When the tail shakes the snake: phylogenetic affinities and morphology of Atractus badius (Serpentes: Dipsadidae), reveals some current pitfalls on the snake's genomic age

Atractus badius has a long and controversial nomenclatural history due to both its antiquity and the brevity of its original description. This species was described based on two syntypes from Java. Later, a lectotype was designated and the distribution range restricted to the Guiana Shield. Although this species has been repeatedly recorded throughout Amazonia and the Andes, these records have been erroneously assigned to A. badius because of a considerable level of confusion in the literature. We found 13 additional specimens of this poorly known snake, expanding our knowledge on its morphological variability, phylogenetic relationships and distribution. In this paper, we report new localities and data on meristic, morphometric, coloration, scales micro-ornamentation, osteology and hemipenial morphology to A. badius. We also determine the phylogenetic position of A. badius as nested in a composite Guiana Shield clade. In addition, we discuss recent advances on the systematics of Atractus and comment on some 'new arrangements' with respect to previously recognized species groups and available morphological evidence. Finally, we highlight the importance of accurate voucher identification before promoting taxonomic changes or implementing nomenclatural acts derived from new phylogenetic hypotheses, and notably propose the synonymy of the recently described A. pyroni with A. roulei.

A new species of emThamnodynastes/em Wagler, 1830 from western Amazonia, with notes on morphology for members of the emThamnodynastes/em empallidus/em group (Serpentes, Dipsadidae, Tachymenini).

The genus Thamnodynastes is the most diverse within the tribe Tachymenini, with an extensive and complex taxonomic history. The brief descriptions and lack of robust diagnostic characters are the main sources for identification errors and for the difficulty to assess the diversity estimates of the genus. The Thamnodynastes pallidus group was briefly designated to encompass the most arboreal species of the genus, with thinner bodies and longer tails: T. pallidus, T. longicaudus, T. sertanejo, and a fourth undescribed species. After its designation, no other paper addressed this group and its morphological variation, especially for the hemipenis, is still undetermined. After the analysis of all species of Thamnodynastes we were able to corroborate the distinctiveness of the T. pallidus group and to accurately diagnose its fourth species from the western portion of the Amazonia lowlands. The new species is distinguishable from all congeners, except T. sertanejo, by the absence of ventral longitudinal stripes, 17/17/11 dorsal scale rows, and dorsal dark brown blotches on the anterior third of the body. The new species is distinguished from T. sertanejo by the higher number of subcaudals, lower number of ventrals, and smaller body and head sizes. We also provide additional diagnostic features for the Thamnodynastes pallidus group, including new data on hemipenial variation. Finally, we briefly discuss the defensive behavior and morphological characters associated with arboreality in members of the T. pallidus species group.

Long known, brand new, and possibly threatened: a new species of watersnake of the genus Helicops Wagler, 1828 (Serpentes; Xenodontinae) from the Tocantins-Araguaia River Basin, Brazil.

We describe a new species of watersnake of the genus Helicops from the Tocantins-Araguaia River Basin based on characters of coloration and hemipenial morphology, also corroborated by a molecular phylogenetic analysis including 18 terminals of 10 additional congeners. The new species superficially resembles the spotted-patterned He. leopardinus, but differs from it in exhibiting dorsal spots fused into irregular bands, and a unique hemipenial structure with two pairs of distinctly enlarged basal spines. In addition, despite the superficial resemblance of color pattern, our genetic evidence indicates that the new species does not belong to the He. leopardinus radiation, representing the sister group of a component including terminals of this species, He. modestus, and He. infrataeniatus. Finally, we discuss the apparent restriction of the new species to the Tocantins-Araguaia Basin with focus on vicariant processes that may have promoted its differentiation, as well as on the conservation challenges in an area severely affected by anthropic impacts associated with the rapid expansion of hydroelectric and agricultural sectors in the Brazilian Cerrado.

A new species of Thamnodynastes Wagler, 1830 from western Amazonia, with notes on morphology for members of the Thamnodynastes pallidus group (Serpentes, Dipsadidae, Tachymenini)

The genus Thamnodynastes is the most diverse within the tribe Tachymenini, with an extensive and complex taxonomic history. The brief descriptions and lack of robust diagnostic characters are the main sources for identification errors and for the difficulty to assess the diversity estimates of the genus. The Thamnodynastes pallidus group was briefly designated to encompass the most arboreal species of the genus, with thinner bodies and longer tails: T. pallidus, T. longicaudus, T. sertanejo, and a fourth undescribed species. After its designation, no other paper addressed this group and its morphological variation, especially for the hemipenis, is still undetermined. After the analysis of all species of Thamnodynastes we were able to corroborate the distinctiveness of the T. pallidus group and to accurately diagnose its fourth species from the western portion of the Amazonia lowlands. The new species is distinguishable from all congeners, except T. sertanejo, by the absence of ventral longitudinal stripes, 17/17/11 dorsal scale rows, and dorsal dark brown blotches on the anterior third of the body. The new species is distinguished from T. sertanejo by the higher number of subcaudals, lower number of ventrals, and smaller body and head sizes. We also provide additional diagnostic features for the Thamnodynastes pallidus group, including new data on hemipenial variation. Finally, we briefly discuss the defensive behavior and morphological characters associated with arboreality in members of the T. pallidus species group.

Molecular phylogeny of the tribe Philodryadini Cope, 1886 (Dipsadidae: Xenodontinae): Rediscovering the diversity of the South American Racers

South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.(AU)

Molecular phylogeny of the tribe Philodryadini Cope, 1886 (Dipsadidae: Xenodontinae): Rediscovering the diversity of the South American Racers

South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.

Molecular phylogeny of the tribe Philodryadini Cope, 1886 (Dipsadidae: Xenodontinae): Rediscovering the diversity of the South American Racers

Abstract South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.

Hemipenial morphology of nine South American species of Mabuya (Scincidae: Lygosominae) with comments on the morphology of the family.

Species of the genus Mabuya are barely recognizable because of their highly conservative external morphology, resulting in unstable systematic and taxonomic status. Considering that hemipenial morphology has been extensively used as a source of systematic information for several groups of Squamata, we described the hemipenial morphology of nine species of Mabuya, searching for diagnostic features useful to taxonomic and systematic studies. To have comparative parameters within the family, we also presented the description of the hemipenes of two other Scincidae species (i.e., Trachylepis atlantica and Tiliqua rugosa). This information, together with the available literature, was analyzed in a comparative framework, allowing us to define some variation for the genus and family. The hemipenial morphology of the species of Mabuya studied is very conservative; features that show subtle variation were the shape of the protuberances present on the asulcate face of the hemipenial body and the presence and type of a lateral fold, on the body. Also, within the family, some variation was found in the shape and length of lobes, length of branches of the sulcus spermaticus, and in the kind of folds and protuberances in both faces of the lobes and hemipenial body. Although these features were not tested in a systematic context, this information suggested variations in hemipenial morphology that could contribute to taxonomic diagnostics and phylogenetic characters. The importance of obtaining proper preparations for gathering accurate information is emphasized, and the use of fresh-killed specimens that shows fewer difficulties for the procedures of preparation is highly recommended.

Taxonomic revision of the Erythrolamprus reginae species group, with description of a new species from Guiana Shield (Serpentes: Xenodontinae).

We perform a review of the Erythrolamprus reginae species group and putative related taxa (E. dorsocorallinus, E. zweifeli, and E. oligolepis), based on external morphology and hemipenial characters. We infer species boundaries among taxa traditionally associated with this group, recognizing two nominal subspecies (Erythrolamprus reginae reginae and E. r. macrosomus) in the species level. We propose the synonymy of E. r. semilineatus with E. reginae and recognize the validity of the related taxa, such as: E. dorsocorallinus, E. zweifeli, and E. oligolepis. In addition, two specimens occurring in the state Amapá, Brazil, are herein described as a new species. Therefore, we provide an identification key for the species of the group and discuss some of the combination of morphological features useful to delimitate the species of this group, in comparison with other representatives of the genus Erythrolamprus.

Taxonomy of the Micrurus spixii species complex (Serpentes, Elapidae).

Historically, the Micrurus spixii species complex comprises four subspecies (M. s. spixii, M. s. martiusi, M. s. obscurus, and M. s. princeps), however, recently, some authors have considered only two full species (M. spixii and M. obscurus). In this paper, we report data on meristic, morphometric, color pattern in life and after preservation, cranial osteology, and hemipenis morphology to Micrurus spixii species complex. We examined 358 specimens throughout the geographical distribution, including the type-series of all taxa. Differences in color pattern and morphology of hemipenis and skull support the existence of only two diagnosable taxa, M. spixii and M. obscurus, both considered here as a full species. We corroborate the synonymy of Micrurus s. martiusi and M. spixii based on wide overlap of meristic and morphometric characters, as well as the similarities of color pattern, hemipenis and skull characters. We can distinguished M. spixii from M. obscurus (in parenthesis) by the combination of the following characters: black cephalic cap (vs. cephalic cap absent, with red parietal region), hemipenial body with spines dispersed on the asulcate surface (vs. spines arranged in rows on the asulcate surface), capitate condition of hemipenis (vs. organ partially-capitate), narrow parietal bone with posterior angular borders (vs. enlarged parietal bone with elliptical posterior border), and relatively long venom inoculating fangs (vs. relatively short venom inoculating fangs).

Morphological variation of the rare psammophilous species Apostolepis gaboi (Serpentes, Dipsadidae, Elapomorphini).

Apostolepis gaboi was described based only on the holotype found in the Queimadas, state of Bahia, northeastern Brazil. Since its original description, no additional specimens were reported in literature and the species was considered to be rare and poorly known. Here, we provide a detailed description for the species based on the examination of the holotype and 34 additional specimens from the type locality and adjacent areas. Additional information is also provided on intraspecific color variation and hemipenial morphology.

A new species of Atractus (Serpentes: Dipsadidae) from Serra do Cipó, Espinhaço Range, Southeastern Brazil, with proposition of a new species group to the genus

We describe a new species of Atractus from Serra do Cipó, at the southeastern versant of Serra do Espinhaço, an inland mountain range nearly parallel to the Brazilian Atlantic coast. The new species is morphologically similar to A. paraguayensis and A. potschi with which it shares: 15 dorsal scale rows; white occipital region in juvenile specimens; dorsal ground color reddish pink to red (in life) with alternate black transversal spots, blotches or transversal bands; seven upper and lower labial scales; ventrals and subcaudals creamish white; hemipenis slightly bilobed, semicapitate and semicalyculate. The new species differs from both taxa mainly on the basis of exclusive coloration characters (number and shape of transversal bands) and hemipenial morphology (median face of the lobes without ornamentation), besides punctual meristic (number of ventral scales and maxillary teeth) and morphometric (adult snout-vent length) differences. Finally, we provide a discussion regarding the potential affinities of the new species and we redefine some Atractus species groups in order to better accommodate species sharing unique combinations of morphological characters.

Descrevemos uma nova espécie de Atractus da Serra do Cipó, na vertente sudeste da Serra do Espinhaço, uma cadeia montanhosa continental aproximadamente paralela à costa Atlântica brasileira. A nova espécie é morfologicamente similar a A. paraguayensis e A. potschi com as quais compartilha: 15 séries de escamas dorsais; região occipital branca em espécimes jovens; coloração dorsal de fundo variando de rosa avermelhado a vermelho (em vida) com pontuações, manchas e/ou bandas transversais pretas; sete supralabiais e infralabiais; ventrais e subcaudais creme esbranquiçado; hemipênis levemente bilobado, semicapitulado e semicaliculado. A nova espécie difere de ambos os táxons principalmente a partir de caracteres exclusivos de coloração (número e forma das bandas transversais), da morfologia hemipeniana (face mediana dos lobos sem ornamentação) além de diferenças merísticas (número de escamas ventrais e dentes maxilares) e morfométricas (comprimento rostro-cloacal dos adultos). Apresenta-se uma discussão sobre as possíveis afinidades da nova espécie e redefinem-se alguns grupos de espécies de Atractus no sentido de acomodar melhor as espécies que compartilham combinações únicas de caracteres morfológicos.

A new species of Atractus (Serpentes: Dipsadidae) from Serra do Cipó, Espinhaço Range, Southeastern Brazil, with proposition of a new species group to the genus

We describe a new species of Atractus from Serra do Cipó, at the southeastern versant of Serra do Espinhaço, an inland mountain range nearly parallel to the Brazilian Atlantic coast. The new species is morphologically similar to A. paraguayensis and A. potschi with which it shares: 15 dorsal scale rows; white occipital region in juvenile specimens; dorsal ground color reddish pink to red (in life) with alternate black transversal spots, blotches or transversal bands; seven upper and lower labial scales; ventrals and subcaudals creamish white; hemipenis slightly bilobed, semicapitate and semicalyculate. The new species differs from both taxa mainly on the basis of exclusive coloration characters (number and shape of transversal bands) and hemipenial morphology (median face of the lobes without ornamentation), besides punctual meristic (number of ventral scales and maxillary teeth) and morphometric (adult snout-vent length) differences. Finally, we provide a discussion regarding the potential affinities of the new species and we redefine some Atractus species groups in order to better accommodate species sharing unique combinations of morphological characters.(AU)

Descrevemos uma nova espécie de Atractus da Serra do Cipó, na vertente sudeste da Serra do Espinhaço, uma cadeia montanhosa continental aproximadamente paralela à costa Atlântica brasileira. A nova espécie é morfologicamente similar a A. paraguayensis e A. potschi com as quais compartilha: 15 séries de escamas dorsais; região occipital branca em espécimes jovens; coloração dorsal de fundo variando de rosa avermelhado a vermelho (em vida) com pontuações, manchas e/ou bandas transversais pretas; sete supralabiais e infralabiais; ventrais e subcaudais creme esbranquiçado; hemipênis levemente bilobado, semicapitulado e semicaliculado. A nova espécie difere de ambos os táxons principalmente a partir de caracteres exclusivos de coloração (número e forma das bandas transversais), da morfologia hemipeniana (face mediana dos lobos sem ornamentação) além de diferenças merísticas (número de escamas ventrais e dentes maxilares) e morfométricas (comprimento rostro-cloacal dos adultos). Apresenta-se uma discussão sobre as possíveis afinidades da nova espécie e redefinem-se alguns grupos de espécies de Atractus no sentido de acomodar melhor as espécies que compartilham combinações únicas de caracteres morfológicos.(AU)