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| Pareas capitulatus Stuart, Seateun, Sivongxay, Souvannavong & Phimmachak, 2025 Narrow-headed Snail-eating Snake | ງູໜ້າສັ້ນດາກຈຶງ || |
Abstract
The slug-eating snakes of the Pareas hamptoni species group consist of approximately 15 species distributed across mainland Southeast Asia into northeastern India and southern China. A single specimen collected from the Dakchung Plateau in Xekong Province of southeastern Laos is shown to be molecularly and morphologically distinct from all related species in the P. hamptoni species group and is described as a new species. Pareas capitulatus sp. nov. is a smooth-scaled species having a distinctively narrow head and pattern on the nuchal region that was recovered as the sister taxon to approximately half of the members of the P. hamptoni species group. The inclusion of additional samples of P. geminatus from northern Laos demonstrated the non-monophyly of that taxon with respect to the morphologically similar P. xuelinensis and P. yunnanensis, all of which have type localities in Yunnan Province of southern China. To reconcile this taxonomic problem, P. geminatus and P. xuelinensis are treated as junior synonyms of P. yunnanensis. With these revisions, three species in the P. hamptoni species group are recognized from Laos: P. capitulatus sp. nov., P. formosensis, and P. yunnanensis. Further field surveys on the Dakchung Plateau and vicinity are needed to determine the geographic distribution and morphological variation in P. capitulatus sp. nov.
Keywords: Dakchung Plateau, Integrative taxonomy, Pareas geminatus, Pareas xuelinensis, Pareas yunnanensis
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| Holotype female (NCSM 78628) of Pareas capitulatus sp. nov. in life A: Anterior body in dorsolateral view. B: Head and neck in dorsolateral view. Photos by Bryan L. Stuart. |
Pareas capitulatus sp. nov.
Diagnosis: Pareas capitulatus sp. nov. is distinguished from all other species of Pareas by having the combination of yellow-brown colouration with transverse dark bars on body; frontal shield-shaped, with lateral sides converging posteriorly; all body scales smooth; single vertebral scale row slightly enlarged; head distinctly narrow, with eyes projecting beyond parallel lateral margins of head in dorsal view; supralabials seven; infralabials six; ventral scales 175; subcaudals 75; a complete light band on occiput followed posteriorly by a complete dark nuchal marking; and two dark stripes on side of head consisting of an oblique dark stripe from posterior margin of eye to mouth and a transverse dark stripe from top of head to near corner of mouth.
Etymology: The specific epithet capitulatus is a Latin adjective for “having a small head,” in reference to the distinctly narrow head of the new species. Suggested common names are Narrow-headed Snail-eating Snake (English) and ງູໜ້າສັ້ນດາກຈຶງ (phonetically Ngou Nasan Dakchung; Lao).
Bryan L. Stuart, Sengvilay Seateun, Niane Sivongxay, Siliphone Souvannavong and Somphouthone Phimmachak. 2025. A New Species in the Pareas hamptoni group (Squamata, Pareidae) from southeastern Laos. Zoological Research: Diversity and Conservation. DOI: doi.org/10.24272/j.issn.2097-3772.2024.028
