Gerrhopilus slapcinskyi, Kraus, 2023

Kraus, Fred, 2023, A revision of Gerrhopilus inornatus (Squamata: Gerrhopilidae) reveals a multi-species complex, Zootaxa 5231 (1), pp. 1-23 : 6-8

Gerrhopilus slapcinskyi sp. nov.

Figs. 1C, D

Holotype. BPBM 18944 (field tag FK 8467), collected 20 October 2003 by John Slapcinsky along Dunch River, 5.6 km (by air) NW of Mt Shungol summit, 6.816° S, 146.692° E, 750 m elevation, Morobe Province, Papua New Guinea.

Paratype. BPBM 18945 , same data as holotype .

Diagnosis. A Gerrhopilus species characterized by the unique combination of having a rounded snout in lateral view; LSR = 20 at midbody; TSR = 298–318; loreal absent; supralabial imbrication pattern T-V; subocular scale one; presubocular scale absent; a sharp, protruding, tail spine that is black basally and white distally; 1–2 glands in the prefrontal, 0–3 in the supraocular, 4–9 in the ocular, 35–39 in the preocular, 0 in the frontal, 3–4 in the subocular; L/W = 35.5–38.6; TL/SVL = 0.034 in one female and 0.043 in one male; and a uniformly dark-brown venter. Its size is small to moderate for this species group ( Table 1 ).

Comparisons with other species. Gerrhopilus slapcinskyi is distinguished from G. fredparkeri , G. hades , and G. suturalis in having 20 longitudinal scale rows at midbody (vs 16 in G. fredparkeri and 18 in G. hades and G. suturalis ). It is further distinguished from G. fredparkeri in its lower number of transverse scale rows (298–318 vs 539 in G. fredparkeri ), from G. hades in having 22 longitudinal scale rows behind the head (vs 18 in G. hades ) and more and smaller glands in the center of the preocular (35–39 vs 10–11 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 ). Gerrhopilus slapcinskyi differs from G. inornatus in having fewer or more transverse scale rows (298– 318 vs 374–375 in G. inornatus ), a greater number of glands in the preocular (35–39 vs 22–24 in G. inornatus ), and longer tail (TL/SVL = 0.034 vs 0.026 in female and 0.043 vs 0.030 in male G. inornatus ).

Description of the holotype. Female. L = 195.5 mm, SVL = 189 mm, TL = 6.5 mm, HW = 4.3 mm, SN = 1.9 mm, SW = 3.5 mm, PSN = 1.0 mm, RW = 1.8 mm, EW = 0.4 mm, W = 5.5 mm, VW = 4.3 mm, TW = 3.8 mm, L/W = 35.5, TL/SVL = 0.034. 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 = 0.42), 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. 1C ); superior nasal large, with sinuous posterior margin, concave dorsally, convex ventrally ( Fig. 1D ). 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, latter wider, same size as frontal but larger than parietals and interparietal, which are also subequal in size. Preocular large, triangular; larger than ocular but smaller than superior nasal. 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 distinct, with large distinct pupil, situated at widest point of ocular and closer to its dorsal than ventral margin, anterior 40% 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 22 behind head, 20 at midbody, and 20 anterior to vent; transverse scale rows 318, ten intercalary scales along vertebral row; subcaudals 15; dorsocaudals 15; apical region with sharp, slightly downturned spine that extends 0.4 mm past last scales.

Rostral, nasals, and preoculars densely covered in pale glands; oculars with 4 (R) and 9 (L) glands, preoculars with 35 (R) and 37 (L), supraoculars with 0 (R) and 1 (L), prefrontal with 2; suboculars with 4 (R) and 3 (L), and frontal without glands.

In preservative, 19 years after preservation, body dark brown above and below but somewhat paler below; no sharp distinction between dorsal and ventral shading; each scale uniformly dark. Anterior tip and margins of rostral, area around nares, first and second supralabials, mental, infralabials, and center of throat to three scales behind mental white; second supralabials white with brown along dorsal margins. Head glands white; tail spine dark brown basally, white distally. Iris dark gray; pupil paler gray. In life, the holotype was black.

Variation. The paratype ( BPBM 18945 ) differs from the holotype in being male, somewhat shorter (L = 170 mm, SVL = 163 mm, TL = 7 mm, Table 1 ), approximately the same width (W = 4.4 mm, L/W = 38.6), and with a longer tail (TL/SVL = 0.043). It too has 22-20-20 longitudinal scale rows, 298 transverse scale rows, nine intercalary scales, 16 subcaudals, 16 dorsocaudals, the eye one-third covered by the preocular, oculars with 8 (R) and 9 (L) glands, preocular with 36 (R) and 39 (L), supraoculars with 3 (R) and 2 (L), prefrontal with 1, frontal with 0, and suboculars with 4 (R) and 3 (L) glands. Like the holotype, it was black in life. The holotype has greater asymmetry in ocular gland numbers and slightly more mid-dorsal scale rows, but otherwise variation between the two specimens is slight.

Etymology. This species is named for malacologist John Slapcinsky, who collected the type specimens and proved a great field companion on several of my expeditions to Papua New Guinea.

Distribution. Known only from the type locality, west of Lae ( Fig. 2 ).

Ecology. Both specimens were taken at night in primary lowland hill rainforest with a canopy of approximately 30 m height and a moderately dense understory. One of the specimens was found while climbing on the trunk of a tree.

Figures

FIGURE 1. Dorsal and lateral views of heads for members of the Gerrhopilus inornatus Group having 20 midbody scale rows. A, B holotype of Gerrhopilus inornatus (BMNH 1946.1.11.80); C, D holotype of Gerrhopilus slapcinskyi (BPBM 18944).

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).