Amalosia saxicola, Hoskin & Couper, 2023

Hoskin, Ad. J. & Couper, Patrick J., 2023, Revision of zigzag geckos (Diplodactylidae: Amalosia) in eastern Australia, with description of five new species, Zootaxa 5343 (4), pp. 301-337 : 318-321

Amalosia saxicola sp. nov.

Rock Zigzag Gecko

( Figures 13–15 )

Material examined. Holotype. Male , QM J91337 ( Fig. 13 ), Mt Zero, Taravale (19° 05’ 34” S, 146° 08’ 33” E), field collection code: conx5062, C. J. Hoskin, 8/9/2011 . Paratypes. (all localities in north-east and mid-east Queensland) QMJ97585, Kirrama Range (18°10’58” S, 145°44’ 26” E) ; J76048, Hinchinbrook Is. (18° 21’ 38” S, 146° 14’ 37” E); QM J76045 , Hinchinbrook Is. (18° 25’ 34” S, 146° 17’ 23” E) ; J76919, Bishops Peak (18° 28’ 48” S, 146° 07’ 46” E) ; J97581–84, Palm Is. (18° 44’ 38” S, 146° 34’ 37” E) ; J91356, Mt Zero, Taravale (19° 05’ 34” S, 146° 08’ 33” E) ; J91119, J91122, Magnetic Is. (19° 07’ 41” S, 146° 52’ 04” E) ; J91170, The Forts , near, Magnetic Is. (19° 07’ 41” S, 146° 52’ 04” E) ; J79803, West Point , Magnetic Is. (19° 08’ S, 146° 47’ E) ; J90964, Gustav Ck , Magnetic Is. (19° 08’ 50” S, 146° 48’ 53” E) ; J91355, Cape Cleveland (19° 17’ 29” S, 147° 01’ 22” E) ; J91379, The Pinnacles , SW of Townsville (19° 23’ 50” S, 146° 38’ 35” E) ; J64872, Cape Upstart , base (19° 42’ S, 147° 45’ E) ; J65150, J65151, Cape Upstart , on top (19° 44’ S, 147° 49’ E) ; J32775, J32776, Brandy Ck, Site 13 (20° 21’ S, 148° 43’ E) ; J64871, Pine Mtn (20° 28’ S, 147° 55’ E) ; J97593, Massey Ck, Eungella (21° 00’ 06” S, 148° 30’ 34” E) ; J64851, Blue Mtn (21° 31’ S, 148° 59’ E) ; J92795, Sandy Creek Gorge, Redcliffe Tableland , N of Nebo (21° 02’ 27” S, 148° 04’ 24” E) ; J82653, Sydney Head (21° 24’ 45” S, 148° 34’ 49” E) .

Diagnosis. A large (max. SVL ~ 65 mm), relatively short-bodied (AG/SVL 0.39–0.48) and short-tailed (oTL/ SVL 0.80–0.92) member of the A. rhombifer group. Dorsal pattern a dark zigzag dorsolateral zone abutting a paler vertebral zone; a pale dot is typically present at the outer corner of each zigzag, such that the dark edging looks broken at each pale triangle apex; the vertebral zone is rarely broken by narrow, transverse lines and there is almost never a transverse band on the nape. Typically, minimal webbing between third and fourth toes. Males with 3–6 large, pointed postcloacal spurs (small and rounded in females) and 0–7 precloacal pores. The first and second supralabials are usually subequal in height, with the second supralabial being wider than the first. Usually, six scales contacting margin of nostril.

Measurements and scale counts of holotype: SVL 60.5 mm, oTL 51.6 mm, oTW 5.6 mm, oTD 4.7 mm, HL 13.1 mm, HW 10.4 mm, HD 5.1 mm, S 5.8 mm, AG 25.2 mm, L1 15.6 mm, FL 6.6 mm, LHL 8.5 mm, BW 11.9 mm, rostral crease 25%, scales contacting dorsal margin of the rostral 3, scales bordering nasal opening 6, scales contacting posterior margin of mental shield 4, supralabials 11, 1 st and 2 nd supralabials subequal in height but 2 nd wider than 1st, infralabials 9, postcloacal spurs 5, precloacal pores 6, pore gap 4, subdigital lamellae 4 th finger 7; subdigital lamellae 4 th toe 7, moderate webbing between 3 rd and 4 th toes.

Description of type series. Measurements ( Table 2). SVL (mm): 52.4–64.6 (n = 23, mean = 58.2). Proportions as % SVL: oTL = 80–92 (n = 12, mean = 85); HL = 21–25 (n = 23, mean = 23); HW = 16–19 (n = 23, mean = 18); HD = 6.9–10.5 (n = 23, mean = 8.2); S = 9.5–11.0 (n = 23, mean = 10.2); AG = 39–48 (n = 22, mean = 44); L1 = 26–31 (n = 22, mean = 28); L2 = 33–42 (n = 17, mean = 38); FL = 11–13 (n = 23, mean = 12); LHL = 14–16 (n = 23, mean = 15); BW = 15–23 (n = 23, mean = 18). Head. Narrow, elongate, distinct from neck; head width 70–87% head length (n = 23, mean = 77); head depth 40–61% head width (n = 23, mean = 47); snout length 40%–47% head length (n = 23, mean = 44); covered in small granules with slightly larger granules on the dorsal and lateral surfaces of the snout; rostral approximately twice as wide as deep, partially divided vertically by a medial groove extending 25–60% rostral height; 2–4 scales contacting dorsal margin of the rostral, lying between the nostrils (n = 27, mode = 3, mean = 3.0); 5–7 scales bordering nasal opening (n = 27, mode = 6, mean = 6.0); supralabials 10–14 (n = 27, mode = 11, mean = 11.4), 2 nd supralabial wider than 1 st supralabial; 2 nd supralabial taller than or subequal to 1 st supralabial; infralabials 9–14 (n = 27, mode = 11, mean = 10.9); 3–6 scales contacting posterior margin of mental shield, between 1 st infralabials (n = 27, mode = 5, mean = 4.7). Neck. Broad. Body. Slender, slightly depressed, covered in small granules; granules on ventral surface noticeably larger than those on dorsum; a row of enlarged postcloacal spurs (3–6, n = 27, mode = 4, mean = 4.7) behind the lower posterior margin of the thigh in both sexes (significantly larger in males and usually with a rounded margin). 0–7 (n = 15, mode = 6, mean = 3.9) precloacal pores present in mature males (and some females), not extending to underside of thigh, and divided medially by 0–6 granular scales without pores (n = 12, mode = 4, mean 3.9). Limbs. Moderate length; digits dorsoventrally compressed and expanded distally; an enlarged pair of apical lamellae followed by a transverse series, divided distally, single proximally; forelimb with 5–9 enlarged lamellae on 4 th finger (n = 27, mode = 6, mean = 6.5), 3–5 split or deeply grooved; hindlimb with 5–8 enlarged lamellae on 4 th toe (n = 27, mode = 6, mean = 6.4), 4–5 split or deeply grooved; basal webbing usually absent or minimal between 3 rd and 4th. Original tail. Moderate length (80–92% SVL), narrow (oTW/oTL = 9–14%), tapered, and slightly to moderately flattened (oTW/oTD = 103–143%) ( Table 2); scales arranged in concentric rings, larger on ventral surface. Pattern in spirit. Dorsal view. Head and body fawn to mid-brown with a pale vertebral zone and a darker, zigzag, dorsolateral pattern (mid-east Queensland specimens are darker than those from Townsville). A dark patch is present on the crown but breaks posteriorly into one, or several, smaller blotches that extend along the vertebral zone. Specimens from mid-east Queensland have some indication of a central stripe on the dorsal surface of the snout but this is usually absent from Townsville specimens.A dark facial stripe, beginning on snout and continuing behind eye, joins the dark zigzag dorsolateral zone, which has a narrow, dark upper edge and extends to the tip of the tail (original). No dark band is present on the nape. The zigzag pattern consists of dark points extending into the pale vertebral zone (seven to nine between, and including, the pectoral and pelvic girdles). These may be either aligned or misaligned, so that the tip of each point aligns with the pale, point interspace on the opposite side. The zigzag points rarely connect across the pale vertebral zone and a pale dot is often present at the base of each zigzag, at its junction with the vertebral zone (specimen QM J64872 has obscure pale bands extending across dorsum, connecting the zigzag interspaces). Flanks. Dark marbling or a solid dark zone containing pale, obscure spots. Original Tail. Pattern as for dorsum. Limbs. Variegated, or heavily blotched (particularly on mid-eastern Queensland specimens). Ventral surface. Pale, unpatterned, off-white. Colour pattern in life ( Fig. 14 ). As described above but paler markings light grey or white (vs cream coloured in preservative) and darker markings generally shades of grey (vs often more brownish in preservative). White flecks on the lateral and dorsolateral surfaces more obvious in life. Regenerated (and sometimes original) tail often has a yellow wash in life. Iris silver or light copper coloured.

Comparisons. Separated from A. queenslandia sp. nov., A. capensis sp. nov. and A. cf. rhombifer by its much larger size (max. SVL 65 mm vs A. queenslandia sp. nov. max. 50 mm, A. capensis sp. nov. max. 51 mm, A. cf. rhombifer max. 53 mm; Table 2; Fig. 15 ); relatively short body (AG/SVL mean 0.44 vs mean ~ 0.48 mm; Table 2); more robust form (e.g., Fig. 15 ), fewer precloacal pores (mean 3.9 vs A. queenslandia sp. nov. 8.5, A. capensis sp. nov. 17.1, A. cf. rhombifer 16.9; Table 2), and more postcloacal spurs (3–6, mode 4 vs usually three in both A. capensis sp. nov. and A. queenslandia sp. nov.). Dorsal pattern also separates A. saxicola sp. nov. from these three species, with the white zigzag typically being more deeply notched (and sometimes broken) and white dots often breaking the outer points of the triangles (vs a cleaner, unbroken dorsal pattern in the other species). From A. cf. rhombifer it is further distinguished by more postcloacal spurs (3–6 vs A. cf. rhombifer 1–2), and from A. queenslandia sp. nov. by almost always having 6 scales contacting the nasal (vs typically 5 in A. queenslandia sp. nov.). Differs from A. nebula sp. nov. in attaining a larger size (SVL max. 65 mm vs A. nebula sp. nov. max. 58 mm), typically having 4 or more postcloacal spurs (vs typically <4 in A. nebula sp. nov.), having a relatively shorter tail (oTL/SVL mean 0.85, max. 0.92 vs A. nebula sp. nov. mean 0.95, max. 1.05), white dots often breaking the outer points of the triangles on the dorsal pattern (vs white dots, if present, contained within dark edging of zigzag pattern), and pale copper or silver iris (vs dark copper in A. nebula sp. nov.). Distinguished from the southern species ( A. hinesi sp. nov., A. jacovae and A. lesueurii ) by numerous traits, including minimal toe webbing (vs moderate–pronounced; Tables 1 , 2), relatively short tail (oTL/SVL 0.80–0.92 vs A. jacovae 0.94–1.02), low number of precloacal pores in males (0–7 vs A. jacovae 13–22, A. lesueurii 7–13), lateral surfaces and limbs with minimal spotting (vs obvious spotting in A. lesueurii ), and lighter iris colour.

Genetic data. Two ND4 sequences deposited on GenBank: OM523369 (specimen: QM J91337 ; holotype; genetic sample code: conx5062; west side of Paluma Range ) and OM523370 (specimen: QM J91355 ; paratype; genetic sample code: conx5075; Cape Cleveland ) .

Etymology. saxicola sp. nov. = ‘rock-dweller’; reflecting that this species is always found in rocky habitats.

Distribution. Coastal ranges and islands along the mid-east Queensland coast from the Mackay region to Hinchinbrook Island ( Figs. 3 , 5 ). There is an apparent break between populations in the Mackay–Bowen region and those in the Townsville–Hinchinbrook Island region. Known to occur as isolated populations on many rocky offshore islands and peninsulas, including the South Cumberland Islands, Whitsunday Islands, Cape Upstart, Cape Cleveland, Magnetic Island, Palm Island and Hinchinbrook Island.

Natural history. Amalosia saxicola sp. nov. is restricted to rocky areas, typically habitats with granite outcropping, such as rocky peaks and slopes, boulder-fields, and rocky gullies. The associated habitat often includes rainforest elements (e.g., Fig. 16 ), but can be dry sclerophyll habitats and upland heaths. Nocturnal, and known to prey on invertebrates (field observations and scat contents, CJH). Hides among rocks during the day, sometimes together as multiple individuals in big rock overhangs, and forages on rock surfaces and associated vegetation at night. At dusk, individuals are often observed to climb out of the rocks and up vines and trees growing among the rocks to forage (CJH observations). Shed skins are regularly found hanging from rock surfaces, vines or spider webs in rock overhangs. Co-occurs in close proximity with A. queenslandia sp. nov. at many sites in the Townsville area, with A. saxicola sp. nov. in rocky areas and A. queenslandia sp. nov. in adjacent woodland.

Figures

FIGURE 3. Map of occurrence records of Amalosia species in Queensland and north-east New South Wales. For each species, individuals included in the ND4 sequencing (Fig. 2) are shown as triangles whereas specimen and sighting records are shown as circles. Records of A. robusta are not shown because the copious records obscure presentation of the focal species.

FIGURE 5. Map of occurrence records of Amalosia species in north-east Queensland. For each species, individuals included in the ND4 sequencing (Fig. 2) are shown as triangles whereas specimen and sighting records are shown as circles.

FIGURE 13. Holotype of A. saxicola sp. nov. (QM J91337); Mt Zero, Paluma. Photo: Conrad Hoskin.

FIGURE 14. Amalosia saxicola sp. nov. in life: (A, B) Magnetic Island; (C) Scawfell Island; (D) Massey Ck, Eungella. Photos: Conrad Hoskin.

FIGURE 15. Adult A. saxicola sp. nov. QM J32775 (Brandy Ck, near Airlie Beach) compared with adult A. queenslandia sp. nov. QM J97599 (Mt Spurgeon). Note the more robust form of A. saxicola sp. nov. Photo: Conrad Hoskin.

FIGURE 16. Habitat of A. saxicola sp. nov. in the Townsville area. Photo: Conrad Hoskin.