Hoplodactylus cryptozoicus, Jewell & Leschen, 2004

Jewell, Tony R. & Leschen, Richard A. B., 2004, A new species of Hoplodactylus (Reptilia: Pygopodidae) from the Takitimu Mountains, South Island, New Zealand, Zootaxa 792 (1), pp. 1-11 : 2-10

Hoplodactylus cryptozoicus n. sp.

Figures 1–2 , 4a

Type Material

HOLOTYPE (juvenile female, NMNZ, Re. 2514): New Zealand, SL, southern branch of Spence Burn , Takitimu Mts, grid ref. NZMG 21099 57879, 45°42S, 167°51E, 1140m, 14 March 1996, Tony Jewell, Hoplodactylus cryptozoicus Jewell & Leschen HOLOTYPE, 2004.

Additional Material Examined

Hoplodactylus cryptozoicus (n = 6): New Zealand, SL (Southland): same data as Holotype, 1 live (captive), 5 live (wild). Hoplodactylus nebulosus (n =14) : New Zealand, SI (Stewart Island): Big Island, 47°08S, 167°31E , D49 20945 53275, 5 (1 live captive; 4 live wild, examined from photographs); NMNZ Re. 1569, 3; NMNZ G.549, 1; NMNZ G.550, 1; Kundy Island, 47°07S, 167°33E , D49 20965 53295, NMNZ Re. 93, 1 (holotype); Stewart Island, OM A98.91 1, (paratype, examined from photographs); Zero Rock , 46°48S, 168°14E , E48 21466 53666, 1 (live captive); Womens Island , NMNZ G.203, 46°49S, 168°14E , E48 21470 53655, 1.

Diagnosis

A medium­sized Hoplodactylus (86–87mm SVL); mouth lining bright orange with a pink tongue; tail shorter than SVL; body scales minute (average length 0.002 x SVL); 1–2 internasal scales present; colour pattern grey with variable markings involving an overall herringboned pattern, often decorated with (or replaced by) irregular orange patches. Distinguished from all described congeners by the combination of mouth colour and tail length.

Description

Shape and Proportions

Measurements of Holotype: live, 63.6mm SVL, 56.2mm tail length; preserved, 60.0mm SVL, 55.0mm tail length. Body stout, limbs slender, pentadactyl; SVL of fully grown adults 86–87mm; intact tail cyclindrical, moderately stout but tapering, distinctly shorter (82–91%) than SVL; adult live weight 16.2–18.4 grams.

Head oviform, 0.87–1.08x longer than broad, forehead flat or slightly convex; snout flat or slightly concave; eye relatively small (diameter about 0.2x head width); not prominent in profile; pupil vertical with slightly serrated margins, eyebrows (= brillar fringe) prominent (width at widest point about 0.4x eye diameter); ear opening of moderate size, 1.5x longer than deep, length 0.5x eye diameter, axis horizontal pointing slightly up and back; distance from snout to eye equal to or slightly longer than distance from eye to ear.

Digits tapering very gradually from sole to claw with faint webbing connecting bases of digits 2–4; proximal portion slightly dilated, the margin between proximal and distal portions indistinct on 1 st digit; 4 th digit the longest (0.08–0.10x SVL) on all limbs, first digit the shortest; 4 th toe of hind foot 3.7x longer than broad, length of dilated portion 0.6x total length of toe, width of dilated portion 1.7x width of distal attenuation.

Scales

Mouth bordered by large and prominent labial scales, each equal or less than as wide as long, 11–13 upper and 10–12 lower, separated at the tip of the snout by a large rostral and mental respectively; rostral 2x wider than deep, subrectangular, touching the nostrils in the upper corners, partially divided in the centre by a short cleft (0.4x rostral depth) extending from the upper margin; nostril also bordered by 4 (usual) or 5 nasals of which the anterior, inner­most is the largest, and the first labial; there are one large (usual) or two small primary internasals followed by 4, 5 (usual) or 6 secondary internasals of varying size; mental about 1.7x wider than deep, trapezium­shaped, usually partially divided by a median cleft (up to half as long as the mental is deep) extending from the posterior margin; one medium­sized postmental separating the 1 st infralabials.

All digits have straight lamellae on the undersurface of dilated proximal portion, with between 7–12 (usually 9–11) unbroken lamellae on the 4 th toe of the hind foot; apical plates undivided, slightly enlargened on 1 st digit only.

Dorsal body scales minute, regular, juxtaposed, conical with domed tips, slightly broader than long, average length 0.002 x SVL, becoming slightly larger laterally; dorsal snout scales minute, similar in size to dorsal body scales, becoming slightly larger towards labials and nasals, regular; throat scales slightly smaller than dorsal scales; ventral body scales approximately twice the size of dorsal scales (average length 0.005x SVL), sub­flattened, mostly juxtaposed but a few subimbricate, distinctively broader than long; precloacal scales about twice the size of belly scales, each perforated with a single pore (consistently in males, inconsistently in females), forming a subtriangular patch 6–7 deep x 23–26 wide in males (up to 28 wide in females), extending onto femora for about a quarter to a third of their length; postcloacal scales slightly larger again, flattened, hexagonal or with rounded posterior margin, base of tail with 2–3 cloacal spurs (slightly enlargened in females, greatly so in males) with pointed to chisel­edged tips; tail scales 2–3x size of dorsal body scales, subimbricate, roughly pentagonal, arranged in whorls around the tail, becoming larger and more regular ventrally, with visible autonomy septa every 8–9 rows across basal half of tail (10–11 in total).

Colour

Skin opaque in all colour phases. Ground colour light grey; one subadult male had a pale olive tint, and the juvenile holotype ranged between light grey and dark brown. Frequently marked with two­tone orange colouration which may consist of irregularly scattered spots, broad expanses around the primary markings ( Fig. 2 ), or may almost entirely replace the ground colour and primary markings; orange markings less extensive on ventral surfaces, and so far only recorded from males (present on 4 of 5 males). Individuals may change colour between lighter and darker tones, and in its darkest brown phase the holotype developed a deep reddish­pink overtone along the lower lateral margins of the body and tail.

Primary dorsal markings a paler shade of the ground colour and sometimes outlined with blackish shadings, consisting of a row of patches arranged in a herringbone configuration (angling forwards from on or near the midline) along either side of the back, sometimes meeting to create a sharp chevron across the midline, and sometimes with a large, paler spot on the lateral extremity; these patches range in shape from narrow bars to narrow triangles, broad triangles, or irregular blotches and are frequently linked longitudinally to create rough­edged dorso­lateral stripes. Usually a series of pale latero­ventral spots present.

On the top of the head the primary markings form a single complex marking on either side, leaving a broad dark median patch on the back of the head, a dark V­shaped mark linking the eyes, and a dark double­triangle (sometimes indistinct or merging into a single mark) linking the front of the eyes across the base of the snout; snout patterned with narrow or broad, pale canthal stripes commonly link in the middle with a backward­pointing chevron to create an irregular pale M­shaped patch across the snout. A dull to bright stripe connects the eye and ear. The jaws have pale colouration extending forwards from below the eye, sometimes almost to the nostrils.

Tail patterned with a continuation of the body markings but usually less regular (especially towards the tip) and commonly with two narrowly separated stripes along the anterior 1/4–3/4. Limbs and upper surfaces of feet and toes coloured as for body but markings small and mostly irregular.

Venter pale grey, sometimes with a pale yellow or pink wash, or grey­brown (holotype), with pale and indistinct grey­white mottling and flecks, sometimes also with indistinct mid­grey speckles; markings more prominent on tail; throat uniform or with barely discernable speckling; undersurface of feet and toes orange­brown to light orange; precloacal scales sometimes pale yellow.

Iris ranges from mid to dark brown with a dark filigree pattern, sometimes becoming grey­brown at the edges, and bordered (just beneath the surrounding skin, but visible when the skin is gently eased back) by a thin black ring. Mouth lining bright orange; throat lining blackish­grey. Tongue pink, usually with a large grey or indigo patch across the anterior half, anterior edges sometimes speckled with orange.

Etymology

The name cryptozoicus , masculine and used as an adjective, is derived from a combination of the Greek words kryptos (hidden) and zoikos (living), referring to the subsurface scree habitat. The common name, Takitimu gecko, is derived from the type locality. Takitimu is derived from Maori folklore and is the name of the ancestral waka (canoe) that was swamped by waves and grounded at the mouth of the Waiau River. According to the mythology of the Murihiku people, the Takitimu Mountains is the waka turned into stone.

Comments

Among the described Hoplodactylus , H. cryptozoicus differs clearly from most species in morphology and its terrestrial habits and presence in the alpine zone. It is most similar to the Stewart Island species H. nebulosus (McCann) and the more widespread species H. granulatus by the sharing of similar colouration and the presence of orange or yellow mouth lining, a character which is also shared with the species H. kahutarae , a group that appears to form a monophyletic group based on this character and 16Sr RNA data ( Hitchmough 1997; Chambers et al. 2001). Hoplodactylus cryptozoicus , though, is probably most closely related to H. nebulosus based on the sharing of grey pigment on tongue, a unique character in the narrow­toed group of the genus, as well as a lightly mottled undersurface. Table 1 provides a full list of differences between the species and Fig. 4 illustrates some of the difference in colour pattern. Hoplodactylus cryptozoicus is larger than H. nebulosus , and has a distinctly shorter tail. The body scales are much smaller, so much so that specimens of H. cryptozoicus have a noticeably smoother texture than similar­sized examples of H. nebulosus . Adult H. cryptozoicus are slate grey or orange in colour, whereas H. nebulosus are typically olive­grey or brown, and never have orange markings.

The original specimen of Takitimu gecko, a large juvenile female ( Fig. 1 ), died after five months in captivity and was preserved in good condition. In January 2000 an adult male ( Fig. 2 ) was collected live to facilitate behavioural studies and is currently being held at the Southland Museum and Art Gallery , Invercargill. Another five examples (one adult female and four subadult males) were examined live by the author and released at the type locality. While a larger series of specimens would normally be preferable before attempting a taxonomic description, the Takitimu gecko is listed as “nationally critical” ( Hitchmough 2002) and further collection to obtain museum specimens is illegal. Perhaps when a more thorough revision of the geckos of New Zealand is initated, with the intention of a more critical evaluation of morphological characters (including osteology), then permission to collect material could be obtained .

Natural History and Evolution

The type locality ( Fig. 3 ) is a steep, south­facing scree slope, which is surrounded by alpine herbfield/short tussock communities, and is isolated from other scree systems in the mountain range. Specimens were found in channels of medium sized rocks (about 20 cm), often close to small islands of vegetation, between 1130–1150m. The climate is characterized by a long cold winter, a high rate of precipitation, exceeding 2500mm, much of which falls as snow, frequent cloud and fog cover, low sunshine hours, and frequent strong winds ( Evans 1969; pers. obs.).

Field observations of specimens found on the scree surface suggest H. cryptozoicus is saxicolous (rock­inhabiting) and is at least partially nocturnal; one specimen, found beneath a rock by day, may have been sun basking. However, excepting these occasional examples found on the scree surface, it has proven virtually impossible to study the species; the extent and nature of its activity beneath the surface of the scree is unknown.

The single adult female found in mid January 2000, was palpated and found to be carrying two, small, but clearly discernable, embryos. Vocalization has been recorded on rare occasions, and only among males when being handled. The call is in the form of a soft chirp.

Hoplodactylus cryptozoicus is the likely sister species of H. nebulosus based on the morphological characters listed above, and this hypothesis is supported by unpublished phylogenetic data based on mitochondrial 16S rRNA and cytochrome­b genes (R.A. Hitchmough pers. comm. 2000). This pair of taxa form a group with H. kahutarae , a species restricted to the Seaward and Inland Kaikoura Ranges in Marlborough and Mt. Arthur in Northwest Nelson ( Whitaker et al. 1999), and the widespread species H. granulatus , by the sharing of an orange­pigmented mouth.

The two sister species occur on separate islands: H. cryptozoicus occurs well inland on the South Island, while H. nebulosus occurs 100–180km further south, on the opposite side of the Foveaux Strait, in the Stewart Island archipelago. These two species may be derived from a more widespread ancestor that was once located in the southern portion of the south island. Though relatively recent, the development of the Foveaux Strait 11,000 years ago (M. Marra, pers. com) may have acted as a barrier to restrict gene flow in the ancestral population that resulted in the formation of two species. Another consideration is that the divergence between H. cryptozoicus and H. nebulosus could have been associated with an ecological shift from an ancestral forest­dwelling and arboreal species to the alpine and saxicolous habit of H. cryptozoicus . The morphological and ecological differences between H. cryptozoicus and H. nebulosus ( Table 1 ) suggests a more ancient divergence, but any questions about the rates of speciation and ecological shifts in the genus requires a robust phylogeny that includes all of the Hoplodactylus species.

Figures

FIGURE 1. Scalation of the head and feet of H. cryptozoicus (specimen: holotype). A) head, lateral view; B) head, frontal view; C) underside of hind foot. Scale bar = 4 mm.

FIGURE 2. An adult male Hoplodactylus cryptozoicus, collected live in January 2000 from the type locality in the Spence Burn, Takitimu Mountains. This specimen illustrates the typical primary markings (i.e., the herringbone­shaped patches connected longitudinally), and the two types of ground colour which occur in adults, grey (in this case restricted to the flanks) and two­tone orange. (Photograph by R. Morris).

FIGURE 3. Habitat of H. cryptozoicus, showing the scree in which the species occurs, and the alpine vegetation, which surrounds it. The holotype was collected 1.5m uphill from the person shown here and the captive male shown in Fig. 2 was collected near the horizon of the scree in line with the tarns, which are visible in the background. (Photograph by T. Jewell)

FIGURE 4. Sloughed skins of Hoplodactylus cryptozoicus (A) and sister­species H. nebulosus (B), illustrating differences in body colour pattern. The H. cryptozoicus skin is from the specimen featured in Fig. 2; the H. nebulosus skin is from a typical example of the species (collected from Big Island). Note the browner colouration of the H. cryptozoicus skin (resulting from the orange pigmentation) and an absence of the dark flecks which embellish H. nebulosus. (Photographs by T. Jewell).