. B–D in KOH + phloxine. Scale bars: A = 100 µm, B = 50 µm, C = 10 µm, D = 5 µm.
Figure 18.
Crittendenia parvispora. A. Basidiomata on the thallus of Bacidia laurocerasi. B. Basidiomata on the thallus of B. polychroa. C. Basidiomata on the thallus of Bacidia sp. Arrows in B and C point to basidiomata. D. Mature basidia. E. Mature basidium with basal clamp. F. Stipe hypha with septum and clamp connection. G. Groups of basidiospores. H. Mature basidia with basidiospores. I. Thin-walled basidiospores. A: holotype, B, D–G: van den Boom 36943, C, H–I: Kalb 26946. D–G in KOH + phloxine, H–I in KOH + phloxine + Congo Red. Scale bars: A = 100 µm, B–C = 200 µm, D–F, H–I = 10 µm, G = 5 µm.
Figure 6.
Crittendenia bacidinae, holotype. A. Basidiomata (arrows) on the thallus of foliicolous Bacidina apiahica. B. Idem, at a higher magnification; arrows indicate own Crittendenia thalli. C. Basidia, one mature with four basidiospores. D. Basidiospores. C–D, in KOH + phloxine. Scale bars: A = 100 µm, B = 20 µm, C–D = 10 µm.
Figure 8.
Crittendenia byssolomatis, holotype. A. Basidiomata on the thallus of Byssoloma maderense. B. Squash preparation of capitulum. C. Basidia originating from one stipe hypha. D. Squash preparation of hymenium. E. Basidiospores. F. Mature basidia with basidiospores. G. Basidia seen from top, each with four mature basidiospores. H. Basidiospores. B, G–H, in KOH + phloxine, C–F, in Melzer's reagent. Scale bars: A = 100 µm, B–E = 10 µm, F = 5 µm, G–H = 2.5 µm.
In some specimens, morphologically different cells are intermixed with mature basidia. They are often rather thick-walled and may be apically attenuated, sometimes resembling a kind of paraphyses or cystidia. They were already reported as ‘cystidium-like structure of unknown function’ and illustrated by Millanes et al. (2021, Fig. 3J). Sometimes, the attenuated end of these structures becomes swollen, then produces holoblastically a kind of ellipsoid spore or conidium with a similarly thickened cell wall (Figs. 9E,G, 15G, 20B). In some specimens, most mature basidia are thick-walled and produce in such a holoblastic way 1–4 spores through thick-walled sterigmata-like structures, in the absence of the typical crown made of minuscule and almost indistinct sterigmata. These kinds of spores are always thick-walled when young, but otherwise resemble in form and size the basidiospores produced on a crown. When maturing, their perispore becomes slightly rough or wrinkled, distinctly larger, then detaches from the rest of the spore, forming an envelope loosely surrounding the spore (Figs. 12E, 17D [upper photo], 20D–E), and finally breaks down and disappears (Figs. 12F, 20D). The resulting spores devoid of a perispore are smooth- and thin-walled and cannot be distinguished from other basidiospores. In some specimens we have even observed spores still attached to their basidium, with the outer layer, not only of the spore (perispore), but also of the upper part of the basidium and the sterigma-like structure becoming enlarged and wrinkled, opening irregularly above and detaching gradually.
Figure 9.
Crittendenia coppinsii. A. Basidiomata on the thallus of Melanohalea exasperatula; note the two more orange brown own thalli of Crittendenia, with basidiomata mainly developing at the margin of these thalli. B. Relatively narrow and tall basidiomata on the thallus of Melanelixia glabratula, the own Crittendenia thallus covering the entire host thallus. C. Broad and short basidiomata on the thallus of Melanohalea exasperata. D. Hymenium with many mature basidia carrying the basidiospores. E. Hymenium with mainly abnormal basidia with an apical swelling; one typical, basidiospores-carrying basidium in the right third. F. Overmature basidia, one still carrying the basidiospores. G. Abnormal basidia, some with an attenuated apex (left and right). H. Basidiospores. A: Holien 8105, B, E, H: holotype, C: Zimmermann 1946, D: Westberg & Olsson (AM1045), F–G: Groner 714. D–E, H, in KOH + phloxine; F–G, in Melzer's reagent. Scale bars: A = 100 µm, B–C = 200 µm, D–G = 10 µm, H = 5 µm.
Figure 15.
Crittendenia lecidellae. A–C. Basidiomata on the thallus of Lecidella elaeochroma; in A tall and narrow, in C broad and short, in B grouped over brown own thalli. D. Mature basidia. E. Immature basidium with basal clamp. F. Mature basidia with basidiospores. G. Abnormal basidium-like ‘sporophore’ producing one spore, both elements surrounded by a perisporal sac; arrows point to real basidiospores. H. Thick-walled basidiospores. A, D–E, G: holotype, B, F, H: Zamora (g), C: Brackel 6418. D–G in KOH + phloxine. Scale bars: A = 100 µm, B–C = 200 µm, D–F = 10 µm, G–H = 5 µm.
Figure 20.
Crittendenia physconiae, holotype. A. Basidiomata on the thallus of Physconia distorta. B. Mature basidia, most producing a single basidiospore. C. Mature basidia producing up to three basidiospores. D. Basidiospores, most with a loose perisporal sac. E. Basidium with three basidiospores and a thick wall around both basidium and basidiospores. B–E, in KOH + phloxine. Scale bars: A = 200 µm, B–C = 10 µm, D–E = 5 µm.
From a practical point of view, studying and measuring spores is difficult, first as the two kinds of spores can hardly be distinguished in many specimens (and we do not even know whether they are ontogenetically and functionally distinct), and second as the holoblastically produced spores initially have a tight perispore that is poorly visible (as this layer is never pigmented or stained), then becomes larger and eventually disappears, the spores thus becoming again smaller. Measurements of numerous spores for statistical purposes therefore inevitably include both types of spores at different degrees of maturity. For that reason also, we are not using a different terminology for each type of spore and always using the term ‘basidiospores’ for all the spores observed.
The outer layer of these ‘unusual’ spores may be comparable to the ‘perisporal sac’, described and discussed in Coprinus by van Waveren (1968) as “a strongly developed perispore, surrounding the entire spore ... has the shape of a strongly wrinkled sac.” Kühner & Romagnesi (1953: 385) insisted on the fact that the perisporal sac in some Coprinus species is well visible when young, but becomes detached and disappears when mature, exactly what we have observed in Crittendenia. Similarly, basidiospores of Leucogaster “are enclosed in a separable perisporal sac” (Miller et al. 2006). Spirin et al. (2005) studied the ultrastructure of the basidiospores in Perenniporia and found that the perispore is a continuation of the outer layer of the sterigmata, thus recalling our observations of a perispore detaching from the spore + sterigma + upper part of basidium in some specimens.
Morphological intraspecific variability.—Species of Crittendenia are not only morphologically poor in taxonomically useful characters—most species differ from genetically distinct species by only a few minor characters—but further, the intraspecific variability in some species is considerable, making the use of morphological characters for species delimitation sometimes next to impossible. As an example, the basidiomatal height in the holotype of Crittendenia coppinsii is 88–144 µm (the 69% probability interval) (Fig. 9B), in specimen Zimmermann 1946 just 79–97 µm (Fig. 9C), but in van den Boom 54983, 148–233 µm; the three specimens have been included in our phylogeny and are obviously conspecific. The capitulum diameter in the holotype of C. lecidellae is 43–78 µm (Fig. 15A), contrasting with 103–201 µm in specimen Brackel 6418 (Fig. 15C). The basidiospores in the holotype of C. absistentis are 6.4–8.5 × 2.4–3.2 µm, SpL/SpB 2.2–3.3 (Fig. 5C), while in specimen Coppins 19800, they are 4.1–6.5 × 2.9–3.9 µm, SpL/SpB 1.2–2.0 (Fig. 5E).
Figure 5.
Crittendenia absistentis. A–B. Basidiomata (arrows) on the thallus of Bacidia absistens. C. Mature basidia with basidiospores. D. Hymenium with mainly immature basidia. E. Mature basidiospores. A, C–D: holotype, B: Acton, E: Coppins 19800. C–E in KOH + phloxine. Scale bars: A–B = 200 µm, C–E = 10 µm.
Do Crittendenia species produce yeasts?—The vast majority of ‘heterobasidiomycete’ taxa in the Agaricomycotina and Pucciniomycotina are dimorphic, i.e., they alternate a haploid unicellular yeast phase and a dikaryotic filamentous phase during their life cycle (Bandoni 1995; Boekhout et al. 2011; Oberwinkler 1987, 2017). It has therefore generally been assumed that lichenicolous heterobasidiomycetes also have a yeast stage and, although less frequently detected by light microscopy than the filamentous phase, basidiospores germinating by budding (i.e., yeasts) have been observed and documented (Diederich 1996; Zamora et al. 2011, 2016). Recent studies have shown that lichenicolous species belonging to Cyphobasidiales and Tremellales frequently produce yeast cells within the host thallus, and that these yeasts are much more common than the sexual stage (Spribille et al. 2016; Tuovinen et al. 2019, 2021). The same could be true for species of Crittendenia. Roberts (1997) illustrated a specimen of C. lecidellae (as Chionosphaera aff. coppinsii) with yeast-like germination of basidiospores. He further wrote about C. coppinsii “germination probably by yeast-like conidia, but not clearly seen.” We have examined over sixty Crittendenia specimens microscopically and measured over 3800 spores, and none of these showed any kind of germination. Many of our microscopical preparations showed numerous yeast-like cells (Fig. 3I), but none of them was budding, and for none of these cells was it possible to demonstrate that they originate from Crittendenia basidiospores, or even if they belong to Crittendenia. Frequently, such cells are adhering to each other or to basidiospores within the mounting medium, and this might erroneously be interpreted as budding cells. Yeast-like cells were observed on basidiomata, either on the stipe or in the basidial layer, or immersed in the host thallus close to the basidiomata, but have also been observed in host areas devoid of basidiomata. It would certainly be useful to obtain pure cultures of Crittendenia species and to study their life cycle, and this would also answer the question about yeast formation.
Crittendenia species are genetically very diverse but extremely rare, or at least are rarely collected, most species being known from just one or a few specimens, sometimes from different continents. One of the critical questions is thus to know where they are hiding, and how they reproduce, when basidiomata are more or less never seen. The most plausible answer may be that they are frequently present asymptomatically within lichen thalli, that they spread with their hosts within vegetative diaspores, and that they only occasionally produce fruiting bodies. They may be present within the host thalli in the form of hyphae or of yeast cells. The latter hypothesis is probably more likely, as this way of life is known and obviously common in lichenicolous Cyphobasidiales and Tremellales, and because of our frequent observations of yeast-like cells close to Crittendenia basidiomata.
Do some Crittendenia species form simple lichenized thalli?—One of our most surprising observations was that some Crittendenia specimens may possess their own gelatinous, translucent lichenized thallus. At a first glance, basidiomata usually appear as growing directly on the host thallus or apothecial margin, without causing any visible symptoms. In reality, they always emerge from portions of the host thallus that are covered by a thin, usually brownish, gelatinous, translucent film that in some specimens may eventually become thicker and occasionally resemble gall-like outgrowths of the host thallus. This brownish, translucent structure is mainly made of hyphae of Crittendenia and should best be regarded as a non-lichenized thallus of this fungus. These minuscule thalli frequently contain, in addition to the hyaline, tubular Crittendenia hyphae, also large numbers of bacteria, some cyanobacteria (especially near the surface), yeast-like cells, and hyaline or brown hyphae from other fungi. In some specimens, mainly of Crittendenia lecidellae, these brownish gelatinous thalli may become olivaceous, due to a large number of algal cells located inside them, and these could represent simple lichenized thalli (Fig. 4A, C). On pale-colored host thalli, the darker Crittendenia ‘thalli’ (lichenized or not) often strongly contrast with the host, and sterile Crittendenia thalli, without basidiomata, can then easily be seen (Fig. 4B). In some specimens, basidiomata are very rare, minuscule and difficult to detect, and they then need to be searched for on the darker Crittendenia thalli. On hosts with a thallus made of minuscule granules or goniocysts, such as Bacidina or Micarea gr. prasina, Crittendenia thalli may be very reduced, hardly pigmented, and difficult to observe (Fig. 6B). Thalli of Crittendenia coppinsi are very similar in color to their hosts (Melanelixia or Melanohalea species), but they can be recognized by their gelatinous and shinier surface (Fig. 9B). In one specimen (Holien 8105, cf. Millanes et al. 2021), C. coppinsii basidiomata are growing in fairy rings at the edge of roundish Crittendenia thalli (Fig. 9A). In the type of Crittendenia stictae, basidiomata develop exclusively over conspicuous, pale to medium brown galls of the host thallus; some of these galls are sterile (Fig. 21A), while others are abundantly covered by basidiomata that arise from their own non-lichenized gelatinous thallus covering these galls (Fig. 21B–D). It was not possible for us to determine whether these galls were caused by the presence of Crittendenia, or if they were induced by another sterile fungal species.
Figure 4.
Putative lichenization of Crittendenia species. A. Crittendenia lecidellae, with olivaceous own thalli containing algae. B. C. lecanorae, with brownish own thalli devoid of algae; arrows point at groups of basidiomata. C. Section through presumed lichenized own thallus of C. lecidellae; CrTh = Crittendenia thallus, CrHy = Crittendenia hyphae, CrPh = Crittendenia photobiont, Cy = cyanobacteria, HTh = host thallus, HPh = host photobiont; the black parts in the host thallus originate from air inclusions in the preparation. A, C: Coppins 22371, B: C. lecanorae, holotype. C in water with traces of phloxine. Scale bars: A–B = 200 µm, C = 20 µm.
Figure 21.
Crittendenia stictae, holotype. A–D. Thallus of Sticta fuliginosa s.l. with conspicuous galls overgrown by numerous basidiomata; arrows point to sterile galls, devoid of basidiomata. E. Basidia before spore-production. F. Basidiospores, some with a distinct thick wall, eventually loosening as a perisporal sac, some with apical appendages. E–F, in KOH + phloxine. Scale bars: A–D = 200 µm, E = 10 µm, F = 5 µm.
Host specificity, semi-cryptic species and number of species.—As Crittendenia populations on most hosts are morphologically quite similar, one could have expected a small number of species that are not host-specific. Our phylogenetic results have shown, however, that populations from the same or closely related hosts often group together, but clearly differ from those from other hosts, suggesting a large number of mainly host-specific species. The best studied species, C. coppinsii, is known to be confined to hosts belonging to the two closely related genera Melanelixia and Melanohalea, and field studies have shown that it does not invade neighboring thalli of other Parmeliaceae genera. Crittendenia lichenicola is currently known from two specimens on members of the Micarea prasina group. Populations on Physciaceae belong to three morphologically and genetically distinct species, one on Heterodermia, one on Physconia, and another one on Phaeophyscia, Physcia and Physciella. Although some species can easily be distinguished based on morphological characters, most species are so similar to others that only minor, often subtle differences are currently known. These apparent differences might just reflect our poor knowledge of the real morphological variability of each and may vanish when the species are better known. We anticipate therefore that the genus Crittendenia includes a large number of genetically distinct species, most being strictly host-specific, and that many of these will best be qualified as semi-cryptic. The identification of such specimens will then either need molecular data or can tentatively be obtained through a combination of morphological characters and the host choice. If our hypothesis is confirmed that Crittendenia species mostly live asymptomatically in lichen thalli, probably in the yeast stage, and only rarely produce basidiomata, then we can even expect the existence of a much larger number of species, some never occurring in the fertile stage, similarly to the observations of Spribille et al. (2016) in the Cyphobasidiales.
Taxonomy
Crittendeniaceae Millanes, Diederich & Wedin, fam. nov. Fig. 2
MycoBank MB 842928
A member of Agaricostilbales (Agaricostilbomycetes), distinguished from Chionosphaeraceae by basidia with a basal clamp and by the lichenicolous habitat.
Type genus: Crittendenia Diederich, Millanes, M.Westb., Etayo, J.C.Zamora & Wedin
Crittendenia Diederich, Millanes, M.Westb., Etayo, J.C.Zamora & Wedin, Millanes et al., Lichenologist 53: 111 (2021). Type: Crittendenia coppinsii (P.Roberts) Diederich, M.Westb., Millanes & Wedin.
Description. Own thallus usually present, in some species reduced, in others spreading over the host thallus, flat or swollen to subspherical, hyaline to more often brownish, often darker than the host thallus, strongly gelatinous, translucent, often containing bacteria, cyanobacteria, yeast-like cells, hyphae of other fungi, in some specimens also algal cells and then may be interpreted as representing a simple, olivaceous brown, lichenized thallus, in one species developing over galls, otherwise never visibly parasitic. Basidiomata developing on lichens, stipitate-capitate, synnemata-like, fleshy waxy, whitish, pale brownish, pinkish, or orangish, slightly translucent; capitulum slightly to strongly differentiated and enlarged. Stipe composed of subparallel, rarely branched hyphae with few septa; primary septa thick, with clamps, secondary septa thin, without clamps; these hyphae apically giving rise to one or several basidia; haustorial branches unknown. Hymenium amphigenous, entirely composed of basidia, without sterile elements or rarely with abnormal basidia-like elements of unknown function, not surrounded by an excipular layer. Basidia apical, tubular, with the largest diameter close to the apex, aseptate, thin- or rarely thick-walled, usually with basal clamps that may proliferate to produce further basidia, when immature apically rounded, when mature with (1–)4–8 apical, short, inconspicuous, sterigmata, collapsing after spore detachment. Basidiospores hyaline, aseptate, shortly to elongate ellipsoid or fusiform, without a distinct basal apiculus (but basally often slightly truncate), not forcibly discharged, often liberating together as a cluster of 3–8 spores, wall usually smooth and relatively thin, sometimes becoming thicker and rough, developing into a loose perisporal sac that eventually detaches, leaving a smaller, smooth-walled spore; germination by budding not observed. Asexual conidial stage unknown. Subspherical yeast-like cells, much smaller than basidiospores, are frequently present and abundant in the hymenium, on the basidiomatal stipe, or in the host thallus surrounding basidiomata, but their connection to Crittendenia is not established.
Ecology. Lichenicolous, associated with a large variety of lichens belonging to different phylogenetic lineages.
Key to the Species of Crittendenia
The key includes not only characters that allow distinguishing between two alternatives, but also additional characters that may help identifying atypical specimens.
The number of basidiospores per basidium is best determined using a microscopic preparation of a mature basidioma, without pressure on the cover glass, allowing the observation of free-swimming groups of spores originating from one basidium. Subsequent pressure on the cover glass and removal of excessive liquid with tissue paper will allow the measurement of a larger number of spores. Additional pressure on the cover glass with lateral movement will separate basidia and allow, in mature specimens, to observe and measure entire basidia. Staining of microscopical preparations is recommended, e.g., in a mixture of phloxine B and 5% KOH.
Measurements refer to the 69% probability intervals. Values without brackets refer to the global interval of a species (all specimens considered together), while values within square brackets refer to intervals of individual specimens (see further explanations in Material and Methods).
Phylogenetic results suggest that most species are host specific, and also that some species are morphologically rather variable. As most species are known from only one or few specimens, their variability is poorly known. The identification of morphologically atypical specimens may therefore be difficult, and then the host choice will be a useful help.
Abbreviations are those explained in Material and Methods.
1 Basidia (5)7–8-sterigmate; basidiospores, when liberated from the basidia, typically remaining together and arranged in form of a hexagon or heptagon with an additional central spore, recalling a daisy flower when observed from above, relatively small, <6.8[8.5] µm long; basidiomata slender, StD <49[80] µm, StH/StD >3.1[2.3] 2
1′ Basidia (1)3–4-sterigmate (on Lecidella up to 6-sterigmate); basidiospores often larger, never arranged in form of a daisy flower with a central spore; basidiomatal stipe in most species thicker 8
2(1) Basidia [16]16–23[25] µm long; basidiospores [3.5]4.1–5.5[5.7] × [2.2]2.3–3.3[3.6] µm; basidiomata [127]140–244[296] µm tall; stipe [17]17–35[36] µm diam.; capitulum [31]33–76[97] µm diam.; on ‘Byssoloma’ kakouettae C. kakouettae [if on Fellhanera species C. aff. kakouettae]
2′ Basidia longer, BaL >21 µm; stipe and capitulum often wider 3
3(2) Basidiomata slender, StD [15]16–27[27] µm, StH/StD [4.5]4.6–8.2[8.4]; basidiospores [4.9]5.0–6.9[7.0] × [2.7]2.7–3.7[3.8] µm; on Micarea gr. prasina C. lichenicola
3′ Basidiomata more robust, StD frequently >27 µm, StH/StD in some species smaller; basidiospores in some species shorter 4
4(3) Basidiospores [4.1]4.9–8.0[8.5] × [2.4]2.6–3.9[4.2] µm, SpL/ SpB [1.2]1.4–2.8[3.3]; on Bacidia absistens C. absistentis
4′ Basidiospores smaller, SpL mostly <6.3 µm, SpL/SpB usually <1.7 5
5(4) Basidiospores relatively narrow, [3.7]3.7–5.2[5.9] × [2.1]2.3–3.2[3.4] µm; SpL/SpB [1.3]1.3–2.0[2.3]; on corticolous Bacidia C. parvispora
5′ Basidiospores broadly ellipsoid, SpB mostly >3.0 µm; SpL/SpB <1.8 6
6(5) Basidiospores subspherical to broadly ellipsoid, SpL [3.5]3.6–4.8[5.1] µm, SpL/SpB [1.0]1.1–1.4[1.4]; capitulum relatively broad, compared to stipe height, CaD/StH [0.4]0.4–1.1[1.3]; basidia 31–42 µm long; on Teloschistes C. teloschistis
6′ Basidiospores broadly ellipsoid, SpL/SpB frequently >1.3; capitulum relatively narrow, compared to stipe height, CaD/ StH <0.8 7
7(6) Basidiospores relatively short, 4.0–5.1 × 3.0–3.9 µm; basidia relatively short, 24–39 µm long; on Bryostigma muscigenum C. bryostigmatis
7′ Basidiospores frequently over 5 µm in length, [4.1]4.2–6.3[7.2] × [3.0]3.1–4.2[4.2] µm; basidia frequently longer, [29]30–50[59] µm long; on Lopadium disciforme C. lopadii
8(1) Basidia 19–31 µm long 9
8′ Basidia >29 µm long 10
9(8) Basidiomata very small and slender, StH 69–116 µm, StD 16–27 µm, CaD 24–54 µm; basidia very short; basidiospores 4.0–6.3 × 2.2–2.9 µm, SpL/SpB [1.2]1.4–2.8[3.3]; on Bacidina apiahica C. bacidinae
9′ Basidiomata taller and more robust, with a broader capitulum, StH 112–165 µm, StD 23–43 µm, CaD 59–96 µm; basidiospores shorter, 3.8–5.0 × 2.4–3.0 µm, SpL/SpB [1.2]1.3–1.9[2.4]; on Byssoloma maderense C. byssolomatis
10(8) Basidiospores relatively long and narrow, SpL/SpB >1.6; on Parmeliaceae 11
10′ Basidiospores ratio SpL/SpB mostly <1.8 (on Lecidella exceptionally longer); on other hosts 14
11(10)Basidiomata very short and broad, StH c. 70–200 µm, StD c. 50–200 µm; basidiospores 8.4–9.7 × 4.0–5.4 µm, SpL/SpB (1.5)1.7–2.3(2.4); on Parmelina quercina C. sp.
11′ Basidiomata more slender, StH/StD >1.3 12
12(11)Basidia very long, BaL [47]66–99[109] µm; basidiomatal stipe relatively thick, StH/StD [0.7]1.3–3.2[4.4]; capitulum only slightly wider than the stipe, CaD/StD [0.8]1.0–1.6[2.0]; StH [79]85–163[233] µm, StD [36]37–87[139] µm, CaD [42]48–105[146] µm; basidiospores mostly with an evenly thickened wall, [6.2]7.0–9.5[10.5] × [3.1]3.3–4.3[4.7] µm, SpL/SpB [1.7]1.9–2.5[2.7]; on Melanelixia and Melanohalea C. coppinsii
12′ Basidia shorter, BaL <53 µm; basidiomata more slender, StH/ StD >3.2; capitulum at maturity often much wider than the stipe, CaD/StD >1.5; basidiospores often with an unevenly thickened wall and an almost rectangular lumen 13
13(12)Basidiospores very large, 8.6–13.1 × 3.5–4.7 µm, SpL/SpB 2.1–3.3; basidiomata very large, StH 218–353 µm, StD 37–63 µm, CaD 69–157 µm; basidia 39–53 µm long; on Melanohalea ushuaiensis C. crassitunicata
13′ Basidiospores smaller, [5.5]5.7–9.4[9.8] × [2.9]3.0–4.3[4.5] µm, SpL/SpB [1.5]1.6–2.7[2.8]; basidiomata smaller, StH [110]116–232[237] µm, StD [17]24–55[68] µm, CaD [52]58–127[137] µm; basidia shorter, [26]29–43[46] µm long; on Hypotrachyna C. hypotrachynae
14(10)Basidiomata reduced to a very large capitulum, 147–390 µm diam.; stipe reduced, not visible macroscopically; basidiospores 5.8–8.0 × 4.7–6.1 µm; on Physconia C. physconiae
14′ Stipe present, but sometimes short, always visible; capitulum rarely >180 µm diam. 15
15(14)Basidiomata arising singly, rarely agglomerated, not over galls or conspicuous differently coloured own thalli; on Physciaceae 16
15′ Basidiomata often grouped, over galls or brownish to olivaceous own thalli; on other hosts 17
16(15)Basidiomata short and broad, StH [47]75–157[198] µm, StD [33]51–153[191] µm, StH/StD [0.5]0.7–2.0[3.4]; capitulum often poorly developed, CaD/StD [0.6]0.9–1.4[1.7]; basidiospores [4.8]5.2–7.0[7.6] × [3.0]3.5–4.9[5.6] µm; on Phaeophyscia, Physcia and Physciella C. physciiphila
16′ Basidiomata long and slender, StH 171–280 µm, StD 21–43 µm, StH/StD 5.1–10.1; capitulum well developed, often very broad, CaD/StD 2.0–3.6; basidiospores narrower, 4.7–6.5 × 3.0–4.1 µm; on Heterodermia comosa C. heterodermiae
17(15)Basidiomata developing over strongly convex galls that are often paler than the host thallus; basidiomata with a relatively large capitulum, CaD 61–172 µm, CaD/StH 0.4–1.1; basidiospores relatively broad, 4.7–7.1 × 3.8–5.4 µm; on Sticta C. stictae
17′ Basidiomata not over galls, frequently over slightly convex, gelatinous and translucent, brownish to olivaceous thalli that may contain algal cells; capitulum often smaller; basidiospores often narrower 18
18(17)Basidiomatal stipe becoming relatively thick when mature, StD [26]22–102[175] µm, StH/StD [0.6]1.2–5.3[7.8]; capitulum relatively large, CaD [26]39–125[201] µm, CaD/StH [0.1]0.2–1.2[1.9]; basidiospores [3.4]4.2–6.8[8.0]×[2.5]3.1×4.9[5.7] µm, SpL/SpB [0.9]1.1–1.7[2.6]; on Lecidella elaeochroma C. lecidellae
18′ Basidiomata more slender, StD [21]22–43[44] µm, StH/StD [3.0]2.8–7.5[10.9]; capitulum smaller, CaD [32]32–79[108] µm, CaD/StH [0.2]0.3–0.5[0.5]; basidiospores [5.1]5.4–6.9[6.9] × [3.0]3.3–4.5[4.6] µm, SpL/SpB [1.4]1.4–1.8[2.1]; on Lecanora C. lecanorae
Crittendenia absistentis Diederich, Coppins & Millanes, sp. nov. Fig. 5
MycoBank MB 842905
Characterized by 5–8-sterigmate basidia, mainly 30–44 µm long, basidiospores mainly 4.9–8.0 × 2.6–3.9 µm, a stipe 121–209 µm long and 21–35 µm diam., and the host choice, Bacidia absistens.
Type: UK. Scotland: VC 103, Mid Ebudes, Ulva, 0.5 km S of Aird Glass, 60 m, on Corylus, on Bacidia absistens, 10 May 2017, B.J. Coppins 25367 (holotype, e 01002244!).
Description. Basidiomata dispersed over the thallus of Bacidia absistens, stipe relatively long and slender, pale brown, translucent, capitulum whitish, StH (80)[108]121–209[234](260) µm, StD (20)[21]21–35[40](50) µm, CaD (30)[41]49–90[98](110) µm, StH/StD (2.8)[3.7]4.1–8.1[9.2](10.5), CaD/StD (1.0)[1.5]1.8–3.3]3.4](4.4), CaD/StH (0.2)[0.3]0.3–0.6[0.7](0.9) (n = 53). Own thallus reduced, whitish. Stipe hyphae thick-walled, 2.5–3.5 µm thick, septa with clamps. Basidia subcylindrical to elongate clavate, upper third distinctly wider, with a basal clamp, 5–8-sterigmate, wall c. 0.5 µm thick before and during spore production, 0.5–1.5 µm after spore production, BaL (25)[28]30–44[49](56) µm, BaD (1.7)[1.7]1.8–2.8[3.1](3.9) µm, BaApD (2.8)[3.0]3.2–4.5[4.6](5.2) µm (n = 29). Basidiospores often elongate ellipsoid, occasionally mixed with broadly ellipsoid basidiospores within the same basidioma, thin- to irregularly thick-walled, smooth, SpL (3.1)[4.1]4.9–8.0[8.5](10.0) µm, SpB (1.8)[2.4]2.6–3.9[4.2](5.5) µm, SpL/SpB (1.0)[1.2]1.4–2.8[3.3](4.3) (n = 225).
Etymology. From Bacidia absistens, the host lichen genus.
Distribution and host. Known from three localities in Scotland, always on the thallus of Bacidia absistens.
Notes. We have obtained sequences from the two recent specimens, including the type, both unfortunately rather reduced, while specimen Coppins 19800 is richer. Within the species with up to 8-sterigmate basidia, the new species differs from C. kakouettae by the longer basidia, from C. lichenicola by the slightly more robust basidiomata with an often broader stipe, and from C. bryostigmatis, C. lopadii, C. parvispora and C. teloschistis by the longer basidiospores.
Additional specimens examined (both on Bacidia absistens). UK. Scotland: VC 105, West Ross, Kinlochewe, Beinn Eighe NNR, Coille na Glasleitir, plantation by Allt Dorchaig, Enclosure 9, 20 m, on Salix by stream, 2001, B.J. Coppins 19800 (e); Argyll, Appin, Glen Creran, oak-dominated old-growth forest at E-SE-facing slope, 56°35′48″N, 5°11′23″W, 60 m, on bark of Sorbus aucuparia, 2018, A. Acton s.n. (pra [ex herb. Palice 25624]).
Crittendenia bacidinae Diederich, van den Boom & Millanes, sp. nov. Fig. 6
MycoBank MB 842906
Characterized by the particularly short, 3–4-sterig-mate basidia, mainly 19–25 µm long, basidiospores mainly 4.0–6.3 × 2.2–2.9 µm, a relatively short and slender stipe 69–116 µm long and 16–27 µm diam., with an often much broader capitulum, 24–54 µm diam., and the host choice and habitat, foliicolous Bacidina apiahica.
Type: PORTUGAL. Azores: Pico, S of São Roque, secondary road on mountain range, from E (500 m) of main road ER-2 to direction of Arrife, 38°26.95′N, 28°18.36′W, 555 m, on leaf of Laurus, on Bacidina apiahica, 31 Aug. 2017, P. van den Boom 56783 & B. van den Boom (holotype, br!).
Description. Basidiomata dispersed over the host thallus or in small groups, stipe relatively short and very slender, pale brown, translucent, capitulum whitish, StH (35)69–116(160) µm, StD (10)16–27(40) µm, CaD (13)24–54(90) µm, StH/StD (2.1)3.0–6.1(12.0), CaD/StD (1.2)1.3–2.4(4.3), CaD/ StH (0.2)0.3–0.6(1.0) (n = 62). Own thallus reduced, hyaline to brownish, gelatinous, translucent, subspherical. Stipe hyphae thick-walled, 2–3 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 3–4-sterigmate, thin-walled, BaL (17)19–25(25) µm (n = 6), BaD (1.8)1.9–2.3(2.4) µm (n = 9), BaApD (2.3)2.5–3.2(3.4) µm (n = 11). Basidiospores ellipsoid, relatively small, wall thin and smooth, c. 0.5 µm thick, SpL (2.7)4.0–6.3(9.5) µm, SpB (1.7)2.2–2.9(3.9) µm, SpL/SpB (1.0)1.5–2.6(4.2) (n = 117).
Etymology. From Bacidina, the host lichen genus.
Distribution and host. Known only from the type locality in the Azores (Pico), on foliicolous Bacidina apiahica.
Notes. This is a remarkable species, distinguished from all other Crittendenia species by the particularly small basidiomata. Indeed, it may be the basidiomycete with the smallest basidiomata known worldwide, the smallest fruiting body measured by us having just 35 µm in height, 17 µm in stipe diameter and 20 µm in capitulum diameter. Basidiomata are so small that even under a binocular microscope (× 50) they are difficult to detect, and macrophotography of them was particularly challenging.
As the species grows in a similar habitat as Crittendenia kakouettae (confined to foliicolous ‘Byssoloma’ kakouettae and possibly Fellhanera species in Macaronesia) and shares with that species the shortest basidia within the genus, we expected a similar morphology and a closer phylogenetic relationship. In addition to the smaller basidiomata, C. bacidinae further appears to differ by the 3–4-sterigmate vs. 7–8-sterigmate basidia. However, this character is yet uncertain, as we did not clearly see free-swimming groups of basidiospores, while mature basidia observed by us mainly had 3 spores attached.
Crittendenia bryostigmatis Diederich & Tønsberg, sp. nov. Fig. 7
MycoBank MB 842907
Characterized by 7-sterigmate basidia, mainly 24–39 µm long, basidiospores mainly 4.0–5.1 × 3.0–3.9 µm, a stipe 106–228 µm long and 24–47 µm diam., and the host choice, Bryostigma muscigenum.
Type: CANADA. British Columbia: Haida Gwaii (Queen Charlotte Islands), Graham Island, Queen Charlotte, 53°15.09′N, 132°07.24′W, 0–5 m, corticolous on twigs of Salix cf. scouleriana overhanging upper part of beach, on Bryostigma muscigenum, 22 Jul. 2003, T. Tønsberg 32070 (holotype, bg!).
Description. Basidiomata dispersed over the thallus of Bryostigma muscigenum, stipe relatively robust, pale brown, translucent, capitulum much broader, whitish to pale brownish, StH (65)106–228(400) µm, StD (20)24–47(80) µm, CaD (35)49–101(140) µm, StH/StD (2.2)3.1–6.8(10.4), CaD/StD (1.3)1.7–2.6(3.2), CaD/StH (0.2)0.3–0.6(0.9) (n = 48). Own thallus poorly visible over the brownish host thallus. Stipe hyphae thick-walled, 1.5–2.5 µm thick, septa with clamps. Basidia subcylindrical, relatively short, apically wider, with a basal clamp, 7-sterigmate, thin-walled, BaL (23)24–39(42) µm, BaD (1.6)1.7–2.1(2.2) µm, BaApD (2.2)2.4–3.1(3.2) µm (n = 8). Basidiospores broadly ellipsoid, wall c. 0.3 µm thick, smooth, SpL (3.3)4.0–5.1(6.5) µm, SpB (2.3)3.0–3.9(4.9) µm, SpL/SpB (1.0)1.1–1.6(2.2) (n = 220).
Etymology. From Bryostigma, the host lichen genus.
Distribution and host. Known only from the type locality on Haida Gwaii (Queen Charlotte Islands), British Columbia, Canada, on the thallus of corticolous Bryostigma muscigenum (identification confirmed by D. Ertz, based on photos and description).
Notes. Although the type specimen is very rich, we did not obtain any sequences. Among the species with up to 8-sterigmate basidia, the new species differs from Crittendenia kakouettae by the longer basidia, from C. lichenicola by the more robust basidiomata with an often broader stipe, from C. absistentis by the smaller basidiospores, from C. teloschistis by the ellipsoid, not subspherical basidiospores and the narrower capitulum, and from C. parvispora by the broader basidiospores. For the characteristics that differentiate Crittendenia bryostigmatis from C. lopadii, see the discussion under C. lopadii.
Crittendenia byssolomatis Diederich, van den Boom & Millanes, sp. nov. Fig. 8
MycoBank MB 842909
Characterized by short, 4-sterigmate basidia, mainly 19–31 µm long, basidiospores mainly 3.8–5.0 × 2.4–3.0 µm, a medium-sized stipe 112–165 µm long and 23–43 µm diam., with a much broader capitulum, 59–96 µm diam., and the host choice, Byssoloma maderense.
Type: PORTUGAL. Azores: Graciosa, S of Ribeirinha, along road R1-2, W of Serra Branca, 39°01.92′N, 28°02.22′W, 285 m, on twigs of Erica azorica, on Byssoloma maderense, 15 Sep. 2021, P. van den Boom 60700 & B. van den Boom (holotype, br!).
Description. Basidiomata dispersed over the host thallus or in small groups, stipe pale brown, translucent, capitulum whitish, StH (90)112–165(200) µm, StD (20)23–43(70) µm, CaD (40)59–96(120) µm, StH/StD (2.3)3.2–5.6(7.2), CaD/StD (1.3)1.8–3.1(4.1), CaD/StH (0.3)0.4–0.7(1.0) (n = 19). Own thallus reduced, hyaline to brownish, gelatinous, translucent. Stipe hyphae thick-walled, 2–2.5 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 4-sterigmate, thin/walled, BaL (19)19–31(35) µm, BaD (1.4)1.6–2.0(2.3) µm, BaApD (1.8)2.0–2.5(2.8) µm (n=17). Basidiospores ellipsoid, relatively small, wall thin and smooth, SpL (3.3)3.8–5.0(5.7) µm, SpB (2.1)2.4–3.0(3.6) µm, SpL/SpB (1.2)1.3–1.9(2.4) (n = 69).
Etymology. From Byssoloma, the host lichen genus.
Distribution and host. Known only from the type locality in the Azores (Graciosa), on Byssoloma maderense on twigs of Erica azorica.
Notes. When we recently collected this species on Byssoloma maderense in the Azores, we were convinced that it would be conspecific with other populations collected on foliicolous Byssoloma kakouettae in Macaronesia. However, the basidiomata on B. maderense are more robust (StH/StD 3.2–5.6) than those on B. kakouettae (StH/StD 5.5–9.6), the basidia 4-sterigmate and slightly longer, 19–31 µm, vs 7–8-sterigmate, 16–23 µm, and the basidiospores slightly shorter, 3.8–5.0 × 2.4–3.0 µm vs 4.1–5.5 × 2.3–3.3 µm. To our surprise, populations on both host species are phylogenetically only distantly related (Fig. 1). Further, the hosts might be only distantly related. While Byssoloma maderense is very similar and probably closely related to B. leucoblepharum, a species belonging to Byssoloma s.str. (Lücking 2008), B. kakouettae has only provisionally been included in Byssoloma and is likely to belong to another, possibly yet undescribed, genus (Sérusiaux et al. 2002). Consequently, Crittendenia byssolomatis on Byssoloma s.str. needs to be accepted as a new species distinct from the new C. kakouettae.
Crittendenia coppinsii (P.Roberts) Diederich, M.Westb., Millanes & Wedin Fig. 9
In Millanes et al., Lichenologist 53: 113 (2021); Chionosphaera coppinsii P.Roberts, Mycotaxon 63: 195 (1997). Type: UK. Scotland: Wester Ross, Torridon, Inveralligan, wood & gorge of Abhainn Alligin, on Melanelixia glabratula, 21 Jun. 1994, B.J. Coppins 16400 & A.M. O'Dare (holotype, e!; isotype, k 39188!).
Description. Basidiomata initially aggregated in small groups, later invading the entire thallus of Melanelixia and Melanohalea, stipe relatively robust, pale to medium brown, translucent, capitulum whitish to pale brown or slightly pinkish, StH (60)[79]85–163[233](300) µm, StD (30)[36]37–87[139](200) µm, CaD (30)[42]48–105[146](200) µm, StH/StD (0.5)[0.7]1.3–3.2[4.4](6.0), CaD/StD (0.7)[0.8]1.0–1.6[2.0](2.8), CaD/StH (0.2)[0.3]0.4–1.0[1.6](2.0) (n = 191). Own thallus brownish, gelatinous, translucent, forming delimited patches or spreading over large areas of the host thallus. Stipe hyphae thick-walled, 1.5–2.5 µm thick, septa with clamps. Basidia subcylindrical, apically distinctly wider, very long, with a basal clamp, (1)4-sterigmate, wall c. 0.5 µm thick before and during spore production, 1–1.5 µm after spore production, BaL (46)[47]66–99[109](136) (n = 58), BaD (1.6)[1.8]2.0–3.2[4.0](4.7) µm (n = 77), BaApD (2.2)[2.5]2.9–4.0[4.6](4.9) µm (n = 77). Basidiospores ellipsoid to elongate ellipsoid, wall c. 0.5 µm thick, smooth, SpL (4.7)[6.2]7.0–9.5[10.5](12.4) µm, SpB (2.6)[3.1]3.3–4.3[4.7](6.2) µm, SpL/SpB (1.3)[1.7]1.9–2.5[2.7](3.1) (n = 426).
Distribution and hosts. The species was known from Belgium, Norway, Russia, Sweden, Switzerland and the UK (Scotland) (Millanes et al. 2021) and is here newly reported from Austria, France and Spain. The known hosts are Melanelixia glabratula (type specimen), M. subaurifera, Melanohalea exasperata, M. exasperatula and M. olivacea.
Notes. Crittendenia coppinsii, the generic type, is the most common species of the genus in Europe and is currently known from nine countries. Nevertheless, it is extremely rare and we believe its rarity is real and not a consequence of being overlooked. Infected thalli are usually abundantly covered by numerous basidiomata and thus eye-catching, and epiphytic macrolichens are usually well studied by lichenologists. It is also the only species of the genus from which many sequences are available, including from asymptomatic thalli adjacent to infected thalli, revealing a cryptic presence in healthy host thalli (Millanes et al. 2021). It is confined to the two very closely related host genera Melanelixia and Melanohalea. Among the Crittendenia species with 3–4-sterigmate basidia and long and narrow basidiospores, this species is distinguished by the particularly long basidia.
Additional specimens. AUSTRIA. Salzburg: Radstädter Tauern, Lungau, NE of Tamsweg, E of Überlinger Hütte, 1720 m, on branch of Picea in coniferous forest, on Melanohalea exasperatula, 2019, R. Cezanne & M. Eichler s.n. (herb. Eichler-Cezanne [photographs seen!]). FRANCE. Puy-de-Dôme: Châteaugay, c. 1 km au NE des Caves, 45.8614°N, 3.1082°E, 520 m, on Quercus, on Melanelixia subaurifera, 2020, P. Pinault s.n. (BR). Pyrénées-Atlantiques: Irati, near Chalet Pedro, near the torrent, on Fagus, on Melanelixia glabratula 1995, J. Etayo 16930 (herb. Etayo). SPAIN. Galicia: Lugo, Faial de Liñares, Liñares LU-623, cerca del alto de San Roque, 42°41′58″N, 7°04′51″W, 1100–1200 m, on Corylus, on M. glabratula, 2021, J. Etayo 33361 & E. López de Silanes (herb. Etayo); Lugo, Courel, Devesa da Rogueira, 42°36′30″N, 7°06′21″W, 1200–1300 m, bosque mixto, on Fagus, on M. glabratula, 2021, J. Etayo 33615 & E. López de Silanes (herb. Etayo). Navarra: valle de Basaburúa Mayor, entre Aizároz y Arrarás, pista cementada camino de Bergañe, hayedo, on Fagus, on M. glabratula, 1994, J. Etayo 14415 (herb. Etayo). UK. Scotland: VC97, Westerness, Ardnamurchan, Kil mory, Bealach Gaoith, 50–65 m, hazel-birch woodland, on Betula, on M. subaurifera, 2009, B.J. Coppins 22784 (e).
Crittendenia crassitunicata Diederich & Etayo, sp. nov. Fig. 10
MycoBank MB 842910
Characterized by the very large basidiomata, mainly 218–353 µm tall, stipe 37–63 µm diam., very large basidiospores, 8.6–13.1 × 3.5–4.7 µm, with a thick wall and an often almost rectangular lumen, the relatively short, (3)4-sterigmate basidia, 39–53 µm long, and the host choice, Melanohalea ushuaiensis.
Type: ARGENTINA. Chubut Prov.: Parque Nacional Los Alerces, on Nothofagus, on Melanohalea ushuaiensis, 4 Nov. 2006, J. Etayo 23715 (holotype, maf-Lich!).
Description. Basidiomata in rather dense groups on the thallus of Melanohalea ushuaiensis, stipe very long and robust, brown, translucent, capitulum whitish, StH (160)218–353(450) µm, StD (30)37–63(80) µm, CaD (40)69–157(200) µm, StH/StD (4.0)4.3–7.5(11.3), CaD/StD (1.0)1.5–3.0(4.7), CaD/ StH (0.2)0.3–0.5(0.6) (n = 34). Own thallus brownish, gelatinous, translucent, spreading over large areas of the host thallus. Stipe hyphae thin- to thick-walled, 2.5–4.5 µm thick, clamps not observed, often branched below basidia. Basidia subcylindrical, wider in the upper half, with a basal clamp, (3)4-sterigmate, wall c. 0.5 µm thick before and during spore production, c. 1 µm after spore production, BaL (32)39–53(54) µm, BaD (2.0)2.1–2.4(2.6) µm, BaApD (2.9)3.0–3.7(3.9) µm (n = 18). Basidiospores elongate ellipsoid, very large, often with a thick wall, especially at the apices, lumen ellipsoid to almost rectangular, initially smooth, later with a rough, enlarging and eventually separating perisporal sac, SpL (6.8)8.6–13.1(16.5) µm, SpB (2.9)3.5–4.7(5.2) µm, SpL/SpB (1.6)2.1–3.3(4.3) (n = 84).
Etymology. From crassus, thick, and tunica, membrane, in reference to the thick-walled basidiospores.
Distribution and host. Known only from the type locality in southern Argentina, on the thallus of Melanohalea ushuaiensis.
Notes. No sequences have been obtained from the type. As this species grows on Melanohalea, a genus that also hosts Crittendenia coppinsii, we hesitated whether this should be included in an enlarged concept of that species or distinguished as a different taxon. Macroscopically, basidiomata of the new species are distinctly larger, and especially taller than those of C. coppinsii (218–353 µm vs. [79]85–163[233] µm). Similarly, basidiospores are distinctly longer (8.6–13.1 µm vs. [6.2]7.0–9.5[10.5] µm). But as we know that basidiomata and basidiospores in Crittendenia are rather variable, the type of C. crassitunicata could be interpreted as an extremely large and well developed C. coppinsii. The main difference between both, however, lies in the basidia that are distinctly shorter in C. crassitunicata (39–53 µm vs. [47]66–99[109] µm).
Crittendenia heterodermiae Diederich, Etayo & Millanes, sp. nov. Fig. 11
MycoBank MB 842911
Characterized by the large basidiomata, mainly 171–280 µm tall, the narrow stipe, 21–43 µm diam., medium-sized ellipsoid basidiospores, 4.7–6.5 × 3.0–4.1 µm, the relatively long, 4-sterigmate basidia, 57–74 µm long, and the host choice, Heterodermia comosa.
Type: BOLIVIA. Dept. Chuquisaca: Prov. Luis Calvo, Parque nacional y área natural de manejo integrado Iñao, Serranía de Iñao, close to Ticucha, Monteagudo, 19°39′50″S, 63°49′14″W, 1022 m, on thin branches, on Heterodermia comosa, 15 Jul. 2015, J. Etayo 32711 (holotype, lpb!).
Description. Basidiomata dispersed over the thallus of Heterodermia comosa, stipe relatively robust, whitish to pale brown, capitulum much broader, whitish to pale brown, StH (150)171–280(320) µm, StD (18)21–43(60) µm, CaD (50)59–114(160) µm, StH/StD (3.3)5.1–10.1(13.0), CaD/ StD (1.7)2.0–3.6(4.0), CaD/StH (0.3)0.3–0.5(0.7) (n = 20). Own thallus hyaline to brownish, gelatinous, translucent, spreading over small areas of the host thallus. Stipe hyphae thick-walled, 2–3 µm thick, septa with clamps. Basidia subcylindrical, relatively long, apically wider, with a basal clamp, 4-sterigmate, thin-walled, BaL (52)57–74(75) µm, BaD (1.9)2.0–2.8(3.0) µm, BaApD (3.1)3.3–4.4(4.7) µm (n = 10). Basidiospores ellipsoid, wall c. 0.3 µm thick, smooth, SpL (3.9)4.7–6.5(8.0) µm, SpB (2.6)3.0–4.1(5.7) µm, SpL/SpB (1.0)1.4–1.8(2.3) (n = 80).
Etymology. From Heterodermia, the host lichen genus.
Distribution and host. Known only from the type locality in Bolivia, on the thallus of Heterodermia comosa.
Notes. The only known specimen of this species is growing on a rather small host thallus, but with plenty of well developed basidiomata. Among the species with mainly 4-sterigmate basidia, this species is distinguished from the parmeliicolous species by the shorter and often broader basidiospores, from Crittendenia physciiphila by the much longer and more slender basidiomata, from C. lecanorae and C. lecidellae by the dispersed, not grouped basidiomata, and from C. stictae by the absence of gall-like structures on the host thallus. In our phylogeny, sequences from this species are sister to a clade comprising C. coppinsii and C. physciiphila, although this relationship is only supported by the Bayesian analysis (Fig. 1).
Figure 11.
Crittendenia heterodermiae, holotype. A. Basidiomata on the thallus of Heterodermia comosa. B. Squash preparation of basidioma. C. Mature basidia. D. Stipe hypha with septum and clamp connection. E. Basidiospores. F. Mature basidia with attached basidiospores (lower part broken). B–F, in KOH + phloxine. Scale bars: A = 100 µm, B = 20 µm, C = 10 µm, D–F = 5 µm.
Crittendenia hypotrachynae Diederich, Etayo, van den Boom & Millanes, sp. nov. Fig. 12
MycoBank MB 842912
Characterized by the medium-sized basidiomata, mainly 116–232 µm tall, and stipe, 24–55 µm diam., the long, but relatively narrow basidiospores, 5.7–9.4 × 3.0–4.3 µm, the relatively short, 3–4-sterigmate basidia, 29–43 µm long, and the host choice, Hypotrachyna species.
Type: PORTUGAL. Azores: Terceira, Camino de Algar do Carvão a Agualva, 38°44′01″N, 27°12′35″W, 630 m, in laurisilva, on Hypotrachyna endochlora, 26 Jul. 2017, J. Etayo 31093 (holotype, po!).
Description. Basidiomata either dispersed over the thallus of Hypotrachyna species or limited to the host soralia, stipe relatively robust, pale brown to orange brown, translucent, capitulum whitish, frequently much wider than the stipe, StH (90)[110]116–232[237](350) µm, StD (20)[17]24–55[68](120) µm, CaD (30)[52]58–127[137](190) µm, StH/StD (2.5)[2.9]3.2–6.1[6.9](9.0), CaD/StD (1.3)[1.6]1.7–3.1[3.3](4.0), CaD/StH (0.2)[0.3]0.4–0.7[0.8](0.9) (n = 76). Own thallus brownish, gelatinous, translucent, present around basidiomata or spreading over large areas of the host thallus. Stipe hyphae 2.5–3.5 µm thick, septa with clamps. Basidia subcylindrical, apically slightly wider, with a basal clamp, 3–4-sterigmate, wall c. 0.5 µm thick before and during spore production, c. 1 µm after spore production, BaL (27)[26]29–43[46](52) µm (n = 45), BaD (1.3)[1.5]1.6–2.3[2.5](2.8) µm (n = 46), BaApD (1.9)[2.2]2.4–3.4[3.6](3.8) µm (n = 47). Basidiospores elongate ellipsoid, relatively long, wall often unevenly thickened, often with a perisporal sac that may eventually detach, SpL (4.0)[5.5]5.7–9.4[9.8](13.4) µm, SpB (2.4)[2.9]3.0–4.3[4.5](6.2) µm, SpL/SpB (1.1)[1.5]1.6–2.7[2.8](4.0) (n = 267).
Etymology. From Hypotrachyna, the host lichen genus.
Distribution and hosts. Known from the Azores (Terceira) and Madeira, always on the thallus of Hypotrachyna species, including H. endochlora and H. laevigata, sometimes in necrosed areas of the host thallus or in soralia.
Notes. Among the Crittendenia species with 3–4-sterigmate basidia and rather long basidiospores, this species is distinguished from C. coppinsii, a taxon also confined to parmelioid hosts, by the more slender basidiomatal stipe, with a StD of mainly 24–55 µm vs. 38–91 µm, a ratio StH/StD of 3.2–6.1 vs 1.2–3.4, and a ratio CaD/StD of 1.7–3.1 vs 1.0–1.5, and the much shorter basidia, mainly 27–44 µm vs 58–99 µm. Crittendenia crassitunicata is distinguished by the much larger basidiospores and basidiomata. In our phylogeny, the species is sister to C. kakouettae, a taxon with 7–8-sterigmate basidia. The two Azores specimens had already been published by Etayo (2018) as Chionosphaera apobasidialis.
Additional specimens examined. PORTUGAL. Azores: Terceira, reserva nacional Serra de Santa Bárbara, domos volcánicos de Mistérios Negros, Lagoa do Negro, 38°44′01″N, 27°17′05″W, 600 m, on Juniperus brevifolia, on Hypotrachyna, 2017, J. Etayo 30945 (herb. Etayo). Madeira: road between Ribeira Brava and S. Vicente, 2 km N of Encumeada, 800 m, on H. laevigata, 1992, P. Diederich 4913 (BR); road between Ribeira Brava and S. Vicente, W of Boca da Encumeada, levada trail, W from tunnel to waterfall, 32°45.14′N, 17°02.41′W, 1010 m, on Hypotrachyna, 2019, P. van den Boom 58213 (br).
Crittendenia kakouettae Diederich, van den Boom & Millanes, sp. nov. Fig. 13
MycoBank MB 842913
Characterized by particularly short, 7–8-sterigmate basidia, mainly 16–23 µm long, basidiospores mainly 4.1–5.5 × 2.3–3.3 µm, a slender stipe 140–244 µm long and 20–33 µm diam., with a much broader capitulum, 33–76 µm diam., and the habitat, on the thallus of ‘Byssoloma’ kakouettae.
Type: PORTUGAL. Azores: Santa Maria, E of Almagreira, along road ER-1-2 to Santo Espirito, Reserva Florestal das Fontinhas, picnic area, 36°57.61′N, 25°04.40′W, 335 m, on needles of Cryptomeria, on ‘Byssoloma’ kakouettae, 16 Sep. 2019, P. & B. van den Boom 58956 (holotype, br).
Description. Basidiomata dispersed over the host thallus or in small groups, stipe very long and slender, pale brown, translucent, capitulum whitish, relatively broad, StH (80)[127]140–244[296](320) µm, S t D (1 5) [ 1 8 ] 2 0 – 3 3 [ 4 2 ] (4 5) µm, C a D (2 0) [ 3 1 ] 3 3 – 7 6 [ 9 7 ] (1 2 0) µm, S t H / S t D (4 . 0) [ 4 . 9 ] 5 . 5 – 9 . 6 [ 1 0 . 7 ] (1 2 . 0), C a D / S t D (1.0)[1.3]1.4–2.7[3.1](4.5), CaD/StH (0.1)[0.2]0.2–0.4[0.5](0.6) (n = 78). Own thallus reduced, hyaline to brownish, gelatinous, translucent. Stipe hyphae thick-walled, 2–3.5 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 7–8-sterigmate, wall c. 0.5 µm thick before and during spore production, 0.5–0.8 µm after spore production, BaL (14)[16]16–23[25](27) µm, BaD (1.2)[1.6]1.9–3.0[3.2](4.2) µm, BaApD (2.4)[2.6]3.1–4.2[4.3](5.3) µm (n = 67). Basidiospores ellipsoid, relatively small, wall thin and smooth, c. 0.5 µm thick, eventually occasionally thicker, SpL (2.9)[3.5]4.1–5.5[5.7](7.0) µm, SpB (1 . 8) [ 2 . 2 ] 2 . 3 – 3 . 3 [ 3 . 6 ] (4 . 7) µm, S p L / S p B (1.2)[1.3]1.4–2.1[2.2](2.7) (n = 241).
Etymology. From Byssoloma kakouettae, the host lichen.
Distribution and host. Known only from Macaronesia in the Azores (Santa Maria), the Canary Islands (Tenerife) and Madeira, on the thallus of foliicolous ‘Byssoloma’ kakouettae (a species that does probably not belong to Byssoloma s.str., see discussion under Crittendenia byssolomatis).
Notes. The new species is distinguished from most members of the genus by the particularly short basidia (mainly 16–23 µm long), a character shared with Crittendenia bacidinae (19–25 µm) and C. byssolomatis (19–31 µm). Crittendenia bacidinae differs by the much smaller basidiomata, 3–4-sterigmate basidia and a different host, Bacidina apiahica, and C. byssolomatis by the more robust basidiomata, 3–4-sterigmate basidia and also a different host, Byssoloma maderense. The three species are phylogenetically distinct (Fig. 1).
Crittendenia kakouettae is surprisingly common, if we consider that the host, ‘Byssoloma’ kakouettae, is a rarely collected species that has a relatively narrow geographical range, being known from Macaronesia and a few localities in the French Pyrénées-Atlantiques, and that further in several infected specimens the host is so much reduced and almost sterile that it would be overlooked by most collectors. Unfortunately, all known specimens, including the type, are extremely reduced. We have nevertheless decided to formally describe the new species, as three specimens, including the type, have been sequenced, and as the species is well characterized by morphology, distinct in our phylogeny, and appears to be confined to a single host species.
Additional specimens examined (all on ‘Byssoloma’ kakouettae). PORTUGAL. Azores: Santa Maria: SE of the island, along road ER-1, between Florestal das Fontinhas and Santo Espirito, just W before Santo Espirito, 36°57.46′N, 25°03.97′W, 400 m, forest with Cryptomeria, on needles of Cryptomeria, 2019, P. van den Boom 58880 (br); E of Almagreira, along road ER-1-2 to Santo Espirito, Reserva Florestal das Fontinhas, picnic area, 36°57.61′N, 25°04.40′W, 335 m, on leaf of Camellia, 2019, P. van den Boom 58949 (br). Madeira: NW of Funchal, road (ER228) from Ribeira Brava to São Vicente, c. 1.5 km N of Boca da Encumeada, large picnic area with open laurisilva, including very small young trees of 2 cm diam., 32°45.64′N, 17°01.08′W, 820 m, on leaf of Laurus, 2012, P. van den Boom 47972 (br). SPAIN. Canary Islands: Tenerife: Montañas de Anaga, Monte de las Mercedes, laurisilva along road and ridge W of Cruz del Carmen, 28°32′N, 16°17′W, 910 m, on leaves of a tree, 2007, P. Diederich 16490 (br); Montañas de Anaga, Monte de las Mercedes, 3.5 km on road S of Chamorga, 28.5592°N, 16.1639°W, 700 m, on leaves of a tree, 2007, P. Diederich 19604 (br).
Crittendenia aff. kakouettae on Fellhanera spp. Fig. 13
Description. Basidiomata dispersed over the host thallus or in small groups, stipe very long and slender, pale brown, translucent, capitulum whitish, relatively broad, StH (80)[98]131–238[242](300) µm, S t D (1 0) [ 1 7 ] 1 7 – 3 5 [ 3 6 ] (5 0) µm, C a D (2 5) [ 3 4 ] 3 8 – 7 6 [ 8 1 ] (1 0 0) µm, S t H / S t D (3 . 4) [ 4 . 8 ] 5 . 2 – 9 . 7 [ 1 0 . 4 ] (1 4 . 0), C a D / S t D (1.3)[1.5]1.5–3.1[3.4](5.0), CaD/StH (0.1)[0.2]0.2–0.4[0.4](0.5) (n = 42). Own thallus reduced, hyaline to brownish, gelatinous, translucent. Stipe hyphae thick-walled, 2–3.5 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 7-sterigmate, wall c. 0.5 µm thick, BaL (12)[14]15–20[20](22) µm, BaD (1.7)[1.8]1.9–2.5[2.6](2.9) µm, BaApD (1.8)[2.0]2.3–3.6[3.9](4.3) µm (n = 34). Basidiospores ellipsoid, relatively small, wall thin and smooth, c. 0.5 µm thick, SpL (3.5)[4.1]4.1–5.5[5.7](7.3) µm, SpB (2.0)[2.3]2.3–3. 0 [ 3. 0 ] (3. 5) µm, S p L / S p B (1. 3) [ 1. 5 ] 1. 5 – 2.2[2.3](2.9) (n = 144).
Distribution and hosts. Known only from the Azores (Pico, Santa Maria), on the thallus of foliicolous Fellhanera azorica and F. bouteillei.
Notes. As the Macaronesian Crittendenia populations growing on foliicolous lichens or on related lichens over tiny twigs are diverse, and based on our knowledge all are confined to a single host species or genus (C. bacidinae on Bacidina apiahica, C. byssolomatis on Byssoloma maderense, and C. kakouettae on ‘Byssoloma’ kakouettae), the two specimens on Fellhanera studied by us most likely represent a distinct species. Unfortunately, both specimens are rather reduced, no sequences could be obtained, and no morphological differences to Crittendenia kakouettae could be observed. Further material allowing DNA sequencing must therefore be awaited before taking a decision on their taxonomic status.
Specimens examined. PORTUGAL. Azores: Pico: ESE of Madalena, NNW slope of volcano Pico, SSW of Santa Luzia, N of main road ER-3, along small road from Redondo to Lourenço Nunes, 38°30.12′N, 28°25.18′W, 770 m, on a needle of Cryptomeria, on Fellhanera bouteillei, 2017, P. van den Boom 56901 (br). Santa Maria: SE of the island, along road ER-1 between Santo Espirito and Castelo, Calheta, 36°56.72′N, 25°01.96′W, 255 m, on leaf of Buxus in a garden, on F. azorica, 2019, P. van den Boom 58920 (br).
Crittendenia lecanorae Diederich & Etayo, sp. nov. Fig. 14
MycoBank MB 842914
Characterized by the medium-sized basidiomata, mainly 92–219 µm tall, the slender stipe, 22–43 µm diam., medium-sized ellipsoid basidiospores, 5.4–6.9 × 3.3–4.5 µm, the relatively long, mainly 3–4-sterigmate basidia, 45–65 µm long, and the host choice, corticolous Lecanora species.
Type: BRAZIL. Alagoas: c. 35 km N of Maceió, 9°30′S, 35°32′W, 1 m, in a mangrove with Rhizophora mangle and Avicennia, on Lecanora, 1 Aug. 1993, K. Kalb 27958 & A. Kalb (holotype, wis!).
Description. Basidiomata aggregated on the thallus of Lecanora species, stipe relatively slender, pale brown, capitulum whitish to brownish, StH (80)[104]92–219[308](320) µm, StD (10)[21]22–43[44](60) µm, CaD (20)[32]32–79[108](120) µm, StH/StD (2.3)[3.0]2.8–7.5[10.9](12.4), CaD/StD (0.7)[1.0]1.2–2.3[3.1](4.0), CaD/StH (0.1)[0.2]0.3–0.5[0.5](0.7) (n = 46). Own thallus brownish, gelatinous, translucent, spreading over small areas of the host thallus. Stipe hyphae thick-walled, 2.0–3.5 µm thick, septa with clamps. Basidia subcylindrical, relatively long, apically wider, with a basal clamp, 3–4-sterigmate, thin-walled, BaL (43)45–65(67) µm (n = 4), BaD (1.6)1.7–2.4(2.6) µm (n = 9), BaApD (2.3)2.5–3.7(3.9) µm (n = 9). Basidiospores ellipsoid to broadly ellipsoid, wall c. 0.5 µm thick, smooth, SpL (4.5)[5.1]5.4–6.9[6.9](8.9) µm, SpB (2.6)[3.0]3.3–4.5[4.6](5.5) µm, SpL/SpB (1.2)[1.4]1.4–1.8[2.1](2.3) (n = 56).
Etymology. From Lecanora, the host lichen genus.
Distribution and hosts. Known from Argentina and Brazil, on unidentified corticolous Lecanora species.
Notes. Among the Crittendenia species with 4-sterigmate basidia, and basidiospores with a length/ breadth ratio below 1.8, this species is distinguished by the basidiomata frequently arising in groups over olivaceous to brownish own thalli. It differs from the similar C. lecidellae by basidiomata with a constantly slender stipe and a smaller capitulum. Unfortunately, none of the two known specimens could be successfully sequenced. It is interesting to note that the specimens show clearly delimited, brownish thalli, from which the basidiomata arise. These are flattened in the Brazilian specimen and elevated to subspherical in the Argentinian specimen. Sterile Crittendenia thalli, devoid of basidiomata, are frequently present. The Argentinian specimen had already been published by Etayo & Breuss (1998) as Chionosphaera cf. apobasidialis.
Additional specimen examined. ARGENTINA. Prov. Tucumán: Dept. Famailla/Monteros, c. 7 km S of El Mollar along road from Tafi del Valle to Famailla, 1600 m, epiphytic on bark of fresh stems of pasture fence, on Lecanora, 1993, W. Till 10242 (li 321179, herb. Etayo 18145).
Figure 14.
Crittendenia lecanorae, holotype. A. Brownish own thallus on the thallus of Lecanora sp., with several basidiomata. B. Squash preparation of basidioma. C. Mature basidia, some with attached basidiospores. D. Basidiospores. B–D in KOH + phloxine. Scale bars: A = 200 µm, B = 20 µm, C = 10 µm, D = 5 µm.
Crittendenia lecidellae Diederich, Etayo & Millanes, sp. nov. Fig. 15
MycoBank MB 842915
Characterized by the medium-sized basidiomata, mainly 88–212 µm tall, the variable, narrow to broad stipe, 22–102 µm diam., medium-sized ellipsoid basidiospores, 4.2–6.8 × 3.1–4.9 µm, the relatively long, mainly 4-sterigmate basidia, 40–71 µm long, and the host choice, Lecidella elaeochroma.
Type: CANADA. British Columbia: bridge at Boston Bar, on Acer macrophyllum, on Lecidella elaeochroma, 7 May 2009, C. Björk 17999 (holotype, ubc!).
Description. Basidiomata dispersed over the thallus of Lecidella elaeochroma, often aggregated in small groups, stipe extremely variable, from relatively slender to short and broad, pale brown, capitulum whitish to pinkish, StH (50)[67]88–212[295](400) µm, StD (20)[26]22–102[175](250) µm, CaD (15)[26]39–125[201](270) µm, StH/StD (0.3)[0.6]1.2–5.3[7.8](10.4), CaD/StD (0.7)[0.8]1.0–1.9[2.5](3.2), CaD/StH (0.1)[0.1]0.2–1.2[1.9](3.3) (n = 178). Own thallus brownish to olivaceous, gelatinous, translucent, spreading over small or larger areas of the host thallus, frequently including algal cells and then representing simple lichen thalli. Stipe hyphae thick-walled, 2.0–3.7 µm thick, septa with clamps. Basidia subcylindrical, relatively long, apically slightly to distinctly wider, with a basal clamp, (1?)4(6)-sterigmate, thin- to thick-walled, BaL (28)[31]40–71[88](96) µm (n = 60), BaD (1.6)[1.7]1.8–2.5[3.3](3.9) µm (n = 66), BaApD (2.2)[2.5]2.8–3.9[4.3](4.4) µm (n = 64). Basidiospores ellipsoid to broadly ellipsoid, wall 0.5–1 µm thick, SpL (2.9)[3.4]4.2–6.8[8.0](9.0) µm, SpB (2.1)[2.5]3.1–4.9[5.7](7.7) µm, SpL/SpB (1.0)[0.9]1.1–1.7[2.6](2.8) (n = 373).
Etymology. From Lecidella, the host lichen genus.
Distribution and host. Known from Europe (France, Italy, Norway, Spain, Switzerland and the UK), the Canary Islands (La Gomera), North America (Canada: British Columbia) and New Zealand, always on the thallus of Lecidella elaeochroma.
Notes. This species is similar to Crittendenia lecanorae, from which it differs by basidiomata with a frequently much more robust stipe and a larger capitulum. Two specimens, including the holotype, have been sequenced. In our phylogeny, they group together, and the clade formed by both is sister to C. lichenicola, but with relatively low support (Fig. 1). Basidiomata usually grow over brownish to olivaceous swellings that sometimes contain an own algal photobiont and thus represent simple lichenized thalli (Fig. 4). Sterile thalli, without basidiomata, are often present. Specimen Coppins 10202 had already been studied by Roberts (1997) who provisionally referred it to C. coppinsii. The specimen from La Gomera had already been published and illustrated as Chionosphaera cf. apobasidialis by Diederich (1996) and Etayo (1996), and the Italian specimen by Brackel (2015) as C. cf. apobasidialis.
Additional specimens examined (all on Lecidella elaeochroma). FRANCE. Orne: Giel-Courteilles, La Rançonnière, 2017, D. Vaudoré s.n. (completely consumed by analysis; photos and measurements seen by us). ITALY. Marche: Ascoli-Piceno, Parco Nazionale dei Monti Sibillini, Val Tenna W Montefortino, Gola dell'Infernaccio, 42°55′07″N, 13°16′26″E, 905 m, on Acer campestre, 2011, W. v. Brackel 6418 (herb. von Brackel). NEW ZEALAND. South Island: Southland, Fiordland National Park, Lake Monowai, 45°51′S, 167°29′E, 200 m, 1981, H. Mayrhofer (wis [ex herb. Kalb 27184]). NORWAY. Hordaland: Voss, W of Strondaelva, along road E16, 0.5 km N of jct (bridge) road to Gjøastein, 60°44′N 6°30′E, 120 m, on Sorbus aucuparia, 1992, T. Tønsberg 17533 (bg L-71712). SPAIN. Canary Islands: La Gomera, Hermigua, mirador de El Bailadero, 1010 m, on Myrica faya, 1994, J. Etayo 13304 (herb. Etayo, [!P. Diederich in 1994, specimen lost at return of loan]). Navarra: Unzué, Peña Unzué, subida desde el pueblo, carrascal en ladera, 42°39′23″N, 1°36′54″W, 900 m, on Quercus rotundifolia, 2012, J. Etayo 27839 (herb. Etayo). Madrid: Horcajo de la Sierra, 41°03′34″N, 3°35′17″W, 1620 m, on Fraxinus angustifolia, 2011, J.C. Zamora (g). SWITZERLAND. Bern: Oberwil, Rossberg, Heideweideni, 46°38′36.2″N, 7°27′25.9″E, 1090 m, on branches of Fraxinus, 2012, E. Zimmermann 815 (herb. Zimmermann [photos seen]). UK. Scotland: VC 101, Kintyre, Knapdale, Taynish NNR, Cmpt 5, avenue N of Taynish House, 10 m, on Ulmus branch, 2007, B.J. Coppins 22371 (e); VC 105, West Ross, Dundonnell, S of Dundonnell House, E side of river, 50 m, on Fraxinus branches, 2007, B.J. Coppins 22464 (e); VC 108, Sutherland, Bettyhill, Invernaver NNR, on Corylus, 1983, B.J. Coppins 10202 (e).
Crittendenia lichenicola (Alstrup, B.Sutton & Tønsberg) Diederich, Millanes & Wedin
In Millanes et al., Lichenologist 53: 113 (2021); Chionosphaera lichenicola Alstrup, B.Sutton & Tønsberg, Graphis Scripta 5: 97 (1993). Type: NORWAY. Hordaland: Fjell, Lokøy, the peninsula S of Storafjellet, alt. 10 m, on Sorbus aucuparia, on Micarea prasina s.l., 27 Aug. 1989, T. Tønsberg 12000 (holotype, bg L-73887!; isotypes, c!, k[former imi]!). Fig. 16
Description. Basidiomata dispersed over the thallus and apothecia of Micarea species, stipe long and slender, pale brown, translucent, capitulum whitish, StH (65)[93]96–165[166](230) µm, StD (10)[15]16–27[27](40) µm, CaD (20)[30]32–65[72](105) µm, StH/StD (3.3)[4.5]4.6–8.2[8.4](12.0), CaD/StD (1.3)[1.5]1.6–3.1[3.3](4.2), CaD/StH (0.2)[0.2]0.3–0.5[0.6](0.9) (n = 58). Own thallus rather indistinct, hyaline to brownish. Stipe hyphae relatively thick-walled, 2–3.5 µm thick. Basidia subcylindrical to clavate, rather short, apically wider, with a basal clamp, 5–8-sterigmate, wall c. 0.5 µm thick before and during spore production, 0.5–1 µm after spore production, BaL (19)[23]21–39[55](54) µm, BaD (1.8)[2.0]2.0–2.6[2.6](3.0) µm, BaApD (2.0)[2.5]2.5–3.8[4.0](4.5) µm (n = 29). Basidiospores elongate ellipsoid, rather long, thin-walled, smooth, SpL (3.9)[4.9]5.0–6.9[7.0](8.1) µm, SpB (2.4)[2.7]2.7–3.7[3.8](5.4) µm, SpL/SpB (1.2)[1.4]1.5–2.4[2.4](2.8) (n = 128).
Distribution and hosts. Known from Norway and Scotland, both on the thallus of Micarea gr. prasina (incl. M. micrococca).
Notes. Although the type specimen on Micarea prasina s.l. is extremely rich, the identity and delimitation of this species was poorly understood. Fortunately, we were able to obtain sequences from the over 30-yr-old type, and these group together with those of a Scottish specimen on M. micrococca, thus suggesting a fungus confined to Micarea hosts. The many other Crittendenia specimens examined with 7–8-sterigmate basidia all differ by minor morphological differences, and those sequenced appear in different places in our phylogenetic tree (Fig. 1). Crittendenia lichenicola differs from the new C. kakouettae by the longer basidia, and from the other species with 7–8-sterigmate basidia by the particularly slender basidiomata. The type specimen had been re-studied by Kirschner et al. (2001) who observed basidia 20–46 × 3–5 µm and basidiospores 5–7 × 2–3 µm. The Scottish specimen had already been published by Aguirre-Hudson & Spooner (2005).
Additional specimen examined. UK. Scotland: Isle of Skye, VC 104, North Ebudes, access road to Kinloch Lodge Hotel, Kinloch & Kyleakin Hills SSSI, 10 m, in wet Betula-Salix woodland, on Betula, on Micarea micrococca, 2005, B.J. Coppins 21517 (e).
Crittendenia lopadii Diederich, Holien & Tønsberg, sp. nov. Fig. 17
MycoBank MB 842916
Characterized by 7-sterigmate basidia, mainly 30–50 µm long, basidiospores mainly 4.2–6.3 × 3.1–4.2 µm, a stipe 104–205 µm long and 24–58 µm diam., and the host choice, Lopadium disciforme.
Type: U.S.A. Alaska: Kodiak Island Borough, Kodiak Island E, along road to Anton Larsen Bay, bank of Red Cloud River, 57°49.0′N, 152°37.6′W, 20 m, on trunk of Alnus, on Lopadium disciforme, 15 May 1991, T. Tønsberg 15250 (holotype, bg L-69060!).
Description. Basidiomata dispersed over the thallus of Lopadium disciforme, stipe relatively slender, pale brown, capitulum whitish to brownish, StH (60)[95]104–205[213](280) µm, StD (15)[20]24–58[80](135) µm, CaD (25)[40]55–115[120](150) µm, StH/StD (1.2)[2.3]2.8–5.3[5.6](7.7), CaD/StD (0.6)[1.2]1.6–2.7[2.8](3.5), CaD/StH (0.3)[0.3]0.4–0.8[0.9](1.1) (n = 59). Own thallus brownish, gelatinous, translucent, spreading over small areas around basidiomata, often swollen. Stipe hyphae thick-walled, 2.5–4 µm thick, clamps not observed. Basidia subcylindrical, apically wider, with a basal clamp, 7-sterigmate, thin-walled, BaL (18)[29]30–50[59](65) µm, BaD (1.5)[1.6]1.6–2.5[2.8](3.2) µm, BaApD (1.6)[2.1]2.2–3.8[4.4](5.2) µm (n = 21). Basidiospores ellipsoid to broadly ellipsoid, wall thin to thick, some with a distinct perisporal sac, SpL (3.2)[4.1]4.2–6.3[7.2](8.4) µm, SpB (2.7)[3.0]3.1–4.2[4.2](6.2) µm, SpL/SpB (1.0)[1.1]1.1–1.8[2.1](2.4) (n = 186).
Etymology. From Lopadium, the host lichen genus.
Distribution and host. Known from North America (Alaska: Kodiak Island) and Norway, always on the thallus of Lopadium disciforme, frequently on twigs of Picea abies.
Notes. The new species resembles Crittendenia bryostigmatis, but is distinguished by longer basidiospores, frequently over 5 µm in length, and longer basidia, frequently over 39 µm. It appears to be confined to thalli of Lopadium disciforme. The host thalli are often sterile and tiny, commonly intermixed with other crustose lichen thalli, and therefore may easily be overlooked or mistaken for thalli of other lichens. Unfortunately, no sequences could be obtained, as all specimens examined were too old.
Additional specimens examined (all on Lopadium disciforme, on twigs of Picea abies). NORWAY. Trøndelag: Sør-Trøndelag, Melhus, S of Korsvegen, N-facing slope E of river Gresja, 190 m, 1998, O. Hilmo (trh); Sør-Trøndelag, Agdenes, E of Ingdalsætra by river Sæterelva, 120 m, 1995, H. Holien 6546b (trh); Sør-Trøndelag, Agdenes, NW- facing slope by river Ingdalselva, 120 m, 1995, H. Holien 6562d (k); Nord-Trøndelag, Overhalla, W of Foss in a ravine, 80 m, 1997, H. Holien 7090 (trh).
Crittendenia parvispora Diederich, van den Boom & Millanes, sp. nov. Fig. 18
MycoBank MB 842917
Characterized by 7–8-sterigmate basidia, mainly 22–36 µm long, small and particularly narrow basidiospores, 3.7–5.2 × 2.3–3.2 µm, a stipe 120–193 µm long and 23–46 µm diam., and the host choice, corticolous Bacidia species.
Type: FRANCE. Finistère: Quimperlé, forêt de Toulfoën (= forêt de Carnoët), in a mixed forest with mainly Fagus and Quercus, on a thin branch of Abies grandis, on Bacidia laurocerasi, 13 Apr. 2021, Y. Quelen (holotype, br!).
Description. Basidiomata aggregated in small or larger groups on the thallus of Bacidia species, stipe slender to sometimes relatively robust, pale brown, slightly translucent, capitulum pinkish white, much broader than the stipe, StH (80)[108]120–193[198](230) µm, StD (20)[22]23–46[52](80) µm, CaD (30)[31]38–116[150](200) µm, StH/StD (2.0)[3.1]3.5–6.1[6.9](7.6), CaD/StD (1.0)[1.3]1.5–3.0[3.4](4.5), CaD/StH (0.2)[0.3]0.3–0.7[0.9](1.3) (n = 46). Own thallus brownish, gelatinous, translucent, developed around basidiomata. Stipe hyphae thick-walled, 1.5–3.5 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 7–8-sterigmate, wall c. 0.5 µm thick before and during spore production, BaL (17)[19]22–36[39](45) µm (n = 52), BaD (1.4)[1.7]1.8–2.8[3.3](4.3) µm (n = 59), BaApD (1.7)[2.3]2.5–3.7[4.1](4.5) µm (n = 58). Basidiospores small, subspherical to broadly ellipsoid, wall usually thin and smooth, SpL (2.9)[3.7]3.7–5.2[5.9](7.0) µm, SpB (1.9)[2.1]2.3–3.2[3.4](4.1) µm, SpL/SpB (1.0)[1.3]1.3–2.0[2.3](3.0) (n = 226).
Etymology. From parvus, small, and spora, designating the particularly small basidiospores.
Distribution and hosts. Known from France (Brittany), Cape Verde and Venezuela, all on corticolous Bacidia s.str. species, including B. laurocerasi and B. polychroa.
Notes. This species is distinguished from all other known Crittendenia species by the particularly narrow basidiospores, less than 3.2 µm broad. It has a remarkably wide geographical distribution, being known from Europe, Africa and South America. The hosts are Bacidia s.str. species, although the Venezuelan host could not be identified to species level. Two sequences have been obtained, including from the type specimen. The Cape Verde specimen had already been published as Chionosphaera cf. apobasidialis by van den Boom (2012).
Additional specimens examined. CAPE VERDE. São Vicente: Monte Verde, just below top of the mountain, 16°52.2′N, 24°56.0′W, 700 m, NW slope with acidic outcrops, shrubs and scattered small trees, on a shrub, on Bacidia polychroa, 2006, P. van den Boom 36943 (br). VENEZUELA. Merida: Distr. Rivas Dávila, Páramo la Negra, c. 20 km W of Bailadores, 8°15′N, 71°50′W, 2750 m, on Bacidia, 1989, K. Kalb 26946 (wis).
Crittendenia physciiphila Diederich, Pinault, Etayo & Millanes, sp. nov. Fig. 19
MycoBank MB 842918
Characterized by the medium-sized robust basidiomata, mainly 75–157 µm tall, the broad stipe, 51–153 µm diam., the frequently poorly developed capitulum, medium-sized ellipsoid basidiospores, 5.2–7.0 × 3.5–4.9 µm, the relatively long, 3–4-sterigmate basidia, 42–72 µm long, and the host choice, Phaeophyscia, Physcia and Physciella species.
Type: FRANCE. Puy-de-Dôme: Châteaugay, 45.8504°N, 3.0855°E, 500 m, on Physcia adscendens, 26 Mar. 2020, P. Pinault s.n. (holotype br!; isotype br!).
Description. Basidiomata dispersed or aggregated in small groups on the thallus of Phaeophyscia, Physcia or Physciella species, stipe rarely slender to most often rather robust, relatively short, often irregular in form, pale to orange brown, often with a rough or irregular surface, slightly translucent, capitulum whitish to pinkish or orange brown, often not well developed and then narrower than the stipe, StH (35)[47]75–157[198](240) µm, StD (30)[33]51–153[191](300) µm, CaD (30)[31]54–185[243](350) µm, StH/StD (0.3)[0.5]0.7–2.0[3.4](4.0), CaD/StD (0.7)[0.6]0.9–1.4[1.7](2.3), CaD/StH (0.2)[0.3]0.5–1.7[2.9](3.6) (n=107). Own thallus brownish, gelatinous, translucent, sometimes reduced or immersed in the thallus of the host lichen, occasionally well developed and swollen. Stipe hyphae thick-walled, 2–3.5 µm thick, septa with clamps. Basidia subcylindrical to clavate, apically wider, with a basal clamp, 3–4-sterigmate, wall c. 0.5 µm thick before and during spore production, 0.5–1 µm after spore production, BaL (37)[38]42–72[93](98) µm (n = 54), BaD (1.5)[1.6]2.0–3.2[3.8](4.0) µm (n = 75), BaApD (1.8)[2.1]2.5–3.8[4.6](4.8) µm (n = 78). Basidiospores ellipsoid, wall usually thin or slightly thickened and smooth, SpL (3.7)[4.8]5.2–7.0[7.6](9.4) µm, SpB (2.5)[3.0]3.5–4.9[5.6](7.3) µm, SpL/SpB (1.1)[1.1]1.2–1.7[1.9](2.5) (n = 483).
Etymology. From Physcia, one of the host lichen genera, and -philus, -loving, designating the predilection for inhabiting Physcia species.
Distribution and hosts. Known from France, Italy, Luxembourg, Spain and the U.S.A. (Massachusetts), on the thalli of Phaeophyscia orbicularis, P. rubropulchra, Physcia adscendens, P. leptalea, P. tenella and Physciella chloantha.
Notes. Among the Crittendenia species with 3–4-sterigmate basidia and ellipsoid basidiospores with a length/breadth ratio <1.7, the new species is distinguished by the short and broad basidiomata mostly arising singly, and the relatively small, often reduced capitulum. We were surprised that specimens on the three host genera Phaeophyscia, Physcia and Physciella were genetically and morphologically so similar that they need to be regarded as a single species. Nevertheless, the small number of available specimens, especially on Phaeophyscia, and the poor condition of some, does not exclude the possibility of a complex of several morphologically similar species, each confined to a single host genus.
Specimens of this species had already been published as Chionosphaera apobasidialis by Etayo (2004, 2009), Brackel (2015) and van den Boom (2021). Bricaud et al. (2009) mentioned C. apobasidialis as diagnostic for foliicolous Fellhanera bouteillei communities in southern France; this information is, however, misleading, as the authors never saw this fungus, but instead copied the information from Llop & Gómez-Bolea (2006) (Bricaud, pers. comm., 12/05/2020). The latter authors reported the species as foliicolous on Buxus leaves in Spain, Barcelona, Osona, El Brull, stream of Picamena, and Girona, Garrotxa, Montagut, Cal Quic (Oix); all our efforts to locate the corresponding specimens were unsuccessful (Dr. Antoni Sànchez i Cuxart, curator of BCN, and Dr. A. Gómez-Bolea and Dr. E. Llop, collectors, pers. comm., 05/10/2020); these authors did not reveal the identify of the hosts, but as we have examined another specimen from Oix on foliicolous Physciella chloantha, we assume that both specimens may belong to Crittendenia physciiphila.
Additional specimens examined. FRANCE. Puy-de-Dôme: Cournols, 45.6474°N, 3.0355°E, 800 m, on Physcia adscendens, 2020, P. Pinault s.n. (br); Châteaugay, c. 1 km NE des Caves, 45.8602°N, 3.0995°E, 500 m, on Phaeophyscia orbicularis, 2020, P. Pinault s.n. (br). ITALY. Lazio: Prov. di Roma, Monti Simbruini, between Livata and Campaegli, below Passo delle Pecore, 41°56′47″N, 13°08′27″E, 1350 m, on Acer pseudoplatanus, on Physcia leptalea, 2013, W. v. Brackel 6731 (herb. von Brackel). LUXEMBOURG. Lamadelaine, Fuussbësch, 49.5408°N, 5.8696°E, 345 m, on Salix, on Physcia tenella, 2008, P. Diederich 16746 (br). SPAIN. Catalonia: W of Oix, Cal Quic, along unpaved road near brooklet, 42°16.48′N, 2°29.87′E, 470 m, on foliicolous Physciella chloantha, 2015, P. van den Boom 53507 (br). Navarra: Oronoz-Mugaire, valle de Bertizarana, Señorío de Bértiz, 200 m, on P. chloantha, 2000, J. Etayo 17385 (herb. Etayo); Urdax, cercanías de la cueva, 50 m, on Salix, on P. chloantha, 2001, J. Etayo 18287 (herb. Etayo). País Vasco: Álava, Puerto de Herrera, subida hacia San León, hayedo y crestas calcáreas hacia el repetidor, 42°35′46″N, 2°41′03″W, 1100–1200 m, on Fagus sylvatica, on P. orbicularis, 2009, J. Etayo 25106 (herb. Etayo). U.S.A. Massachusetts: Berkshire Co., Town of Adams, Mount Greylock State Reservation, W slope of Mt. Fitch along Notch Road, 42°39′N, 73°10′W, 825 m, on Phaeophyscia rubropulchra, 1995, W.R. Buck 27763 (ny).
Figure 19.
Crittendenia physciiphila. A–B. Basidiomata on the thallus of Physcia adscendens. C. Basidiomata on the thallus of Phaephyscia rubropulchra. D. Basidiomata on the thallus of Phaeophyscia orbicularis. E. Basidiomata on the thallus of Physciella chloantha. F–I. Mature basidia and basidiospores. J–K. Basidiospores. A–B, J: holotype, C: Buck 27763, D: Pinault (Châteaugay, on P. orbicularis), E: Etayo 18287, F–I: Pinault (Cournols), J: van den Boom 53507. F–K in KOH + phloxine + Congo Red. Scale bars: A–E = 100 µm, F–I = 10 µm, J–K = 5 µm.
Crittendenia physconiae Diederich, J.C.Zamora & Millanes, sp. nov. Fig. 20
MycoBank MB 842919
Characterized by basidiomata with an extremely reduced or missing stipe and a very large capitulum, 147–390 µm diam., subspherical to broadly ellipsoid basidiospores, 5.8–8.0 × 4.7–6.1 µm, and the host choice, Physconia distorta.
Type: SPAIN. Madrid: San Lorenzo de El Escorial, alrededores de la Silla de Felipe II, on Crataegus monogyna, on Physconia distorta, 3 Jun. 2010, J.C. Zamora (holotype, g!).
Description. Basidiomata dispersed over the host thallus or apothecial margin of Physconia, stipe reduced, immersed, macroscopically not visible, capitulum pale pinkish brown, StH (40)57–187(300) µm, StD (120)146–387(650) µm, CaD (120)147–390(650) µm, StH/StD (0.2)0.3–0.7(0.8), CaD/StD (1.0)1.0–1.0(1.1), CaD/StH (1.3)1.4–3.6(5.8) (n = 27). Own thallus usually indistinct. Stipe hyphae thick-walled, 1.5–2.5 µm thick. Basidia subcylindrical, apically distinctly wider, basal clamp not observed, 1–3-sterigmate, basidia and sterigmata thick-walled, BaL 47–56 µm (n = 3), BaD (2.1)2.3–2.8(2.9) µm (n = 12), BaApD (2.8)3.2–4.5(5.4) µm (n = 15). Basidiospores ellipsoid, at the beginning surrounded by a thick perispore that becomes more and more loose and wrinkled, and eventually separates as a perisporal sac, leaving a smooth- and thin-walled spore, SpL (5.3)5.8–8.0(10.1) µm, SpB (4.0)4.7–6.1(7.4) µm, SpL/SpB (1.0)1.1–1.5(1.9) (n = 71).
Etymology. From Physconia, the host lichen genus.
Distribution and host. Known only from the type locality in Spain, on the thallus of Physconia distorta.
Notes. This species is remarkable by the particularly short basidiomatal stipes that are visible only in microscopic section, and the exceptionally large capituli. The type specimen has been sequenced and is sister to a clade comprising Crittendenia lecidellae and C. lichenicola, although this relationship is only supported by the Bayesian analysis (Fig. 1). We have observed typical basidia producing up to 3 three basidiospores, but also unusual basidia producing only one spore. The basidial wall is very thick and is continuous with that of the sterigmata and basidiospores, eventually separating as a perisporal sac surrounding the spores and sometimes also the upper part of the basidia. We do not know whether the development of this perisporal sac is due to the age of possibly postmature basidiomata, or if this character is constant within the species, and this can only be understood when more specimens become available.
Crittendenia stictae Diederich, Etayo & Millanes, sp. nov. Fig. 21
MycoBank MB 842920
Characterized by the large and robust basidiomata, mainly 118–191 µm tall, the relatively thick stipe, 39–74 µm diam., medium-sized, broadly ellipsoid basidiospores, 4.7–7.1 × 3.8–5.4 µm, the medium sized, mainly 3–4-sterigmate basidia, and the growth on large, conspicuous galls on the thallus of the host, Sticta fuliginosa s.l.
Type: BOLIVIA. Laguna Vizcachani, camino de La Paz a Zongo, 16°11′45″S, 68°07′33″W, 3675–3860 m, on Sticta fuliginosa s.l. on bushes, 30 May 2011, J. Etayo et al. 26611 (holotype, lpb!; isotype, herb. Etayo!).
Description. Basidiomata densely covering galls on the thallus of Sticta fuliginosa s.l., relatively robust, pale brown, translucent, capitulum whitish to brownish, StH (100)118–191(260) µm, StD (35)39–74(100) µm, CaD (50)61–172(240) µm, StH/StD (1.5)1.9–3.9(4.9), CaD/StD (1.2)1.5–2.5(2.9), CaD/StH (0.3)0.4–1.1(1.4) (n = 22). Own thallus brownish, gelatinous, translucent, abundantly developed and often thick around basidiomata, developing over large, superficial, subspherical, pale to medium brown, smooth galls, 0.2–1 mm diam. Stipe hyphae thick-walled, 2–3.5 µm thick, clamps not observed. Basidia subcylindrical, apically slightly wider, basal clamp not distinctly seen, 3–4-sterig-mate, BaL c. 44–49 µm (n = 2), BaD c. 1.6–2.6 µm, BaApD c. 1.9–2.9 µm (n = 5) (most basidiomata postmature). Basidiospores broadly ellipsoid, more rarely elongate ellipsoid, thick-walled, some with indistinct apical appendages, eventually with a perisporal sac, SpL (3.6)4.7–7.1(9.3) µm, SpB (2.8)3.8–5.4(6.8) µm, SpL/SpB (1.0)1.1–1.5(2.0) (n = 72).
Etymology. From Sticta, the host lichen genus.
Distribution and host. Known with certainty only from the type locality in Bolivia, on the thallus of Sticta fuliginosa s.l.
Notes. The type specimen is very rich. The host thallus is covered by numerous large, convex galls, some without basidiomata, but most covered by numerous basidiomata. This would be the only known species of Crittendenia to induce galls on the host thallus. However, it is not possible to identify whether the galls are induced by Crittendenia or perhaps by another lichenicolous fungus devoid of fructifications. Unfortunately, most basidiomata are postmature, and therefore only a small number of entire basidia could be observed and measured. We nevertheless decided to formally describe it as a new species, as sequence data exist, thus allowing further specimens to be easily identified when sequences are available. Among the Crittendenia species with 3–4-sterigmate basidia and broad basidiospores (SpL/ SpB <1.5), the new species is remarkable by the relatively large and robust basidiomata developing over conspicuous galls.
We have seen another specimen on Sticta (ECUADOR. Imbabura: Reserva Ecológica Regional Cotacachi-Cayapas, desde Irunguicho a Lagunas de Piñan, 2700–3100 m, on saxicolous S. weigelii s.l., 2003, J. Etayo 25434). It is very reduced and differs considerably from the type of Crittendenia stictae, so that we decided not to include it in that species, pending the discovery and study of further specimens on Sticta. Basidiomata are very slender and do not grow over galls, StH (120)123–210(230) µm, StD (15)19–36(35) µm, CaD (20)25–52(55) µm, StH/StD (3.4)4.6–8.2(8.7), CaD/StD (0.9)0.9–2.0(2.3), CaD/StH (0.1)0.2–0.3(0.3) (n = 6), basidia 4-sterigmate, and basidiospores very narrow, SpL (5.4)6.0–7.0(7.8) µm, SpB (2.7)2.9–3.6(4.1) µm, SpL/SpB (1.3)1.8–2.2(2.4) (n = 44). This specimen had already been published as Chionosphaera apobasidialis by Etayo (2017). A further specimen grows on an old Sticta thallus overgrown by a sterile Coenogonium, thus simulating a growth on Coenogonium (BOLIVIA. Dept. Santa Cruz: Prov. Caballero, camino de las orquídeas, zona baja, 17°49′20″S, 64°42′31″W, 2340 m, Yungas cloud forest, 2012, J. Etayo 28835). It also does not grow over galls, and some morphological characters are intermediate between the type specimen and Etayo 25434, hence we also provisionally exclude it from Crittendenia stictae: StH (100)98–178(180) µm, StD (25)26–42(45) µm, CaD (30)30–90(110) µm, StH/StD (2.2)2.5–6.2(7.2), CaD/StD (1.0)1.0–2.5(2.8), CaD/ StH (0.3)0.3–0.6(0.6) (n = 5), basidia 2–4(?)-sterigmate, SpL (5.4)6.0–7.0(7.8) µm, SpB (2.7)2.9–3.6(4.1) µm, SpL/SpB (1.3)1.8–2.2(2.4) (n = 44).
Crittendenia teloschistis Diederich, Etayo, F.Berger & Millanes, sp. nov. Fig. 22
MycoBank MB 842921
Characterized by 6–8-sterigmate basidia, mainly 31–42 µm long, relatively small basidiospores, 3.6–4.8 × 3.0–4.0 µm, a stipe 116–198 µm long and 31–70 µm diam., and the host choice, Teloschistes species.
Type: SPAIN. Canary Islands: La Gomera, NP Garajonay, on Teloschistes flavicans, Jul. 2012, M. Koller s.n. (holotype, br [ex herb. Berger 26836]!).
Description. Basidiomata dispersed over the thallus of Teloschistes species, stipe relatively narrow to robust, pale brown, capitulum much broader, whitish to pale brownish, StH (65)[98]116–198[212](250) µm, StD (20)[26]31–70[81](100) µm, CaD (35)[62]62–153[180](240) µm, StH/StD (1.0)[1.6]2.1–5.0[5.7](7.0), CaD/StD (1.3)[1.5]1.6–2.8[2.9](3.6), CaD/StH (0.3)[0.4]0.4–1.1[1.3](1.7) (n = 45). Own thallus hyaline to brownish, gelatinous, translucent, developed around basidiomata, in the type specimen strongly swollen. Stipe hyphae thick-walled, 2–3 µm thick, septa with clamps. Basidia subcylindrical, relatively long, apically wider, with a basal clamp, 6–8-sterigmate, thin-walled, BaL (28)31–42(46) µm, BaD (1.5)1.6–2.6(3.1) µm, BaApD (2.3)2.7–3.7(4.0) µm (n = 20). Basidiospores subspherical to shortly ellipsoid, wall c. 0.3 µm thick, smooth, SpL (2.7)[3.5]3.6–4.8[5.1](5.6) µm, SpB (2.3)[2.9]3.0–4.0[4.2](4.8) µm, SpL/SpB (1.0)[1.0]1.1–1.4[1.4](1.8) (n = 105).
Etymology. From Teloschistes, the host lichen genus.
Distribution and hosts. Known from the Canary Islands (La Gomera) and South America (Bolivia), on the thallus of Teloschistes exilis and T. flavicans.
Notes. Among the Crittendenia species with mainly 7–8-sterigmate basidia, this species is distinguished by a combination of subtle differences, mainly the particularly short, often subspherical basidiospores, and the relatively large capituli. Specimens on both host species differ considerably, the one on Teloschistes flavicans having relatively robust basidiomata, StH 98–170 µm, StD 42–81 µm, StH/StD 1.6–2.9, and often develop over a small swollen own thallus, while the type on T. exilis has slenderer basidiomata, StH 148–212 µm, StD 26–53 µm, StH/StD 3.8–5.7, without a swollen own thallus. In our phylogeny, both specimens form a clade that is sister to a clade comprising almost all other Crittendenia species, although this relationship is only supported by the Bayesian analysis (Fig. 1). Specimen Etayo 13215 had already been published and illustrated by Diederich (1996) and Etayo (1996) as Chionosphaera cf. apobasidialis.
Additional specimens examined. BOLIVIA. Dept. Tarija: Prov. Burnet O'Connor, close to Los Pinos, old road between Entre Ríos and Tarija, 21°24′50″S, 64°18′33″W, 2150 m, Boliviano-Tucumano forest, on Teloschistes exilis, 2015, J. Etayo 32788 (lpb). SPAIN. Canary Islands: La Gomera, Hermigua, Contadero, pista hacia la Ermita, 1000 m, on Teline stenopetala, on T. flavicans, 1994, J. Etayo 13215 (herb. Etayo [!P. Diederich 1994, specimen lost at return of loan]).
Crittendenia sp. on Parmelina quercina
Description. Basidiomata developing on old thallus lobes of Parmelina quercina, pinkish brown, stipe short, StH c. 70–200 µm, StD c. 50–200 µm, CaD c. 50–400 µm. Basidia subcylindrical to elongate clavate, 4-sterigmate, c. 38–63 µm long and 2.5–3 µm thick. Basidiospores ellipsoid, wall thin to thick, some with a distinct perisporal sac, SpL (7.7)8.4–9.7(10.0), SpB (3.7)4.0–5.4(6–7) µm, SpL/SpB (1.5)1.7–2.3(2.4) (n = 27). [Description obtained from notes dating 1994 and from an old microscopical slide.]
Distribution and host. Known from Spain (Mallorca and Tarragona), on the thallus of Parmelina quercina.
Notes. A specimen of ‘Chionosphaera cf. apobasidialis’ had been studied and published by Diederich (1996), illustrated by a macroscopical photograph and line drawings. Unfortunately, the specimen was lost during the return of a loan, but a microscopical slide exists. A second specimen is so poor that no basidioma could be found. Following our observations, this represents a distinct species of Crittendenia, but additional specimens are needed for a formal description. It differs from the other parmeliicolous Crittendenia species by the very short and broad basidiomatal stipe, and from the other species with 4-sterigmate basidia by the spores with a length/breadth ratio above 1.7.
Specimens examined (both on Parmelina quercina). SPAIN. Mallorca: carr. Soller-Lluc, km 40, entrada a la propiedad Monnaber, carrascal con foliáceos en ramas, 670 m, 1994, J. Etayo 12503 (herb. Etayo, [!P. Diederich 1994, specimen lost at return of loan; microscopical slide extant]). Tarragona: Baix Ebre, Roquetes, camino ports de Beceite, a 2 km cruce con carretera a monte Caro, 1115 m, encinar aclarado, 1995, J. Etayo 17192 (herb. Etayo [no basidioma left]).
Acknowledgments
We thank the curators of the herbaria and the owners of private collections mentioned under Material and Methods for the loan of specimens. Franz Berger (Kopfing, Austria), Brian Coppins (Edinburgh, Scotland), Håkon Holien (Steinkjer, Norway), Patrick Pinault (Châteaugay, France), Tor Tønsberg (Bergen, Norway) and J. C. Zamora (Geneva, Switzerland) kindly accepted to co-author new species. Yann Quelen (Quimperlé, France) generously offered us his recent specimen of Crittendenia parvispora. Damien Ertz (Meise, Belgium) and Mikhail Zhurbenko (Saint Petersburg, Russia) provided precious comments on the manuscript. The Laboratory of Molecular Systematics (MSL) at the Swedish Museum of Natural History—in particular Bodil Cronholm (MSL)—is warmly thanked for excellent technical support. This paper was financially supported by The Swedish Taxonomy Initiative (Svenska Artprojektet, administered by the Swedish Species Information Centre/ArtDatabanken, STI dha 2016-27 4.3 and 2020.4.3-231) and the Swedish Research Council (VR 2016-03589) through grants to M. Wedin, and by the Spanish Ministry of Economy and Competitiveness (CGL2016-80371-P) and Universidad Rey Juan Carlos (URJC-Proyecto Puente) through grants to A. Millanes.
