Gerrhopilus wallachi, Kraus, 2023

Kraus, Fred, 2023, A revision of Gerrhopilus inornatus (Squamata: Gerrhopilidae) reveals a multi-species complex, Zootaxa 5231 (1), pp. 1-23 : 12-13

Gerrhopilus wallachi sp. nov.

Figs. 5A, B

Typhlops inornatus Wallach 1996: 113 .

Gerrhopilus inornatus Pyron & Wallach 2014: 79 .

Holotype. MCZ 140724 (field tag Y-14092), collected on 24 April 1973 by Fred Parker at Afore, 9.14 S, 148.39 E, 760 m a.s.l., Oro Province, Papua New Guinea.

Diagnosis. A Gerrhopilus species characterized by the unique combination of having a rounded snout in lateral view; LSR = 22 at midbody; TSR = 430; loreal absent; supralabial imbrication pattern T-V; subocular scale one; presubocular scale absent; a short, blunt, scale on the tail tip that is light brown and downturned; 9 glands in the prefrontal, 3–5 in the supraocular, 9–11 in the ocular, 33–35 in the preocular, 0 in the frontal, and 3–4 in the subocular; L/W = 42.6; TL/SVL = 0.036; and a dark-brown venter with scattered white scales mid-ventrally on the posterior half of the body. Its size is large for this species group ( Table 1 ).

Comparisons with other species. Gerrhopilus wallachi is distinguished from G. fredparkeri , G. hades , G. inornatus , G. slapcinskyi , and G. suturalis in having 22 longitudinal scale rows at midbody (vs 16 in G. fredparkeri , 18 in G. hades and G. suturalis , and 20 in G. inornatus and G. slapcinskyi ). It is further distinguished from G. fredparkeri , G. polyadenus , and G. slapcinskyi in having fewer transverse scale rows (430 vs 539 in G. fredparkeri , 294–320 in G. polyadenus , and 298–318 in G. slapcinskyi ); from G. inornatus in having more transverse scale rows (430 vs 374–375 in G. inornatus ), a short, blunt, downturned tail spine (vs sharp and protruding in G. inornatus ) more glands in the prefrontal (9 vs 2–3 in G. inornatus ), ocular (9–11 vs 0–6 in G. inornatus ) and preocular (33–35 vs 22–24 in G. inornatus ); from G. papuanorum in having a short, blunt, downturned tail spine (vs sharp and protruding in G. papuanorum ), more glands in the ocular (9–11 vs 0–3 in G. papuanorum ) and preocular (33–35 vs 18–28 in G. papuanorum ), and a longer tail (TL/SVL = 0.036 vs 0.021 –0.026 in G. papuanorum ); from G. hades in having 24 longitudinal scale rows behind the head (vs 18 in G. hades ); and from G. suturalis in having a single postocular on each side of the head (vs two in G. suturalis ) and lacking a presubocular (vs present in G. suturalis ). It is further distinguished from all of these species in having a venter that is brown with white (possibly yellow in life) mid-ventral scales throughout the posterior third of the body (vs venter uniformly brown in all the other species).

Description of the holotype. Female. L = 217.5 mm, SVL = 210 mm, TL = 7.5 mm, HW = 4.1 mm, SN = 1.7 mm, SW = 3.5 mm, PSN = 1.2 mm, RW = 2.0 mm, EW = 0.5 mm, W = 5.1 mm, VW = 4.4 mm, TW = 3.8 mm, L/W = 42.6, TL/SVL = 0.036. Head slightly wider than neck. Snout rounded in dorsal and lateral views. Snout anterior to lower jaw angled slightly ventrally. Rostral moderately large (RW/HW = 0.49), oval dorsally, lateral margins convex, posterior border extending approximately two-thirds way between naris and eye, posterior margin straight; ventrally surface papillose, with straight sides and posterior margin concave. Nasals separated dorsally by prefrontal ( Fig. 5A ); superior nasal large, with sinuous posterior margin, concave dorsally, convex ventrally ( Fig. 5B ). External naris semicircular, oriented obliquely, close to rostral, anterior half covered by inferior nasal; superior nasal suture extending anterodorsally from naris to rostral; inferior nasal suture complete, contacting second supralabial well posterior to latter’s contact with first supralabial. Prefrontal and supraoculars subequal in size, larger than frontal, parietals, and interparietal, which are also subequal in size. Preocular large, triangular; larger than ocular but smaller than superior nasal, posterior margin sinuous. Ocular large, smaller than preocular, extending dorsally well above preocular, extending ventrally to ~2/3 depth of preocular, bordered posteroventrally by subocular of less than half its size. Eye obscure, with indistinct margin and large but obscure pupil, situated at widest point of ocular and approximately midway along its height, anterior half covered by preocular plate in lateral view. Four postoculars bordering ocular and subocular between parietal and fourth supralabial. Four supralabials, third the largest, all with long axis oblique to long axis of body, first approximately rectangular. Supralabial imbrication pattern T-V, posterior border of second supralabial overlaps anteroventral margin of preocular, that of third supralabial overlaps anteroventral margin of subocular and ends just posterior to rear margin of preocular. Mental crescentic, wider than long, projecting slightly beyond curve of lower jaw and fitting into notch on upper lip when mouth is closed. Infralabials two on each side, second much longer.

Longitudinal scale rows 24 behind head, 22 at midbody, and 22 anterior to vent; transverse scale rows 430, 15 intercalary scales along vertebral row; subcaudals 15; dorsocaudals 14; apical region with short, blunt, downturned scale that extends only short distance past last scales.

Rostral, nasals, and preoculars densely covered in small pale glands; oculars with 11 (R) and 9 (L) glands, preoculars with 35 (R) and 33 (L), supraoculars with 5 (R) and 3 (L), prefrontal with 9; suboculars with 4 (R) and 3 (L), and frontal without glands.

In preservative, 49 years after preservation, body dark brown above and below; no sharp distinction between dorsal and ventral shading; each scale uniformly dark. Venter with mid-ventral line of scattered white scales on posterior half of body, only single scale wide except one small blotch that is 2–3 scales wide, these joining into a discontinuous line of white scales on portion of posterior third of body but becoming only scattered white scales again before vent; vent bordered anteriorly by white blotch two scales wide; row of four white blotches under tail that are 1–2 scales wide. Anterior tip and margins of rostral, area around nares, first supralabial, mental, infralabials, and center of throat to two scales behind mental pale straw yellow; second, third, and fourth supralabials pale straw yellow with brown along dorsal margins. Head glands pale straw yellow; tail tip corneus brown, paler than remaining body scales. Iris dark gray, obscure; pupil paler gray.

Etymology. The species name is a genitive singular honorific for Van Wallach in recognition of his numerous contributions to the systematics of blindsnakes.

Distribution. Known only from the type locality ( Fig. 2 ).

Remarks. The sole specimen was examined by Wallach (1996) and Pyron & Wallach (2014) who listed it as Typhlops inornatus .

Figures

FIGURE 2. Map of southern Papua New Guinea showing collecting localities for Gerrhopilus inornatus (star), G. flavinotatus (diamond), G. lorealis (hexagon), G. papuanorum (square), G. polyadenus (open circles), G. slapcinskyi (filled circle), and G. wallachi (triangle).

FIGURE 5. Dorsal and lateral views of heads for members of the Gerrhopilus inornatus Group having 22 midbody scale rows and venters marked with yellow. A, B holotype of Gerrhopilus wallachi (MCZ 140724); C, D holotype of Gerrhopilus flavinotatus (MCZ 175100); E, F holotype of Gerrhopilus lorealis (BPBM 2272).