Guarçoni 2015 (Conference Paper) Dyckia

Morphometric analyses of the Dyckia saxatilis complex (Bomeliaceae)

Author(s):—E. Guarçoni & A. Costa in Benko-Iseppon, A.M.; Alves, M. & Louzada, R. (2015) An overview and abstracts of the First World Congress on Bromeliaceae Evolution. Rodriguésia 66(2): A1-A66.

Publication:— (2015).

Abstract:—Dyckia is the second largest genus of the subfamily Pitcairnioideae, with 163 species occurring throughout Brazil and neighboring countries (Argentina, Bolivia, Paraguay and Uruguay). Brazil retains 140 species, of which 127 are endemic and mostly grow in cerrado areas (80 spp.). Recent molecular work split the genus intofour ecological groups, although infrageneric molecular data are presently poorly defined, with paraphyletic or polyphyletic groups. This situation is probably due to taxonomic problems in the delimitation of its species, as Dyckia shows only a limited range of morphological variations, contributing to a number of uncertainties in the delimitation of its species. While some species of Dyckia can be easily distinguished morphologically, others require additional tools to assist in their delimitations due to the absence of clear morphological discontinuities between some groups of species in terms of their vegetative and reproductive characters. In this context, analyses of morphological variations in natural populations have proven useful in distinguishing species from different genera in the family. In order to delimit the species of the Dyckia saxatilis complex,we sampled 256 individuals representing 14 populations occurring in areas of rocky field vegetation in Minas Gerais State. Discriminant analysis of 30 morphological variables showed clear distinctions between species occurring in the Iron Quadrangle and those occurring in the central region of the Espinhaço Range. The populations occurring in the municipalities of Ouro Preto (type locality of the species) and Mariana were separate from the others. The lengths and distances between the leaf spines and the extent of filament connation were the variables that most contributed to grouping the populations. Eleven species (two of which were restored from synonymy with Dyckia saxatilis, and two new ones) were identified. These results demonstrate that morphometric analyses associated with intensive fieldwork are fundamental to defining species delimitations.

Keywords:—Taxonomy; Poales; Discriminant Analysis.