Avaliação do status taxonômico de Chironius flavolineatus (JAN, 1863) (serpentes: colubridae) do estado do Ceará

Abstract

The snake genus Chironius Fitzinger 1826 has a history of taxonomic instability, with some of its species renamed and classified in other genera. According to recent studies, based on multispecies coalescence, Chironius flavolineatus (Jan, 1863) has been proposed as a species complex, with the proposition of cryptic lineages throughout its distribution, including the native population of the state of Ceará. However, the samples of sequenced specimens are limited and, in addition, the collection and analysis of morphological characters, hemipenis and population genetics has not yet been properly conducted. Therefore, the present study aimed to evaluate the taxonomic status of the population currently identified as Chironius flavolineatus in the state of Ceará, through an integrative approach. Meristic, anatomical and qualitative characters of specimens deposited in scientific collections representing herpetofauna in Brazil were analyzed. Furthermore, genetic sequences of the 16S gene generated in the study, complemented with others available in GenBank, collaborated to test the limits between populations and their evolutionary relationships. The study partially recovered some evolutionary hypotheses regarding the species, such as the strong support for the population in the state of Goiás, which is genetically distinct from the others. Most of the analyzed morphological characters of C. flavolineatus were conserved. However, a statistically significant variation was noted between some morphometric measurements and pholidosis between the population of the state of Ceará and the others, mainly in males, such as CRC, CC, Cca and subcaudal scale count. New characters for the species and a certain frequency of manifestation of some of them were observed in the population of the state of Ceará, also presenting a hemipenis with characteristics similar to C. diamantina, a congeneric species. This finding may represent clues to access the evolutionary history of the species of the genus, since the sequenced genes available for consultation do not present a good phylogenetic signal for recovering the phylogeny of the group. Although morphometric characters, hemipenis morphology and pholidosis of the subcaudals indicate a taxonomic signal, the sampling was still considered limited, thus adopting parsimony in making taxonomic decisions involving the taxon. In this way, the taxonomic status of the Chironius flavolineatus population in the state of Ceará is maintained.