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PLEUROTHALLIDINAE: HOW MANY GENERA?

WESLEY E. HIGGINS

Center for Tropical Plant Research and Conservation, Marie Selby Botanical Gardens, 811 South Palm Avenue, Sarasota, FL 34236-7726 USA.

NORRIS H. WILLIAMS

Florida Museum of Natural History, University of Florida, Dickinson Hall, Gainesville, Florida 32611-7800 USA

ABSTRACT: The Neotropical orchid subtribe Pleurothallidinae contains over 4,000

species, which represents 16% of Orchidaceae (World Checklist of Monocotyledons 2004). This hyper-diverse group is distributed from Florida to Argentina with interesting disjunctions in Brazil and the Lesser Antilles, but is most diverse in Colombia, Ecuador, Peru, and Bolivia. The current classification by Luer recognizes 4100+ species in 60 genera. The classification system of Chase et al. only recognizes 32 genera including two that were moved out of Laeliinae. When the classification schemes of the subtribe by Pridgeon and Chase and Luer are compared, we find that the differences are more substantial than just splitting and lumping. Taking into account other treatments by Garay, Szlachetko, Barros, and Archila an additional 20 monotypic genera have been described. This results in 116 generic names in current use, but with different circumscriptions for the genera. A classification based on total evidence and including morphology will produce clades with specific morphological characteristics. Keywords: Taxonomy, Orchidaceae, Nomenclature

I. Introduction The Neotropical orchid subtribe Pleurothallidinae contains over 4,000 species, which

represents ±16% of Orchidaceae. This hyper-diverse group is distributed from Florida to Argentina with interesting disjunctions in Brazil and the Lesser Antilles, but is most diverse in Colombia, Ecuador, Peru, and Bolivia (Jorgensen & León-Yánez 1999, Dodson 2004, Vásquez & Ibisch 2000).

Pleurothallids exhibit a broad array of growth habits (epiphytic, terrestrial, rheophyte,

lithophyte) and occupy many habitats (e.g., nearly all Neotropical forests, paramo, mangroves, deserts). A typical pleurothallid is an epiphyte with a restricted distribution, frequently endemic, that lives in sympatry with other pleurothallids in extremely moist forests in the Andes (1800-2800 m) and is pollinated by flies (Valencia et al. 2000, Ibisch et al 2003, Christensen 1994, Blanco 2005, Borba and Semir 2001, Borboa et al. 2001a, 2001b, 2002). Figures 1 and 2 illustrate the vegetative and floral diversity in Pleurothallidinae. Several pleurothallid species are pioneers and tend to appear and dominate major disturbance

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landscapes (e.g., road constructions, grounds covered by volcanic ashes after eruptions, coffee and cacao plantations).

Based on molecular data, pleurothallids form a monophyletic group that is firmly

positioned as a member of the Epidendreae (van den Berg et al. 2005). Despite the great variation in size and form, pleurothallids are easily identified by an articulation between the ovary and the pedicel. Another distinctive feature of pleurothallids is a stem (ramicaul) bearing one leaf that always lacks pseudobulbs (Luer 1986).

Pleurothallid genera have been traditionally circumscribed on the basis of morphological

characters, e.g., number of pollinia (8,6,4, or2), presence or absence of an active lip, presence of a funnel-like lepanthiform sheath that surrounds the stem (known as the ramicaul by many pleurothallid workers), the degree to which the column protrudes beyond the lip, among other features. Even though the classification solely based on morphological characters has been of great utility, experts of the group as well as users of the classification have recognized several problems at generic and infrageneric levels, especially in the genus Pleurothallis s.l., the largest genus of the subtribe (Luer 2002, Dressler 1993). Pridgeon et al. (2001) presented the first molecular evidence for a reclassification of the Pleurothallidinae, which was followed by many premature taxonomic changes (Pridgeon & Chase 2001) that created a great deal of controversy (Luer, 2004).

The nomenclatural instability of the group has greatly affected two activities. 1)

Horticulturally, pleurothallid orchids have a high commercial value and are regulated by the Convention on International Trade in Endangered Species (CITES). The implementation of CITES is very difficult, as many stakeholders (e.g., customs personnel, traders, final users) cannot agree on which classification system to use. 2) Moreover, conservation efforts (e.g., the creation of Red Lists of Ecuador and Peru) not only have become a taxonomic nightmare, but they are also delaying research and obstructing fund raising for researchers and NGOs interested in population and habitat protection. It is the aim of this collaboration to produce a more stable and predictive classification for this group of orchids that form the core of Neotropical orchid diversity.

Current status of Pleurothallidinae taxonomy – The lifetime work of Carl Luer M.D.,

widely regarded as the expert on this subtribe (he has described over 2,000 species and 30 genera), has been published in 29 volumes of the Icones Pleurothallidinarum, which are part of series of Monographs in Systematic Botany of the Missouri Botanical Garden. During the last 30 years, Luer has prepared alpha-taxonomic treatments of the entire subtribe, with the exception of the genera Octomeria, Stelis and many Brazilian species. Luer (1984) stated that the taxonomy of Pleurothallidinae was fraught with problems and unnatural groups have been recognized as subtle and obvious differences and similarities have eluded researchers. At that time Luer (1984) believed that Pleurothallidinae would contain over 4000 species in 30 genera.

These numbers are amazingly close to Chase et al. (2003) classification (3999 species in

32 genera). The current classification by Luer (2005) recognizes 4100+ species in 60 genera. The classification system of Chase et al. only recognizes 32 genera including two that were

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moved out of Laeliinae. When the classification schemes of the subtribe are compared, we find that the differences are more substantial than just splitting and lumping (Pridgeon & Chase 2001; Luer 2002). Taking into account other treatments (see Table 1), an additional 20 monotypic genera have been described.

A new classification of Orchidaceae based on both molecular and morphological evidence

is highly desirable (Chase 2003). Currently the two major conflicting classifications for Pleurothallidinae, Pridgeon and Chase (2001; 35 genera), Luer (ongoing studies; 60 genera) result in 89 generic names in current use, but with different circumscriptions for the genera. A classification based on total evidence and including morphology will produce clades with specific morphological characteristics. Thus it will be more user-friendly and bring order to the artificial megagenus Pleurothallis (with over 1,500 species) and a subtribe that has confounded taxonomists since the time of Lindley (1830). Recent molecular research (Pridgeon et al. 2001) indicates that several genera, as presently defined, are paraphyletic. The cladogram in Figure 3 shows a polyphyletic Pleurothallis.

Figure 1. Plant habit variation in Pleurothallidinae orchids. A. Pleurothallis tripterantha B. Pleurothallis calypso C. Trichosalpinx berlineri D. Lepanthes numularia E. Trichosalpinx chamaelepanthes F. Zootrophion hirtzii G. Brachionidium ephemerum H. Masdevallia strattoniana I. Dresslerella sp. J. Zootrophion dayanum K. Dracula ubangina L. Trichosalpinx amygdaladora M. Brachionidium hirtzii N. Myoxanthus fimbriatus O. Pleurothallis aspergilium P. Dracula sodiroi Q. Restrepia muscifera R. Pleurothallis alpina S. Pleurothallis fastidiosa Figure 2. Flower variation in Pleurothallidinae orchids. A. Stelis nexipous B. Porroglossum portillae C. Pleurothallis bivalvis D. Teagueia sp. E. Trisetella fisadens F. Masdevallia coccinea G. Platystele johnstonii H. Teagueia zeus I. Restrepia sp. J. Scaphosepalum fimbriatum K. Stelis columnaris L. Dracula chestertonii M. Zootrophion hirtzii N. Masdevallia mendozae.

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Table 1. - Recent classifications

Taxonomist Genera Species

Luer (1984) 30 4000

Dressler (1993) 28 3021

Pridgeon et al. (2001) 35 --

Chase (2003) 32 3999

Luer (2006) 96 4100+

Previous Research - Preliminary morphological (Neyland et al. 1995) and molecular

(Pridgeon & Chase 2001) studies of the subtribe have been conducted and these studies demonstrated the need for additional phylogenetic research. These independent studies differed in the source of characters and the resulting phylogeny. Neyland et al. (1995) performed a cladistic analysis of subtribe Pleurothallidinae based on 45 anatomical/morphological characters. Their ingroup comprised 24 genera (34 species); the large genus Pleurothallis consisted of two subgenera and ten species complexes. Their hypothesis that subtribe Pleurothallidinae has undergone a unilinear reduction in the number of pollinia was not supported by their study. Their cladistic analysis suggests that Pleurothallis is not a natural genus and may be divided into several discrete genera.

Pridgeon et al. (2001) evaluated the monophyly of subtribe Pleurothallidinae and the

component genera based on molecular data. They sequenced the nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2) and 5.8S gene for 185 taxa. In addition, to improve the overall assessments along the spine of the topology, plastid sequences from matK, the trnL intron, and the trnL-F intergenic spacer were added for a representative subset of those taxa in the ITS study. The sequence data from all three data sets were combined in a separate analysis of 58 representative species (28 genera). There was support in most analyses for the monophyly of Pleurothallidinae and in some support for inclusion of Dilomilis and Neocognauxia (formerly in subtribe Laeliinae). Although most genera in the nine clades identified in their analyses were monophyletic, all data sets revealed the polyphyly of Pleurothallis and its constituent subgenera as presently understood.

Both studies concluded that Pleurothallis sensu Luer is not monophyletic. These studies

represent preliminary phylogenetic research of the subtribe and the low sampling (24 genera and 58 taxa) may not reflect the evolutionary history of the group. Relationships in Trichosalpinx remain unresolved, and extensive DNA sampling will be required before taxonomic conclusions can be made with confidence (Pridgeon & Chase 2001). Chase et al. (2003) even state that the classification they presented is expected to be ephemeral, and that this new classification will facilitate further research ( Pridgeon & Chase 2001; Chase et al. 2003).

The DNA-only phylogeny of Pridgeon et al.(2001) sampled only 185 (4.6%) out of 4000 species for one gene region (ITS) and 58 taxa (1.4%) for the 3-gene analysis. The low sampling of the ITS study resulted in a largely unsupported/unresolved phylogeny. Many of

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their results support many genera proposed by Luer’s morphology-based taxonomy. On the other hand, some of their results deviate so greatly from it that they invite skepticism (Jost & Endara 2004).

Generic limits have been changed with little regard to use and current taxonomic

treatments offer little hope of stability unless the revisions are based upon a well-sampled molecular/morphological phylogenetic hypothesis. Preliminary molecular data (Pridgeon et al. 2001) confirm the suspected paraphyly of some genera in Pleurothallidinae. Neotropical orchid floras must confront such taxonomically difficult genera in their treatments, but such treatments are hampered by conflicting, arbitrary, and unsupported non-monophyletic generic concepts proposed by various taxonomists (see Pupulin 2003). Previous work has demonstrated that combined molecular/morphological data sets can yield highly supported cladograms that can serve as the basis for stable, objective classifications (Higgins 2002, Albert 1994).

Figure – 3. Cladograms. A. Preliminary Pleurothallidinae phylogeny based on molecular data (Pridgeon, et al. 2001). B. The discordant elements of Pleurothallis in its traditional sense are shown in red (Jost & Endara, 2004). Segregate genera shown in other colors.

Holomorphology

Holomorphology (total form) refers to a complete collection of characters or a complete description of an organism (Hennig 1966). This concept is particularly useful for organisms that have more than one life stage, such as insects. This total-evidence approach has been defined as the analysis of an unpartitioned matrix of all available data. Williams

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(1994) characterizes such a body of evidence as one that produces the best-fitting phylogenetic hypothesis, when used in cladistic methods that maximize character congruence for a group of terminal taxa. Proponents of holomorphology hold that all of the independent characters available to the systematists should be combined and then analyzed using parsimony. Simulation studies have shown that a greater number of characters translate into greater accuracy under a variety of circumstances (de Queiroz et al. 1993). A logical extension of that argument suggests that all available taxa be combined in a single phylogenetic analysis (Huelsenbeck et al. 1996). Graybeal explored the effects of adding taxa and/or characters on phylogenetic accuracy, taxon resolution, and clade support; he found that when the total number of characters remains constant, accuracy is much higher if the

characters are distributed across a large number of taxa (Graybeal 1998). Similar conclusions, namely that denser species sampling yields a more robust phylogeny, have been reached by others (Lecointre et al. 1993, 1994; Hillis 1996; Purvis & Quickie 1997).

The possibility that two data sets may represent different phylogenetic histories has become an argument against combining data in phylogenetic analysis. However, two data sets that are sampled for a large number of taxa may differ in only a portion of their histories. In this situation the relative advantages of combined, separate, and consensus analysis become much less clear. Wiens (1998) proposed a simple methodology for dealing with this situation: analyzing the data sets separately; then combining the data but considering unresolved those parts of the combined tree that are strongly contested in the separate analyses until a majority of unlinked data sets support a single resolution. Computer simulations suggest that the accuracy of combined analysis for recovering the true phylogeny may exceed that of either of two separately analyzed data sets, particularly when the mismatch between phylogenetic histories is small and the estimates of the underlying histories are imperfect (high homoplasy). Combined analysis may provide a poor estimate of the species tree in areas of the phylogenies with different histories but gives an improved estimate in regions that share the same history. Thus, when there is a localized mismatch in the topology of two data sets, the separate, consensus, and combined analyses may all give unsatisfactory results in certain parts of the phylogeny. Similarly, approaches that allow data combination only after a global test of heterogeneity will suffer from the potential failings of either separate or combined analysis, depending on the outcome of the test. Elimination of conflicting taxa is problematic, in that doing so may obfuscate the position of conflicting taxa within a larger tree, even when their placement is congruent between data sets (Wiens 1998).

Total evidence produces the least assumption-burdened estimate of genealogy, and it maximally describes all of the available character evidence (Eernisse & Kluge 1993). During phylogenetic reconstruction, the influence of different evolutionary processes (environmental, genetic) need to be considered (Donoghue and Sanderson 1998). Unique topologies are sometimes found when combining matrices. A combined analysis increases the number of characters, which is known to increase the statistical support for the topology (Bremer et al. 1999). Combined analyses provide improved resolution with higher support (Kron& Judd 1997). Eernisse and Kluge (1993) propose that data sets be analyzed both separately and combined to potentially increase the descriptive effectiveness and explanatory power of the data. Albert (1994) used both molecular and morphological characters in his analysis of the relationships among the slipper orchids (Cypripedioideae).

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Morphological data - Morphological characters, in particular those of the flower and

more specifically those of the anther, have been the foundation for orchid classification since Swartz (1800). Characters such as anther orientation, pollinium number and orientation, and types of pollinium stalks have been used to define taxa from subfamily to genus (Dressler 1993). Other floral characters used to distinguish genera include number of stigma lobes, sepal connation, resupination, and similarity of perianth parts (Luer 1986). Luer also placed great weight on the evolution of lip mobility and segregated species having any one of the various mechanisms in which this trait has independently evolved (Luer 1986, 1987, 2000, 2006). Recent molecular studies of the orchids have demonstrated the homoplasious nature of these characters (e.g., Freudenstein & Chase 2003), which is not surprising since they are intimately involved in pollination mechanisms. This level of homoplasy is not a problem per se, since it is now clear that highly homoplasious data sets can still be highly structured (Källersjö et al. 1999). Given the small size of the morphological data sets constructed thus far, it has not been possible to obtain significant resolution within the subtribe based solely on morphological data.

Anatomical data - Pridgeon (1982) conducted an anatomical survey of 200 species in 22 genera of subtribe Pleurothallidinae and indicated which vegetative characters were of diagnostic value and at what taxonomic level. The established subtribal phylogenetic trends of reduction in number of pollinia and specialization of the perianth may be correlated with particular morphological trends, which are either reductionary or involve specializations directly related to the water relations of the epiphytic habit. The morphological analysis of Freudenstein and Rasmussen (1999) showed little resolution at lower taxonomic levels. Morphological data alone are not sufficient because of the relatively low number of characters compared to the large number of taxa to be studied (Chase et al. 2003).

Ongoing Research

Williams and Higgins are conducting a morphological analysis of the same species that are used for molecular data collection using species as terminals (Kron & Judd 1997). Our morphological data includes both floral and vegetative characters and most of the characters traditionally emphasized in orchid classification (e.g., Kurzweil 1987, 1988; Freudenstein and Rasmussen 1996, 1999; Freudenstein et al. 2002). See Table 2 for a list of 95 morphological characters. The previous cladistic analyses of the family scored relatively few characters, which is typical for morphological data sets in general. For example, Burns-Balogh and Funk (1986) scored 70 characters for 37 terminals within the family, whereas Freudenstein and Rasmussen (1999) used 71 characters for 98 generic level exemplars from across the family. Given that we are sampling a much larger number of taxa in a more narrowly defined group than any previous morphological study of orchids, we have increased the number of characters for the analysis. This is in part because the high sampling density will make characters that previously would have been autapomorphies (and were therefore excluded in the sparsely sampled data set) now relevant as synapomorphies. Although the total number of morphological characters will probably be relatively small compared to the molecular data, they can still play an important role in affecting and describing the topology (e.g., Baker et al. 1998). Careful morphological analysis will allow us to diagnose the clades recovered and characterize them in a user-friendly key, which cannot be done using molecular data alone.

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Table 2. Morphological characters (95) for Pleurothallidinae. Attrribute; state 0, state 1, state 2, state 3, state 4. plant characters:; plant habit: repent, cespitose; plant height (excluding inflorescence): <10 cm, > 10 cm; stem habit: superposed, distinct; rhizome: ascending, prostrate, pendent; stem characters:; stem: abbreviate, conspicuous; stem form: not cane-like, cane-like; stem internodes: 1, 2+; annulus: absent, present; cauline sheaths1: laterally compressed, tubular; cauline sheaths2: not speckled, speckled; stem sheaths1: enclosed imbricating sheaths, sheath near middle, several at base; stem sheaths2: not lepanthiform, lepanthiform; stem sheaths3: not overlapping, overlapping; stem sheaths4: glabrous, scurfy/pubescent; stem length1: shorter than leaves, longer than leaves, equal; stem length2: shorter than rhizome, longer than rhizome, equal; sheath surface: glabrous, pubescent; leaf characters:; leaf: not sheathing, sheathing; leaf base: not cordate, cordate; leaf surface: glabrous, ciliate/pubescent; leaf1: sessile, attenuate into a petiole; leaf2: membranous, coriaceous; leaf length: < 3 mm, 5+ mm; cuticle surface: smooth, papillose; epidermal papillae: absent, present; embedded inflorescence peduncle: absent, present; glandular trichomes: absent, 1 surface, both surfaces ; stomatal apparatus: flush with epidermis, raised above epidermis; inflorescence characters:; spathaceous bract1: not foliaceous, foliaceous, inconspicuous; spathaceous bract2: not enclosing flowers, enclosing flowers; floral bracts: not spiculate, spiculate; flowering: successive, simultaneous, solitary flower; flower stalk: pedicellate, sessile; inflorescence emergence point: leaf apex, middle of leaf, terminal on stem, lateral on stem, rhizome; inflorescence: racemose, paniculate, fasciculate, solitary; resupination: resupinate, nonresupinate, variable; perianth shape; parts similar, parts dissimilar; pedicel surface: not verrucose, verrucose; peduncle: laterally compressed, terete; peduncle length: shorter than leaf, longer than leaf; sepal characters:; sepal veins: 1-veined, 2-3 veined; sepals1: not verrucose, verrucose; sepals2, not spiculate, spiculate; sepals3: not caudate, caudate; sepals4, not echinate, echinate; sepal substance: fleshy, membranous; sepal-sepal fusion1; apices fused, apices free; sepal-sepal fusion2: basally connate, variously connate below apex, coherent, free; lateral sepal fusion to dorsal: not fused, fused forming trilobed fan-like calyx; lateral sepals1: not carinate, transversely carinate at base; lateral sepals2: without transverse callus, with transverse callus; lateral synsepal shape: different from dorsal sepal, similar to dorsal sepal; synsepal: absent, present; sepal apex: without callus pad, with callus pad; sepal interior; pubescent, glabrous; petal characters:; petal apex: not thickened, thickened; petal margins: entire, fimbriate to lacerate; petal shape: transversely bilobed, linear; petal length: subequal to sepals, distinctly smaller than sepals; petal substance: membranous, fleshy-thickened; petals1; not transverse, transverse; petals2; not auriculate at base, auriculate at base; petals3: no callus along labellar margin, callus on labellar margin; petals4: not angled, angled; labellum characters:; labellum attachment: not clawed, clawed; labellum base1: appressed to column foot, adnate to column foot, free; labellum base2: arm-like calli, other calli; glenion: absent, present; labellum carinate; no, yes; labellum divided into epichile/hypochile: no , yes; labellum hinge1: simple to column foot, articulated to bulbous apex of column foot, not hinged; labellum hinge2: under tension, loose; labellum shape: entire, lobed; labellum: radiating lamellae, hair-like appendages; labellum-column relation: not embracing column, embracing column; ovary, column, anther, stigma characters:; ovary: not ornamented, ornamented; ovary-pedicel: not articulate, articulate; column1: arching, straight; column2: not membranous, membranous; column3: not winged, winged; column foot1; absent, present; column foot2: pedestal-like, not pedestal-like; column foot3: curved, straight; column foot4: laterally compressed, not laterally compressed; column foot5; not bulbous, bulbous; column apex: not hooded, hooded; clinandrium: toothed, not toothed; anther position: apical, incumbent; pollinia number: 8, 6, 4, 2; pollinia shape: spherical, ovoid; pollinia size: unequal, equal; stigma1: apical, ventral; stigma2: entire, bilobed; stigma opening: not hooded, hooded;

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Current Pleurothallidinae taxonomy The current classification by Luer recognizes 4100+ species in 96 genera. The

classification system of Chase et al. only recognizes 32 genera including two that were moved out of Laeliinae. When the classification schemes of the subtribe by Pridgeon & Chase and Luer are compared, we find that the differences are more substantial than just splitting and lumping. Taking into account other treatments by Garay, Szlachetko, Barros, and Archila 34 monotypic genera have been described. This results in 116 generic names in current use, but with different circumscriptions for the genera. From a nomenclatural point of view eight of the proposed 124 generic names for Pleurothallidinae genera are invalid and can be excluded (Table 3). The invalid genera are: Anthereon, Barbrodria, Brachycladium, Echinella, Otopetalum, Physothallis, Triaristella, and Vestigium. Thus the question of Pleurothallidinae: How Many Genera? remains unanswered.

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Table 3. - Pleurothallidinae Generic Names with number of species per genus Aberrantia 1 Acianthera 220 Acinopetala 20 Acostaea 9 Acronia 37 Alaticaulia 117 Anathallis 118 Ancipitia 27 Andinia 12 Andreettaea 1 Anthereon 6 Antilla 12 Apatostelis 33 Apoda-prorepentia 7 Areldia 1 Arthrosia 11 Atopoglossum 3 Barbosella 39 Barbrodria 1 Brachionidium 72 Brachycladium 35 Brenesia 11 Buccella 9 Byrcella 42 Chamelophyton 1 Colombiana 6 Condylago 1 Crocodeilanthe 66 Cryptophoranthus 46 Cucumeria 1 Didactylus 4 Dilomilis 8 Diodonopsis 5 Dondodia 1 Draconanthes 2 Dracontia 17 Dracula 145 × Dracuvallia 2 Dresslerella 11 Dryadella 48 Echinella 9 Echinosepala 8 Elongatia 10 Empusella 1 Epibator 3 Expedicula 2 Fissia 3 Frondaria 1 Gerardoa 1 Gyalanthos 2 Incaea 1 Jostia 1 Kraenzlinella 17 Lepanthes 1133 Lepanthopsis 54 Lindleyalis 7 Loddigesii 1 Lomax 1 Lueranthos 1 Luerella 1 Luzama 30 Madisonia 1 Masdevallia 591 Masdevalliantha 2 Megema 7 Mirandopsis 1 Mixis 1 Muscarella 48 Myoxanthus 60 Mystacorchis 1 Neocogniauxia 2 Octomeria 201 Ogygia 1 Ophidion 4 Orbis 1 Otopetalum 1 Pabstiella 6 Panmorphia 47 Petalodon 4 Phloeophila 20 Physosiphon 30 Physothallis 3 Platystele 110 Pleurothallis 2083 Pleurothallopsis 16 Porroglossum 35 Proctoria 1 Pseudolepanthes 10 Pteroon 2 Regalia 10 Reichantha 18 Restrepia 107 Restrepiella 13 Restrepiopsis 21 Rhynchopera 10 Rodrigoa 9 Ronaldella 2 Rubellia 1 Salpistele 6 Sarcinula 25 Sarracenella 2 Scaphosepalum 67 Specklinia 39 Spectaculum 1 Spilotantha 35 Stelis 1051 Streptoura 1 Sylphia 4 Talpinaria 1 Teagueia 11 Tomzanonia 1 Triaristella 12 Tribulago 1 Trichosalpinx 157 Tridelta 1 Triotosiphon 6 Trisetella 25 Tubella 72 Unciferia 10 Unguella 2 Vestigium 1 Xenosia 2 Zahleria 3 Zootrophion 20 Zosterophyllanthos 53

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Concluding Objectives The goals of this research are to bring the various taxonomic approaches into a

unified analysis to produce 1) a stable nomenclature at the generic level; 2) to produce a user-friendly classification scheme that is presented via an interactive polyclave key for genera of Pleurothallidinae, that will allow scientists, commercial breeders, control authorities for CITES, USDA plant inspectors, and hobbyists to identify species in this group of orchids. The expected outcome of this project is a classification system based on total evidence in a rapidly evolving group of organisms that will further our understanding of the evolutionary history of morphological traits.

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