Hebius atemporalis

Hebius atemporalis (Bourret, 1934) Tables 1, 2, Figs 2, 3, 4, 5 Syntypes. MNHN-RA-1935.0077 –0078. Type locality: “ Tonkin ” [i. e., now northern Vietnam]. Bourret (1934) gave the type locality as Tonkin; later authors (e. g., Malnate and Romer 1969) referred to Tam Dao National Park, Phu Tho Province, northern Vietnam, but this does not constitute a formal restriction under the ICZN. Examined material (n = 15). The two syntypes and 13 additional specimens of Hebius atemporalis were examined in this study (see Table 1). Revised diagnosis. Hebius atemporalis can be distinguished from its congeners by the following combination of characters: (1) small body size, maximum snout-vent length 294 mm; (2) head small, narrow, and moderately distinct from neck; (3) maxillary teeth 27–36, gradually enlarged posteriorly; (4) supralabials 6, with the 3 rd and 4 th entering the orbit; (5) temporal scale absent or represented by a small narrow scale; (6) infralabials 6–7; (7) dorsal scale rows 17-17 - 17, weakly keeled except for the outermost 1–6 rows; (8) ventrals 123–140; (9) subcaudals 63–79, paired; (10) ventral surface of head white, scattered with black spots or streaks; (11) sutures of infralabials strongly edged in black; (12) a white to orangish nuchal collar present; (13) dorsal ground color gradually changing from reddish brown or dark brown anteriorly to blackish brown posteriorly (based on data of Bourret (1934); Malnate and Romer (1969); this study). Description (based on 15 examined materials). Head small, narrow, and moderately distinct from neck (HL / HW 1.65–2.18); body slender, with maximum total length 427 mm; tail length 28–33 % of total length. Eye moderate, with round pupil. Body scalation. Dorsal scales in 17-17 - 17 rows; anterior rows smooth or weakly keeled on the upper 5–11 rows, midbody and posterior rows weakly keeled except the outermost 1–3 rows; ventrals 123–140 (123–134 in males, 132–140 in females); cloacal plate divided; subcaudals 63–79 (63–74 in females, 71–79 in males), paired. Head scalation. Rostral broad, visible from above, slightly projecting between internasals; internasals paired, nearly triangular, broader than long, broadly in contact medially, curved outward, not contacting loreal; prefrontals paired, pentagonal, rather large, wider than long, bordering loreal laterally and preocular and supraocular posteriorly; frontal hexagonal, distinctly longer than wide, posteriorly embedded into parietals; parietals paired, much longer than wide; nasals wider than high, divided below nostril, contacting 1 st – 2 nd supralabials; loreal single, quadrangular, about as wide as high, bordering 2 nd – 3 rd supralabials (2 nd only in ZMMU NAP- 07877 and right side of CIB 8447), not entering orbit; preocular single, much higher than wide; supraocular single, elongated, narrowing anteriorly, in contact with parietal posteriorly; postoculars 2, the upper markedly larger and broader than the lower; temporal scale absent or represented by a small narrow scale enclosed by postoculars, parietal, and 5 th supralabial; supralabials 6, first four gradually increasing in size posteriorly, 3 rd – 4 th entering orbit, 5 th largest, dorsal border contacting parietal; infralabials 6–7, first pair in broad contact behind mental, 1 st – 4 th contacting anterior chin shields; chin shields pairs two, anterior pair in broad contact medially; posterior pair longer and contacting anterior pair. Coloration and pattern. In life, dorsal head dark brown; internasals and prefrontals light brown, scattered with small black dots (CIB 121809 bears a worm-like yellow pattern on head), a pair of irregular light spots present symmetrically along parietal suture; supralabials 1 st – 4 th white with strong black edging, 5 th brownish with a large black-edged white elliptical spot anteriorly, 6 th dark brown occasionally with a small white dorsal spot; a white or orange collar present on the neck, separated from parietal suture by 3–4 dorsal scales, usually 1–3 scales wide, wider dorsally, sometimes broken medially, and occasionally extending slightly posteriorly; dorsal surface of body and tail color reddish to dark brown anteriorly, gradually darkening to blackish brown or dark olive posteriorly, speckled with small dark blotches and spots; a series of light spots on the 3 rd – 5 th dorsal scale rows, separated by 1–2 scales, extends posteriorly from behind the collar, fading or becoming indistinct towards the tail; ventral surface of head white, scattered with black spots or streaks; infralabial sutures strongly black-edged; ventral surface of body and tail white to pale yellow, with two series of black dots of variable intensity along the lateral margins of ventrals and subcaudals. In preservative, overall pattern similar as in life, though dorsal brown tones darken slightly, the neck collar and yellowish lateral spots fade to pale white, and ventral surfaces become uniformly pale white. Dentition. Maxillary teeth 27–36, without diastema, gradually enlarged posteriorly (data from Malnate and Romer 1969; this study). Distribution. Hebius atemporalis sensu stricto is confirmed from northern Vietnam (including Phu Tho, Tuyen Quang, Dien Bien, and Nghe An) and southern and central China (including Hong Kong, Guangdong, Guangxi, Guizhou, Hunan, Hubei and Chongqing), occurring at elevations of 400–1,700 m a. s. l. (Fig. 5). Several additional records from other regions remain unverified. For instance, Deuve (1970) reported the species from Laos, but without providing voucher specimens or supporting data. David et al. (2023) subsequently clarified that the presence of H. atemporalis in Laos remains unconfirmed. In contrast, populations from the Yunnan-Guizhou Plateau (Guizhou and Yunnan, China), previously referred to H. atemporalis, are morphologically and genetically distinct, and are herein recognized as a new species, formally described below. Natural history notes. Hebius atemporalis inhabits low- to mid-elevation subtropical montane regions and appears to tolerate a variety of habitats. In Vietnam, a specimen from Pu Mat NP, Nghe An Province (950 m a. s. l.), was found on the ground at ca. 16 h 30 in secondary evergreen forest with dense shrubs. In China, one specimen from Houhe NNR, Hubei Province was collected near a forested stream, whereas Malnate and Romer (1969) reported individuals from Hong Kong SAR near the summit of Tai Mo Shan (ca. 914 m a. s. l.) in a comparatively dry environment without streams. The species therefore appears to occupy both primary and secondary montane forest habitats. Activity is mainly diurnal, with most specimens collected during the day, although some remain active into the late afternoon. When disturbed, individuals move rapidly and emit a strong, unpleasant odor as a defensive behavior. Its diet remains poorly known, but it is presumed to feed primarily on earthworms.