Morphological variation, polymorphism, and Taxonomy of the Atractus torquatus complex (Serpentes: Dipsadidae)

Abstract

The taxonomic status of Atractus torquatus is revised on the basis of concordance between quantitative and qualitativeanalyses of morphological characters (meristic, morphometric, colour pattern, and hemipenis) throughout its geographicaldistribution. We propose the synonymy of Atractus davidhardi, A. janethae, and A. lucilae based on wide overlap of mor-phological characters (qualitative and quantitative). Despite some differences in the frequency of the number of suprala-bials, infralabials and maxillary teeth among A. torquatus populations, we find that these characters exhibit a high levelof polymorphism and therefore cannot unambiguously diagnose Guiana Shield and Amazon Basin populations. Addition-ally, we discuss the polymorphism and geographical variation in A. torquatus and its appropriateness for hypotheses of landscape evolution in Amazonia.

Redescription ofAtractus punctiventrisand Description of Two NewAtractus(Serpentes: Dipsadidae) from Brazilian Amazonia

“…This large time lapse is not very surprising because the taxonomy of the genus is currently in a state of flux. Despite the high species richness in Colombia, the scientific collections of the country have been neglected until recently (Passos et al 2009a,d,e;Passos and Prudente 2012;Passos et al 2013b). Paradoxically, the number of snake samples from cis-Andean lowland regions of Colombia (i.e., Amazon and Llanos) is low as compared with the amount of specimens in collections from Andean highland or trans-Andean lowland areas of the country.…”

“…Data from additional specimens of Atractus previously examined can be found in Passos et al (2005), Passos et al (2007a,b), , , Passos et al (2009a,b,c,d,e), Passos et al (2010a,b,c), Passos and Lynch (2011), Passos and Prudente (2012), , Passos (2008, 2010), Passos et al (2013a,b,c,d), Almeida et al (2014), and Salazar-Valenzuela et al (2014). We prepared fully everted and almost maximally expanded hemipenes from the following specimens: IBSP 47078, MNRJ 16511, MNRJ 18035, MNRJ 24363, MPEG 17908, MPEG 23930, MUFAL 10462, and ICN 12162.…”

A morphological and molecular study ofHydrodynastes gigas(Serpentes, Dipsadidae), a widespread species from South America

“…However, in many cases, species are difficult to delimit due to the limited number of morphological differences or the absence of them, preventing the recognition of valid cryptic species ( Bickford et al, 2007 ). Morphology alone might result in more than one name being assigned to individuals belonging to the same evolutionary lineage (i.e., species) ( Passos & Prudente, 2012 ; Passos, Martins & Pinto-Coelho, 2016 ; Mângia et al, 2020 ). Many species are described based solely on morphological patterns, which could merely reflect interpopulational variation, instead of evidence of lineage separation (e.g., Brusquetti et al, 2014 ; Mângia et al, 2020 ).…”