Revisão taxonômica do complexo Crotalus durissus (Squamata: Viperidae).

Abstract

Crotalus durissus complex is formed by 11 subspecies, which six occurs in Brazil. The original description of C. durissus was made by Linnaeus in 1758 and since then, there has been much disagreement regarding the taxonomic classification and geographical distribution of this species. The absence of the holotype, lost since 1828, the chaotic taxonomic history, and the morphological overlap impede a comprehensive taxonomic review for a long time. Here, we analyze the morphology of rattlesnakes, considering patterns and variations of spots, coloration, scales counting, morphometric measurements and analysis of hemipenis. We focus on Brazilian populations, considering the biomes Amazon, Caatinga, Cerrado, Atlantic Forest, ecotone areas, and other ecoregions of South, Central and North America. Through original descriptions, current literature, and analyzes of specimens listed in zoological collections, we verify the distribution of populations, testing sexual dimorphism and possible patterns and variations within and between subspecies. The subspecies were morphologically grouped by NMDS in two large groups, south of the Amazon River group, formed by C. d. durissus, C. d. ruruima and Crotalus vegrandis, and the north group, by C. d. cascavella, C. d. collilineatus, C. d. marajoensis and C. d. terrificus. Considering the neotype from Suriname, defined in 2005 by Savage et al., the International Code of Zoological Nomenclature and the morphological analyzes with statistical support, we elevated and redescribed the following species Crotalus durissus, Crotalus terrificus, Crotalus cascavella, Crotalus collilineatus, Crotalus marajoensis and Crotalus ruruima. The main diagnostic characteristics include extension of the paravertebral stripes, presence or absence of a white arc in the supraocular scale, spots in the anterior region of the head, count of dorsal scales and quantity and distribution of hemipenial spines. An identification key is provided. We found that C. durissus, C. marajoensis and C. ruruima have more restricted distributions and smaller sample sizes.