Gehyra chrysopeleia, Kraus, 2024

Kraus, Fred, 2024, New species of Gehyra (Squamata: Gekkonidae) from Papua New Guinea, Zootaxa 5512 (2), pp. 240-271 : 242-251

Gehyra chrysopeleia sp. nov.

urn:lsid:zoobank.org:act:4B4042BC-B1D9-4A53-AE32-E3760F19A19C

Figs. 2 , 3A , 4A

Gehyra vorax Beckon 1992: 451 [part].

Gehyra membranacruralis Flecks et al. 2012: 205 [part].

Gehyra sp. Sudest, PNG Heinicke et al. 2011: 588.

Holotype.— BPBM 19772 (field tag FK 9751 ), mature male, given to F. Kraus by local villagers, forest just west of Araeda , Sudest Island, 11.4362° S, 153.4301° E, ~ 10 m a.s.l., Milne Bay Province, Papua New Guinea, 21 April 2004.

Paratypes (n=2).— Papua New Guinea: Milne Bay Province: Joe Landing, [11.416° S, 153.383° E], 0–100 m a..s.l., Sudest Island, 15 August 1956 ( AMNH 76753 ), west slope Mt. Rio , 250–350 m a.s.l., Sudest Island , 23 August 1956 ( AMNH 76763 ) .

Diagnosis.—A large ( SVL of adult males 133–142 mm, of adult female 125.5 mm) species of Gehyra having entirely undivided subterminal lamellae on all toes; 17–20 T 4 lamellae; 15–16 T 1 lamellae; extensive webbing between all toes ( T 3– T 4webL/ T 4L = 0.38–0.48, T 4– T 5webL/ T 4L = 0.21–0.30); small eye ( EY / EN = 0.48–0.53); long snout (SN/HL = 0.51–0.55, EN/HL = 0.44–0.45); 44–46 precloacal/femoral pores in a continous row in males ( AMNH 76753 has 23 pores on right leg, so that count doubled to arrive at 46); single row of enlarged subcaudal scales; rounded tail lacking serrations; lateral, antecubital, and popliteal skin folds well developed; rostral quadrangular; postmentals elongate; supranasal bordered posteriorly by at least one scale that is>50% the size of supranasal; and dorsal color pattern pale yellow gray with vaguely defined brown bands on the dorsum and limbs.

Comparisons with other species.—Among Melanesian Gehyra , G. chrysopeleia is easily distinguished from G. baliola , G. barea , G. insulensis , G. interstitialis , G. lampei , G. leopoldi , and G. papuana by having undivided (vs. divided) subapical lamellae under all toes. Gehyra chrysopeleia differs from G. cf. dubia in having extensive webbing between the digits (vs. absent or only basal in G. cf. dubia ); from G. oceanica and G. serraticauda in its much larger adult size ( SVL = 133–142 mm vs. ≤ 102 mm in G. oceanica and 91 mm in G. serraticauda ) and well-developed skin folds on trunk and on anterior of arm (vs. absent in G. oceanica and G. serraticauda ) as well as in having a single row of enlarged subcaudals (vs. small, subequal subcaudals in multiple rows in G. oceanica ) and a rounded tail lacking lateral serrations (vs. tail dorsoventrally compressed and with lateral serrations in G. serraticauda ); from G. marginata in having a rounded tail in cross section (vs. flattened in G. marginata ), a single row of enlarged subcaudals (vs. small, subequal subcaudals in multiple rows in G. marginata ), and fewer T 4 lamellae (17–20 vs. 20–27 in G. marginata ); from G. rohan in having fewer T 4 lamellae (17–20 vs. 22–26 in G. rohan ), homogeneous (vs. heterogeneous in G. rohan ) dorsal scales, elongate (vs. short in G. rohan ) postmentals, and brown (vs. orange in G. rohan ) scales encircling the eye; and from G. vorax in having fewer precloacal/femoral pores (44–46 vs. 58–90 in G. vorax ), fewer T 4 lamellae (17–20 vs. 23–34 in G. vorax ), a relatively longer snout (SN/HL = 0.51–0.52 vs. 0.44–0.48 in G. vorax ), a uniformly white chin and throat (vs. heavily fleckd with brown in G. vorax ), and similarly pale dorsal and ventral colors (vs. dorsum much darker than venter in G. vorax ).

G. chrysopeleia is morphologically most similar to G. georgpotthasti and G. membranacruralis . It differs from the former in having postmentals that are elongate (approximately twice as long as wide) but not longer than the mental (vs. postmentals three times longer than wide and longer than mental in G. georgpotthasti ), fewer T 4 lamellae (17–20, mean 19.0 vs. 18–30, mean 23.2 in G. georgpotthasti ), prominent dermal folds on the trunk (vs. indistinct in G. georgpotthasti ), prominent dermal folds on the posterior forelimbs (vs. none in G. georgpotthasti ), postsupranasals including one scale that is>50% the size of supranasal (vs. all postsupranasals <<50% size of supranasal in G. georgpotthasti ), and a pale yellow-gray ground color (vs. darker brown or orange in G. georgpotthasti ).

Gehyra chrysopeleia differs from G. membranacruralis in its larger size (SVL = 133–142 vs. up to 127 mm in G. membranacruralis ), smaller eye (EY/EN = 0.52–0.53 vs. 0.56–0.59 in G. membranacruralis ), more extensive toe webbing (T3–T4webL/T4L = 0.38–0.48, T4–T5webL/T4L = 0.25–0.30 vs. 0.25–0.29 and 0.15–0.22, respectively, in G. membranacruralis ), elongate postmentals (vs. short in G. membranacruralis ), a prominent dermal fold on both anterior and posterior of forelimb (vs. absent in G. membranacruralis ), the enlarged scales anterior to the pore-bearing series extending laterally 14–17 scales on either side of the pore series’ apex before transitioning abruptly to small scales (vs. the enlarged scales decreasing gradually in size away from the apex of the pore series, with no abrupt transition in size in G. membranacruralis ), and postsupranasals include at least one scale that is>50% the size of supranasal (vs. all postsupranasals <<50% size of supranasal in G. membranacruralis ).

Gehyra chrysopeleia is most easily visualized as different from the other large species G. vorax and G. georgpotthasti in bivariate space by contrasting numbers of T4 lamellae and numbers of precloacal/femoral pores for males ( Fig. 1 ). This serves to supplement and confirm the comparisons among these species noted above.

Description of holotype.—A mature male of large size (SVL = 133.0 mm) with a right-lateral incision behind the pectoral region; liver removed. Head relatively long (HL/SVL = 0.21) and wide (HW/HL = 0.84), distinct from neck. Loreal region inflated; no distinct canthus rostralis. Top of snout and area above central supralabials shallowly concave. Snout tapered and rounded at tip, relatively long (SN/HL = 0.52), more than twice eye diameter (SN/EY = 2.2). Eye of modest size (EY/HL = 0.24, EY/EN = 0.52); pupil vertical, constricted into four lobes; supraciliaries only slightly larger than adjacent granules. Ear opening small (Ear/HL = 0.077), narrowly compressed dorsoventrally; distance between ear and eye one-third again as large as eye diameter (EE/EY = 1.3). Rostral almost twice as wide (5.6 mm) as high (3.2 mm), quadrangular but slightly higher just medial to nares, length 1.0 mm, with medial suture extending half its length. Supranasals separated by two large internasals along posterior rostral margin. Rostral in contact with first supralabials, two supranasals, and two internasals. External nares circular; each bordered by rostral, single supranasal, first supralabial, and three postnasals. Each supranasal bordered posteriorly by two postsupranasals, one of which is>50% size of supranasal ( Fig. 2A ). Mental triangular, 4.2 mm wide, rear margin scalloped. Mental bordered posteriorly by two elongate postmentals that are longer than mental ( Fig. 2B ), each bordered posteriorly by four round scales, two of which larger than those on chin, two subequal to chin granules. Postmentals bordered laterally by shorter elongate subinfralabials, gradually decreasing in size posteriorly. First infralabial bordered below by single subinfralabial, second and third infralabials by two subinfralabials, and fourth infralabials by three subinfralabials. Supralabials to mid-orbital position 14 on right, 12 on left; three small supralabials posterior to this; angle of jaw bordered with granular scales. Infralabials 12 on each side.

Body of fairly robust habitus (TrL/SVL = 0.42), slightly depressed. Dorsal scales on head, limbs, body, throat and sides small juxtaposed granules, smallest on neck, head, dorsal patches, and limbs, largest on sides and remainder of dorsum; tubercles absent. Two dorsal and several lateral patches of skin with smaller granules that likely represent regenerated skin. Ventral scales larger, flat, smooth, subimbricate, larger midventrally, gradually decreasing in size laterally to become granular. Well-developed lateral fold present on body; popliteal fold prominent; dermal folds on front and rear of forelimbs prominent.

Enlarged precloacal/femoral scales in single series of 44 scales extending in a curved chevron to near end of each thigh ( Fig. 2D ), each containing a single pore, series on left thigh interrupted by two small scales; thigh scales anterior to this row flat, subimbricate, much larger than those posterior to row, which are round to granular; enlarged scales anterior to pore-bearing series extending laterally 18 (R) or 17 (L) scales from apex of pore series before transitioning abruptly to small scales. Enlarged, imbricate scales form a pubic patch between precloacal series and vent, decreasing in size posteriorly; 14 scales in a row between apex of enlarged precloacal series and vent, first ten large, last four rows tiny, granular. Scales under arms granular, those under hindlimbs granular anteriorly, enlarged, flat, and imbricate posteriorly; scales on palms and soles rounded, flattened, smooth, subimbricate.

Fore- and hindlimbs well-developed (FA/SVL = 0.10, CS/SVL = 0.12). Digits well-developed, with broad pads on toes (T4W/T4L = 0.46), all but first fingers with recurved claws; clawed terminal phalanges on all digits except T1 laterally compressed, free above, arising from toe pad, inset from its margin, extending slightly beyond it; claw on T1 small, terminal, extending slightly beyond toe-pad margin. Subdigital lamellae narrow and smooth, all undivided, most forming a shallowly curved chevron medially ( Fig. 2C ); lamellae extend for more than half length of each toe (T4lamellaeL/T4L = 0.60). Lamellae of manus 14-15-19-20-16 on right, 14-16-19-20-16 on left; of pes 16-17-21-20-19 on right, 16-17-21-20-18 on left. Relative lengths of digits on manus and pes I <II <V <III <IV. Webbing present between all digits, most extensive between T3 and T4 (T3T4webL/T4L = 0.38, T4T5webL/T4L = 0.25).

Tail 103 mm, seemingly slightly truncated at end, dorsoventrally compressed but not flat, no lateral serrations. Tail with small subimbricate scales dorsally; under tail with single midventral row of enlarged, flat, imbricate subcaudals, bordered laterally by much smaller, flat, subimbricate scales that decrease in size laterally and dorsally ( Fig. 3A ). Cloacal sacs swollen, with single external orifice situated near each lateral margin of vent; two enlarged, blunt postcloacal spurs on each side of tailbase; midventral scales of sac flat, subimbricate, larger posteriorly, slightly larger than those ventrolaterally.

Color in preservative: Dorsal ground color on body, head, and limbs pale tan with very vague, poorly defined, slightly darker-brown markings, paler laterally; supralabials with darker-brown markings.All ventral surfaces white, lacking markings. Lamellae slightly darker gray tan. Iris pale tan with network of brown veins.

Color in life.—In life, the holotype was pale yellow gray with vaguely defined brown bands on the dorsum and limbs and scattered, tiny black spots ( Fig. 4A ). The lateral skin folds were white, and the iris was the same color as the dorsum with narrow brown veins.

Measurements (in mm).—SVL = 133.0, TailL = 103, TrL = 56.1, FA = 13.9, CS = 15.5, HL = 28.5, HW = 23.8, HH = 16.2, Ear = 2.2, EE = 8.5, EY = 6.7, SN = 14.8, EN = 12.8, IN = 5.3, T4L = 16.0, T4W = 7.3, T4lamellaeL = 9.6, T3T4webL = 6.0, T4T5webL = 4.0, mass in life = 51.7 g.

Variation.—The two males are larger than the sole female ( SVL = 133–142 mm vs. 125.5 mm). Greatest mensural variation of importance in the small sample available is in the extent of webbing, which extends approximately one-third to one-half the length of T4 between that toe and T3 and 20–30% the length of T4 between that toe and T5 ( Table 1 ). Meristically, variation in numbers of lamellae under the first and fourth toes is not high, and this is true as well for numbers of supralabials and infralabials, though the holotype does have an anomalously high number of 14 supralabials to mid-eye on its right side. Numbers of enlarged precloacal/femoral scales varies from 40–44, and the sole male with undamaged scalation in this region (the holotype) has 44 precloacal/femoral pores, with the second specimen having 35 and estimated to have 46 were the left series not damaged. The number of internasals is two or three, postnasals are uniformly three, and a large number of tiny granular scales borders the posterior margin of the postmentals ( Table 1 ).

Color pattern shows little variation among the three specimens, with all being pale grayish white dorsally with tiny black dots and white ventrally.

Etymology.— Chrysopeleia is the Latinized name of one of the Greek hamadryads, nymphs of trees and woodlands. The name literally means “golden dove”, which is appropriate for this lizard with a slightly yellowish cast.

Range.—Known from three nearby localities on Sudest Island from sea level to approximately 300 m elevation a.s.l. ( Fig. 5 ). It may occur on some of the many small islets that comprise the Calvados Chain, all of which lie within the large fringing reef that encompasses Sudest Island and would have been connected to Sudest with lower sea levels during the Pleistocene.

Ecology.—The holotype was collected active at night in a disturbed low-elevation forest near the coast. One of the paratypes also came from low-elevation forest, likely near the coast, but the second came from inland primary rainforest. Otherwise, no ecological information is available for this species.

Remarks.—The skin on the underside of the forearms in G. chrysopeleia is relatively loose and expansive, giving it a “baggy” appearance, and this can result in the impression of either an antecubital skin fold, a postcubital skin fold, or both, depending on how the specimen was arranged during fixing. Irrespective of this appearance in any particular specimen, this extensive loose skin clearly serves to distinguish G. chrysopeleia from G. membranacruralis .

This species has historically been known from only the two paratypes, and it had been assigned to Gehyra vorax once Beckon (1992) clearly distinguished that large Pacific island species from G. oceanica and assigned all large Gehyra with entire lamellae ranging from the Moluccas through Melanesia to G. vorax . The Sudest animals were later assigned to G. membranacruralis once Flecks et al. (2012) removed G. georgpotthastii from G. vorax and referred all western Melanesian specimens to G. membranacruralis . On the basis of DNA-sequence data, Heinicke et al. (2011) correctly surmised that the population of large Gehyra residing on Sudest Island was in fact a distinct species, diagnosed and described herein. A study in progress by P. Oliver and co-authors shows that G. vorax and G. georgpotthasti are rather distantly related to the lineage containing G. membranacruralis , G. chrysopeleia , and the next species (partially shown too in Oliver et al. 2016).

Figures

FIGURE 1. Bivariate plot of numbers of precloacal/femoral pores vs. numbers of subdigital lamellae on the fourth toe. Lamellae numbers for each specimen are averages of the numbers from each foot. Star = Gehyra aquilonia, solid circle = G. chrysopeleia, diamonds = G. georgpotthasti, open circles = G. membranacruralis, triangles = G. vorax.

FIGURE 2. Details of holotype of Gehyra chrysopeleia, BPBM 19772. (A) close-up of snout showing supranasal (SN) and enlarged postsupranasal (PSN), (B) chin, (C) right foot, and (D) precloacal/femoral pore series. Scale bars = 5 mm.

FIGURE 3. Ventral views of tails of (A) Gehyra chrysopeleia, BPBM 19772, holotype; (B) G.aquilonia, BPBM 34745, holotype; (C) G. maculicincta, BPBM 19771, paratype, showing small, subequal subcaudals of an original tail; (D) G. maculicincta, UMMZ 244055, holotype, showing wide, thin subcaudals of a regenerated tail; (E) G. louisiadensis, BPBM 19763, holotype. Scale bars = 5 mm.

FIGURE 4. Portraits in life of (A) Gehyra chrysopeleia, BPBM 19772, holotype; (B) G. aquilonia, BPBM 34745, holotype; (C) G. maculicincta, UMMZ 244056, paratype; (D) G. louisiadensis, BPBM 19764, paratype; (E) G. oceanica, American Samoa; (F) G. membranacruralis, UMMZ 247752, Varirata National Park, Central Province, PNG. Photo credits: (A) G. Shea, (E) U.S. Geological Survey, (F) V. Weijola, remainder F. Kraus.

FIGURE 5. Map of the Milne Bay region of Papua New Guinea showing collecting localities for species described herein. Solid circle = type locality for both Gehyra chrysopeleia and G. louisiadensis, open circles = additional localities for G. louisiadensis, solid square = type locality for G. maculicincta, open squares = additional localities for G. maculicincta.