Thursday, December 24, 2020

[Herpetology • 2020] Levitonius mirus • A New, Miniaturized Genus and Species of Snake (Cyclocoridae) from the Philippines

Levitonius mirus 
Weinell, Paluh, Siler & Brown, 2020

Waray Dwarf Burrowing Snake ||

The Philippine archipelago is an exceptionally biodiverse region that includes at least 112 species of land snakes from 41 genera and 12 families. Recently, Cyclocoridae (formerly Lamprophiidae: Cyclocorinae) was proposed as a distinct, Philippine-endemic family, containing four genera: Cyclocorus, Hologerrhum, Myersophis, and Oxyrhabdium. Here, we describe an additional cyclocorid genus and species, Levitonius mirus, new genus and species, from Samar and Leyte Islands, Philippines. Molecular data support Levitonius, new genus, to be most closely related to Myersophis and Oxyrhabdium, and it shares multiple skeletal characteristics with these genera; Levitonius, new genus, differs from all of these taxa in body size, scalation, and other characters. Skeletal and other phenotypic data suggest that Levitonius, new genus, is fossorial and likely has a diet that is specialized on earthworms. Levitonius mirus, new genus and species, has a maximum total length of 172 mm and is at present the smallest known species in Elapoidea. Our results highlight the need for future work on Samar and Leyte Islands, which have received relatively little attention from systematists, in part because of a prevailing biogeographic paradigm that predicted (not necessarily correctly) that these islands would simply have a nested faunal subset of the Mindanao faunal region land vertebrates. The discovery of a strikingly distinct and phylogenetically divergent snake lineage on these landmasses joins numerous related studies calling for a wholesale reconsideration of the Pleistocene Aggregate Island Complex model (the PAIC paradigm of diversification) biogeographic framework.

Fig. 1 (A) Elevation map of the Philippines, showing location of islands and PAICs mentioned in this article; B.I. = Babuyan Island Group, Sb. = Sibuyan Island, Sq. = Siquijor Island, C.S. = Camiguin Sur, Tb. = Tablas.
(B) Samar, Leyte, and nearby islands; red star indicates the type locality of Levitonius mirus, new genus and species; blue circle indicates a second occurrence locality;
(C) karst rainforest habitat at the L. mirus, new genus and species, type locality (Barangay San Rafael, Municipality of Taft, Samar Island).

Fig. 4 Comparison of selected cranial bones of cyclocorid species. (A) Skull of Levitonius mirus, new genus and species, showing the position of bones i–iv; from left to right: bones of L. mirus, new genus and species, Myersophis alpestris, Oxyrhabdium leporinum, Hologerrhum philippinum, and Cyclocorus lineatus; i = postorbital bone, ii = supratemporal bone, iii = quadrate bone, and iv = maxilla. White scale bars = 1 mm.

Levitonius, new genus
 Dwarf Burrowing Snakes 
Type species.— Levitonius mirus, new species.

Diagnosis.— Members of the genus Levitonius can be distinguished by the possession of five supralabial scales, 15 longitudinal rows of dorsal scales throughout the length of the body, and subcaudal scales unpaired.
Etymology.— The new generic appellation Levitonius is a masculine noun and a patronym in the genitive singular, honoring the numerous contributions and life-long dedication of Alan E. Leviton to the study of the systematics of Philippine snakes.

Fig. 7 Photographs of Levitonius mirus, new genus and species, type specimens (alcohol preserved): holotype PNM 9872 (A), and paratypes KU 311288 (B) and KU 305488 (C).
Dorsal view of body (A, top left; B–C, left); ventral view of body (A, bottom left; B–C, center); dorsal view of head (A–C, top right); lateral view of head (A–C, center right); ventral view of head (A–C, bottom right). Thick black scale bars = 10 mm; thin black scale bars = 1 mm.


Fig. 8 Head scalation of Levitonius mirus, new genus and species, holotype (PNM 9872); (A) ventral, (B) lateral, and (C) dorsal views of head.
 Illustrations by Errol D. Hooper (2019). Black scale bar = 1 mm.

Levitonius mirus, new species
 Waray Dwarf Burrowing Snake
Diagnosis.— Levitonius mirus can be distinguished from all other SE Asian snake species by having the following combination of characters: small size (largest total length known 172.1 mm); five supralabial scales; 15 longitudinal rows of dorsal scales throughout length of body; subcaudal scales unpaired; pair of internasal scales present; anterior temporal scale present; preocular scale absent; loreal scale present, not in contact with eye; mental scale broadly in contact with anterior chin shields; scales smooth, iridescent; dorsum ground color may be light brown to nearly black; one pale transverse band present on posterior of head, crosses parietals, temporals, and posterior supralabials; pale midventral line present or absent.

Distribution.— The new species is currently only known from Samar and Leyte Islands, southeastern Philippines.

Etymology.— The species epithet mirus is a Latin adjective, meaning unexpected finding or surprise—a fitting specific epithet for the miniaturized, phylogenetically unique evolutionary lineage represented by the new genus and species described here. The suggested common name, the Waray Dwarf Burrowing Snake, honors the Waray-waray people of the eastern Visayas, in particular the Samareños who live in vicinity of the type locality, among the forested mountains of Samar Island, and the Leyteños who inhabit the new genus' only other documented locality in the montane forests of Leyte Island.


Jeffrey L. Weinell, Daniel J. Paluh, Cameron D. Siler and Rafe M. Brown. 2020. A New, Miniaturized Genus and Species of Snake (Cyclocoridae) from the Philippines. Copeia. 108(4); 907-923. DOI: 10.1643/CH2020110