Colubroelaps adleri, Poyarkov & Bragin & Nguyen, 2024

Colubroelaps adleri sp. nov.

Table 1 View Table 1 , Figs 2 View Figure 2 , 3 A – C View Figure 3 , 4 A View Figure 4

Holotype.

• ZMMU Re-18000 (field tag NAP-15227), adult female, collected by Nikolay A. Poyarkov and Andrey M. Bragin on June 17, 2023, from Dam Bay Research Station , Hon Tre Island, within Nha Trang Bay in Vinh Nguyen Ward, Nha Trang City, Khanh Hoa Province, Vietnam (12.198 ° N, 109.289 ° E; at the elevation of 30 m asl.). GoogleMaps

Diagnosis.

Colubroelaps adleri sp. nov. can be distinguished from C. nguyenvansangi by the following combination of morphological characters: body size small (TL 402 mm); tail relatively short (ratio TaL / TL 0.10); dorsal scales in 14–14 – 14 rows; supralabials six, third and fourth entering orbit; infralabials seven; loreal present; ventral scales 234; subcaudals 30, all divided; cloacal plate divided; dorsal coloration pale brown with narrow and interrupted dark stripe along spine; body flanks dark gray lacking bluish iridescence; ventrally uniform off-white; head black with rostral, nasals, prefrontals, preoculars, loreal, and the two anterior supralabials, as well as the anterior parts of supraoculars and frontal shields dirty yellowish-brown with dark brown spots.

Description of the holotype.

Adult female specimen in a good state of preservation (Fig. 2 View Figure 2 ). Body strongly elongated, very thin, vermiform, round in cross-section. Tail obtusely rounded, comparatively short, the tip of tail blunt (SVL 362 mm; TaL 40.2 mm; TL 402.2 mm; ratio TaL / TL 0.10) (Fig. 2 E – G View Figure 2 ). Head very small, rounded, slightly dorso-ventrally depressed, covered by large, regular, symmetric shields (Figs 2 A – D View Figure 2 , 3 A – C View Figure 3 ), not distinct from the neck (HL 7.99 mm; HW 5.16 mm; ratio HW / HL 0.65). Snout wide, short, bluntly rounded in dorsal view (Fig. 2 A, B View Figure 2 ), slightly tapering in lateral view (Fig. 2 C, D View Figure 2 ). Rostral barely visible in dorsal aspect, triangular (Figs 2 A View Figure 2 , 3 A View Figure 3 ). Eyes very small with round pupils (ED 0.51 mm, EN 1.46 mm, SnL 2.78 mm) (Fig. 2 C, D View Figure 2 ). Single nasal on each side of head (1 / 1 nasals); nostril oval-shaped, with horizontal orienatation, completely enclosed in nasal scale, located closer to the posterior edge of nasal (Figs 2 C, D View Figure 2 , 3 B View Figure 3 ); single (1 / 1) loreal, small, almost triangular in shape, shorter than the eye diameter, in contact with nasal, 1 st and 2 nd supralabial, preocular, prefrontal and internasal; single (1 / 1) preocular, large, elongated pentagonal in shape, subequal to the eye diameter, in contact with 2 nd and 3 rd supralabial, the orbit, supraocular, prefrontal and loreal; single (1 / 1) postocular, trapezoidal in shape, smaller than the eye diameter, in contact with 4 th supralabial, parietal, supraocular and the orbit; single (1 / 1) supraocular, large and wide, ca. twice longer than the eye diameter, in contact with the orbit, postocular, parietal, frontal, prefrontal and preocular (Figs 2 C, D View Figure 2 , 3 B View Figure 3 ). Six supralabials on each side of the head (6 / 6), fourth one the largest, third and fourth supralabials in contact with eye, posterior edge of fourth supralabial in contact with anterior temporal, separating fifth supralabial from parietal; fourth supralabial in contact with parietal, postocular, and anterior temporal (Figs 2 C, D View Figure 2 , 3 A View Figure 3 ); seven (7 / 7) infralabials, the anterior-most pair in contact with each other behind the mental (Figs 2 B View Figure 2 , 3 C View Figure 3 ); the first four pairs of infralabials in contact with the anterior pair of chin shields (Figs 2 B View Figure 2 , 3 C View Figure 3 ); fourth and fifth infralabials in contact with the posterior pair of chin shields (Figs 2 B View Figure 2 , 3 C View Figure 3 ). Three gular scales aligned between the chin shields and the first preventral (Figs 2 B View Figure 2 , 3 C View Figure 3 ). One pair of enlarged internasals, in contact with each other; one pair of enlarged prefrontals, in contact with each other; one wide, pentagonal frontal shield; one pair of wide, triangular parietals, in contact with each other, anteriorly separated by the protruding posterior edge of frontal (Figs 2 A View Figure 2 , 3 B View Figure 3 ), posteriorly barely extending beyond posterior edges of upper posterior temporals (Fig. 3 B View Figure 3 ). Single (1 / 1) anterior temporal, quadrangular in shape; two (2 / 2) posterior temporals, lower one the largest, two and a half times larger than upper posterior temporal (Fig. 3 A, B View Figure 3 ), upper one rectangular-shaped, narrow, notably protruding beyond the upper edge of lower posterior temporal (Figs 2 C, D View Figure 2 , 3 B View Figure 3 ), in dorsal aspect notably protruding beyond the posterior edge of parietal (Fig. 3 B View Figure 3 ). Dorsal scales in 14–14 – 14 rows. Dorsal scales rhomboid, tile-shaped, all smooth, and of the same size (Fig. 2 G View Figure 2 ). Ventrals 234; cloacal plate divided (Fig. 2 E View Figure 2 ); 30 subcaudals, all divided (Fig. 2 E, F View Figure 2 ).

Coloration in life.

Body glossy but lacking the metal / bluish iridescence (Figs 2 A – G View Figure 2 , 4 A View Figure 4 ). Dorsal background coloration pale brown, with narrow and interrupted dark stripe along spine (Figs 2 G View Figure 2 , 4 A View Figure 4 ), formed by small, ca. 1 scale in size, dark brown to black, diamond-shaped blotches (Fig. 2 A View Figure 2 ); body flanks dark gray, nearly black, with indistinct light gray mottling along the scale edges; ventral surface of body and tail off-white with light greenish tint (Fig. 2 E, F View Figure 2 ). Head black to dark brown with rostral, nasals, prefrontals, preoculars, loreal, the first two supralabials, as well as the anterior part of supraoculars and frontal shield dirty yellowish-brown with dark brown irregular spots (Fig. 2 A – D View Figure 2 ). Ventral surfaces of the head white with chocolate-brown blotches (Fig. 2 B View Figure 2 ). After one year in preservative, the background dorsal color faded to beige-gray, and yellowish parts faded to off-white; overall, the pattern of dark markings remained unchanged.

Comparisons.

The main differences between the new species and C. nguyenvansangi are summarized in Table 1 View Table 1 . Colubroelaps adleri sp. nov. can be easily distinguished from C. nguyenvansangi by having notably shorter tail (TaL / TL 0.10 in a single female vs. 0.21 in females and 0.21–0.23 in males; however, this character should be taken cautiously: the tail of Colubroelaps adleri sp. nov. holotype may be incomplete; cases of caudal autotomy were earlier reported for the members of Sibynophiidae and likely may also occur in Colubroelaps ; see Mendelson, 1991), lower number of body scale rows (DSR 14–14 – 14 vs. 16–16 – 16); lower number of ventrals (VEN 234 in a single female vs. 267 in female, 282–292 in males); much lower number of subcaudals (SC 30 in a single female vs. 81 in female, 86–87 in males). Furthermore, the new species can be easily diagnosed from C. nguyenvansangi by having three gular scales between the chin shields and the first preventral (vs. two) (Fig. 3 C, F View Figure 3 ); by fourth infralabial in contact with parietal and anterior temporal, separating fifth infralabial from parietal and postocular (vs. fifth infralabial in contact with parietal and postocular) (Fig. 3 A, D View Figure 3 ); by upper posterior temporal being elongated and much narrower than lower one, noticeably protruding beyond the level of the posterior edge of parietals (vs. upper posterior temporal small, as long as lower posterior temporal, not protruding beyond the level of the posterior edge of parietals) (Fig. 3 A – E View Figure 3 ). Colubroelaps adleri sp. nov. can be further diagnosed from C. nguyenvansangi by having pale brown dorsum with narrow and interrupted dark stripe along spine (vs. reddish-brown dorsum with narrow and continuous dark stripe along spine) (Fig. 4 A, B View Figure 4 ); by lacking the metallic iridescence on dorsum and body flanks (vs. body with bluish metallic iridescence) (Fig. 4 A, B View Figure 4 ); and by having dirty yellowish-brown anterior part of head with irregular dark brown blotches (vs. uniform light yellow to white blotch on anterior part of head lacking dark markings) (Fig. 4 A, B View Figure 4 ).

Etymology.

The species epithet ‘ adleri ’ is a patronymic adjective in genitive singular. We name the new species in honor of Dr. Kraig Adler, Professor Emeritus at Cornell University (New York, USA), in recognition of his outstanding support to the international herpetological community as well as his remarkable scientific contribution to Asian herpetology. We suggest the following common names for the new species: “ Adler’s lace snake ” (in English), “ Shnurkovaya zmeya Adlera ” (Шнурковая змея Адлера, in Russian), and “ R ắn h ổ nư ớc Át-Lơ ” (in Vietnamese).

Distribution and natural history notes.

Currently, Colubroelaps adleri sp. nov. is known only from a single locality in secondary dry maritime evergreen forest on Hon Tre Island, Khanh Hoa Province, South Central Coastal Region of Vietnam (Figs 1 View Figure 1 , 5 View Figure 5 ). The new species is also expected to inhabit other islands of the Nha Trang Bay, though they are much smaller than Hon Tre, and on some of them, forest vegetation has been greatly destroyed. The only known specimen of Colubroelaps adleri sp. nov. was collected during the daytime (14 h 00) while crossing the road. The individual was collected near a garbage dump at the Dam Bay Research Station at 30 m a. s. l. elevation (Fig. 5 A View Figure 5 ), ca. 10 m from a dry maritime mixed low evergreen forest. The forest near the type locality is dominated by Buchanania reticulata Hance , Choerospondias axillaris (Roxb.) Burtt. & Hill , Pentaspadon annamense (Evrard & Tardieu) Ph ạmh., Spondias pinnata (L. f.) Kurz, and Ormosia sp. , including occasional trees of Sindora siamensis Teijsm. ex Miq. , Streblus ilicifolius (S. Vidal) Corner , and Eurya turfosa Gagnep , and with an undergrowth formed primarily by Dracaena sp. and with occasional specimens of Cycas rumphii Miq. (Fig. 5 B View Figure 5 ) (plant identification — A. N. Kuznetsov, pers. comm.). Other species of snakes recorded in sympatry with the new species at the type locality included Lycodon davisonii (Blanford, 1878) , L. capucinus (Boie, 1827) , Ptyas korros (Schlegel, 1837) , Ophiophagus hannah (Cantor, 1836) , and Trimeresurus albolabris (Gray, 1842) .

A parasitic invasion of the Acanthocephala (Kölr.) worm was found in the subcutaneous cavity between the skin and the body muscles in the posterior third of the specimen length on its dorsal side (Figs 2 C View Figure 2 , 4 A View Figure 4 ). The presence of this parasite may indicate that Colubroelaps adleri sp. nov. likely feeds on insects, as these animals are the intermediate hosts for acanthocephalan parasitic worms. All other aspects of the ecology of Colubroelaps adleri sp. nov., including information on diet, preferred microhabitats, reproduction, and predators, remain unknown.