Cyrtodactylus atremus, Kraus & Weijola, 2019

Kraus, Fred & Weijola, Valter, 2019, New species of Cyrtodactylus (Squamata: Gekkonidae) from Karkar Island, Papua New Guinea, Zootaxa 4695 (6), pp. 529-540 : 530-536

Cyrtodactylus atremus sp. nov.

Fig. 1 , 3A , 5C, D

Cyrtodactylus sp. ‘Karkar’ Tallowin et al. 2018

Holotype. UMMZ 247747 (field tag FK 17685 ), mature male collected by V. Weijola above Mom, 4.6248°S, 145.9378°E, 500–645 m a.s.l., Karkar Island , Madang Province, Papua New Guinea, 26 February 2018.

Paratypes (n = 8). Male: Papua New Guinea: Madang Province: Karkar Island : same data as holotype ( UMMZ 247746 ) ; Females: Papua New Guinea: Madang Province: Karkar Island : same data as holotype ( UMMZ 247748– 51 ) , Mom, 4.61°S, 145.92°E, 290 m a.s.l. ( AMS R24744, R28901) , Kevasob , 4.7°S, 145.9°E, 130 m a.s.l. ( AMS R124604 ) .

Diagnosis. A moderately large (adult SVL = 108–118 mm) species of Cyrtodactylus with a small patch of somewhat enlarged precloacal scales (ca. 2–3 times size of nearby femoral scales), no enlarged femoral scales, no precloacal/femoral pores in males, and having a highly tuberculate dorsum, 22–24 rows of dorsal tubercles between the lateral skin folds, dorsal tubercles 3–5 times size of adjacent granules, 24–31 scale rows below the fourth toe, 9–11 supralabials to the center of eye, 10–13 infralabials to rictus, 40–47 mid-belly scale rows, 5–6 dark dorsal crossbands to the base of the tail, uniformly brown top of head, and lips dirty white with some brown stippling.

Comparisons with other species. The absence of enlarged femoral scales and precloacal/femoral pores in males distinguishes the new species from all other Papuan Cyrtodactylus except C. sermowaiensis ( Kraus 2008) . From that species, C. atremus differs in its larger size (adult SVL = 108–118 mm versus 85–94 mm in C. sermowaiensis ; adult mass = 24.3–25.8 g versus 10.3–15.8 g in C. sermowaiensis ); more tuberculate dorsum, limbs, and head (cf. Fig. 1 versus Fig. 2 ), with tubercles 3–5 times size of adjacent granules (versus 2–3 times in C. sermowaiensis ); greater average number of rows of dorsal tubercles between the lateral skin folds (mean = 22.6, range = 22–24, SD = 0.799 versus mean = 20.3, range = 18–25, SD = 0.843 in C. sermowaiensis ); fewer dark dorsal crossbands from head to tail base (mean = 5.8, range = 5–6, SD = 0.167 versus mean = 8.0, range = 7–9, SD = 0.365 in C. sermowaiensis ); top of head uniformly brown (cf. Fig. 1A , 3A versus heavily patterned with dark-brown blotches, cf. Fig. 2A , 3B, C, D in C. sermowaiensis ); and lips dirty white with some brown stippling (cf. Fig. 1B , 3A versus dark brown with few white or yellow spots, cf. Fig. 2B , 3B, C, D in C. sermowaiensis ).

Description of holotype. A mature male, with right-lateral incision. Animal large (SVL = 111 mm, TrL = 49.9 mm); preserved with tail folded back on itself and unamenable to accurate measurement in preservative, but 113 mm in life. Head relatively long (HL/SVL = 0.28) and wide (HW/HL = 0.66), not depressed (HH/HL = 0.43), distinct from neck ( Fig. 1A ). Loreal region slightly inflated; canthus rostralis poorly defined. Interorbital region and top of snout concave. Snout relatively long (SN/HL = 0.40), much longer than eye diameter (SN/EY = 1.7). Eye relatively large (EY/HL = 0.23); pupil vertical, with weakly crenellated margins; supraciliaries large, frill-like, well-differentiated from adjacent granules. Ear opening small (Ear/HL = 0.058), taller than wide ( Fig. 1B ); distance between ear and eye larger than eye diameter (EE/EY = 1.3). Rostral wider (4.9 mm) than high (2.5 mm), highest just medial to nares, lower between these points, length 2.3 mm; dorsal surface with weak (0.2 mm) medial groove at posterior end. Two enlarged supranasals separated by single internasal; internasal bordered anteriorly by supernumerary scale otherwise surrounded by posterior lobes of rostral. Rostral in contact with first supralabials, two supranasals, one internasal, and one postnasal (on right). External nares circular; each bordered by rostral, supranasal, first supralabial, and four postnasals. Three rows of small scales separate orbit from supralabials at narrowest point. Mental shield shaped, posterior margins shallowly concave, wider (4.0 mm) than long (2.7 mm). Mental bordered posteriorly by two enlarged postmentals. Infralabials bordered by slightly enlarged, elongate scales that gradually decrease in size posteriorly. Supralabials to mid-orbital position nine on right side, 11 on left; to angle of jaw 12 on right, 14 on left. Infralabials 12 on each side.

Body moderately robust (TrL/SVL = 0.45), with lateral skin folds consisting of scales approximately same size as adjacent ventral scales and dorsal granules on its ventral and dorsal surfaces, respectively, and with larger scales along its lateralmost margin. Dorsal scales on head, body, and limbs tiny, juxtaposed granules. Both raised and flattened tubercles intermixed and dense on head, body, and limbs ( Fig. 1 ); 3–5 times areal size of adjacent granules; distinct from granules in profile; each with small dorsal keel, highest posteriorly. Tubercles arranged in approximately 23 rows between the lateral folds. Ventral scales flat and smooth; those on chin and throat smaller and juxtaposed; those on abdomen larger and subimbricate, arrayed in 41 rows across mid-venter.

Precloacal and femoral pores absent. Scales of femoral regions of approximately uniform size, smaller than those on abdomen. A diamond-shaped patch of slightly enlarged precloacal scales (ca. 2–3 times larger than nearby femoral scales) approximately six rows deep mid-ventrally and 17 scales across at its widest. No precloacal groove. Scales on palms and soles rounded, smooth.

Fore- and hindlimbs relatively well-developed (FA/SVL = 0.15, CS/SVL = 0.18). Digits well-developed, inflected at basal interphalangeal joints; all with robust, recurved claws surrounded by two scales. Subdigital scales consisting of several rows of basal lamellae, followed distally by ca. 6–8 rows of small granular scales, and terminally by several additional rows of lamellae not as expanded as those basally. Subdigital scales of manus 16 (tip missing)–22–24–26–22 on right, 18–23–25–26–22 on left; of pes 18–22–29–31–26 on right, 17–23–27–31–25 on left. Relative lengths of digits on manus I <V <II <III <IV; on pes I <II <V <III <IV. Slight interdigital webbing on manus, slightly more on pes.

Tail regenerated, with rather narrow base (TW/SVL = 0.067), tapering to a blunt point. Cloacal sacs swollen, with small external orifices situated near lateral margins of vent; midventral scales of sac not distinctly larger than those ventrolaterally. Scales of tail small, flat, smooth, subimbricate, slightly larger ventrally than dorsally; with approximately eight rows of enlarged dorsal tubercles just before regenerated tail; four enlarged postcloacal spurs on each side of tailbase.

Color in preservative: Dorsal ground color brown with six dark-brown bands including nuchal collar and band above hindlimb insertion. Lateral ends of the dark scapular band extend posteriorly as narrow stripes to almost meet the following band; last three bands narrowly divided vertebrally by ground color. Nuchal collar narrowly indented posteromedially ( Fig. 1A ). Regenerated tail uniformly brown. Dorsal tubercles dirty white stippled with brown. Head and limbs brown vaguely mottled with dark brown ( Fig. 1A, D ); labials white stippled with brown, paler than head ( Fig. 1B ). Venter pale brown to naked eye; each scale dirty white punctated with brown under magnification. Palmar and plantar surfaces pale brown but basal lamellae dirty white. Iris copper, heavily veined with brown; pupil gray ( Fig. 1B ).

Measurements (in mm). SVL = 111, TrL = 49.9, TW = 7.4, FA = 16.2, CS = 19.6, HL = 31.0, HW = 20.6, HH = 13.3, Ear = 1.8, EE = 9.6, EY = 7.2, SN = 12.3, EN = 10.4, IN = 4.4, IO = 8.3, mass = 24.3 g.

Variation. There appear to be no meaningful morphometric differences between the sexes, though there are suggestions in the small samples available that juveniles may have relatively larger eyes (EY/SVL, EY/EN) and narrower heads (IN/SVL, IO/SVL, HW/HL, EN/IN) ( Table 1 ). The dark crossbands often have a few dark spots along their anterior or posterior margins, and some of them (usually the posterior ones) may be narrowly divided by ground color vertebrally. In UMMZ 247749, one band is split into anterior and posterior portions on the right side, and one band in UMMZ 247748 is also offset anteriorly on the right side. UMMZ 247748 also has more ventrolateral brown stippling than the other specimens.

Color in life. Field notes for UMMZ 247749 recorded the animal as golden brown with dark-brown bands, each partially and narrowly margined in pale golden white; legs with many pale golden spots; head marbled golden white and brown; iris brass; venter pale golden white. UMMZ 247750 differed from this in being brown above with dark-brown bands, no pale golden spots, iris darker brass and brown, and venter pale purplish. UMMZ 247746 had a medium-brown ground color, with darker-brown bands having a few chocolate-brown spots along the margins and superciliaries that were yellowish with brown spots ( Fig. 3A ).

Etymology. The name is a Latinized masculine compound adjective formed from the Greek a, meaning without, and trema, meaning hole. It refers to the lack of precloacal/femoral pores in males of this species.

Range. Known from the western slopes of Mount Uluman at altitudes between 130–650 meters on Karkar Island, but no doubt ranges across the lower elevations of the entire island ( Fig. 4 ) where suitable habitat occurs. Karkar attains of maximum elevation of 1840 m, and it is likely that this species will only occur up to approximately 1000–1200 m elevation—depending on the elevation at which cloud forest begins—although that remains to be determined.

Ecology. The six UMMZ specimens were all found uphill from the village of Mom on the western slopes of Mount Uluman at altitudes between 500–650 m a.s.l. The tropical rainforests in this area are still fairly intact and recently undisturbed though appearing open enough to be of secondary development ( Fig. 5A, B ). All individuals were caught during daytime head down on larger tree trunks or saplings, one to three meters from the ground ( Fig. 5C, D ). All were easy to approach and capture, which is not usual for Cyrtodactylus active at night, so we presume they were sleeping, though we have never seen such exposed resting behavior in the several other Cyrtodactylus species we have collected. Day- and night-time searches in disturbed habitats along the coast and lowland coconut plantations did not yield any specimens. Data for the AMS specimens are for the villages of Mom and Kevasob (ca. 270 and 130 m a.s.l., respectively). We have never previously found Cyrtodactylus species in villages per se, so we presume that those lizards were collected in the forests adjacent to the villages. In any event, like several other Papuan Cyrtodactylus , C. atremus seems to persist well in secondary forest.

Other geckos present on Karkar include Gehyra oceanica , Gekko vittatus , Hemidactylus frenatus , and Nactus sp. Of these, Nactus sp. is an inhabitant of forest interiors, though it lives under debris on the forest floor, and the arboreal G. oceanica was found in the forest in the same vicinity as our specimens of C. atremus though hidden in leaf axils and under bark. It is unclear to what extent the other species might share the forest habitat of C. atremus , though overlap is probably not great as each typically occurs in more disturbed habitats.

Among the females captured in late February, two (UMMZ 247749–50) are of adult size (109–112 mm), lack enlarged ova, but have small oocytes, suggesting that they recently laid eggs prior to capture. The other two females captured the same day (UMMZ 247748, 247751) each have two enlarged white eggs in their abdomens that were presumably near to deposition. AMS R24744 and R124604 are immature at 77 mm SVL and 66 mm SVL, respectively.

One specimen (UMMZ 247749) has numerous nymphs of the lungworm Kiricephalus pattoni (Pentastomida, catalogued as HWML- 111019) between the skin and underlying musculature of the trunk; some of these have their heads protruding into the body cavity. This species has previously been reported in Papua New Guinea under the name Kiricephalus sp. from the lizards Cyrtodactylus louisiadensis , Sphenomorphus jobiensis , and S. simus ( Bursey et al., 2005, 2008a; Goldberg et al., 2009a) as well as the frogs Cornufer boulengeri , C. schmidti , and Papurana supragrisea ( Bursey et al., 2008b; Goldberg et al., 2009b).

Figures

FIGURE 1. (A) Top of head, (B) side of head, (C) mid-dorsum, and (D) left leg of holotype of Cyrtodactylus atremus sp. nov., UMMZ 247747, Karkar Island, Madang Province, PNG.

FIGURE 2. (A) Top of head, (B) side of head, (C) mid-dorsum, and (D) left leg of Cyrtodactylus sermowaiensis, BPBM 35618, Waven, Adelbert Mts., Madang Province, PNG.

FIGURE 3. Portraits in life of (A) paratype of Cyrtodactylus atremus sp. nov., UMMZ 247746, Karkar Island, Madang Province, PNG; (B) Cyrtodactylus sermowaiensis, BPBM 23317, Parkop, Torricelli Mts., West Sepik Province, PNG; (C) Cyrtodactylus sermowaiensis, BPBM 23320, base of Mt. Sapau, Torricelli Mts., West Sepik Province, PNG; and (D) Cyrtodactylus sermowaiensis, BPBM 35598, Yefehi, Prince Alexander Mts., East Sepik Province, PNG.

FIGURE 4. Map of New Guinea and surrounding islands showing known localities taken from American and Australian museum catalogues for Cyrtodactylus atremus sp. nov. (star), C. sermowaiensis (dots), and an undescribed species of Cyrtodactylus in the C. sermowaiensis species group (diamond). The type locality for C. sermowaiensis is along the Sermowai River in Indonesian New Guinea, approximately 200 km WNW of the westernmost locality shown on this map. Contour intervals are 0 (white), 500 (light gray), and 1000 (dark gray) meters a.s.l.

FIGURE 5. (A), (B) Habitat of Cyrtodactylus atremus sp. nov. on the lower northwestern slopes of Mt. Uluman, Karkar Island, Madang Province, PNG; (C) UMMZ 247751, and (D) UMMZ 247750 in situ showing their head-down resting position during the daytime.