Synopsis of Tridactyle (Orchidaceae: Epidendroideae: Vandeae: Angraecinae) in São Tomé and Príncipe, with the Description of Four New Species

International audienceA synopsis of Tridactyle Schltr. (Orchidaceae) in São Tomé and Príncipe is presented. We recognize nine species in São Tomé and Príncipe, including four new species. We describe here T. amadorii D’haijère, T. cocophila D’haijère, T. levelevis D’haijère & Stévart, and T. oboensis D’haijère & Stévart. Tridactyle armeniaca (Lindl.) Schltr., recorded by previous studies, is native to West Africa and is not found in São Tomé and Príncipe. Tridactyle exhibits an important diversification in São Tomé and Príncipe, with seven species being endemic (endemism rate > 75%). Here, new records are registered; the natural distribution ranges, habitat, ecology, and conservation status based on IUCN guidelines are detailed for all species; two names are lectotypified; and an identification key is provided

Taxonomic description and pollination ecology of Cyrtorchis okuensis (Orchidaceae, Angraecinae), a new species endemic to the Cameroon Volcanic Line

International audienceBackground and aims-A recent taxonomic and molecular study of the genus Cyrtorchis revealed three new species. Here, we describe one of these new species, endemic to the Cameroon Volcanic Line (CVL), and compare it to its closest relatives. Its conservation status is provided along with detailed information on its ecology and reproductive biology. Material and methods-A detailed examination of 21 herbarium specimens was performed using standard practices of herbarium taxonomy. The conservation status of the new species was assessed using the IUCN Red List Categories and Criteria. Furthermore, we investigated the reproductive biology of the new species in an easily accessible subpopulation in Cameroon and tested the hypothesis of hawkmoth pollination in the genus Cyrtorchis. Key results-The newly discovered species, here named C. okuensis, is restricted to the montane forest (1600 to 2500 m elevation) of the CVL and is currently assessed as Near Threatened (NT). Among angraecoid orchids in which hawkmoth pollination is recorded (~16 species), C. okuensis has the shortest nectar spur (19-40 mm). In situ observations revealed hawkmoths with short proboscis of the genus Hippotion (H. celerio, H. eson, and H. osiris) as the main pollinators. The rate of pollination and fruiting under natural conditions was low and among the 448 surveyed flowers only 38.8% (174/448 flowers) had their pollinia removed, 19% produced fruits (87/448 flowers), and 16% (70/448 flowers) set mature fruits. Conclusion-Cyrtorchis okuensis is clearly differentiated from C. submontana by its longer and wider floral bracts, longer anther caps, and wider triangular dorsal sepal

An Elegy to Rangaeris, Including a Description of Two New Genera in the Cyrtorchis–Tridactyle Clade (Orchidaceae, Angraecinae)

International audienceThe phylogenetic position of Rangaeris (Schltr.) Summerh. has been one of the most problematic issues of angraecoid orchid taxonomy. A recently published phylogenetic tree with nearly comprehensive taxon sampling of African angraecoid orchids suggested that this genus was polyphyletic, as its species appear nested within different subclades of the Cyrtorchis–Tridactyle clade. However, the lack of DNA data for the generic type, R. muscicola (Rchb. f.) Summerh., and for the little-known species R. longicaudata (Rolfe) Summerh. and R. trilobata Summerh., has precluded an integrative reappraisal of the delimitation of this genus. Here we present the results of a new phylogenetic analysis of one nuclear (ITS) and five plastid markers (matK, rps16, trnC-petN intergenic spacer, trnL-trnF intergenic spacer, ycf1) for all six species of Rangaeris, including those recently transferred to Podangis Schltr. and Ypsilopus Summerh., together with a representative sampling of 14 other species of the genera Cyrtorchis Schltr., Listrostachys Rchb. f., Plectrelminthus Raf., Summerhayesia P. J. Cribb, Tridactyle Schltr., and Ypsilopus. Based on molecular and morphological evidence, R. muscicola is transferred to Podangis, where Rangaeris is reduced to the rank of section. In addition, R. longicaudata and R. trilobata are each moved to new monotypic genera, Planetangis Stévart & Farminhão and Aziza Farminhão & D’haijère, respectively. An identification key for all genera of the Cyrtorchis–Tridactyle clade is presented, together with one for the three species of recircumscribed Podangis. Finally, taxonomic accounts of the new genera are presented, including amended descriptions, illustrations, distribution maps, and preliminary conservation status assessments of their species

Integrating systematics and reproductive biology into African orchid conservation: a case study with the genus Cyrtorchis Schltr. (Angraecinae, Vandeae)

International audienceDeveloping conservation strategies of threatened species involves understanding their taxonomy, ecology and reproductive biology, and to integrate this knowledge into rational conservation management actions. Focusing on Cyrtorchis, we present here an approach that combine taxonomy and reproductive biology to develop the conservation of this angraecoid genus renowned for its challenging species delimitation problem. Indeed, its showy white long-spurred flowers, indicating a probable sphingophilous syndrome, constitute a suitable model for studieson reproductive biology of epiphytic orchids, a first step indispensable for their conservation. By using phylogenetic analyses, we tested the monophyly of 23 species hypotheses delimited using morphometrical analyses to clarify species delimitation. Based on this taxonomic background, we chose seven well-resolved species (C. aschersonii, C. ringens, C. cf ringens, C. chailluana, C. letouzeyi, C. monteiroae and a new species) to study, in our living collection in Yaoundé and in two natural populations, their breeding and pollination systems. A protocol involving phenological monitoring of 414 living specimens was implemented during which 330 hand-controlled pollination tests (177 self-vs 153 cross-pollinations) were conducted to assess factors affecting fruit set and seed viability. Pollination efficiency and reproductive success were assessed using fruit set and viable seeds production. Camera and insect light trapping were used for survey and identificationofpollinators. Preliminary results show that the flowering period of 13 species occurring in Cameroon occurs from February to November, with a flowering peak during the rainy season. For the first time in Central Africa, hawkmoths were confirmed as potential pollinators of three species of Cyrtorchis. Seeds produced are used to supply the African orchid seed bank housed at the University of Yaoundé I which currently includes 146 specimens representing 50% of Cyrtorchis species

A near comprehensive phylogenetic framework gives new insights toward a natural classification of the African genus Cyrtorchis (Angraecinae, Orchidaceae)

International audienceThe genus Cyrtorchis is renowned for its conspicuous white, long-spurred flowers, but also for its challenging problems of species delimitation due to the great morphological resemblance of their flowers. Based on a preliminary visual inspection of 1752 specimens, 27 morphogroups were defined including 6 unpublished taxa. Then, we used a representative sampling of 171 dried and alcohol-preserved specimens representing 20 morphogroups to perform linear morphometrics through multivariate analyses on 43 morphological characters in order to confirm morphogroups delineation and identify their discriminant characters. Moreover, the monophyly of the two sections and of 21 morphological entities was tested through molecular analyses in order to produce a natural classification of the genus. DNA sequences from 69 Cyrtorchis specimens belonging to 15 published taxa (seven from C. sect. Homocolleticon, eight from C. sect. Cyrtorchis), six putative new Cyrtorchis taxa, as well as four taxa used as outgroups, were produced using one nuclear (nrITS-1) and five plastid regions (matK, rps16, trnC-petN intergenic spacer, trnL-trnF intergenic spacer, ycf1), and were analyzed using maximum likelihood and Bayesian approaches. We used this phylogenetic framework to infer the morphological character-state evolution of six floral traits and assess their taxonomic value. Morphological analysis revealed two groups corresponding to the published sections. However, while molecular results recovered the monophyly of C. sect. Cyrtorchis, C. sect. Homocolleticon appears paraphyletic. Of the 21 morphologically defined taxa that were included in the molecular analyses, eight, namely C. aschersonii, C. henriquesiana, C. monteiroae, C. praetermissa, C. ringens, and three new taxa were proven monophyletic. The delimitation of the 19 remaining morphologically identified taxa was assessed using morphological approach only. The ancestral state reconstruction provided new insights into character-state evolution in the genus by inferring the insertion point of the stipites at the rear third of the length of the viscidium as one of the main synapomorphic characters supporting the monophyly of the genus. Furthermore, viscidium structure, stipites shape, and the lateral lobes of the rostellum were found to be important to infer phylogenetic relationships within the genus