Lycodon walli ( Stejneger, 1907 ) Nguyen & Poyarkov & Vogel, 2025

Lycodon walli ( Stejneger, 1907) stat. nov.

Table 2 View Table 2 , Fig. 4 View Figure 4 , Suppl. material 1: table S 1, figs S 12, S 13

Dinodon rufozonatus walli Stejneger 1907: 358. Holotype: USNM [National Museum of Natural History, Smithsonian Institution, Washington, USA] 34007 was collected in June 1899 by A. Owston. Type locality: Ishigaki Island, Yaeyama Group, Ryukyu Islands, Japan. View in CoL

Material examined.

Three adult males were examined; see in Suppl. material 1: table S 1.

Referred material.

A total of 37 specimens were used for reference ( 20 males and 17 females) and were reported by Stejneger (1907), Takara (1962), and Maki (1931); see Suppl. material 1: table S 1.

Diagnosis.

Large-sized species, maximum snout-vent length up to 922 mm; loreal not contacting the eye; dorsal scale rows 17 (19) – 17–15; all smooth at midbody; 164–198 ventrals; 71–90 subcaudals, paired; cloacal plate undivided; 8 supralabials with 3–5 touching the eye; 1 preocular, 2 postoculars; temporals 2 + 3; dorsum chocolate colour with dorsal crossbands grey-brown or dirty cream, wide, separate ground colour into ellipse-shaped patches, 39–51 crossbands on body and tail on tail; head grey-brown the plates conspicuously margined with pale brown; venter cream or pale yellow, no banded (based on Stejneger 1907; Maki 1931; Takara 1962; this study).

Description of the holotype

( Fig. 4 View Figure 4 ): The body is robust and slightly laterally compressed. The tail is relatively long, thin, and tapering. The head is elongated, longer than wide, and moderately flattened, with a distinct separation from the neck. The snout is elongated, flattened, and slightly projects beyond the lower jaw. The nostrils are relatively large, positioned dorsolaterally, and rounded in shape. The eyes are relatively large, with vertical pupils.

Body size. SVL 600 mm; TaL 190 mm; ratio TaL / TL 0.241.

Body scalation. Dorsal scale rows 17–17 – 15, all smooth; scales of the vertebral row not enlarged; no apical pit detected; 190 ventrals; 87 subcaudals, all paired; cloacal plate undivided.

Head scalation. Rostral heptagonal, wider than high, slightly visible from above; nasal single, elongated; nasal surrounded by the first two supralabials, rostral, internasal, and prefrontal; internasals two, curved, slightly wider than longer, in contact with rostral anteriorly, nasal, and prefrontal; prefrontals two, large, subrectangular, prefrontal length slightly shorter than frontal length; prefrontals in contact with internasals, nasals, preoculars, and frontal; frontal rather small, pentagonal, tapering posteriorly, shorter than the distance from tip of snout to frontal; parietals longer than wide, in contact approximately the length of the frontal; 1 / 1 supraocular, distinctly wider than high, in contact with prefrontal; 1 / 1 loreal, not contacting with the eye; 1 / 1 preocular, slightly large, higher than wide, in broad contact with prefrontal; subocular absent; 2 / 2 postoculars; 2 + 3 temporals; 8 / 8 supralabials, first and second in contact with nasal, second and third in contact with loreal, third and fourth in contact with eye, sixth largest; infralabials 10 / 10, first pair in broad contact with each other, first to fifth in contact with anterior pair of chin shields; posterior chin shields equal anterior ones, separated from each other by a small pair of scales.

Colouration in preservative: The dorsal surface is chocolate-coloured, with 25 narrow grey-brown or dirty cream crossbands on the body and 18 on the tail. Each pale crossband is approximately one dorsal scale wide, interconnecting to divide the ground colour into elliptical patches. The ventral surface of the body is predominantly cream, but fine stippling and mottling are present, increasing in density and contrast posteriorly, especially on the tail. The head is black, with a distinct inverted V-shaped marking on the nape. Pale stripes extend downward from the top of the temporal scales to the last supralabial scale.

General description and variation

(see Table 2 View Table 2 ; Suppl. material 1: table S 1, figs S 12, S 13). Morphology variation based on three examined specimens as well as data morphology of 14 specimens was reported by Stejneger (1907), Maki (1931), and Takara (1962).

The longest known specimen is 1,165 mm long (adult male; SVL 922 mm, TaL 243 mm, KUZ 62999 ). The longest known female is 960 + mm long ( SVL 840 mm, TaL 120 + mm (tail incomplete); Sci. Coll. Kyoto e). Body elongated; head distinct from neck, markedly flattened; eye medium; pupil vertically oval; rostral triangular, broader than high, clearly visible from above; internasals as broad as long, approximately half the length of the prefrontal; prefrontal shorter than frontal; frontal hexagonal; parietals large, longer than wide; nasal divided; one loreal, nearly rectangular, narrowing posteriorly, protruding somewhat beneath the preocular, not entering the eye and internasals; one preocular; two postoculars; two anterior temporals; three posterior temporals; eight (7) supralabials, 1 st and 2 nd SL in contact with the nasal, 2 nd and 3 rd SL in contact with the loreal, 3 rd – 5 th SL entering orbit, 6 th and 7 th SL largest; ten infralabials; first pair in contact with each other, 1 st – 5 th IL in contact with anterior chin shields, 5 th and 6 th IL largest; 17 or 19 dorsal scale rows at the head, 17 dorsal scale rows at midbody, 15 dorsal scale rows at the vent, the upper dorsal and vertebral scale rows entirely smooth; ventrals 164–198 (187.95 ± 6.21, n = 40), without sexual dimorphism, vertebral scale slightly enlarged, distinctly angulate laterally; cloacal plate undivided; subcaudals 71–90 (82.11 ± 4.37, n = 37), without sexual dimorphism; relative tail length 0.196 –0.288 (0.217 ± 0.016, n = 33), without sexual dimorphism.

Colouration.

The dorsal surface of the body and tail is chocolate or black-grey, with 25–34 narrow grey-brown or dirty cream crossbands on the body and 15–22 on the tail. Each pale crossband is ~ 1.5–2.5 dorsal scales wide, interconnecting to divide the ground colour into elliptical patches. The ventral surface of the body is predominantly cream, but fine stippling and mottling are present, increasing in density and contrast posteriorly, especially on the tail. The head is brownish-grey with a distinct, inverted V-shaped marking on the nape. Pale pinkish or cream-coloured oblique stripes extend from the upper temporal region downward to the posterior margin of the last supralabial.

Etymology.

According to Stejneger (1907), the subspecies is named for Captain Frank Wall (1868–1950), of the Indian Medical Service, author of “ A prodromus of the snakes hitherto recorded from China, Japan, and the Loo Choo Islands ”, as well as many papers on Indian snakes. We recommend the following common names for this species: Sakishima Wolf Snake (in English); Sakishima Grosszahnnatter (in German); サキシママダラ “ Sakishimamadara ” (in Japan); Окинавский краснопоясный волкозуб “ Okinavskiy krasnpoyasnyi volkozub ” (in Russian).

Comparison.

Lycodon walli stat. nov. differs from L. rufozonatus sensu stricto by the following characteristics: smaller body size in both sexes (maximum SVL 922 mm in males, 840 mm in females vs 1,122 mm in males, 1145 mm in females); fewer crossbands on the body and tail ( BB + TB 39–51, mean 45.40 vs 60–106, mean 79.06); slightly lower number of ventral scales in both sexes ( VEN 164–198, mean 187.95 vs 186–216, mean 199.60); differences in colouration: dorsum blackish-grey or chocolate-brown with grey-brown or dirty cream crossbands vs black dorsum with pinkish or reddish-brown crossbands in L. rufozonatus .

Distribution

(Fig. 1 View Figure 1 ). This species is endemic to the southern Ryukyu Islands, Japan. It has been recorded on Miyako Island and in the Yaeyama Islands, including Ishigaki Island and Iriomote Island ( Maki 1931; Takara 1962; Goris and Maeda 2004; this study).

Natural history notes.

In the southern Ryukyus, where the species Lycodon walli stat. nov. occurs, it is uncommon in the Miyakojima Islands with a decreasing population, whereas it is common and stable in the Yaeyama Islands ( Ota 2014). Lycodon walli stat. nov. is an oviparous species, with mating occurring in April and clutch sizes of 6– 7 eggs laid in June or July. It is nocturnal and inhabits a wide range of habitats. Its diet includes other snakes, lizards (e. g., Plestiodon barbouri (Van Denburgh )) , frogs (e. g., Bufo miyakonis Okada ), and turtles (e. g., Mauremys mutica kami Yasukawa, Ota & Iverson ). Based on observations in captivity, it is also likely to prey on rodents and small birds. On Nakanogan Island, it has been recorded consuming the eggs and chicks of seabirds. This species is terrestrial, occurring at elevations of ca 10–300 m asl, and is sympatric with Lycodon multifasciatus Maki and Protobothrops elegans (Gray) ( Li et al. 2017; Goris and Maeda 2004; Takeuchi 2019; TVN, pers. obs.).