Species richness and composition of snake assemblages in poorly accessible areas in the Brazilian Amazonia

Abstract

Snakes are a diverse group of terrestrial vertebrates of the order Squamata. Despite that, in the Amazonian biome, information about distribution and identification of snakes is limited when compared to other groups. Additionally, in Amazonia there is a sampling bias towards areas geographically close to urban centers and more densely populated areas. This in turn leads to false distribution gaps in poorly accessible areas of Amazonia. In this article we report the composition of snake assemblages in six areas of the Brazilian Amazonia, based on field sampling conducted over four years using standardized methods. We sampled 70 species from eight families: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7), and Viperidae (n=5). The largest number of species was recorded in the Trombetas River area and the lowest in the Jatapu River area. The total beta diversity was 0.40 and the snake assemblages were structured mainly by replacement (72.5%). The time-limited search was the method that recorded the greatest number of individuals in the studied areas (44.1%) and also the greatest number of species (n=40). However, some species were recorded only by other methods such as interception by pitfall traps with directional fences. Despite the large number of species sampled in the study, no particular area comprised more than 40% of species registered in all the areas, indicating that snakes are poorly detected even with large sampling effort across multiple areas of a species distribution. Riqueza de espécies e composição de assembleias de serpentes em áreas pouco acessíveis na Amazônia brasileiraResumo: Serpentes compõem um diverso grupo de animais vertebrados terrestres pertencentes à ordem Squamata. Apesar de serem um dos grupos mais diversos do mundo, na Amazônia, as informações acerca da taxonomia e distribuição de serpentes são limitadas quando comparadas com as disponíveis para outros grupos de vertebrados. Além disso, na Amazônia existe um viés de amostragem em áreas geograficamente próximas aos centros urbanos e locais densamente povoados. Isso por sua vez leva a falsas diferenças de distribuição em áreas pouco amostradas. Neste artigo nós apresentamos a composição de assembleias de serpentes em seis áreas na Amazônia brasileira, baseada em amostragens de campo padronizadas e realizadas durante quatro anos. Foram amostradas 70 espécies de oito famílias: Typhlopidae (n=1), Leptotyphlopidae (n=1), Anillidae (n=1), Boidae (n=5), Colubridae (n=15), Dipsadidae (n=35), Elapidae (n=7) e Viperidae (n=5). A maior riqueza foi registrada no Rio Trombetas e a menor no Rio Jatapu. A beta diversidade total foi de 0.40 e a substituição foi a principal força que estruturou as

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