Rhacodactylus willihenkeli, Köhler & Sameit & Seipp & Geiss, 2024

Rhacodactylus willihenkeli sp. nov.

Rhacodactylus cf. leachianus (Houailou, N) : VENCES et al., 2001

Figs. 2 View FIGURE 2 , 4–5 View FIGURE 4 View FIGURE 5

Holotype. SMF 105137 About SMF , an adult female from about 12.5 airline km NE Bourail (GPS coordinates ca. -21.517°, 165.606°; about 750 m above sea level; see remarks in Geographic Distribution and Conservation), central New Caledonia, collected September 1987 by Friedrich Wilhelm Henkel und Joachim Sameit.

Paratypes. One adult male ( SMF 106563 About SMF ) and one adult female ( SMF 107305 About SMF ), same collecting data as holotype, still alive at the time of writing ( Fig. 6 View FIGURE 6 ), to be deposited in the collection of Senckenberg Forschungsinstitut Frankfurt, Germany, after they have died. ZFMK 73575 About ZFMK (adult male), same collecting data as holotype .

Diagnosis. A species of the genus Rhacodactylus (sensu Bauer et al. 2012a) that differs from all congeners except R. leachianus by the following combination of characters (1) adult SVL> 200 mm; (2) skin of head coossified with skull; (3) webbing between digits IV and V present; (4) folds of loose skin on posterior surface of hind limb; (5) folds of skin at mandibular margins. Rhacodactylus willihenkeli differs from R. leachianus by having a darker overall coloration with almost no discernable pattern (versus a wide range of color variation, usually with a bold reticulated body pattern and also usually with distinct pale ocellated blotches along flanks in R. leachianus ; Figs. 2 View FIGURE 2 , 3 View FIGURE 3 , 6 View FIGURE 6 ). In addition, the two taxa are genetically divergent with a genetic distance of 5.0% in the 16S gene fragment and 8.5% in the ND2 fragment, respectively.

Description of the holotype ( Figs. 4 View FIGURE 4 and 5 View FIGURE 5 ). Adult female (SVL 220.0 mm) as indicated by absence of hemipenial bulge and femoral and precloacal pores. Body robust, slightly depressed. Head triangular with a blunt snout, large (ratio HL/SVL 0.23), wide (ratio HW/HL 0.73) and depressed (ratio HH/HL 0.47), weakly offset from neck; interorbital/frontal region somewhat depressed, nasal region with a distinct, shallow indentation; canthus weakly inflated; snout long (ratio SL/HL 0.87). Scales on dorsum of snout slightly larger than of those on occipital region. Eye small (ratio EYD/HL 0.22); pupil oval, margins crenellated. Ear opening small, horizontally elongate (ratio EarL/HL 0.07); eye to ear distance much longer than diameter of eyes (ratio EED/EYD 1.92). Rostral and mental region damaged with scar tissue. Scales in 2–4 rows medial to infralabials somewhat enlarged and elongate. Dorsal scales heterogeneous with flat tiny scales interspersed among even smaller scales; ventral scales about half the size of dorsals, smooth, flattened, juxtaposed, slightly enlarged on posterior abdomen, in precloacal region and on base of thighs. Approximately 282 scale rows around midbody. Ventrolateral skin folds present. Scales on palms and soles smooth, flattened. Forelimbs and hind limbs short and thick (ratio FAL/SVL 0.13; ratio SHL/SVL 0.15), axillary pocket weakly developed. Digits short, all bearing robust and strongly recurved claws. Relative length of digits of manus: IV> III> V> II> I, and of pes: IV> III> V> II> I; digits moderately webbed. Subdigital lamellae of digits unpaired, except for distal portion of 4 th finger on right side. Claw of digit I, manus and pes, with medial apical scansor. Lamellar counts (including all scales> twice size of scales at base of digits) from right (and left) sides 8-11-14-18-10 (7-9-15-16-10) manus and 9-15-17-20-16 (9-13-16-18-17) pes. No precloacal pores or femoral pores. Regenerated tail 38% of SVL, slender, round in cross section. Coloration in life, based on Fig. 2 View FIGURE 2 (upper portion), was recorded as follows: Dorsal and lateral ground color of head body, and limbs Light Drab (268) with suffusions of Hair Brown (277) and Citrine (119) and with scattered Sulphur Yellow (91) and Medium Greenish Yellow (88) splotches; dorsal surface of tail base Glaucous (291), regenerated portion of tail Brownish Olive (292) with Smoky White (261) splotches; ring around eye Sulphur Yellow (91); iris Light Neutral Gray (297) with Pale Neutral Gray (296) splotches.

Genomic characterization. Whole genome sequencing and assembly yielded 298,315,598 Illumina short reads with a total data size of 102.4 Gb. The k-mer analysis resulted in an estimated genome size of 1.56 Gb and a heterozygosity of 0.6%. The mitochondrial genome was assembled into one linear contig with a total length of 15,957 bp (accession number OR288172). A total of 37 genes could be annotated, including all 13 protein coding genes, 2 rRNAs and 22 tRNAs. Pairwise alignment to the complete mitochondrial genome of Correlophus ciliatus (GenBank accession No. OQ506627) revealed a pairwise identity of 83.9%.

Variation. Coloration in life of an adult male, based on Fig. 2 View FIGURE 2 , was recorded as follows: Dorsal ground color of head body, and limbs Pale Cinnamon (55) with Verona Brown (37) streaks on head and suffusions on body, grading into Olive Horn Color (16) in flank region; labial region and ring around eye Sulphur Yellow (80); iris Smoky White (261) with Smoke Gray (266) stipples. See Fig. 6 View FIGURE 6 for photos in life of the paratypes.

Etymology. The species name willihenkeli honors Friedrich Wilhelm Henkel, nickname “Willi”, who has studied geckos of the genus Rhacodactylus in their natural habitat during about a dozen excursions to New Caledonia and while keeping and breeding these fascinating animals in terrariums for decades. Friedrich Wilhelm Henkel coauthored research articles as well as a popular science book about these geckoes.

Natural history notes. At the time of collection of the holotype of Rhacodactylus willihenkeli , the type locality was located in a large, forested area in the mountains ( Figs. 7 View FIGURE 7 and 8 View FIGURE 8 ). Henkel and Sameit were accompanying a group of lumberjacks, checking the fallen trees for geckos.

Geographic Distribution and Conservation. As currently known, Rhacodactylus willihenkeli is known only from its type locality in central New Caledonia ( Fig. 9 View FIGURE 9 ). Unfortunately, at the time of collection of the holotype, no GPS device was available and, therefore, the precise coordinates are unknown. From the type locality, they could see both coasts, and at night the lights of the city of Houaïlou. FWH and JS started their excursion from Bourail and it took them 1.5 h along a dirt road to reach the place where they camped and collected the holotype of R. willihenkeli . On a landscape photo taken at the type locality ( Fig. 8a View FIGURE 8 ), a narrow bay, enclosed by mountain ridges is visible. This bay clearly corresponds to Canala Bay on the east coast of central New Caledonia. Thus, we consider the locality information (i.e., northern New Caledonia, west of Houaïlou) given by Vences et al. (2001) for their R. cf. leachianus sample as erroneous.

Given the little we know about this species, we classify R. willihenkeli as Data Deficient based on the IUCN Red List Categories and Criteria ( IUCN 2012 ). This species is oviparous and has been bred in captivity. The following observations were made by JS who has bred about 15 individuals of this species: Females lay three or four clutches of two eggs each per year. After an incubation period of about 90 days the juveniles hatch with a SVL of about 60 mm. The adults that are still alive have been kept by JS for almost 40 years now and are probably more than 50 years old since these were collected as adults in 1987.