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| [H] Atractus xaxi [A-F] Atractus nemosophis Esqueda, Rojas-Runjaic, Prudente, Bazó, Navarrete, Camargo-Sillet, Ortiz, Correa, Guerrero & Urra, in Esqueda, Rojas-Runjaic, Prudente, Bazó, Navarrete, Carmargo-Sillet, Ortiz, Correa, Guerrero et Urra, 2025. |
Abstract
This study constitutes the first evolutionary investigation that adds Venezuelan species of sleepyhead snakes of the genus Atractus, the most diverse and with the largest number of species with a restricted distribution area above 1000 m asl, whose estimated divergence occurred 21–22 MY. In this context, phylogenetic analyses using a combination of mitochondrial (16S, Cytb, ND4) and nuclear (RAG1, NT3) markers within the framework of maximum likelihood and Bayesian models, as well as morphological and meristic data, support the recognition of two new species that inhabit montane semideciduous forests and cloud forests between 1800 and 2200 m asl: A. nemosophis sp. nov. a polymorphic species related to A. meridensis, instead, A. xaxi sp. nov. exhibits a uniform dorsal pattern very closely with A. mariselae and A. mijaresi, respectively. Finally, we provide new data on the diversity and distribution of the Atractus from the cordillera de Mérida, including a dichotomous key and a novel perception of their conservation status when considered the most diverse and dominant snakes of the Andean Mountain landscapes. Atractus nemosophis sp. nov. and Atractus xaxi sp. nov. should be included in the Vulnerable category according to criteria Ac and B2 (i,ii,iii,iv).
Keywords: Cryptozoic and semifossorial snakes, Northern Andes, Cordillera de Mérida, Montane semideciduous forests and cloud forests, Taxonomy and conservation
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| Images of Atractus nemosophis sp. nov. in life. Holotype MZUC 47720: dorsal view of the body and head, showing the black vertebral line and a very attenuated light band behind the parietals; ventral view of the body and tail, displaying a reddish pattern with three spots on each scale, forming incomplete longitudinal lines (A–B). MZUC 47729: dorsal view of the body and head, exhibiting a grayish-brown pattern with an interrupted white line between the 1st and 3rd dorsal scale rows and a whitish surface heavily pigmented with black (C–D). MZUC 47726 and MZUC 47718: reddish pattern with a black vertebral line and a strongly pigmented orange belly (E–G). MZUC 47735: olive-brown pattern with a black vertebral line, with supralabials and the ventral surface of the head showing a yellowish hue (H). Image of Atractus xaxi sp. nov. in life: head and dorsum of the body entirely black (© Daniel Quihua) |
Atractus nemosophis sp. nov. Esqueda, Rojas-Runjaic, Prudente, Bazó, Navarrete, Camargo-Sillet, Ortiz, Correa, Guerrero & Urra.
Etymology. The specific name is an adjective derived from the Greek words “nemos,” which means forest or wood with pasture for cattle, and ophis m., which means “snake” (Brown, 1956), to refer to the place where it was found, which originally corresponds to a semicaducifolious forest Andean montane (Ataroff & Sarmiento, 2004), but currently they have been transformed, giving rise to new novel landscapes called anthromes (Ellis et al., 2010).
Atractus xaxi sp. nov. Esqueda, Rojas-Runjaic, Prudente, Bazó, Navarrete, Camargo-Sillet, Ortiz, Correa, Guerrero & Urra.
Etymology. The word “xaxi” is a toponym of the first indigenous settlers of the area (the Chamas tribes) and that, with the arrival of the Spanish people, was transformed morphologically to be known today as “Jají” (Gordones-Rojas & Meneses-Pacheco, 2004). The town is one of the oldest in Mérida state, Venezuela, founded in 1580.
Luis Felipe Esqueda, Fernando J.M. Rojas-Runjaic, Ana Prudente, Santos Bazó, Luis Fernando Navarrete, Edward Carmargo-Sillet, Juan Carlos Ortiz, Claudio Correa, Pablo Guerrero and Félix Urra . 2025. A First Phylogenetic and Taxonomic Approach to Sleepyhead Snakes from Venezuela (Dipsadidae: Atractus), with the Description of Two New Andean Species. Organisms Diversity & Evolution. DOI: doi.org/10.1007/s13127-025-00682-1 [01 August 2025]
Palabras clave: Andes septentrionales, Northern Andes, Cordillera de Mérida, Bosques semicadufolios montanos y bosques nublados, Taxonomía y conservación
