To be, or not to be a Stelis

Abstract

Despite the availability of multiple sources of evidence and consistency in the support for a broadly circumscribed Stelis Sw. (Orchidaceae: Pleurothallidinae), some authors continue to be hesitant in its use. It is certain that the more typical species of Stelis, with their triangular, flattish flowers with very short fleshy petals and lip, form a monophyletic group that is easily recognized. However, it is likewise undisputed that they are not an isolated lineage in the subtribe and that several groups of species with a similar vegetative habit but that lack the typical Stelis flower are in fact very close relatives, sharing a relatively recent common ancestor. Those species groups need to be classified in a way that also reflects their own evolutionary history, and alternatives to a broadly circumscribed Stelis are possible yet neither straightforward or practical at this time. An infrageneric classification for the whole group is provided here in an attempt to clarify which species actually belong where in this highly complex affinity. Emphasis is made on the difficulty of diagnosing the less typical members of each proposed subgenus or section, and on the importance of floral convergence and divergence as a result of pollinator adaptation. As here defined, Stelis is the largest genus in the Pleurothallidinae, with 1243 species.
 Key words: convergence; evolutionary history; floral morphology; generic circumscription; Pleurothallidinae; pollinator adaptation

Typification of Costa Rican Orchidaceae described by Rudolf Schlechter. Species variorum collectorum

“…However, based on the collection data of the label of the lectotype at US and the isolectotype at CR herbaria (not cited by , the main collector Figures as Paul Biolley According to the most recent infra-generic classification of Stelis, P. listerophora is placed under Stelis subgen. Unciferia (Luer) Karremans (2019), where it is treated as S. listerophora (Schltr.) Pridgeon & M.W.Chase (2001).…”

Stelis breviloba (Orchidaceae, Pleurothallidinae), a new species from Mexico

“…(Karremans et al 2013), and that it constitutes a wellsupported monophyletic group within this genus. Therefore the group was recently recognized as a subgenus of Stelis (Karremans 2019, Karremans & Vieira 2020, which is sister to a clade that includes S. subgen. Niphantha (Luer) Karremans, S. subgen.…”

A new Stelis (Orchidaceae: Pleurothallidinae) from the Western Andes of Colombia

“…Introduction. With +1240 species in its broadest circumscription, the Neotropical genus Stelis Swartz (Orchidaceae) is the largest in subtribe Pleurothallidinae, and one of the largest genera of the Orchidaceae family (Karremans 2019). Many of the taxa occur in large sympatric populations restricted to the humid environment from Florida (USA), through Central America and the Antilles, to Brazil and Paraguay (Karremans 2013, GBIF 2020.…”

“…Many of the taxa occur in large sympatric populations restricted to the humid environment from Florida (USA), through Central America and the Antilles, to Brazil and Paraguay (Karremans 2013, GBIF 2020. Stelis is one of the most important epiphytic components of the Andean forest, especially the members of Stelis subgen Stelis which include over 1030 species with the typical Stelis flower morphology (Karremans 2019).…”

“…In this way, Colombia accounts for about 48% of the global diversity of that subgenus and the 40% of the genus Stelis in its broadest circumscription. Because of the complexity and variety of ecosystems, high rainfall, microclimate diversity and orographic factors, in Colombia, there are still gaps in our knowledge of orchid biodiversity, in particular, the forest canopy remains to be throughly explored (Reina-Rodríguez 2016, 2019.…”