Considerações filogenéticas e taxonômicas na tribo Hureae Dumort. (Euphorbioideae- Euphorbiaceae)

Abstract

Euphorbiaceae s.s., with five subfamilies and about 6.300 tropical and subtropical species, is one of the most complex and diversified angiosperm lines. Under a phylogenetic perspective, the approaches concerning the family are scarce and restricted to the highest levels. Among the Euphorbiaceae subfamilies, Euphorbioideae is prominent since it aggregates the most variate and derivate groups. In this subfamily, the Hureae tribe is interest in some aspects: because it is paraphyletic; because it is close to Hippomaneae, an also unknown tribe; because of the difficult delimitation between the species; and because of the lack of knowledge about the evolution relations among the taxa, what highlights the need for phylogenetic studies. Composed of three American genera and about 20 species, Hureae is prominent because of the simplicity and homogeneity of its morphological-floral characters and its imprecise specific composition. Therefore, this study aimed to perform a morphological cladistic analysis of the Hureae tribe, seeking to investigate the validity of the morphological characters used in the genus definitions, besides a synoptic treatment to the tribe. Seventeen species were recognized and distributed among the genus Algernonia Baill. (11 species), Hura L. (1 spp.) e Ophthalmoblapton Allemão (4 spp.). Tetraplandra was treated as a subgenus of Algernonia. Most species are distributed in the Atlantic Forest domain, mainly dispersed in the southeastern region and associated to Ombrophilous Forests and resting forests. For the cladistic analysis, by consulting 500 voucher speciemens (including internal and out group) and the literature, 106 morphological characters were surveyed for 16 species of Hureae (internal group), eight species of the Hippomaneae tribe and the monotypical Pachystromatearesulted in 36 trees similarly parcimonious with a consistence index (CI) = 0,470 and a retention index (RI) = 0,625. Hureae was shown as monophyletic and it had Pachystromateae as the closest sister group. Algernonia and Ophthalmoblapton appeared as monophyletic taxa with 70% e 60% bootstrap, respectivly. Hura was pointed as a basal group, while Algernonia surged as a more derivate one. The clade for the Algernonia genus consisted of the subgenus Algernonia and Tetraplandra. In addition, it is proposed here a new classification for Ophthalmoblapton.e (both external groups). The maximal parcimony analysis.