Revisión Taxonómica de las Especies de Eryngium (Apiaceae) Presentes en Paraguay, y de los Taxones E. stenophyllum var. corymbosum y E. subinerme, Endémicos de Brasil
Abstract
Eryngium L. is a monophyletic genus and one of the most taxonomically complex in the family Apiaceae. Based on molecular phylogenetic studies, two subgenera are recognized and, informally, several lineages (or clades). The South American lineage of the subgenus Monocotyloidea Wörz is the richest in number of species and is extremely diverse morphologically and ecologically. Given the complexity and high richness of this lineage, its species have been studied taxonomically by region or country. One of the main centers of species richness for the lineage is found in Paraguay, southern Brazil, and northeastern Argentina. The Eryngium species that grow in Paraguay, in particular, represent a gap in the knowledge of the biodiversity of both the lineage and the genus. Therefore, the objective of this study was to conduct a taxonomic revision of the species of Eryngium that grow in Paraguay. Two taxa endemic to Brazil (E. stenophyllum Urb. var. corymbosum Urb. and E. subinerme (H. Wolff) Mathias & Constance) are also treated because of their affinity with species occurring in Paraguay and the taxonomic uncertainty surrounding them. To achieve this objective, the vegetative and reproductive morphology, as well as the geographic distribution and habitats of the species, were examined. The analysis was based on field studies and on more than 2600 herbarium specimens, including the original material of each name. For groups of species that are difficult to circumscribe (e.g., E. plantaginifolium H. Wolff–E. ciliatum Cham. & Schltdl, E. stenophyllum–E. sellowii H. Wolff, E. subinerme–related taxon), univariate and multivariate morphometric analyses were performed. In total, this work recognizes 29 species of Eryngium that inhabit Paraguay, seven of which are endemic to the country. Eryngium luzulifolium Cham. & Schltdl. is reported for the first time in Paraguay, and E. subinermifolium P. Esquivel Mattos & C. I. Calviño is described as a new species. For the taxa treated that are endemic to Brazil, E. stenophyllum var. corymbosum is elevated to species rank as E. corymbosum (Urb.) P. Esquivel Mattos & C. I. Calviño and recognized as morphologically distinct from E. stenophyllum and E. sellowii. A key for species recognition is provided. For each species, a list of accepted synonyms, a detailed morphological description, a distribution map, habitats, phenology, vernacular names, notes on morphological affinities between species, discussion, and resolution of nomenclatural problems are presented. In total, nine new synonyms are recognized, and four species are excluded from the flora of Paraguay: E. ciliatum, E. junceum Cham. & Schltdl., E. paniculatum Cav. & Dombey ex F. Delaroche, and E. serra Cham. & Schltdl. Twenty names are typified with 17 lectotypes, two neotypes, and one epitype, resolving historical confusions or uncertainties regarding species circumscription. New scientific illustrations are provided for eight species: E. eburneum Decne., E. hassleri H. Wolff, E. paraguariense Urb., E. plantaginifolium, E. rochei Constance, E. rojasii H. Wolff, E. sellowii, and E. subinermifolium, and four published illustrations from floras are modified: E. chamissonis Urb. (fruit), E. horridum Malme (basal leaf), E. juncifolium (Urb.) Mathias & Constance (basal leaf and fruit), and E. pandanifolium Cham. & Schltdl. (basal leaf). This study indicates that Paraguay is an important center of diversity and endemism for Eryngium. The results provide a fundamental framework for future studies on the systematics, biogeography, and conservation of Eryngium and the South American flora.
