Gerrhopilus lorealis, Kraus, 2023

Kraus, Fred, 2023, A revision of Gerrhopilus inornatus (Squamata: Gerrhopilidae) reveals a multi-species complex, Zootaxa 5231 (1), pp. 1-23 : 15-16

Gerrhopilus lorealis sp. nov.

Figs. 5E, F

Holotype. BPBM 2272 , collected on 14 May 1961 by H. Clissold at upper Watut River near Bulolo, 7.28 S, 146.56 E, Morobe 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 = 380; loreal present; supralabial imbrication pattern T-V; subocular scale one; presubocular scale absent; a sharp, protruding spine on the tail tip that is yellow; 4 glands in the prefrontal, 8–9 in the supraocular, 4 in the ocular, 29–34 in the preocular, 0 in the frontal, and 7–8 in the subocular; L/W = 50.3; TL/ SVL = 0.032; and a dark-brown venter with 1–3 mid-ventral scale rows on the posterior half of the body yellow. Its size is moderate for this species group ( Table 1 ).

Comparisons with other species. Gerrhopilus lorealis 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 and G. wallachi in having fewer transverse scale rows (380 vs 539 in G. fredparkeri , 430 rows in G. wallachi ) and apparently from G. papuanorum (407–414 rows in G. papuanorum ). It is further distinguished from G. inornatus and G. slapcinskyi in having more glands in the supraocular (8–9 vs 2–3 in G. inornatus and 0–3 in G. slapcinskyi ) and subocular (7–8 vs 0–2 in G. inornatus and 3–4 in G. slapcinskyi ); from G. hades in having glands in the ocular and subocular scales (vs none 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 lorealis is distinguished from all other Melanesian Gerrhopilus in having a loreal scale; and it is distinguished from all other species except G. flavinotatus and G. wallachi in having yellow mid-ventral scales on the posterior third of the body. Gerrhopilus lorealis is further distinguished from G. flavinotatus in its much more slender habitus (L/W = 50.3 vs 26.7 in G. flavinotatus ), in having more transverse scale rows (380 vs 327 in G. flavinotatus ), and in having glands in the ocular (vs absent in G. flavinotatus ); and from G. wallachi in having fewer transverse scale rows (380 vs 430 in G. wallachi ), a sharp, protruding tail spine (vs short, blunt, and downturned in G. wallachi ), and fewer glands in the ocular (4 vs 9–11 in G. wallachi ). Among the other species with 22 longitudinal scale rows, G. lorealis may be further distinguished from G. polyadenus in its greater number of transverse scale rows (380 vs 294–320 in G. polyadenus ), more slender habitus (L/W = 50.3 vs 36.2–36.3 in G. polyadenus ) and far fewer glands in the ocular (4 vs 11–23 in G. polyadenus ), preocular (29–34 vs 42–50 in G. polyadenus ), and prefrontal (4 vs 11–29); and from G. papuanorum in having fewer transverse scale rows (380 vs 407–414 in G. papuanorum ) and greater number of glands in the supraocular (8–9 vs 0–4 in G. papuanorum ) and subocular (7–8 vs 0–2 in G. papuanorum ).

Description of the holotype. Female. L = 196 mm, SVL = 190 mm, TL = 6 mm, HW = 4.0 mm, SN = 2.2 mm, SW = 3.4 mm, PSN = 1.1 mm, RW = 1.8 mm, EW = 0.4 mm, W = 3.9 mm, VW = 4.2 mm, TW = 4.2 mm, L/W = 50.3, TL/SVL = 0.032. Head slightly wider than neck. Snout rounded in dorsal and lateral views. Snout anterior to lower jaw horizontal. Rostral moderately large (RW/HW = 0.45), 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. 5E ); superior nasal large, with sinuous posterior margin, concave dorsally, convex ventrally ( Fig. 5F ). 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 just posterior to latter’s contact with first supralabial. Prefrontal smaller than supraoculars, subequal to frontal, parietals, and interparietal, which are all subequal in size. Narrow, crescentic loreal between superior nasal and preocular, oriented anteroventrally to dorsoposteriorly. Preocular large, triangular; approximately same size as ocular but smaller than superior nasal. Ocular large, approximately same size as preocular, extending dorsally well above preocular, extending ventrally to ~2/3 depth of preocular, bordered posteroventrally by subocular of approximately half its size. Eye with indistinct margin and large 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 anterior 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. Ventral slit from mouth to approximately 50 scale rows posteriorly; another ventral slit on posterior third of body and another under tail.

Longitudinal scale rows 22 behind head, 22 at midbody, and 22 anterior to vent; transverse scale rows between rostral and tail tip 380, six intercalary scales along vertebral row; subcaudals 17; dorsocaudals 17; apical region with short, projecting spine.

Rostral, nasals, and preoculars densely covered in pale glands; oculars with 4 glands, preoculars with 29 (R) and 34 (L), supraoculars with 8 (R) and 9 (L), prefrontal with 4; suboculars with 7 (R) and 8 (L), and frontal without glands.

In preservative, 61 years after preservation, body medium brown above and below; no sharp distinction between dorsal and ventral shading; each scale uniformly dark. Venter with scattered mid-ventral yellow scales on anterior third of body, mid-ventral largely continuous line of yellow scales on posterior two-thirds of body, these expanding laterally to include 2–3 scale rows on posterior third of body, though many scales in these rows brown and not yellow, imparting a jagged appearance to this yellow stripe posteriorly. Anterior tip and margins of rostral, area around nares, first two supralabials, mental, first infralabials, and center of throat to four scales behind mental pale straw yellow; third and fourth supralabials pale straw yellow with brown along dorsal margins. Head glands pale straw yellow; tail spine and adjacent scales yellow. Iris dark gray, obscure; pupil paler gray.

Etymology. The species name is a Latinized masculine adjective of the English loreal in recognition of the most distinctive feature of this species.

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

Remarks. This is the only specimen of Typhlops inornatus examined by McDowell (1974), but it has not been reported on by subsequent authors. McDowell remarked that the scale he found wedged between the superior nasal and preocular—which I here refer to as a loreal—was not mentioned in the original description of T. inornatus ( Boulenger 1888) , but so few specimens of nominal G. inornatus were collected by that time that he was uncertain whether this scale represented “random or geographic variation”, by which I presume he meant intraspecific variation. I interpret the symmetry and regular appearance of this scale on each side of the head of BPBM 2272 to reflect that this scale is not a random anomaly, and, hence, I interpret it as diagnostic of a distinct species, a conclusion supported by a host of other features when compared to other samples of the G. inornatus group (see Comparisons section above). Even were the loreal scale presumed to be an individual anomaly of this specimen and not diagnostic of a separate species, the unique combination of other characters ( Table 2 ) does not allow this specimen to be readily assigned to any of the other species recognized herein.

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).