Morphological Extremes—Two New Snakes of the Genus Atractus from Northwestern South America (Colubridae: Dipsadinae)

Abstract

Two new Andean snakes exhibit extreme morphology in a genus of South American dipsadine colubrids. One, Atractus attenuatus, new species, is a slender, exceptionally attenuated snake 420 mm in total length (adult male holotype), with 17 scale rows, a high ventral + subcaudal count (226), and an extremely vague pattern of numerous, closely spaced, indistinct dark crossbars on a brown ground color. Atractus attenuatus comes from 1000 m elevation in the northern end of the Cordillera Central (Sabanalarga, Antioquia, Colombia). A geographic neighbor, Atractus sanguineus Prado, is of similar morphology but differs in having distinct, widely spaced crossbars on a red ground color.At another extreme, Atractus gigas, new species, is a very robust snake that exceeds a meter in length (adult female holotype 1040 mm in total length), with a hint of pale transverse dorsal bars on a brown ground color. It is the largest known Atractus, differing in color pattern and details of scutellation from the several other congeners that attain lengths . 700 mm. The only known specimen has an azygous frontonasal scale that is atypical of colubrids (but is not an obvious aberrancy). Atractus gigas comes from 1900 m elevation on the Pacific versant of the Andes (Bosque Protector Río Guajalito, Pichincha, Ecuador). RESUMENDos serpientes nuevas Andinas exhiben morfología extrema en un género Suramericano de colú bridos dipsadineos. Una de ellas, Atractus attenuatus, especie nueva, es una serpiente

Description of two new species from Venezuela in the highly diverse dipsadine genus Atractus (Serpentes: Colubridae)

“…Despite of improvements on the fieldwork and facilities to examine specimen collections in the past 50 years, the actual scenario have not much change and many species still named on the basis of single individuals (Myers, 2003;Silva, 2004;Esqueda and La Marca, 2005; Jorge da Silva et al, 2005;Myers and Schargel, 2006;Myers and Donnelly, 2008;Passos and Fernandes, 2008).…”

“…Some authors have advocated that apparent rarity of most Atractus species was due to their secretive habits or endemism (Savage, 1960;Schargel and García-Pérez, 2002;Myers, 2003;Myers and Schargel, 2006). Passos, CisnerosHeredia and Salazar-V (2007) pointed out that study of museum specimen's revealed several Atractus species to be common rather than rare within certain distributional range.…”

La comunidad de serpientes del Distrito Metropolitano Quito (DMQ), provincia de Pichincha, Ecuador, con comentarios sobre su biogeografía

“…En Ecuador se encuentra distribuida en los bosques siempreverdes montanos bajos y bosques de neblina montanos al occidente de los Andes, en las provincias de Cotopaxi y Pichincha, en altitudes entre 1680 y 2307 m [26][27][28][29]. En el DMQ, esta especie ha sido encontrada en la parroquia de Nanegal (Bosque Protector Santa Lucía), a 2307 m de altitud [29].…”

FIRST RECORD OF Atractus manizalesensis Prado, 1940 (SQUAMATA: COLUBRIDAE) IN THE DEPARTMENT OF ANTIOQUIA, COLOMBIA

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Wagler, 1828 is the most speciose genus of snakes in the world, with 143 valid species, from which 18 have been described in the course of the present decade (Uetz et al, 2019). With the exception of a single species present in Gorgona Island (A. medusa), this genus is confined almost entirely to the South American mainland, extending northward only to Central Panama (Myers & Schargel, 2006;Passos et al, 2009b;Wallach et al, 2014). However, the greatest diversity of the genus occurs in the Andes, particularly in Colombia, the country with the highest diversity of Atractus, with 64 species recorded (40

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