Phylogeny and revision of Psyllocarpus Mart. ex Mart. & Zucc. (Rubiaceae, Spermacoceae), an endemic genus from Brazil

SALAS, R.M.; SIMOES, A.O.; CARMO, J.A.M.

Copenhagen

Conferencia; VII International Rubiaceae and Gentianales Conference; 2017

Natural History Museum of Denmark - Botanica

Psyllocarpus belongs to the Spermacoce clade within Spermacoceae, being considered one of the morphologically well-defined genera in the tribe and preliminarily supported in phylogenetic studies. It was recovered as monophyletic with maximum support in an analysis based on two species and two nuclear regions, sister to a clade of Spermacoce species. In the last taxonomic revision of the genus, it was classified in two sections, based on morphologyand geographic distribution. Psyllocarpus sect. Psyllocarpus is characterized by terete leaves, homostylous flowers, prolate-spheroidal pollen grains, non-perforated and spinulose along each side of the colpi exine, and bilobate stigma. This section occurs in the ?cerrado? and ?campos rupestres? from the Espinhaço range and the Planalto Central of Brazil, comprising five species. Psyllocarpus sect. Amazonica also presents capsules strongly compressed parallelto the septum but is characterized by planar leaves, heterostylous flowers, oblate-spheroidal pollen grains, perforated, finely and evenly spinulose exine, and bifid stigma, being restricted to white-sand Amazonian ?campinas?, comprising three species. More recently, two species from the Espinhaço range were described but not classified in any section. The objectives of this study are to produce a taxonomic revision of Psyllocarpus and to infer its phylogeny. We consulted 28 herbaria, accounting for ca. 1500 specimens analysed. Field expeditions were carried out to collect fresh samples for the molecular study. We estimated a phylogeny based on two plastid regions (rps16 and trnL-F) and nine species using Bayesian inference. We discovered four new species, which are being described. Notably, P. laricoides is a species complex. Psyllocarpus sect. Psyllocarpus was supported as monophyletic with maximum support. Psyllocarpus densifolius is not related to the other species of the genus and formeda long branch. We still need to produce sequences from nuclear regions and include the missing species in our analysis.