New records of lichens and lichenicolous fungi from Latvia, with a list of lichenicolous fungi reported from Latvia

Four species of lichen-forming fungi (Calicium pinastri, Chaenotheca laevigata, Lecania croatica and Pycnora praestabilis) and two lichenicolous fungi (Arthrorhaphis aeruginosa and Chaenothecopsis epithallina) are reported as new for Latvia. The first comprehensive list of lichenicolous fungi in Latvia is also presented, including their hosts and distribution in Latvia (northern Europe).

Our knowledge of the lichens and allied fungi in Latvia (northern Europe) has been considerably advanced in recent years. Currently ca 640 taxa of lichenized fungi are recorded for Latvia (Āboliņa et al 2015, Moisejevs 2015, Motiejūnaitė et al. 2016, Moisejevs and Degtjarenko 2017, which is comparable to the 620 taxa known from the geographically similar territory of Lithuania (Motiejūnaitė 2017).
Lichenicolous fungi, on the other hand, have been understudied in Latvia. The first mention of lichenicolous species can be found in the paper by Mereschkowski (1913), who reported Acolium sessile from Jaunugulbene (Vidzeme). Later, Diploschistes muscorum was reported from the Gauja river valley and Riga city environs (Malta 1926, Vimba 1971. During the 13th International Symposium of Lichenologists and Mycologists of the Baltic States, two more species of lichenicolous fungi were reported (Motiejūnaitė and Piterāns 1998); a further four species were reported in the first annotated Latvian checklist of lichens (Piterāns 2001) and 16 more were added by Motiejūnaitė et al. (2006), Czarnota and Kukwa (2010) and Motiejūnaitė and Grochowski (2014). The second annotated checklist of lichens listed 15 lichenicolous taxa as supplementary data (Āboliņa et al. 2015). Further contribution was made by Motiejūnaitė et al. (2016), with 33 lichenicolous fungi reported for the first time from Latvia, complemented by the paper of Moisejevs (2017). Since a full and up-to-date list of lichenicolous fungi for Latvia is still lacking, a comprehensive list is provided here.
The current paper reports four new species of lichenforming and two lichenicolous fungi new to Latvia, together with a list of lichenicolous fungi (61 taxa) known for Latvia, including their hosts and distribution data in the country (Table 1).

Material and methods
The material was determined by means of routine lichenological methods (Smith et al. 2009). Spot-tests were determined with 10% KOH (K), sodium hypochlorite (C), paraphenylenediamine in ethanol (Pd) and Lugol's solution (I), and secondary chemistry by thin layer chromatography (TLC) using solvent C (Orange et al. 2001). Specimens of the newly recorded species, according to the nomenclature of Wirth et al. (2010), are kept in the lichenological herbarium of University of Daugavpils (DAU).
The list of lichenicolous fungi presented below is a combination of published literature data and herbarium collections from DAU and the University of Latvia (RIG), together with those species reported in the current paper. Data on species distribution are derived from literature sources and herbarium collections (DAU and RIG). Regions of Latvia ( Fig. 1) are abbreviated in the list as follows: K -Kurzeme (Kurland), V -Vidzeme, L -Latgale, R -Pieriga, Z -Zemgale, LV -all regions of Latvia; # = lichenicolous fungus.

Notes
The collected specimen was sterile, but it was recognized by the characteristic colour of the infected host thallus. Only A. aeruginosa is known to turn the infected lichen an aeruginose colour and, as stated in the protologue of the species '... is therefore easily recognized even when sterile' (Santesson and Tønsberg 1994).

Notes
The lichen was found growing close to Calicium parvum, a species that resembles C. pinastri, but has clavate asci, while C. pinastri has cylindrical asci when mature.

Distribution
Chaenotheca laevigata is a rare lichen with a wide distribution in Northern Hemisphere, being known from Europe (Wirth et al. 2010, Nordin et al. 2011, Asia (Titov 2000) and North America (Hardman et al. 2017).

Notes
Chaenotheca laevigata can be confused with Chaenotheca chlorella, from which it differs by its immersed thallus, ellipsoid to short cylindrical ascospores and longer ascomata.

Chaenothecopsis epithallina differs from the similar species
Chaenothecopsis nigra by its association with C. trichialis, darker ascospores with less contrasting septum and dark green hypothecium.

Notes
The collected sterile specimen was checked using TLC, but no secondary compounds were found. The species was distinguished from species with a similar morphology and chemistry following the same characters as employed by Motiejūnaitė et al. (2012) and Tsurykau (2017).

Distribution
Pycnora praestabilis is known in North America (Hodkinson 2009

Notes
From similar species of Pycnora and several morphologically similar species from Xylopsora genus, P. praestabilis differs in its lack of soredia, normally abundant pycnidia up to 0.3 mm diam., typical spot test reactions and presence of alectorialic acid.

Discussion
According to our data, 61 species of lichenicolous fungi have been recorded from Latvia. Acolium inquinans mentioned by Āboliņa and Vimba (1959), who described it as 'a parasitic lichen, growing on thalli of other lichens', has been excluded since it is a lichenized species that lacks a lichenicolous habit (Tibell 1999). Specimen on which the record was based is lacking, therefore it is impossible to check its identity. Furthermore, Piterāns (1982) did not mention A. inquinans in his list of Latvian lichens and Āboliņa et al. (2015) described the species as an epiphytic lichen; therefore, it can be assumed that the aforementioned report was based on misidentification. Specimens of Biatoropsis usnearum reported by Motiejūnaitė et al. (2006) (both on Usnea subfloridana) are housed in the herbaria of the Institute of Botany, Nature Research Centre (BILAS) and University of Tartu (TU); the BILAS specimen and DAU specimens were checked in accordance with the description of B. usnearum (s. str.) given by Millanes et al. (2016), so it is assumed that only one species of Biatoropsis is known from Latvia.