Diversidade taxonômica e distribuição potencial do gênero Amerotyphlops (Squamata: Typhlopidae) no estado de Alagoas, nordeste do Brasil e fisiologia térmica do Amerotyphlops brongersmianus (Vanzolini, 1976)

Abstract

Scolecophidia is a group of fossorial snakes with a main tropical distribution. The most specious family of this infraorder is Typhlopidae with approximately 275 current species. Among the 18 genera allocated to this family, Amerotyphlops, with neotropical distribution, includes 15 species, seven of which have already been recorded for Brazil and four for the state of Alagoas. However, this diversity is probably underestimated because, due to its fossorial habit and consequent difficulty in finding and collecting, there are still gaps in both taxonomic knowledge (Linnean deficit) and geographic distribution (Wallacean deficit) for this group of snakes. To fill these gaps, the use of different approaches has been shown to be efficient. In this study, morphological and molecular data were integrated to assess the taxonomic diversity of Amerotyphlops in Alagoas. Through species distribution modeling (SDM), areas in Alagoas with environmental suitability for some species were identified directing field efforts. And finally, the thermal physiology of a species of Amerotyphlops was measured in the laboratory.Seventeen Amerotyphlops specimens had their morphology (16 continuous and four discrete characters) checked. Nineteen samples of muscle or liver tissue from five locations in Alagoashad the total genomic DNA extracted, and a fragment of the mitochondrial gene 16SrRNA amplified, sequenced and aligned with its cospecific sequences. SDM using 62 occurrence points for A. brongersmianus and eight points for A. paucisquamus, and eight environmental variables were performed using Maxent algorithm. And for thermal physiology, the preferentialtemperature (Tpref), minimum and maximum voluntary temperatures (Vtmin and Vtmax), minimum (Ctmin) and maximum (Ctmax) critical temperatures and the thermal safety margin of five individuals of A. brongersmianus were measured. This study confirmed that four speciesof Amerotyphlops occur in the state of Alagoas (A. amoipira, A. arenensis, A. brongersmianus and A. paucisquamus), with the record of A. arenensis having its distribution extended by 280 km to the southern of its type-locality in Areia, Paraíba. The SDM pointed east Alagoas as an area with high environmental suitability for the occurrence of A. brongersmianus, while southwest Alagoas showed environmental suitability for A. paucisquamus to occur, being these areas indicated to direct collection efforts. The individuals of A. brongersmianus had a mean Tpref of 27.06ºC, a mean Vtmin and Vtmax of 25.4ºC and 28.7ºC, respectively, and a thermalsafety margin of 3.3ºC. The average values of critical temperatures were Ctmin 11.53ºC and Ctmax 40.18ºC. With this, we observe that this species may become susceptible under the scenario that predicts a warming of 4.5ºC. The data obtained in this study contribute to reduce the Wallacean deficit and bring new data on thermal physiology for this little-known genus of fossorial snake.