Nactus kunan, Zug, George R. & Fisher, Robert N., 2012

Zug, George R. & Fisher, Robert N., 2012, A preliminary assessment of the Nactus pelagicus species group (Squamata: Gekkonidae) in New Guinea and a new species from the Admiralty Islands, Zootaxa 3257, pp. 22-37 : 26-30

Nactus kunan sp. nov. Fisher & Zug

( Fig. 1 )

Holotype. USNM 576300, adult female from Papua New Guinea, Admiralty Islands, Manus Island, Sohoniliu Village [2.11296S 147.14912E], collected by Robert N. Fisher and villagers from Sohoniliu Village, 26 May 2010.

Paratype. Same collection data as holotype PNGNM 25190 (RNF8981), juvenile female.

Diagnosis. Nactus kunan sp. nov. is a member of the Nactus pelagicus species group and differs from all other members except N. galgajuga by a pattern of broad alternating dark (black or dark brown) and light bands on neck, trunk, and tail. It differs from N. galgajuga by the golden yellow of its light bands instead of the white bands of N. galgajuga . N. kunan sp. nov. also possesses a unique head pattern among Nactus taxa with a sharply contrasting yellow crown and eyelids on a black background.

Description of holotype. An adult female, 56.6 mm SVL, 57 mm tail length (~ 53 mm regenerated), 23.8 mm TrunkL, 22.5 mm SnForel, 14.8 mm HeadL, 9.9 mm JawW, 6.3 mm HeadH, 3.8 mm EyeD, 5.1 mm NarEye, 4.4 mm Interorb, 2.0 mm SnW. Body proportions, 42% TrunkL/SVL, 40% SnForel, 26% HeadL/SVL, 18% JawW/ SVL, 67% JawW/HeadL, 4% EyeD/SVL, 14% EyeD/HeadL, 35% NarEye/HeadL, 30% Interorb/HeadL, 14% SnW/HeadL.

Head scales small and granular except for enlarged scales bordering nares and mouth. Large horizontal rectangular rostral scale with a slight middorsal notch, cleft on midline of middorsal half and distinctly depressed on its midposterior two-thirds; five large supralabials (left and right, Suplab) and four infralabials (left and right, Inflab) in front of anterior edge of orbit, first supra- and infralabials largest of respective series. Nasal scale contacts first supralabial, rostral, supranasal, and posteriorly four granular loreal scales, dorsalmost one largest. Supranasals moderate sized separated on midline by four granular scales contacting rostral. Scales on outer edge of eyelid slightly enlarged forming low crenate border. Chin with large trapezoidal mental and no postmentals (PostM = 0). Dorsum of neck and trunk with numerous rows of enlarged tubercles from nape unto tail; on trunk rows reach ventrolaterally to edge of venter, 17 entire rows (DorsTub), and only to mid-laterally on neck; tubercles in each row usually separated by single granular scale yielding 47 tubercles per row (TUBROW); 8 rows transversely between hindlimbs (TubHip). Few scattered tubercles on dorsal half of forelimb; hindlimb with numerous tubercles (Tub- Hindl = 2), and tubercles abundant fore and aft (TubDens = 1). Base of tail with tubercle rows dorsally, laterally, and slightly overlapping onto ventral surface. Tail nearly totally regenerated and regenerated portion covered with uniform small keeled scales (Subcaud = 0). Pair of cloacal spurs (CloacS) on right, none on left; distal edge truncate (CST = 0). Ventral scales from chin to vent small, granular and unicarinate or tricarinate. Forefoot with narrow digits, their lengths 2≈3≈4>1≈5; 18 lamellae beneath fourth digit (4FingLm), 4 scale rows between lamellae at base of first and fifth fingers (Palm). Hindfoot with narrow digits, their lengths 3≈4>5>2>1; 20 lamellae beneath fourth digit (4ToeLm); lamellae of first digit extend onto sole of foot to its heel as row of greatly enlarged scales.

1 standard deviation, range, and statistically significant dimorphism * (Student’s t p 0.0 5); sample size in brackets; SVL &

HeadL in mm.

TAXON SVL TRUNKL/SVL SNFOREL/SVL HEADW/HEADL EYED/HEADL SNW/HEADL

Nactus pelagicus ( Fiji Ids)

females [27] 58.5±6.61 0.42±0.029 0.41±0.020 0.68±0.047 0.28±0.025 0.15±0.011 48.0–70.0 0.34–0.46 0.37–0.44 0.59–0.75 0.23–0.33 0.12–0.17

Nactus pelagicus (Admiralty Ids.)

females [21] 56.6±2.90 0.38±0.032 0.42±0.010 0.70±0.056 0.23±0.032 0.15±0.008 49.1–61.1 0.32–0.42 0.37–0.46 0.57–0.78 0.17–0.29 0.13–0.17

Nactus kunan sp. nov. (Manus Isl.)

females [1] 56.6 0.42 0.40 0.69 0.26 0.14

Nactus galgajuga ( Australia)

adults [5] 47.5±2.07 0.42±0.039 0.43±0.039 0.66±0.021 0.29±0.024 0.16±0.008 (4 females) 44.3–50.0 0.37–0.49 0.42–0.45 0.62–0.68 0.24–0.31 0.15–0.17

Nactus eboracensis ( Australia)

females [25] 47.9±4.08* 0.42±0.019 0.40±0.019 0.69±0.049* 0.27±0.023 0.15±0.013 41.1–56.7 0.37–0.46 0.38–0.44 0.63–0.82 0.22–0.30 0.12–0.18 males [34] 45.8±3.70* 0.41±0.028 0.42±0.029 0.67±0.033* 0.27±0.021 0.16±0.014 37.9±53.5 0.34–0.45 0.34–0.50 0.61–0.75 0.22–0.31 0.12–0.17

Nactus multicarinatus ( Vanuatu)

females [35] 53.7±3.79 0.41±0.030 0.42±0.024 0.70±0.028 0.26±0.030 0.15±0.012 46.7–59.8 0.37–0.49 0.38–0.47 0.65–0.76 0.22–0.33 0.12–0.18 males [26] 51.8±3.52 0.40±0.020 0.41±0.020 0.70±0.030 0.26±0.032 0.15±0.010 45.6–58.2 0.37–0.43 0.37–0.44 0.65–0.75 0.22–0.33 0.13–0.18 Nactus sp 1 (Madang Province)

females [27] 57.5±4.43* 0.41±0.005 0.40±0.020 0.66±0.056 0.13±0.013 0.15±0.016 47.0–64.3 0.35–0.46 0.37–0.44 0.47–0.73 0.10–0.16 0.09–0.17 males [24] 53.5±3.83* 0.40±0.022 0.41±0.021 0.66±0.048 0.14±0.012 0.15±0.013 48.2–61.0 0.34–0.44 0.38–0.46 0.56–0.74 0.12–0.16 0.13–0.18

1 Three Nactus pelagicus group morphotypes occur in the coastal lowlands of Madang Province. We selected the most abundant morphotype for comparison with the Admiralty Islands’ populations. The selected morphotype displays sexual dimorphism in SVL, TrunkL, SnForel, HeadL, and PmLab.

In life, N. kunan is a strikingly bright gecko of alternating yellow and black on the dorsum and sides ( Fig. 1 A). Dorsal surface of head predominantly yellow from tip of snout to first black transverse bar on nape. Various sized black markings on dorsal surface of head: small, longitudinal one over supranasal suture, small round one on midline in middle of snout, narrow interorbital bar at anterior end of orbit, small, ill-defined marks on crown, and small white scarred area on parietal area ( Fig. 1 B). Black, irregular edged stripe from nares above ear-opening to groin; dorsally bordered by narrow, clear yellow postocular stripe ending at posterior end of head. Upper and lower lips with alternating bars of black and yellow; yellow ones about half width of black ones and centered on interlabial sutures of both upper and lower lips. Neck and trunk with six black transverse bars at nape, mid neck, three on trunk, and sacral one, clefted by yellow on dorsal midline; neck and trunk bars extending ventrally, nearly to venter. Black bars become bands encircling tail (based on paratypes ( Fig. 1 C), holotype’s tail largely regenerated with only the black band at base); yellow interspaces on trunk about two-thirds width of black on trunk and less than half on tail. Dorsally fore- and hindlimbs also yellow and black, transverse barring better developed on hindlimbs. Venter, including limbs, is dusky brown from chin onto base of tail.

In preservative, yellow color is brownish white; pattern as described above.

Description. A moderate-sized Nactus with body proportions of two individuals: 42% TrunkL/SVL, 40% SnForel, 26% HeadL/SVL, 18% JawW/SVL, 67% JawW/HeadL, 4% EyeD/SVL, 14% EyeD/HeadL, 35% Nar- Eye/HeadL, 30% Interorb/HeadL, 14% SnW/HeadL.

The paratype differs little from holotype. It possesses 4 Suplab and 3 Inflab, 16 Dorstub, 45 TubRow, 23 HindfL, and 6 Palm. Both specimens are females and lack preanal and femoral pores. Paratype is reproductively a subadult. The yellow color of the holotype was a muted grayish white in paratype when alive. We tentatively suggest an ontogenetic color shift at maturation and suspect no sexual dimorphic differences in adults.

Distribution. Presently known only from Sohoniliu Village, Manus Island of the Admiralty Archipelago. Papua New Guinea. Probably widespread in the highlands of Manus Island where forest patches remain intact.

Etymology. The specific name comes from the Tokples people’s (Nali language) term for bumblebee; this is in reference to the striking bicolor yellow and black banding of holotype ( Fig. 1 A).

Comparison to other taxa. Nactus kunan sp. nov. was compared to other Nactus pelagicus complex individuals ( Tables 2, 3 ) from Manus and Los Negros Islands in the Admiralty Archipelago, the dominant (most abundant) N. pelagicus group member on the adjacent mainland (Madang Province), N. multicarinatus from Vanuatu, and two species ( N. eboracensis , N. galgajuga ) from Australia. Presently, except for N. galgajuga and N. kunan sp. nov., all known species, undescribed ones as well, of the Nactus pelagicus and vankampeni groups have a brown to medium-dark brown ground color with dark brown bars on the dorsum from head to tail. N. galgajuga and N. kunan sp. nov. are transversely banded in dark and light colors. The dark color is black in both taxa; the light color is white in the former and yellow in the latter. N. kunan has a robust habitus, perhaps slightly heavier than the average N. pelagicus but distinctly heavier than the emaciated habitus of N. galgajuga . The slender habitus of N. galgajuga give the impression that it has longer limbs than the other Nactus species; its limb lengths are the same, although strikingly more slender. Among other differences, N. galgajuga has unkeeled scales on the ventral trunk and beneath the tail in contrast to the distinctly keeled scales of N. kunan sp. nov.

N. kunan sp. nov. is larger than any member of the N. vankampeni group, and assuming the SVL of the holotype is about average, N. kunan sp. nov. is the same size as the unisexual N. pelagicus and many New Guinea bisexual populations of the pelagicus group ( Table 2), although distinctly larger than the Australian species ( N. cheverti , adult females 41–57 mm SVL; N. eboracensis adult females 42–57 mm). N. kunan sp. nov. shares many features of its scalation ( Table 3 ) with other Nactus pelagicus group members. It differs from most New Guinea populations (except those of western Gulf and Western Districts) by the absence of postmental scales (PostM). It also possesses many more tubercles (47 TubRow) in the dorsal tubercle rows, contrasting to means of 31 or less for other New Guinea populations.

Natural history. Nactus kunan sp. nov. is known from the two types; both specimens were collected within a hundred meters of each other along a forested ridgeline on the south side of the Lauis River. The two animals collected were on two different village house structures in small openings in the forest at night at approximately 200 m elevation. Surveys were conducted for more individuals for another couple of hours and no additional specimens were detected. Additionally a week of surveys in other areas north and east of this site on Manus Island, and surveys on Los Negros and Pityilu Islands all failed to detect any further individuals of this species.

1 Three Nactus pelagicus group morphotypes occur in the coastal lowlands of Madang Province. We selected the most abundant morphotype for comparison with the Admiralty Islands’ populations. The selected morphotype displays sexual dimorphism in SVL, TrunkL, SnForel, HeadL, and PmLab.

Figures

FIGURE 1. Nactus kunan sp. nov. of Manus Island, Admiralty Islands, Papua New Guinea. A. dorsal aspect of whole body of the holotype USNM 576300; B, dorsal aspect of head of holotype; C, dorsal view of the juvenile and paratype PNGNM 25190 (RNF 8981).

Tables

TABLE 3. Summary of variation in select meristic characters in adult samples of the Nactus pelagicus species group. Median ± 1 standard deviation, range, and statistically significant dimorphism * (Student’s t p 0.05); sample size in brackets. TAXON SUPLAB POSTM DORSTUB TUBROW FOREFLM HINDFLM Nactus pelagicus (Fiji Ids)

females [27] 4±0.50 10±2.51 3–4 6–16	18±1.47 16–21	27±1.66 23–30	19±1.01 17–20	22±1.16 20–25
Nactus pelagicus (Admiralty Ids.) females [21] 4±0.59 10±3.01 3–5 8–18	15±1.57 12–19	33±2.48 28–37	20±0.97 19–22	25±1.37 21–26
Nactus kunan sp. nov. (Manus Isl.) females [1] 5 0	17	47	18	20
Nactus galgajuga (Australia) adults [5] 4±0.57 11±1.93 (4 females) 3–5 8–14	12±0.84 10–13	22±2.07 20–26	14±0.74 13–15	17±0.95 16–19
Nactus eboracensis (Australia) females [25] 4±0.51 12±2.70 3–4 8–20 males [34] 3.5±0.51 14±3.69 3–4 10–24	14±0.87 13–16 15±1.39 12–18	23±4.50 15–34 24±3.64 19–35	15±1.22 12–17 14±0.97 12–16	19±1.42 16–21 18±1.52 25–22
Nactus multicarinatus (Vanuatu) females [35] 3±0.13 14±4.64 2–4 2–22 males [26] 3±0.31 14±4.27 3–4 8–22	17±1.31 14–19 16±1.82 13–20	27±2.98 22–33 28.5±3.01 19–33	17±1.15 14–19 17±1.05 15–19	21±01.04 19–23 21.5±0.99 20–23
Nactus sp 1 (Madang Province) females [27] 3±0.50 10±5.62 3–4 0–22 males [24] 3±0.44 12±3.48 3–4 4–18	18±1.49 16–22 18±1.24 15–20	31±3.33 22–35 29±2.65 25–35	17±1.00 15–19 17±1.00 15–19	21±1.58 19–25 21±1.37 19–24