Statistical analyses of morphological variation in the Gymnopodium floribundum complex (Polygonaceae): definition of three subspecies

Abstract

Background and Aims: Morphological variability in Gymnopodium floribundum along its distribution area has been the source of taxonomic and nomenclatural inconsistencies, sometimes recognizing up to three species and two varieties. In this paper we present morphometric analyses of variation in 224 specimens of G. floribundum in order to determine the existence of morphological patterns that correspond to geographically structured phenotypic diversity.Methods: The data matrix consisted of 224 specimens and 32 characters, 21 were quantitative and 11 qualitative. A dendrogram was estimated with UPGMA’s algorithm and the Gower´s coefficient. The 21 quantitative characters were subjected to principal components analysis. With the groups identified in the dendrogram, we performed a PERMANOVA using all quantitative characters. Canonical Variate Analyses of leaf shape and perianth segment shape of all specimens were executed.Key results: The results of multivariate analyses suggest the existence of three phenetic groups, which mostly correspond to three geographic regions: Belize, the Pacific Coastal Plain and the Yucatán Peninsula. These groups are distinguished by the presence or absence of indument on leaf blade, ochrea and petiole, the distances between the floral fascicles, and the length and width of the external and internal segments of the perianth. Two of the geographic groups correspond to infraspecific taxa previously recognized by Standley and Steyermark. Our distances and shape morphometric analyses uncover a third group from the southern Pacific region which presents novel characters.Conclusions: Based on these results we raise the rank of two varieties G. floribundum var. antigonoides and G. floribundum var. floribundumto subspecies, and propose to recognize a new third subspecies: Gymnopodium floribundum subsp. chiapensis.