Morphology and systematics of the pitvipers (Viperidae: Crotalinae) of austral South America

CARRASCO, P. A., MATTONI, C. I., LEYNAUD, G. C., SCROCCHI, G. J.

Calci, Italia

Conferencia; 3rd Biology of the Vipers Conference; 2010

Museum Natural History and Territory, University of Pisa, Italy

Systematics of the pitvipers of the genus Bothrops and closely related genera (Bothrocophias, Bothriopsis) is complex because of the morphological and ecological diversity of these species. Some authors suggested that this great diversity is probably due to a relatively recent colonisation in a continent previously devoid of vipers, and attributed the low support obtained for most of the groups to a rapid speciation. Moreover, Bothrops and Bothriopsis species distributed in Bolivia and Peru have been rarely included in phylogenetic analyses and systematic affinities of some of them still remain unclear. In general, phylogenetic relationships within the Bothrops complex have been analysed mostly using molecular evidence, and rigorous morphological examinations and a deeper understanding of polymorphisms are still needed for a total evidence approach. In this study, we made an extensive revision of the morphology of the species of Bothrocophias, Bothrops and Bothriopsis distributed in austral South America, including those species that remain incertae sedis, and we analyzed this evidence with cladistic methods. The morphological study was performed examining lepidosis and color pattern, hemipenial morphology and cranial osteology of Bothrops ammodytoides, B. alternatus, B. cotiara, B. jonathani, B. diporus, B. mattogrossensis, B. barnetti, B. andianus, B. pictus, B. roedingeri, B. sanctaecrucis, B. jararacussu, B. brazili, B. jararaca, B. atrox, Bothrocophias microphthalmus, B. hyoprora, Bothriopsis chloromelas, B. bilineata smaragdina, and B. oligolepis. Discrete (60) and continuous (30) characters were analysed using the program TNT (Goloboff et al., 2008). Polymorphic characters were coded using different criteria of presence and weight, and alternative analyses were carried out only with morphology data and combining morphology with mitochondrial characters obtained from GenBank. Crotalus durissus, Lachesis muta and Cerrophidion godmani were included as outgroups. The results suggest that at least two different radiations may have occurred, and that basal taxa comprise species associated with the Andes. The groups of species recovered in several of the alternative analyses also show that the current taxonomy for the Bothrops complex requires reevaluation.