Lepidodactylus dialeukos, Kraus, 2019

Kraus, Fred, 2019, New species of Lepidodactylus (Squamata: Gekkonidae) from New Guinea and adjacent islands, Zootaxa 4651 (2), pp. 305-329 : 321-324

Lepidodactylus dialeukos sp. nov.

Fig. 6

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Holotype. BMNH 1974.3028 , mature female, collected by L.E. Cheesman, Mt. Baduri , 1.75°S, 136.25°E, 1000 ft [305 m], Yapen Island, Papua Province, Indonesia, March–April 1938.

Diagnosis. A medium-sized species (adult SVL 46.5 mm) species of Lepidodactylus having a subcylindrical tail without a lateral fringe of enlarged scales; one divided subterminal scansor on digits; 14 enlarged scales of the pore-bearing series limited to precloacal region; 9–10 T4 lamellae, 8–9 T1 lamellae; toes relatively long (T4/SVL = 0.12) and wide (T4W/T4L = 0.36), poorly webbed (T3T4webL/T4L = 0.20), with lamellae covering only about half their length (T4lamellaeL/4TL = 0.53); nine small precloacal scales between apex of pore-bearing series and cloaca; dorsum uniformly gray with a row of dorsolateral white spots on each side, lacking dark spots in this region; white postocular stripe; narrow bands or patches of white scales on dorsal surfaces of forearms, wrists, shanks, ankles, and digits; and black punctations widely scattered ventrally.

Comparisons with other species. The subcylindrical tail without a lateral fringe of enlarged scales and the single divided subterminal scansors under the toes place Lepidodactylus dialeukos sp. nov. in Brown and Parker’s (1977) Group II. Lepidodactylus dialeukos sp. nov. differs from all other Melanesian members of this group in being the only species with only a single divided subterminal scansor (versus having 2–4 in the other species) and extensive white markings. It further differs from other Melanesian members of this group as follows: from L. guppyi , L. pul- cher, and L. shebae in having fewer enlarged precloacal scales (14 versus 39–52, 18–20, and 34, respectively, in the other species), and further from L. shebae in its larger adult size (SVL 46.5 mm versus ~ 36 mm in L. shebae ). It differs from L. novaeguineae in having less coverage of the fourth toe by lamellae (T4lamellaeL/4TL = 0.53 versus 0.65–0.94 in L. novaeguineae ), a longer fourth toe (T4/SVL = 0.12 versus 0.086–0.11 in L. novaeguineae ), a white postocular stripe (absent in L. novaeguineae ), dorsum with a dorsolateral row of white spots (absent in L. novaeguineae ), and bands or patches of white scales on dorsal surfaces of digits (absent in L. novaeguineae ). It differs from L. mitchelli sp. nov. in its larger adult size (SVL = 46.5 mm versus mean 40.3, range = 35–45.5 mm in L. mitchelli sp. nov.), white postocular stripe (absent in L. mitchelli sp. nov.), dorsum with a dorsolateral row of white spots (absent in L. mitchelli sp. nov.), and bands or patches of white scales on dorsal surfaces of digits (absent in L. mitchelli sp. nov.). It differs from L. kwasnickae sp. nov. in having fewer T4 lamellae (10 versus 12–20 in L. kwasnickae sp. nov.), dorsum uniform gray (boldly patterned with brown in L. kwasnickae sp. nov.), bands or patches of white scales on dorsal surfaces of digits (absent in L. kwasnickae sp. nov.), and black punctations widely scattered ventrally (many posteroventral and plantar scales uniformly brown in L. kwasnickae sp. nov.).

Description of holotype. A female of medium size (SVL = 46.5 mm, TrL = 16.0 mm). Head relatively long (HL/ SVL = 0.19) and wide (HW/HL = 0.85), distinct from neck. Loreal region inflated; no distinct canthus rostralis. Top of snout, area between nares, and area posterior to nares concave. Snout tapered and rounded at tip, long (SN/HL = 0.60), almost twice as long as eye diameter (SN/EY = 1.9). Eye relatively large (EY/HL = 0.32, EY/EN = 0.70); pupil vertical, constricted into series of four lobes on right, rounded on left; supraciliaries same size as adjacent granules. Ear opening small (Ear/HL = 0.080), approximately round; distance between ear and eye larger than eye diameter (EE/EY = 1.4). Rostral wider (3.3 mm) than high (1.1 mm), highest just medial to nares, lower between these points; length (0.5 mm). Scales on snout tip undifferentiable due to loss of keratin layer. External nares circular. Mental shallowly triangular, wider (2.1 mm) than long (1.1 mm), with a short, medial suture posteriorly. Mental bordered posteriorly by three enlarged postmentals, these bordered posteriorly by three rows of enlarged gulars that are followed by smaller scales decreasing in size to granular chin scales. First four infralabials bordered below by somewhat enlarged scales; remaining scales below infralabials of approximately twice size of central throat scales. Supralabials to mid-orbital position ten on each side; to angle of jaw 13 on each side. Infralabials 11 on each side.

Body of modest habitus (TrL/SVL = 0.34), slightly depressed. Dorsal scales on head, body, limbs, and throat tiny, juxtaposed granules, larger on sides and snout; tubercles absent. Ventral scales larger, flatter but somewhat beaded, smooth, subimbricate, gradually decreasing in size laterally to become granular.

Enlarged precloacal scales in single series of 14, all but one bearing a tiny indentation but lacking true pores with sebaceous plugs; no enlarged scales on thighs. Enlarged scales form a pubic patch between the precloacal series and vent; no tiny scales inserted between the precloacal series and the pubic patch on either side; ten scales in a row between apex of enlarged precloacal series and vent. Scales on palms and soles rounded, smooth.

Fore- and hindlimbs relatively small but well-developed (FA/SVL = 0.11, CS/SVL = 0.11). Digits well-developed, fairly widely dilated throughout their length (T4W/T4L = 0.36), all but first fingers and toes with recurved claws; clawed phalanges laterally compressed, free above and extending slightly beyond terminal scansors. Subdigital lamellae narrow and smooth, all digits with single divided subterminal scansor; lamellae extend for approximately half length of each toe (T4 scansor L/T4L = 0.53). Lamellae of manus 8–8–9–13 –8 on right, 8–9–10 –9–8 on left; of pes 8–9–12 –?–7 on right, 9–10–10–11 –7 on left; fourth toe on right pes missing tip. Relative lengths of digits on manus and pes I <II <V <III <IV. Webbing present between all digits, basal between most digits but more extensive between T3 and T4 (T3T4webL/T4L = 0.20).

Tail appears to be entirely original, subcylindrical, somewhat compressed, relatively narrow (TW/SVL = 0.080); lateral margins without skin flanges or spines. Scales of tail small, flat, smooth, subimbricate, slightly larger ventrally than dorsally. Cloacal sacs swollen, with small external orifices situated near lateral margins of vent; no postcloacal spur on either side of tailbase; midventral scales of sac slightly larger than those ventrolaterally.

Color in preservative: Dorsal ground color pale gray with white spots laterally and dorsolaterally, largely arrayed into rows ( Fig. 6 ). Narrow (1–3 granules wide) white dorsal crossbands before and after forearm insertion; another vaguely suggested on back of neck. Narrow white postocular stripe, another running behind ear opening, another short white line from corner of jaw to throat. Labials white spotted with black. Narrow white crossbands on forearm, wrist, shank, ankle, and each digit. Narrow white bands on tail bordered anteriorly with one or two dark-brown spots, first band behind legs connecting to short white vertebral stripe that extends to above hindlimb insertion, where it is margined anteriorly with a short, broken black chevron. White spots scattered on thighs. Venter pale gray, heavily stippled with black punctations, denser laterally. Iris silver veined with black.

Measurements (in mm). SVL = 46.5, TrL = 16.0, TW = 3.7, FA = 5.2, CS = 5.3, HL = 8.8, HW = 7.5, Ear = 0.7, EE = 3.9, EY = 2.8, SN = 5.3, EN = 4.0, IN = 2.3, T4L = 5.5, T4W = 2.0, T4 scansor L = 2.9, T3T4webL = 1.1.

Etymology. The name is a masculine possessive Greek adjective meaning marked with white. The name is in reference to the numerous narrow white markings that typify this species.

Range. Known only from the type locality, but likely ranges widely across Yapen Island ( Fig. 2 ), although the species has apparently not been collected in 80 years.

Ecology. The elevation of the sole specimen suggests that it is an inhabitant of interior forested areas.

Remarks. In recognizing their phenetic Group II Brown and Parker (1977) defined it as comprising those species having 1–4 divided subterminal lamellae. Above I noted that L. dialeukos sp. nov. is unique, so far as I can determine, in having consistently only a single divided subterminal scansor. The observations of single divided subterminal scansors made by Brown and Parker in other species represent only occasional outliers on single digits in species for which the large majority of digits are characterized by 2–4 divided lamellae. Hence, the consistent condition of only a single divided subterminal scansor across all digits seems unique to L. dialeukos sp. nov.

Figures

FIGURE 2. Map of New Guinea and surrounding islands showing type localities for Lepidodactylus aignanus sp. nov. (diamond), L. dialeukos sp. nov. (triangle), L. kwasnickae sp. nov. (square), L. mitchelli sp. nov. (circle), and L. zweifeli sp. nov. (star).

FIGURE 6. Dorsal view of holotype of Lepidodactylus dialeukos sp. nov., BMNH 1974.3028.