Gehyra georgpotthasti, Flecks & Schmitz & Böhme & Henkel & Ineich, 2012

Flecks, Morris, Schmitz, Andreas, Böhme, Wolfgang, Henkel, Friedrich Wilhelm & Ineich, Ivan, 2012, A new species of Gehyra Gray, 1834 (Squamata, Gekkonidae) from the Loyalty Islands and Vanuatu, and phylogenetic relationships in the genus Gehyra in Melanesia, Zoosystema 34 (2), pp. 203-221 : 210-215

Gehyra georgpotthasti n. sp.

( Figs 3-9 )

Gehyra vorax – Boulenger 1883: 119. — Boulenger 1885: 153 (partim). — Strauch 1887: 29 (partim). — Roux 1913: 104. — De Rooij 1915: 45 (partim). — Baker 1928: 297.— Beckon 1992:450 (partim). — Sadlier & Bauer 1997: 80. — Bauer & Sadlier 2000: 118. — Ineich 2011: 198.

TYPE MATERIAL. — Holotype: Loyalty Islands, Dudun Island, off the coast of Maré , 21°21’36”S, 167°43’48”E ( Fig. 3 ), adult ♂, with hemipenes everted and tongue stuck out, F. W. Henkel ( ZFMK 91004 ).

Paratypes (2 ♀♀, 4 ♂♂): same data as holotype, 2 adult ♀♀ ( ZFMK 73578 , 91018), adult ♂, with hemipenes everted ( ZFMK 73902 ). — Vanuatu, Espiritu Santo, Butmas , 15°22’26.64”S, 166°58’27.42”E, 566 m asl, 2 adult ♂♂, with tails separated, 3.XII.2007, I. Ineich ( MNHN 2007.0055, 0056). — Vanuatu, Espiritu Santo, Tasmate , 15°12’43.56”S, 166°39’38.05”E, subadult ♂, 9.XI.2006, I. Ineich ( MNHN 2009.0321) .

OTHER MATERIAL EXAMINED. — Vanuatu. Malakula , 3 specimens ( MNHN 1894.0208-0210). — Pentecost , 4 specimens ( MNHN 1894.0211, 0212, 0214, MNHN 1934.0054). — Epi , 3 specimens ( MNHN 1974.1423, 1424, 1426). — Espiritu Santo , 1 specimen ( MNHN 2010.0246). — Indeterminated , 3 specimens ( ZFMK 76990 , 76991, 84310) .

New Caledonia. Loyalty Islands, Maré, 7 specimens ( NHMB 7029 , 7031-7033, 7035, 7037, 7038). — Loyalty Islands, Lifou, 1 specimen ( ZFMK 70455 ) .

French Polynesia. Tuamotu, Fakarava , 2 specimens ( ZFMK 91002 , 91003) .

DISTRIBUTION. — The species is currently known from many of the larger islands of Vanuatu where it does not extend further north than Espiritu Santo ( Ineich 2011) and from Lifou and Maré (including the satellite islet Dudun) in the Loyalty Islands ( Fig. 3 ). It has been introduced to Fakarava in the Tuamotu Archipelago, French Polynesia and probably also to Norfolk Island ( Fig. 1 , see discussion).

ETYMOLOGY. — This species is dedicated to Mr. Georg Potthast, in recognition of financial support for biodiversity research and nature conservation through the BIOPAT programme (www.biopat.de).

DIAGNOSIS. — A large (up to 142 mm from snout to vent), stoutly build gecko ( Fig. 4 ) belonging to the genus Gehyra . Subdigital lamellae under the dilated portion of the toes are not longitudinally divided. Toes of G. georgpotthasti n. sp. are webbed up to about half of their length. Extensive dermal folds are present anterior of the forelimb and posterior of the hindlimb, spanning from shoulder to base of toe and from cloaca to base of toe, respectively. Gehyra oceanica has only slightly developed folds on limbs, which span directly between knee and elbow, and toes are only rudimentarily webbed. Furthermore, G. oceanica has fewer subdigital lamellae (max. 20, but usually less than 18 under 4th toe, compared to at least 18 in G. georgpotthasti n. sp.; see Table 2 ). Maximum snout-vent length of G. oceanica is smaller; in a series of 241 adult specimens from French Polynesia the largest was 93 mm (Ineich 1987), the by far largest specimen in the ZFMK collection is a male from western Samoa of 96 mm, and Beckon (1992) mentions 102 mm as maximum snout-vent length, whereas G. georgpotthasti n. sp. can grows up to 142 mm (see Table 2 ). Gehyra oceanica has at least 9-10 dark bands on tail (versus 5 to 6 such bands in G. georgpotthasti n. sp.). Subcaudal scalation of G. georgpotthasti n. sp. consists of enlarged, plate-like scales arranged in a median row, whereas G. oceanica and G. marginata have subequal scales or multiple (two or three) median rows of slightly enlarged, nearly subequal scales. Gehyra marginata also differs in having a flattened rather than rounded tail in section and has distinct dermal folds posterior of the forelimb and anterior of the hindlimb, both are merged with a broad fold along trunk. Gehyra membranacruralis lacks dermal folds on forelimb. G. vorax differs in shape of postmentals (short vs elongated in G. georgpotthasti n. sp.) and postrostral scale numbers (up to two vs. two or more in G. georgpotthasti n. sp.). Morphological characters of G. georgpotthasti n. sp. and similar species are summarised in Table 2.

DESCRIPTION

Holotype

Snout-vent length 115 mm. Forehead has a median groove extending from between nostrils to below eyes. Dorsocranial scalation uniform, consisting of small granular scales. Supralabials are 14 and 13, left and right respectively; infralabials are 14 on each side. Rostral shield possesses a median suture and two further sutures originating from corner of posterior indention of the rostral. Two scales are embedded into this indention. These are posteriorly bordered by a single, large internasal ( Fig. 5 ). Nostril bordered by rostral shield, 1st supralabial, nasorostral (as large as 1st supralabial), and three postnasals (two to four times larger than surrounding granules). Mental shield pentagonal, slightly smaller than 1st infralabials. Postmentals about three times longer than wide, twice as long as the mental, and reaching into gular granules ( Fig. 5 ). Infralabials bordered by a series of scales larger than other gular scales, but diminishing in size posteriorly from postmentals.

63 precloacal-femoral pores arranged in a Wshaped line ( Fig. 6 ). Three clustered precloacal tubercles on each side of tail base. Original tail 91 mm long and subcircular in section.Tail dorsally whorled, with longitudinally ten scales per whorl, which are about twice as large as granules on back. Subcaudal scales arranged in one median row of enlarged plates, these sometimes with a median suture ( Fig. 7 ).

Fingers and toes broad, with webbing that extends to about half the toe length between 3rd and 4th toe. Subdigital lamellae undivided, counting 23 on left 3rd finger, 22 on right 3rd finger, 21 on left 4th toe, and 22 on right 4th toe. First finger without claw, but a rudimentary sheath is present. First toe bears a small terminal claw. Remaining fingers and toes with large claws on free phalanges.

Dermal folds present, well-developed anterior of the forelimb, spanning from shoulder to base of 1st finger, and posterior of the hindlimb, spanning from cloaca to base of 5th toe ( Fig. 6 ).

Colouration in ethanol is brownish-grey on the dorsal side, with faint darker patches. Ventral side off-white with very fine freckles, flanks more or less mottled with brown. Colouration in life was brown with five dark brown saddle patches between forelimbs and base of tail. Head, tail and flanks also with dark patches ( Fig. 4 ). Ventral side light brown with a yellow hue, which becomes more intense in precloacal region. Iris brown.

Variation

Detailed data on morphometric and meristic characters of this species are presented in Table 3 . Noteworthy variation was observed in the number of subdigital lamellae, of which can be to 30 under the 4th toe as in one paratype (ZFMK 73902) and the number of male precloacal-femoral pores, which range from 27 to 68 (43 to 68 in paratypes). Number and shape of postrostral scales is very variable, often asymmetrical, but generally consisting of two or more scales located between the rostral and the two nasorostrals and more-or-less larger than cranial granules. Postmental scalation is uniform with little variation compared to the holotype.

Colouration is variable, mostly consisting of brown and grey, but yellow, reddish or olive elements are not uncommon. The tail has five to six dark bands, which are especially distinct in juveniles and less distinct or even absent in adults. On Santo, there is a “red” ( Fig. 8 ) and an “ornated” morph ( Fig. 9 ). The first shows a similar colouration to that described for the holotype, but has reddish elements on the dorsum. The ornated morph has the dorsal saddle patches dissolved and shows light and dark ocellalike patches on greyish-brown ground.

Besides the precloacal-femoral pores, which are only present in males, there are no differences between sexes concerning scalation. According to our data, males grow larger than females: the largest male specimen (MNHN 2007.0056) has a snout-vent length of 142 mm, mean value of all examined males with visible pores is 115 mm; the largest female (NHMB 7038) measures 125 mm, mean value of all adult females is 105 mm.

REMARKS

Predominantly nocturnal and arboreal, occupying habitats in rainforest and along beaches. At Dudun, the species, however, dwells on coconut trees and screwpines ( Pandanus ). Inactive specimens were observed during daytime hiding in between dead leaves of Pandanus . Specimens from Maré were collected on coconut trees ( Roux 1913).

Eggs obtained from a captive specimen originating from Dudun (ZFMK 91018) are hard-shelled, spherical, and measure 16.0-16.5 × 17.4-18.8 mm (n = 3). Eggs from Santo range from 16.59-18.11 x 18.59-19.75 mm (n = 3; Ineich 2011). Beckon (1992) mentions egg lengths of 17.2 mm (Maré) and 15.8 mm (Espiritu Santo). For comparison, eggs of G. vorax from Viti Levu are 18.6-19.4 × 19.4- 20.4 mm (n = 3). Gibbons & Zug (1987) report egg sizes of 18 × 20 mm from the same island. A hatchling out of an egg from Santo measured 41 mm in snout-vent length and 39 mm in tail length.

It is worth mentioning that two specimens, MNHN 2007.0055 from Santo and ZFMK 91002 from Fakarava, had part of their skin damaged when captured, revealing conspicuously green coloured muscle tissue on shoulder and neck ( Fig. 8 ). We did not observe this feature in other specimens, but this is mostly owing to the fact that the colouration does not persist in alcohol. A specimen of G. vorax photographed at Viti Levu has damaged its skin at the same body part, but no greenish colouration is visible. So far, we have no explanation for the biological function of green muscle tissue.

Figures

FIG. 3. — Detailed distribution of Gehyra georgpotthasti n. sp.: type locality (); other localities (); islands only records (). Localities for Loyalty Islands were compiled from museum specimens and data for Vanuatu from Ineich (2011).

FIG. 4. — Male holotype of Gehyra georgpotthasti n. sp. (ZFMK 91004) in life; total length of the specimen: 206 mm. Scale bars: 10 mm. Photographs: F. W. Henkel.

FIG. 5. — Scalation features on head: A, holotype of Gehyra georgpotthasti n. sp. (ZFMK 91004), dorsal view; B, same specimen, ventral view; C, G. vorax Girard, 1857 (ZFMK 55269), ventral view. Scale bar: 5 mm.

FIG. 6. — Precloacal region and dermal folds of the holotype (ZFMK 91004) of Gehyra georgpotthasti n. sp. Scale bar: 10 mm. Photograph: F. W. Henkel.

FIG. 7. — Subcaudal scalation at mid portion of the tail: A, holotype of Gehyra georgpotthasti n. sp. (ZFMK 91004); B, G. vorax Girard, 1857 (ZFMK 55269); C, G. marginata Boulenger, 1887 (ZFMK 84308); D, G. oceanica (Lesson, 1830) from Fiji (ZFMK 44722). Scale bar: 5 mm.

FIG. 8. — Adult male of Gehyra georgpotthasti n. sp. (paratype MNHN 2007.0055), red colour morph from Santo, note the green muscle tissue onshoulder where skin is shred.Photograph:I. Ineich.

FIG. 9. — Adult male ofGehyra georgpotthasti n.sp.(paratype MNHN 2007.0056),ornated colourmorph from Santo.Photograph:I. Ineich).

FIG. 1. — Distribution of giant Gehyra Gray, 1834 in the Pacific region: outlines delimit ranges of G. marginata Boulenger, 1887 (ma), G. membranacruralis King & Horner, 1989 (me), G. georgpotthasti n. sp. (ge), and G. vorax Girard, 1957 (vo); archipelagos, islands and regions with known occurrences are shaded black; arrows connect populations introduced to Polynesia (l) and the doubtful record from Norfolk Island (N) with their respective origins; grey hatched areas illustrate distribution of G. oceanica (Lesson, 1830).