Abstract
BackgroundPsilochilus is a poorly studied orchid genus distributed from southern Mexico to south-eastern Brazil. A taxonomic revision of this Neotropical endemic based on morphological data is presented.Material and MethodsOver 170 dried herbarium specimens and flowers preserved in liquid of Psilochilus were analyzed. Morphological variation among examined taxa was described based on multivariate analysis. To evaluate the similarity between niches occupied by various Psilochilus species ecological niche modeling (ENM) was applied. Species richness and the distribution patterns of Psilochilus representatives were analyzed based on squares of 5° latitude and longitude while similarities among floras between biogeographical units were measured using the Bray-Curtis index for presence/absence data.Results and DiscussionA new species of the P. physurifolius-complex is described based on Central American material. Psilochilus crenatifolius is reduced to the rank of variety as P. macrophyllus var. crenatifolius. A key to 18 accepted Psilochilus species is provided. The illustrations of perianth segments of all recognized taxa are presented. The climatic niches preferred by the particular Psilochilus representatives are well separated based on ecological niche modeling analysis. Their distribution is limited mainly by the isothermality and temperature seasonality. The highest Psilochilus species richness is observed in the North Andean, Panamanian, Brazilian Planalto and Central American biogeographical provinces. A high level of endemism is observed in all those regions as well as Yungas biogeographical province. Most Psilochilus species occur in areas above 800 m of elevation. The populations were most often reported from the tropical rain forest and tropical moist deciduous forest.
Highlights
The orchid genus Psilochilus was described in 1882 (Barbosa Rodrigues, 1882) based on P. modestus
Morphological study Over 170 dried herbarium specimens (Fig. 1, Annex 1) and flowers preserved in liquid deposited or borrowed from herbaria AMES, COL, F, K, MEDEL, McPherson 9679 (MO), NY, R, UGDA, US, and W were examined according to the standard procedures
During examination of the herbarium material several specimens which based on their morphology could not be classified within any currently known Psilochilus representative were found
Summary
The orchid genus Psilochilus was described in 1882 (Barbosa Rodrigues, 1882) based on P. modestus. Pogonia Jussieu (1789), the genus which for a long time was recognized as a large taxon that included rather primitive, tropical, terrestrial species Those orchids were recognized based on subsimilar tepals, lip ornamented with various forms of calli and having slender gynostemium with an apical anther and soft, mealy pollinia. Several genera were segregated from Pogonia s.l., e.g. the New World Cleistes Richard ex Lindley (1840), Isotria Rafinesque-Schmaltz (1808) and Triphora Nuttall (1818), as well as Paleotropical Nervilia Commerson ex Gaudichaud-Beaupre (in Freycinet, 1829) These taxa may be distinguished one from another based on structure of pollinia, gynostemium and seeds as well as based on the foliage. The climatic niches preferred by the particular Psilochilus representatives are well separated based on ecological niche modeling analysis Their distribution is limited mainly by the isothermality and temperature seasonality. The populations were most often reported from the tropical rain forest and tropical moist deciduous forest
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