Sistemática de Rhynchospora seç. Pauciflorae Kük. (Cyperaceae).

Abstract

Rhynchospora Vahl (Cyperaceae) has approximately 400 known species, is a highly diverse genus in the Americas, particularly in the Neotropics, and has significant levels of endemism in tropical and subtropical savannas. It is also the richest genus of Cyperaceae in Brazil, with species occurring in all states and phytogeographic domains. The genus was revised and divided by Kükenthal into two subgenera and 28 sections, which have since been revisited by other researchers. Rhynchospora sect. Pauciflorae has never been revised since its establishment by Kükenthal in 1949. It is part of an informal group created by the author, "Pars Capitatae," which also includes R. sect. Pluriflorae. Researchers who have revised R. sect. Pluriflorae have emphasized the importance of taxonomic and systematic studies in R. sect. Pauciflorae to test the monophyly of the section and better understand its relationship with its sister section, as the two share traits used in its circumscriptions sensu Kükenthal. Rhynchospora sect. Pauciflorae had 20 species, 13 from the subsect. Plumososetosae, occurring in the Neotropics, Australia and Asia, and 7 from the subsect. Scabrosetosae, restricted to Asia and Australia. The objective of this project was to conduct taxonomic, and morphological, studies on Rhynchospora sect. Pauciflorae (Cyperaceae) to elucidate biodiversity, and refine the circumscription of the taxa studied. Field expeditions were conducted to collect botanical material, along with in-person consultations of herbarium collections in Brazil and the United States, as well as databases and images from international herbaria. The taxonomic treatment was carried out through consultation of original works and nomenclatural types. We are proposing 24 first-step lectotypifications, and 2 second-step lectotypifications. Scanning Electron Microscopy (SEM) images of the external micromorphology of the fruits were taken. More than 2,500 specimens were analyzed, with 16 species of R. sect. Pauciflorae treated for the Neotropics, three of which were described during this revision. This study presents chapters describing a new species of R. sect. Pluriflorae, a chapter with 17 lectotypifications in R. sect. Pauciflorae, descriptions of two new species in sect. Pauciflorae, and a taxonomic revision of Neotropical R. sect. Pauciflorae, in this chapter first-step lectotypifications were made for Rhynchospora barbata (Vahl) Kunth, R. trichochaeta C.B. Clarke, and a second-step lectotypification for R. subplumosa C.B. Clarke, as well as for section Pauciflorae and subsections Scabrosetosae and Plumososetosae. Additionally, Rhynchospora unisetosa T. Koyama is proposed as a new synonym for R. hirta (Nees) Boeckeler, and Rhynchospora denticulata Huber is being reinstated as an accepted species.