REDESCRIPTION OF ATRACTUS ALBUQUERQUEI (SERPENTES: COLUBRIDAE: DIPSADINAE), WITH COMMENTS ON GEOGRAPHICAL DISTRIBUTION AND INTRASPECIFIC VARIATION HUSSAM ZAHER 1 IVAN SOUZA 2 DAVID J. GOWER 3 ERIKA HINGST-ZAHER 4 NELSON JORGE DA SILVA JR. 5 ABSTRACT Atractus albuquerquei Cunha and Nascimento, 1983 was previously known from a holotype from eastern Pará, and 15 specimens from Rondônia and Acre, all in Brazil. We report on 23 additional specimens from the Brazilian states of Rondônia, Goiás, Mato Grosso, and Mato Grosso do Sul. These specimens extend the known range of A. albuquerquei substantially, and beyond the southern limits of the Amazon basin. The holotype of A. albuquerquei is redescribed and intraspecific variation in external morphology, hemipenes, and colour is documented. Sexual dimorphism exists in total length, and number of ventral (significantly greater in females) and subcaudal scales (greater in males). There is a significant correlation between number of subcaudal scales and longitude (decreasing from East to West) for both males and females. KEYWORDS: Serpentes, Dipsadinae, Atractus albuquerquei, variation, distribution. INTRODUCTION Species of the neotropical colubrid snake genus Atractus are known to be poorly represented in museum collections (Myers, 2003), although there are exceptions (e.g. Atractus reticulatus). As a result, knowledge of the natural history, morphological variation, and geographical distribution of most species of Atractus is far from satisfactory. Atractus albuquerquei is one of the many species of this genus that has been recorded only sporadically after its formal description by Cunha and Nascimento (1983). These authors based their 1 Museu de Zoologia, Universidade de São Paulo, Caixa Postal 42494-970, 04218-970, São Paulo, SP, Brasil. E-mail: hzaher@ib.usp.br 2 Museu de Zoologia, Universidade de São Paulo, Caixa Postal 42494-970, 04218-970, São Paulo, SP, Brasil. E-mail: souzai@terra.com.br 3 Department of Zoology, The Natural History Museum, London, SW7 5BD, England. davig@nhm.ac.uk 4 Museu de Zoologia, Universidade de São Paulo, Caixa Postal 42494-970, 04218-970, São Paulo, SP, Brasil. E-mail: hingstz@usp.br 5 Centro de Estudos e Pesquisas Biológicas, Universidade Católica de Goiás, Av. Universitária, 1440, Setor Universitário, 74605-010, Goiânia, GO, Brazil. Volume 45(2):19-32, 2005