Disentangling Cuscuta identification in Brazil: a first taxonomic contribution to the northeast region species

Abstract

Cuscuta is a genus of Convolvulaceae distributed worldwide and comprises about 200 species, of which 26 were reported to Brazil. They are characterized by being holoparasites, leafless, gamopetalous, bisexual and usually pentamerous flowers. Studies available for South American Cuscuta are mostly from late XIX and early XX centuries. The restriction of taxonomic bibliographies, together with the fact that taxonomic informative characters are restricted to their tiny flowers, make the species identification a challenge. In this context, this work aimed to study the diversity of Cuscuta for the northeast region of Brazil and allow species identification. Field works were carried out in all northeast region states and about 150 specimens from 17 herbarium collections were analyzed. A lectotypification is proposed for C. racemosa. Cuscuta orbiculata, cited to Mexico, Guatemala and Brazil (Goiás and northeast region), is synonymized under C. tinctoria. Eight species were recognized, occurring mainly in areas of Caatinga, that predominates in the region. Descriptions, taxonomic comments, illustrations and an identification key are presented.

Key words:
dodders; floristic; Holoparasites; parasitic plants