Dalechampia L. (Euphorbiaceae) na Amazônia Brasileira

Abstract

Euphorbiaceae Juss. is acknowledged as one of the largest and most complex families of Angiosperms, with about 6.300 species and 245 genera. In Brazil it is represented by 63 genera and 950 species, distributed among all regions. In Amazon, there is still a gap in the taxonomic knowledge of this family, with Dalechampia being an example of a genus whose species have not yet received an updated treatment. This genus comprises several indeterminate or poorly identified samples in the collections of the herbaria, and it is therefor desirable to continue the studies on the species occurring in the region. In view of the above, a taxonomic study is proposed on the species of Dalechampia occurring in the Brazilian Amazon, updating their identifications, descriptions, nomenclature and geographical distribution. For this purpose, exsiccatae in national and international herbaria were studied: BHCB, F, HAMAB, HUEFS, HRB, IAN, INPA, K, MG, MICH, MIRR, MO, NY, R, RB, RON, SP, UFACPZ, UFG, UFMT and US, including some types and pictures of types, as well as samples of some specimens collected in the field. The study methods were those traditionally used in works on plant taxonomy, consisting basically of dissection, morphological anaysis, and description of the samples with the aid of a CARL ZEISS® stereoscopic microscope. 23 species were recognized in the Brazilian Amazon, namely: Dalechampia attenuistylus Armbr., D. affinis Müll.Arg., D. brownsbergensis G.L. Webster & Armbr., D. cissifolia Poepp., D. cujabensis Müll. Arg., D. dioscoreifolia Poepp., D. fragrans Armbr., D. gentryi Armbr., D. hastata G.L.Webster, D. heterobractea Armbr., D. juruana Ule, D. liesneri Huft, D. magnoliifolia Müll.Arg., D. megacarpa Armbr., D. micrantha Poepp., D. olympiana Kuhlm. & W.A.Rodrigues, D. parvibracteata Lanj., D. pernambucensis Baill., D. scandens L., D. sylvestris S.Moore, D. tenuiramea Müll. Arg., D. tiliifolia Lam. and D. triphylla Lam. Of these, two new occurrences are recorded for the Brazilian Amazon, one of them for Brasil and both for the state of Pará, as well as one synonymization and one lectotipification. The following taxa were excluded, which were believed to occur in the Brazilian Amazon: D. bangui Pax & K. Hoffm., D. linearis Baill. and D. weddeliana Baill., with D. bangui not occurring in Brazil, and D. linearis and D. weddeliana belonging to the Legal Amazon. Taxonomic commentary, dichotomous key, as well as maps and illustrations of the species are presented.