Taxonomic revisions in Fridericia (Bignonieae, Bignoniaceae) I: the “Acrodromous venation” and “Piriadacus” clades

Abstract: Fridericia is a conspicuous genus of neotropical lianas, with 60 species distributed among seven lineages that are broadly distributed through the neotropics in both dry and wet environments. As part of ongoing taxonomic studies of the genus, we provide taxonomic revisions of two clades: (1) the “Acrodromous venation” clade and (2) the “Piriadacus” clade. The former is characterized by 1- or 2-foliolate leaves with acrodromous venation, tubular calyces and coriaceous fruits with slightly raised edges. The latter is recognized by the red, pink-reddish or orange, tubular corolla and exserted or sub-exserted anthers. We recognize two species in each lineage and provide identification keys, morphological descriptions, illustrations, distribution maps and comments on the distribution, phenology, conservation status and taxonomy. We propose the lectotypification of 13 names: Arrabidaea brachypoda var. acuminata, A. brachypoda var. attenuata, A. brachypoda var. firma, A. brachypoda var. induta, A. brachypoda var. rigida, A. platyphylla var. lasiorrhachis, A. platyphylla var. puberula, Bignonia brachypoda var. firmula, B. erubescens var. breviflora, B. erubescens var. subtruncata, B. regnelliana, Cuspidaria erubescens var. glabrescens and Petastoma simplicifolium. We further correct the typification of B. erubescens var. breviflora and B. erubescens var. subtruncata and propose two new synonyms for F. platyphylla (i.e. A. celastroides and B. violacea). Citation: Kaehler M. & Lohmann L. G. 2021: Taxonomic revisions in Fridericia (Bignonieae, Bignoniaceae) I: the “Acrodromous venation” and “Piriadacus” clades. – Willdenowia 51: 181–194. Version of record first published online on 21 June 2021 ahead of inclusion in August 2021 issue.


Introduction
Fridericia Mart. emend. L. G. Lohmann is one of the largest and most complex genera in the plant family Bigno niaceae (Kaehler & al. 2019). This genus belongs to tribe Bignonieae, which includes lianas and is broadly distributed throughout the neotropics, where they occur in both wet and dry habitats (Lohmann & Taylor 2014). The generic classification of Bignonieae remained problematic for more than a century due to overlapping patterns of morphological variation and a lack of diagnostic generic characters. Molecular phylogenetic data (Lohmann 2006) allowed for a re-circumscription of monophyletic genera diagnosed by morphological synapomorphies (Lohmann & Taylor 2014). Under this new generic classification system, Fridericia is much more broadly circumscribed, including many species of the previously recognized Arrabidaea DC.
Arrabidaea originally included four Brazilian species (Candolle 1838). Its circumscription was later expanded to accommodate 21 species (Candolle 1845). By the time the monumental treatment of Flora brasiliensis was published, Arrabidaea included 70 species and an incredible range of morphological variation (Bureau & Schumann 1896). The Flora brasiliensis remains the most comprehensive treatment of Arrabidaea to date. To help organize the broad range of morphological features included in the genus, three sections distinguished by the number and arrangement of ovules per locule were proposed (Bureau & Schumann 1896), as follows: (1) A. sect. Microcarpaea K. Schum., with fewer than five ovules in each of the two locule rows; (2) A. sect. Macrocarpaea K. Schum., with more than five ovules in each of the locule rows; and (3) A. sect. Paracarpaea K. Schum., with ovules affixed in four rows (Bureau & Schumann 1896). This infrageneric system was followed by subsequent authors who described new species within the genus (e.g. Kränzlin, Pittier, Rusby and Sprague). The circumscription of Arrabidaea continued to grow in subsequent years, especially due to the inclusion of the species-rich genera Cremastus Miers, Panterpa Miers, Paramansoa Baill. and Petastoma Miers (Sandwith 1968). The most-comprehensive treatment of the Bignoniaceae prior to the availability of phylogenetic data recognized an Arrabidaea with c. 100 species (Fisher & al. 2004). Despite a large number of species in the genus, the infrageneric classification system proposed by Bureau & Schumann (1896) was subsequently refuted by morphology (Sandwith 1968) and molecular characters (Lohmann 2006;Kaehler & al. 2019).
The first molecular phylogeny that sampled multiple members of Arrabidaea (Lohmann 2006) indicated that the genus was polyphyletic, leading to a revised circumscription (Lohmann & Taylor 2014). Namely, A. rego (Vell.) DC. [= Fridericia rego (Vell.) L. G. Lohmann], the type of Arrabidaea, was placed within the same clade as F. speciosa Mart., the type of the monotypic Fridericia, indicating that these taxa were best treated within a single genus (Lohmann 2006). Because Fridericia is the older name, 66 species of Arrabidaea were transferred into Fridericia, leading to a broadly circumscribed Fridericia with 67 species (Lohmann & Taylor 2014). The remaining species of Arrabidaea were shown to be more closely related to Cuspidaria DC., Tanaecium Sw. and Xylophragma Sprague and were transferred into those genera instead. While Fridericia is clearly monophyletic, the genus remained morphologically variable (Lohmann & Taylor 2014;Kaehler & al. 2019). The 60 species currently recognized in Fridericia are distributed in seven lineages characterized by morphological traits in an informal classification system (Kaehler & al. 2019).
Most species of Fridericia are lianas, although some are shrubs or treelets; the prophylls of the axillary buds are minute, triangular and distichous, sometimes concentrically disposed or foliaceous; the leaves are usually ternate with the terminal leaflet often replaced by a simple tendril, although 1-foliolate leaves are also found; the corolla is usually in shades of pink, less commonly white, red, orange or yellow; the ovary is lepidote, with two lines of ovules per locule; the fruits are linear, usual-ly coriaceous, rarely woody, bearing winged seeds, with two hyaline or papyraceous wings (Lohmann & Taylor 2014;Kaehler & al. 2019).
As part of ongoing taxonomic studies of Fridericia, we provide taxonomic revisions of the "Acrodromous venation" and "Piriadacus" clades, both of which are exclusively South American and centred in Brazil. The "Acrodromous venation" clade is the first diverging lineage in Fridericia, whereas the "Piriadacus" clade is a small lineage within the following polytomy. Due to their small size, these two clades are treated together in this study. We provide an identification key, typifications, morphological descriptions, illustrations, distribution maps and comments on the geographical distribution, phenology, conservation and taxonomy for each clade.
Types are listed alphabetically and herbarium accession numbers are provided when available. Whenever herbarium accession numbers were lacking, specimen barcodes were provided instead. Taxonomic headings include type information provided in the labels of each specimen and the phenological condition of each specimen. Whenever the data provided in the label differed from those included in the protologue, the additional information provided in the protologue was added between square brackets.
Distribution maps were prepared using QGis 3.14.1 Pi (QGis Development Team 2020) using the Americas Base Map (Bletter & al. 2004). The conservation status of each species was estimated using the GeoCAT (Bachman & al. 2011). Because all species treated here have wide Extent of Occurrence (more than one million km 2 ), we opted to estimate the Area of Occupancy using the auto-value option for the cell width (50 km of cell width for all species). The 2 km cell width recommended by the IUCN (2019) is too small for broadly distributed species with relatively small density of collections within this large area (Lughadha & al. 2018). tion" and "Piriadacus" clades and included species

Taxonomic treatments
The "Acrodromous venation" clade The species of the "Acrodromous venation" clade are characterized by 1-or 2-foliolate leaves with acrodromous venation, tubular calyces and smooth, coriaceous fruits, without prominent midrib and with edges slightly raised. These morphological features are consistent between the two species of this group and are not found concomitantly in any other species of Fridericia. The morphological complexity of this clade is mainly due to the wide morphological variation of F. platyphylla (Cham.) L. G. Lohmann. Note -The protologue of Bignonia regnelliana Sond. does not provide any information about where the type was deposited, nor about where the holotype was collected. Four specimens of Regnel I-295 were located, three of which do not contain any evidence that Sonder studied them. The first specimen is deposited in P and includes Regnell's handwritten note "Ad Caldas in Provincié Mina Ger. Brasl [sic]" in the label. The second is deposited in BM and includes the same locality of the specimen deposited in P and the species name handwritten by Regnell. The third is deposited in MO (MO-083287) and includes two labels. One of those labels includes two notes handwritten by Regnell using two different pen colours as follows: (1) "Entre M C Lopes e a Capella -illegible -Sta Rita" and (2) "Ad Beau 1867 I.295." The second label was typed within a printed label from the Uppsala herbarium that describes the collection locality as "entre Lopes Jaguary e St. Rita" and the collection date as "24 Apr 1862". The fourth speci-  (1894), we found only three specimens of Glaziou 12970, one in C without locality and date, and two in P, one of them with Glaziou's handwritten indication that the gathering was made in Ipanema on 23 April 1881. The specimens in P were donated to the herbarium after Glazious's death in 1907 (Bureau 1908) and, therefore, after the publication of the new varietal name. Despite lacking detailed gathering information, we have selected C10021773 as the lectotype because it is a wellpreserved specimen and was annotated by Bureau. = Arrabidaea brachypoda var. induta Bureau in Vidensk.

Fridericia prancei
Phenology -Produces flowers all year long. Fruiting specimens were collected in July, August and November.
Distribution and habitat -Fridericia prancei is distributed in lowland Amazonian rainforest in Venezuela (Am-
Remarks -Fridericia prancei can be easily identified because of the large and coriaceous leaves with marked suprabasal acrodromous venation, tubular, not costate calyx, long and narrowly infundibuliform, white or whitish pink corolla, and stamens at the same height as the tube mouth. Al Gentry annotated "12822" over his collector's number typed (12882) on the isotype deposited in MO. However, he did not mention the differential notation in the protologue or in any other published work. Lohmann and Taylor (2014) cited the number handwritten by Gentry (in sched.). Since the protologue and all remaining isotypes found have the number 12882, we consider this to represent the correct collecting number.
Phenology -Produces flowers from March to November. Fruits unknown.
Remarks -Among the paratypes of Fridericia ornithophila, Gentry (1978) listed the sterile gathering Prance 58902 deposited in MO and NY. We found a fertile specimen of this gathering in UB that allowed us to identify it as F. trailii (Sprague) L. G. Lohmann. When sterile, this species is very similar to F. ornithophila due to the leaf size, shape and discolorous pattern. However, F. trailii has denser inflorescences with 4 -6 branching orders without glandular capitate trichomes, the calyx rim is truncate and shortly 5-cuspidate, also lacking the glandular capitate trichomes, and the corolla is slender. On the other hand, F. ornithophila has a lax inflorescence with 2 -4 branching orders covered with glandular capitate and simple trichomes, the calyx rim is bilabiate (sometimes irregularly split) with glandular capitate trichomes and the corolla is thick.