Lankesteriana International Journal on Orchidology ISSN: 1409-3871 [email protected] Universidad de Costa Rica Costa Rica Rojas Alvarado, Gustavo; Karremans, Adam P. ADDITIONS TO THE COSTA RICAN MYOXANTHUS (ORCHIDACEAE: PLEUROTHALLIDINAE) Lankesteriana International Journal on Orchidology, vol. 17, núm. 2, 2017, pp. 203-214 Universidad de Costa Rica Cartago, Costa Rica Available in: http://www.redalyc.org/articulo.oa?id=44353160008 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative LANKESTERIANA 17(2): 203–214. 2017. doi: http://dx.doi.org/10.15517/lank.v17i2.29933 ADDITIONS TO THE COSTA RICAN MYOXANTHUS (ORCHIDACEAE: PLEUROTHALLIDINAE) GUSTAVO ROJAS-ALVARADO1,4 & ADAM P. KARREMANS2,3 1 Regional Postgraduate Program in Biology, University of Costa Rica, P.O. Box 302-7050 Cartago, Costa Rica 2 Lankester Botanical Garden, University of Costa Rica 3Naturalis Biodiversity Center – Leiden University, The Netherlands 4 Author for correspondence: [email protected] ABSTRACT. Pleurothallis cerea, a species described based on a specimen collected by Lankester in Costa Rica, and commonly placed under the synonymy of Myoxanthus octomeriae or M. congestus, is here recognized as distinct. The species is easily distinguished by the shape and size of the leaf, as well as various floral details, especially of the lip. A new combination, tentatively suggested by Carl Luer but never published, is required and therefore validated. Additionally, the vegetatively striking Myoxanthus affinis is recorded from Costa Rica for the first time based on two recent collections. The species is variable within its broad distribution from Co- lombia to Bolivia and, although differences with the original material from Peru are evident, we cannot be sure at this time that ours represents a different species. Both species are described and illustrated based on living plants. KEY WORDS: Carl Luer, Myoxanthus affinis, M. octomeriae, Pleurothallis cerea, taxonomy Introduction. Myoxanthus (Orchidaceae: Pleuro- cies and transferred 33 others to his newly re-circum- thallidinae) was proposed by Poeppig and Endlicher scribed Myoxanthus, with the previously mentioned (1835) to accommodate a species collected by the first Chaetocephala, Duboisia and Duboisia-Reymondia author in Peru, Myoxanthus monophyllus Poepp. & among its synonyms. The establishment of the genus Endl. The genus was, however, soon treated as a syn- was supported by the anatomical studies made by onym of Pleurothallis R. Br. by Lindley (1836), and Pridgeon and Stern (1982). A few years after, Luer its only species was transferred to the latter as Pleuro- (1986) broadened the circumscription of Myoxanthus thallis poeppigii. The second attempt to propose a new by transferring Pleurothallis aspasicensis Rchb.f. and generic name for a species of Myoxanthus was made Pleurothallis pan Luer, later selected as type species by Karsten (1847), when he proposed the genus Du- of Myoxanthus subgen. Satyria Luer, and Myoxan- boisia, later renamed Duboisia-Reymondia H. Karst. thus subgen. Silenia Luer respectively, and their al- due to a preexisting name in the Solanaceae (Karsten lies to the genus. In his monograph of Myoxanthus, 1848). Both were treated as synonyms of Pleurothallis Luer (1992) included 47 species and divided them by Reichenbach (1852). The proposal of Chaetoceph- into three subgenera, Myoxanthus subgen. Myoxan- ala Barb. Rodr. (1882) was the third attempt at rec- thus (with sections Antenella Luer, Myoxanthus, and ognition for the species of Myoxanthus as segregates Scandentia Luer), Myoxanthus subgen. Satyria, and from Pleurothallis. But that genus was also placed Myoxanthus subgen. Silenia. The morphological under Pleurothallis shortly after, on this occasion by features of the seven members of subgenera Silenia Cogniaux (1896). and Satyria were very unlike the species of subgenus The situation would remain virtually unchanged Myoxanthus, shedding doubt on their affinities within for almost a century, and it is not until 1982 that Luer the genus. Reconsidering his initial interpretation, reconsiders this group of species, and segregates Luer (1995) transferred the two sections to Pleuro- them from Pleurothallis. He described one new spe- thallis subgen. Acianthera (Scheidw.). Received 15 May 2017; accepted for publication 23 July. First published online: 29 July 2017. Licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Costa Rica License 204 LANKESTERIANA The DNA evidence published by Pridgeon, So- trachychlamys (Schltr.) Luer, as cited by the first, lano and Chase (2001) showed that Myoxanthus is but without expressly excluding them. With the later indeed not closely related to Pleurothallis, and that it addition of Myoxanthus sotoanum Pupulin, Bogarín is monophyletic with the exclusion of the species be- & Mel.Fernández, a new species similar to M. scan- longing to subgen. Silenia and subgen. Satyria. These dens (Ames) Luer, published by Pupulin, Bogarín two subgenera were finally segregated into a novel ge- and Fernández (2010), eight species of Myoxanthus neric concept under the name Echinosepala Pridgeon are currently reported for the country. Two additional & M.W Chase (Pridgeon & Chase 2002). Karremans species are here recognized for the flora of the coun- (2016) suggests that Echinosepala and Myoxanthus are try, bringing the total to ten. One, Myoxanthus affinis sister genera within the Restrepia affinity, which is the (Lindl.) Luer, is newly reported based on two recent same we have found in our own unpublished analyses, collections, while Pleurothallis cerea Ames, a spe- albeit with weak support. cies described from Costa Rica and commonly placed Myoxanthus as defined by Pridgeon (2005) and under the synonymy of Myoxanthus octomeriae Karremans (2016) is an easily recognizable and mono- (Schltr.) Luer or M. congestus (A. Rich. & Galeotti) phyletic genus within the Pleurothallidinae with some Soto Arenas, is recognized as a distinct species and 49 accepted species, distributed from southern Mex- transferred to Myoxanthus. ico, throughout Central America, to Bolivia and Bra- Taxonomic treatment zil (Luer 1986, 1992). The highest diversity is found in Ecuador (with 25 species), Colombia (14 species), Myoxanthus affinis (Lindl.) Luer, Selbyana 7: 35. 1982. Peru (13 species) and Venezuela (11 species). The ge- Bas.: Pleurothallis affinis Lindl., Companion Bot. nus has one of the broadest altitudinal distributions Mag. 2: 354. 1837. within the Pleurothallidinae, ranging from 3 m (in Homotypic synonym: Humboldtia affinis (Lindl.) Brazil) to 3200 m (in Colombia) (Pridgeon 2005), but Kuntze, Revis. Gen. Pl. 2: 667. 1891. being more frequent at elevations between 1000 and TYPE: Peru. Dept. of San Martín: Lithophytic, Prov- 2500 m (Luer 1992). ince of Chachapoyas, 1835, Mathews 1899 (holotype, The plants of Myoxanthus are epiphytes, litho- K; photo of type!; Fig. 1). phytes, or occasionally terrestrial, herbs, with caespi- tose, repent, or scandent habits, characterized by hav- Heterotypic synonyms: Pleurothallis rigidifolia ing rhizomes and ramicauls with hispidulous, scurfy Rchb.f., Bonplandia 3: 224. 1855. Humboldtia ri- sheaths (Luer 1992) with unicellular trichomes ar- gidifolia (Rchb.f.) Kuntze, Revis. Gen. Pl. 2: 668. ranged in lines perpendicular to the axis of the stem 1891. (Pridgeon & Stern 1982). The sepals are usually fleshy TYPE: Peru. Dept. of San Martín: Lithophytic near and often pubescent, the laterals usually connate; the Chachapoyas, 1840, Mathews 3187 (holotype, G; petals are usually linear, fleshy or thickened toward photo of type!). the apex, sometimes with osmophores (Luer 1982). Pleurothallis furfuracea F.Lehm. & Kraenzl., Bot. The lip is thick, variously shaped, and delicately Jahrb. Syst. 26(3–4): 441. 1899. hinged to a thick column-foot. The column is semite- TYPE: Ecuador. Prov. of Morona Santiago: Andes east rete, variably winged or toothed, the anther is ventral, of Sigsig, 1887, F. C. Lehmann 6511 (holotype, K; with a pair of ovoid pollinia, brought together by a pair photo of type!; Fig. 2). a whale-tail like caudicles. The anther cap is cellular- glandular, often ciliate, fimbriate or papillose on the Plant large, epiphytic, densely caespitose. Roots upper edge (Luer 1992). flexuous, branching, 1–2 mm in diameter. Ramicauls Pupulin (2002) cited seven species of Myoxan- stout, erect, up to 70 cm long, 3–5 mm in diameter, thus in his catalogue of the orchids of Costa Rica, enclosed by overlapping, tubular sheaths. Sheaths whereas Luer (2003) would include only five of them light brown, papyraceous, 6–10 cm long, covered by in the Manual de Plantas, and only mentioning Myo- trichomes except the uppermost, trichomes dark, dis- xanthus exasperatus (Lindl.) Luer and Myoxanthus posed in rows perpendicular to the ramicaul axis. Leaf LANKESTERIANA 17(2). 2017. © Universidad de Costa Rica, 2017. ROJAS-ALVARADO & KARREMANs — Additions to Myoxanthus 205 FIGURE 1. Holotype of Pleurothallis affinis Lindl. (≡ Myoxanthus affinis) deposited at K. Reproduced with the kind permission of the Director and the Board of Trustees Royal Botanic Gardens, Kew. LANKESTERIANA 17(2). 2017. © Universidad de Costa Rica, 2017. 206 LANKESTERIANA FIGURE 2. Holotype of Pleurothallis furfuracea F.Lehm. & Kraenzl. (= Myoxanthus