TAXON 59 (3) • June 2010: 911–921 Labiak & al. • Leucotrichum, a new fern genus from the Neotropics Phylogeny and taxonomy of Leucotrichum (Polypodiaceae): A new genus of grammitid ferns from the Neotropics Paulo H. Labiak,1 Germinal Rouhan2 & Michael Sundue3 1 Universidade Federal do Paraná, Departamento de Botânica, Caixa Postal 19031, CEP 81531-980, Curitiba-PR, Brazil 2 Muséum national d’Histoire naturelle, UMR CNRS 7205 ‘Origine, Structure et Evolution de la Biodiversité’, Botanique, 16 rue Buffon CP39, 75005 Paris, France 3 The New York Botanical Garden, 200th St & Southern Blvd. 10458-5126, Bronx, New York, U.S.A. Author for correspondence: Paulo H. Labiak, [email protected] Abstract A new genus of grammitid ferns, Leucotrichum, is described. Segregated from Lellingeria on the basis of molecular analyses and morphological characters, it comprises five species distributed in the Antilles, Central America, and Southeastern Brazil. We present a phylogeny based on two cpDNA genes, atpB and rbcL, showing the relationships between Leucotrichum and other genera of grammitid ferns. Both Bayesian and Maximum Parsimony analyses support the monophyly of Leucotri- chum, with bootstrap value of 100% and posterior probability value of 1.0, and its sister-group relationship to the Terpsichore lanigera group. Leucotrichum is characterized by seven morphological characters: arching fronds, clathrate rhizome scales, blackish rhizome scale cell walls, laterally marginate petioles, laminar apices subconform to the lateral pinnae, pinna costae without blackish sclerenchyma, and hairs bearing acicular branch cells. We also provide a key, descriptions, complete synonymy, discussions, specimens examined, and illustrations for all the species. Keywords cpDNA; Grammitidaceae; Lellingeria ; Neotropics; phylogeny; Terpsichore INTRODUCTION apiculata group (including the type of the genus L. apiculata (Kunze ex Klotzsch) A.R. Sm. & R.C. Moran)—characterized Recent molecular phylogenetic studies have provided valu- by mostly unbranched, hyaline, and acicular hairs, and densely able information on the relationships of major fern groups, es- short-hirsute petioles; (2) the L. suprasculpta group—char- tablishing a more robust and defensible system of classification, acterized by membranaceous, pendent, 1-pinnate-pinnatisect particularly at the order and family ranks (Smith & al., 2006, blades; (3) the L. myosuroides group—characterized by very 2008). Despite these advances, generic circumscriptions and narrow blades, with a single sorus per segment, with evident relationships within some families are still not well understood veins on fertile segments, and glabrous rhizome scales; (4) and and are in need of more focused studies. Among the problematic the L. mitchellae group—characterized by a thickened lamina families are Polypodiaceae, which comprise about 56 genera with numerous, long, tawny hairs that bear an inconspicuous and over 1200 species (Smith & al., 2008), with most of the lateral cell at the base. Smith & al. (1991) mentioned four species species occurring in both the Old and New World tropics. Fol- belonging to this group: L. mitchellae, L. organensis, L. pseu- lowing the most recent classification (Smith & al., 2008), the domitchellae and L. schenckii. ‘grammitid ferns’ are a monophyletic lineage nested within Here, we focus on the Lellingeria mitchellae group, which Polypodiaceae (Ranker & al., 2004; Schneider & al., 2004; has been recovered as sister to the Terpsichore lanigera group Schuettpelz & Pryer 2007), which comprise about 25 genera by recent analyses, instead of being related to the remaining and 750 species, with most of the species occurring as epiphytes species of Lellingeria (Ranker & al., 2004; Sundue & al., in or epipetrically in tropical regions (Parris, 1990, 2007). Recent press). Even though it is clear that this group does not belong to phylogenetic studies demonstrate that several grammitid genera Lellingeria, the limited sampling does not allow assessment the are not monophyletic, and need further study (Ranker & al., actual limits of these clades, and whether they should be consid- 2004; Geiger & al., 2007; Sundue & al., in press). One of these ered a single genus or not. In an attempt to solve this question, is Lellingeria A.R. Sm. & R.C. Moran, which comprises about we have greatly expanded the number of taxa for both genera 60 species and occurs primarily in the Neotropics, but also in (Terpsichore, Lellingeria), and present a more comprehensive Africa, Madagascar, and the southern Pacific (Smith & al. 1991). analysis for these two groups in particular. Previous phylogenetic studies of grammitid ferns, which have Using DNA sequence data from two chloroplast markers, included only a few Lellingeria species, suggest that as tradi- and a morphological data matrix of 87 characters, we aim to tionally defined, Lellingeria comprises two or three distinct test their monophyly and position within the grammitid ferns. clades (Ranker & al., 2004; Sundue & al., in press). Smith & al. As a result, we describe the Lellingeria mitchellae clade a (1991) defined the genus primarily by having a radially symmet- new genus, establish diagnostic characters for it as well as the rical rhizome, unequally forked hairs and clathrate stem scales, Terpsichore lanigera clade, make necessary combinations, and and recognized the following four groups: (1) the Lellingeria present a taxonomic treatment for all of the known species. 911 Labiak & al. • Leucotrichum, a new fern genus from the Neotropics TAXON 59 (3) • June 2010: 911–921 MATERIALS AND METHODS and revised when necessary. The two data matrices were con- structed using Mesquite v.2.6 (Maddison & Maddison, 2009) Taxonomic sampling. — To test the hypothesis that Lel- and analyzed using equally weighted maximum parsimony lingeria and Terpsichore are polyphyletic, and also to access (MP) and a Bayesian inference (BI). which groups are most closely related to the L. mitchellae MP analyses for each dataset were performed using TNT group, a large sampling of the Neotropical grammitid diversity v.1.1 (Goloboff & al., 2008). For all MP analyses, heuristic was included. To assess the relationships between the species searches were performed with 1000 parsimony ratchet repli- within the L. mitchellae group, all four previously described cates (Nixon, 1999) (200 iteration ratchet, the up- and down- species were included. Three of these species (L. mitchellae, weights set to 5% each), holding 20 trees per ratchet, followed L. organensis, L. schenckii) were represented by multiple by TBR-max branch swapping. Support for nodes was calcu- specimens that had been collected from different regions, to lated by bootstrap analyses (expressed in percentages: BP), with identify possible conflicts in species delimitation. In addition, 1000 replicates doing 10 ratchets per replicate, holding 20 trees we sampled one specimen of Xiphopteris mortonii Copel., that per ratchet, and keeping only the strict consensus. likely belongs to the Lellingeria mitchellae group. The Bayesian analyses were performed using MrBayes From the Terpsichore lanigera group, the suspected sister v.3.1.2 (Ronquist & Huelsenbeck, 2003). Nucleotide substitu- group, six species were included; these account for approxi- tion models suggested as best fit to the data under the hier- mately 25% of the estimated species in the group (Moguel, archical likelihood ratio test (hLRT) and the Akaike infor- 2005). Sampling within the remaining groups of Lellingeria mation criterion (AIC), as implemented in MrModeltest v.2.3 included 17 representative species (~35% of the total). Based on (Nylander & al., 2004), were used in the analyses of each studies by Schneider & al. (2004) and Ranker & al. (2004), we separate marker. Both criteria suggested the same model for chose four genera of Polypodiaceae outside of the grammitids both genes, GTR + Г + I. The partition strategy included the as outgroups for the present study: Microgramma percussa, Pe- models and separate codon positions for each marker. Three cluma alfredii, Polypodium glycyrrhiza, and Campyloneurum independent runs were started from random trees, consisting of angustifolium. In total, the final matrix includes 113 terminals, four chains each, one cold and three hot, with the temperature corresponding to 90 species and 24 genera. parameter set to 0.05 to ensure good mixing. The analyses Voucher information and GenBank accession numbers are were run for 10 million generations, sampling every 1000th listed in Table S1 in the Electronic Supplement 1 to the online generation. The “burn-in” period was identified visually and version of this article. trees sampled before stable posterior probability values (PP) DNA extraction. — Genomic DNA was isolated from ei- had been reached were exluded from consensus. In order to ther field-collected, silica gel–dried fronds or from herbarium assess if MCMC reached stationarity, we used AWTY (Wil- specimens. Total genomic DNA was extracted using the Qia- genbusch & al., 2004). gen DNEasy Plant Mini Kit (Valencia, California, U.S.A.), The consensus topologies from each of the two markers following the manufacturer’s protocol, but with an additional analyses were compared for potential conflicts. The combined proteinase K digestion during the lysis step: 30 μL of pro- dataset was analyzed using MP and BI analyses, with settings teinase K (20 mg/mL) and 30 μL of β-mercaptoethanol (98%) as for the separate datasets. added per tube, with the tubes incubated