Gehyra aquilonia, Kraus, 2024

Kraus, Fred, 2024, New species of Gehyra (Squamata: Gekkonidae) from Papua New Guinea, Zootaxa 5512 (2), pp. 240-271 : 251-256

Gehyra aquilonia sp. nov.

urn:lsid:zoobank.org:act:6E35E54A-BAA6-4C9F-9319-DE162026F8C8

Figs. 3B , 4B , 6

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

Gehyra membranacruralis Heinicke et al. 2011: 592 .

Holotype.— BPBM 34745 (field tag FK 13301 ), mature male, given to F. Kraus by local villagers, collected at Mindangua Stream, Prince Alexander Mts. , 3.6056° S, 143.4921° E, 410 m a.s.l., East Sepik Province, Papua New Guinea, 15 September 2009.

Paratypes (n=7).— Papua New Guinea: Madang Province: Wanuma, Adelbert Mts , 4.90° S, 145.32° E, ~ 670 m a.s.l., 23 October 1967 ( AMNH 103191 ) , near Sempi , 5.01° S, 145.79° E, 12 July 1969 ( AMNH 105032 ) ; Morobe Province: Lae ( AMNH 95215–16 ) ; West Sepik Province: Lumi, Torricelli Mts. , 3.48° S, 142.04° E, 550 m a.s.l., July 1966 ( AMNH 100088–89 ) , Miliom, 3.2 km E Lumi, Torricelli Mts. , 3.48° S, 142.05° E, 460 m a.s.l., 24 July 1966 ( AMNH 100090 ) .

Diagnosis.—A large ( SVL of adult males 124–134 mm, of adult females 108–118 mm) species of Gehyra having entirely undivided subterminal lamellae on all toes; 16–22 T 4 lamellae; 11–16 T 1 lamellae; extensive webbing between all toes ( T 3– T 4webL/ T 4L = 0.26–0.38, T 4– T 5webL/ T 4L = 0.15–0.28); short snout (SN/HL = 0.46–0.52, EN/HL = 0.37–0.43); wide head ( HW /HL = 0.75–0.92); 43–50 enlarged precloacal/femoral scales; 43–47 precloacal/femoral pores in a continuous chevron in males; single row of enlarged subcaudal scales; tail rounded anteriorly, somewhat depressed posteriorly, lacking serrations; lateral, antecubital, and popliteal skin folds well developed; elongate postmentals; 3–6 scales in posterior contact with postmentals; typically four (but sometimes three) postnasals; all postsupranasal scales small, with none>50% size of supranasal; dorsal color pattern varying shades of brown with or without obscure darker-brown blotches; chin and throat white, often with brown markings.

Comparisons with other species.—Among Melanesian Gehyra , G. aquilonia 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 the toes. Gehyra aquilonia 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 size ( SVL = 114–130 mm vs. ≤ 102 mm in G. oceanica and 91 mm in G. serraticauda ), presence of well-developed skin folds on trunk and anterior of arm (vs. absent in G. oceanica and G. serraticauda ), and in having a single row of enlarged subcaudals (vs. small, subequal subcaudals in multiple rows in G. oceanica ) and a tail lacking lateral serrations (vs. tail 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 (16–22 vs. 20–27 in G. marginata ); from G. rohan in having fewer T 4 lamellae (16–22 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 its smaller size (up to 134 mm SVL vs. up to 188 mm in G. vorax ), fewer precloacal/femoral pores (43–47 vs. 58–90 in G. vorax ), and fewer T 4 lamellae (16–22 vs. 23–34 in G. vorax ).

Gehyra aquilonia differs from G. membranacruralis in having elongate postmentals (vs. short in G. membranacruralis ), a prominent antecubital skin fold (vs. absent in G. membranacruralis ), a prominent skin fold on trunk (vs. weakly developed in G. membranacruralis ), wider head ( HW /HL = 0.75–0.92 vs. 0.71–0.80 in G. membranacruralis ), the enlarged scales anterior to the pore-bearing series extending laterally ~10 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 ), usually four postnasals (vs. three in G. membranacruralis ), and dorsal coloration of varying shades of brown (vs. pale yellow gray in G. membranacruralis ).

Gehyra aquilonia is most similar morphologically to G. georgpotthasti and G. chrysopeleia . It differs from the former in having postmentals that are not as elongate (approximately twice as long as wide vs. three times longer than wide in G. georgpotthasti ), fewer T4 lamellae (16–22, mean 19.2 vs. 18–30, mean 23.2 in G. georgpotthasti ), and distinct dermal folds on the sides of the body (vs. indistinct in G. georgpotthasti ). Gehyra aquilonia differs from G. chrysopeleia in its somewhat smaller size (SVL = 108–134 vs. 133–142 mm in G. chrysopeleia ); all postsupranasals small, with all <<50% size of supranasal (vs. one postsupranasal>50% size of supranasal in G. chrysopeleia ); typically four postnasals (vs. three in G. chrysopeleia ); and dorsal coloration of varying shades of brown (vs. pale yellow gray in G. chrysopeleia ).

As seen for Gehyra chrysopeleia , G. aquilonia 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 the comparisons among these species noted earlier.

Description of holotype.—A mature male of large size (SVL = 130.0 mm) with a right-lateral incision behind the pectoral region; liver removed; left arm missing. Head relatively long (HL/SVL = 0.23) and wide (HW/HL = 0.83), distinct from neck. Loreal region slightly 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 = 0.51), more than twice eye diameter (SN/EY = 2.2). Eye of modest size (EY/HL = 0.23, EY/EN = 0.54); pupil vertical, narrowly constricted into slit; anterior supraciliaries slightly larger than adjacent granules, posterior ones subequal to adjacent granules. Ear opening small (Ear/HL = 0.028), narrowly compressed dorsoventrally; distance between ear and eye half again as large as eye diameter (EE/EY = 1.5). Rostral almost twice as wide (5.9 mm) as high (3.1 mm), highest just medial to nares, lower medially; length 1.6 mm. Supranasals separated by single large internasal along posterior rostral margin. Rostral in contact with first supralabials, two supranasals, and one internasal. External nares circular; each bordered by rostral, single supranasal, first supralabial, and four postnasals. Supranasal bordered posteriorly by three (R) or five (L) small postsupranasals, all <<50% size of supranasal ( Fig. 6A ). Mental triangular, 4.4 mm wide, rear margin scalloped. Mental bordered posteriorly by two elongate postmentals that are longer than mental ( Fig. 6B ), these each bordered posteriorly by two round scales larger than those on chin. Postmentals bordered laterally by shorter elongate subinfralabials, gradually decreasing in size posteriorly. First infralabial bordered below by single subinfralabial, second infralabial by two subinfralabials, and third and fourth infralabials by three subinfralabials; infralabials 5–9 bordered below by two rows of smaller subinfralabials that are still much larger than adjacent chin granules. Supralabials to mid-orbital position 13 on each side; four (R) or three (L) small supralabials posterior to this; angle of jaw bordered with granular scales. Infralabials 13 on right, 14 on left.

Body of fairly robust habitus (TrL/SVL = 0.43), slightly depressed. Dorsal scales on head, body, limbs, and throat small juxtaposed granules, smaller on neck, head, and limbs, largest on sides and dorsum; tubercles absent. Ventral scales larger, flat, smooth, subimbricate, larger midventrally, gradually decreasing in size laterally to become granular. Well-developed lateral skin fold present on trunk; popliteal and antecubital skin folds prominent; no dermal fold on rear of forelimb.

Enlarged precloacal/femoral scales in single series of 43 scales extending in a curved chevron to center of each thigh ( Fig. 6D ), each containing a single pore, pores larger medially; thigh scales anterior to this row flat, subimbricate, much larger than those posterior to row, which are round and subimbricate to granular; enlarged scales anterior to pore-bearing series extending laterally approximately ten (R) or six (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; 13 scales in a row between apex of enlarged precloacal series and vent, first nine large, last four rows tiny, granular. Scales under arms granular, those under hindlimbs enlarged, flat, imbricate; scales on palms and soles rounded, flattened, smooth, subimbricate.

Fore- and hindlimbs well-developed (FA/SVL = 0.10, CS/SVL = 0.13). Digits well-developed, with broad pads on toes (T4W/T4L = 0.45), 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. 6C ); lamellae extend for more than half length of each toe (T4lamellaeL/T4L = 0.61). Lamellae of manus 15-16-18-18-17 on right; of pes 13-20-18-18-18 on right, 14-18-20-20-19 on left. Relative lengths of digits on manus and pes I <II <III <V <IV. Webbing present between all digits, about the same between T3, T4, and T5 (T3T4webL/T4L = 0.29, T4T5webL/T4L = 0.28).

Original tail 45 mm, regenerated tail 40 mm, 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. 3B ); subcaudals under regenerated tail wider and thinner than those on original tail. Cloacal sacs swollen, with single external orifice situated near each lateral margin of vent; three (R) or two (L) slightly 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 light brown, irregularly marked with dark-brown blotches and ragged spots and flecks, with black flecks on nape, between hindlimbs, and on anterior tail; dark markings concentrated into four vague large blotches from nape to between hindlimbs. Original tail as for trunk; regenerated tail darker brown. Labials and rostral heavily dusted with dark brown. Venter white, heavily marked with brown flecks on chin and throat; palms and soles same as venter; lamellae under expanded portions of digits gray. Iris pale tan heavily veined with dark brown.

Color in life.—Field notes for the holotype read “Dorsum brown with 5 obscure darker-brown blotches on body, giving it a rather mottled appearance. Iris tan veined with dark brown. Venter yellow, paler laterally and on throat, lemon yellow medially.” A photo of this animal ( Fig. 4B ) also shows the ground color to be darker middorsally than dorsolaterally or laterally, with several scattered, tiny dark-brown spots on the dorsum, a very dark-brown field on the posterior of the head and nape, a whitish postocular stripe, whitish loreal spot, and a whitish field behind the dark-brown blotch on the nape.

Measurements (in mm).—SVL = 130.0, TrL = 55.3, FA = 13.3, CS = 17.3, HL = 29.3, HW = 24.4, HH = 14.4, Ear = 3.7, EE = 9.8, EY = 6.7, SN = 14.9, EN = 12.4, IN = 5.5, T4L = 15.3, T4W = 6.9, T4lamellaeL = 9.3, T3T4webL = 4.5, T4T5webL = 4.3, mass in life = 49.8 g.

Variation.—Males are larger than females (SVL = 124–134 mm vs. 108–118 mm). Greatest mensural variation of importance is in snout length, toe width, and the extent of toe webbing, which extends approximately one-third the length of T4 between that toe and T3 and one-fifth to one-quarter the length of T4 between that toe and T5 ( Table 1 ). Meristically, variation in numbers of lamellae under the toes is rather high (16–22 under T4, 11–16 under T1). Variation in numbers of supralabials and infralabials is also rather large ( Table 1 ). Numbers of enlarged precloacal/femoral scales varies from 43–50, and precloacal/femoral pores in undamaged males from 43–47. The number of internasals varies from zero to three, postnasals are three or four, and most specimens have six granular scales bordering the posterior margin of the postmentals ( Table 1 ). The enlarged row of subcaudal scales varies significantly in size and shape. The three animals from Lumi, Torricelli Mts. (AMNH 100088–90) have thinner and wider subcaudals on the regenerated portions of their tails than on the basal original tails of the same specimens.

Dorsal color pattern for most specimens is generally uniform pale brown; however, AMNH 95216 is reddish brown, and BPBM 34745 and AMNH 100089 have a head band and wide body bands that are darker than the remainder of dorsum. AMNH 100089 also has five bands of large beige spots across the body and base of tail, and AMNH 100090 has two narrow dark-brown bands across the nape.All specimens have labials heavily suffused with brown, with darker specimens having more brown suffusion. All specimens are white or white with a faint yellow cast ventrally, and three have a small amount of brown dusting on the chin and angle of jaw, with the holotype having the most.

Etymology.—The species name is the feminine Latin adjective meaning “northern” in recognition of the distribution of this species across the foothills of the northern coastal mountain ranges of Papua New Guinea.

Range.—Known from several localities along the north-coast ranges of Papua New Guinea, from near sea level to ~ 670 m a.s.l. ( Fig. 7 ).

Ecology.—The holotype came from lowland rainforest in the vicinity of a stream. The paratypes were collected near villages, suggesting that they may have come from secondary forests. All animals have been found in foothill forest.

Remarks.—As also seen in Gehyra chrysopeleia , the skin on the underside of the forearms in G. aquilonia 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 feature clearly serves to distinguish G. aquilonia from G. membranacruralis .

Heinicke et al. (2011:588, 592)included in their phylogenetic tree of Gehyra a specimen of“ G.membranacruralis ” from Sibilanga, West Sepik Province, PNG. Judging from its locality, this specimen will surely represent G. aquilonia . They found it to be sister taxon to G. chrysopeleia but with a deep divergence from that species. They did not have true G. membranacruralis in their sample.

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 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 6. Details of holotype of Gehyra aquilonia, BPBM 34745. (A) close-up of snout showing supranasal (SN) with small postsupranasals behind it, (B) chin, (C) left foot, and (D) precloacal/femoral pore series. Scale bars = 5 mm.

FIGURE 7. Map of Papua New Guinea showing collecting localities for Gehyra aquilonia along its northern coast. Solid circle = type locality; open circles = additional localities.