Cophixalus hinchinbrookensis, Hoskin, Conrad J., 2012

Hoskin, Conrad J., 2012, Two new frog species (Microhylidae: Cophixalus) from the Australian Wet Tropics region, and redescription of Cophixalus ornatus, Zootaxa 3271, pp. 1-16 : 10-11

Cophixalus hinchinbrookensis sp. nov.

Hinchinbrook Island Nursery-frog ( Figs 2 C, 2D)

Material examined. Holotype: QMJ44166, male, upper Gayundah Ck, Hinchinbrook Island (18°22′S, 146°15′E, elevation 850 m), north-east Queensland, G. B. Monteith and D. J. Cook, 11 November 1984. Paratypes: QMJ44163, QMJ44164, QMJ44231, upper Gayundah Ck, Hinchinbrook Island (18°22′S, 146°15′E, elevation 850 m); QMJ76065, near Mt Diamantina, Hinchinbrook Island (18°25′34S, 146°17′23″E, elevation 750 m); QMJ76066, summit Mt Bowen, Hinchinbrook Island (18°21′31″S, 146°15′55″E, elevation 1100 m); QMJ76067, near Mt Diamantina, Hinchinbrook Island (18°24′48″S, 146°16′55″E, elevation 740 m). Additional material: An additional 88 individuals were measured in the field, and mating calls were measured from 14 of these ( Table 1).

Diagnosis. Cophixalus hinchinbrookensis sp. nov. can be identified from similar congeners, except C. australis sp. nov. and C. ornatus , by the presence of large, truncated finger pads and by call, which is a ‘beep’ rather than a call with obvious pulses or notes. Cophixalus hinchinbrookensis sp. nov. can be reliably identified from C. australis sp. nov. and C. ornatus genetically, using the loci outlined in Hoskin et al. (2011). For 16S mtDNA, diagnostic SNPs are presented in Table 3 . It can also be readily identified based on distribution, as it does not co-occur with the other two species and is restricted to Hinchinbrook Island. Cophixalus hinchinbrookensis sp. nov. differs from C. australis sp. nov. and C. ornatus in multivariate analyses of mating call and some aspects of morphology (Hoskin et al. 2011), but these three species cannot be distinguished on any known single trait. Regarding colour pattern, the groin and posterior thigh generally lack a yellow wash in C. hinchinbrookensis sp. nov. (vs. typically present in C. ornatus ).

Etymology. The name is derived from the fact that this species occurs only on Hinchinbrook Island, with the - ensis extension being latin for ‘belonging to’. The epithet is to be treated as a noun in apposition.

Description of holotype ( Fig. 2 C). QMJ44166; male. Measurements (mm): SVL 19.0; TL 7.7; FL 4.4; HW 7.6; HL 5.2; ED 1.7; EN 1.5; IN 1.3; 3FL 2.8; 3DW 1.1; 4TL 3.9; 4DW 0.9. Head: About same width as body, snout triangular in dorsal view and moderately truncated at the nares, rounded in profile; canthus rostralis rounded, loreal region steep; nares much closer to tip of snout than to eye, nares anterolateral on tip of snout; eyes large; eye diameter greater than eye to naris distance; internarial distance about equal to distance from eye to naris; tympanum small (less than half diameter of eye) and indistinct beneath overlying skin, bordered dorsally by indistinct supra-tympanic fold. Body: Rotund. Limbs: Hindlimbs short, forearms relatively long; fingers and toes unwebbed; relative finger length 3>2>4>1; fingers 2, 3 and 4 long and slender with large and truncated discs, first finger short with small round disc; low, rounded outer palmar tubercle and smaller rounded inner palmar tubercle; subarticular tubercles low, moderately prominent; relative length of toes 4>3>5>2>1, toe 4 very long and slender; large, truncated discs on toes 2, 3 and 4, discs smaller and more rounded on toes 1 and 5; low, ovoid inner metatarsal tubercle, no outer metatarsal tubercle; subarticular tubercles low and rounded; discs on longest fingers larger than discs on longest toes. Skin: Ventral surfaces generally smooth, finely granular on belly; dorsal surfaces smooth with scattered low tubercles; indistinct supra-tympanic fold. Colour pattern in preservative: Dorsal surfaces pale brown with darker blotching and mottling, particularly on shoulders and between eyes; grey triangle on head, grey eyelids; dark smudging on the lateral surface above the axilla; pale lumbar ocelli bordered posteriorly by a dark blotch; dark cloacal region; indistinct dark bar from nare to eye and along tympanic fold. Tympanum pale brown. White patches at the base of the finger and toe discs. Dark brown dorsal colouration merges to lighter brown on flanks. Ventral surface of head and body creamy-brown with fine pale spotting, particularly under throat. Ventral surfaces of limbs creamy-brown; discs and tubercles pale.

Description of type series (N = 7). Data presented as range followed by mean in brackets. Adult measurements (mm): SVL 17.1–23.8 (20.4); TL 7.5–9.8 (8.6); FL 3.8–5.7 (4.7); HW 6.5–8.5 (7.6); HL 4.3–6.0 (5.3); ED 1.7–2.6 (2.0); EN 1.3–1.9 (1.6); IN 1.2–1.7 (1.4); 3FL 2.4–3.3 (2.9); 3DW 0.8–1.3 (1.0); 4TL 3.8–4.7 (4.3); 4DW 0.7–0.9 (0.8). Adult proportions: TL/SVL 0.40–0.44 (0.42); FL/SVL 0.20–0.25 (0.23); FL/TL 0.51–0.58 (0.55); HW/SVL 0.35–0.40 (0.37); HL/SVL 0.23–0.27 (0.26); HW/HL 1.39–1.55 (1.45); ED/SVL 0.09–0.11 (0.10); EN/HL 0.29–0.32 (0.30); EN/IN 1.08–1.27 (1.15); EN/ED 0.66–0.90 (0.79); 3FL/SVL 0.13–0.15 (0.14); 3DW/SVL 0.042–0.060 (0.051); 4TL/SVL 0.18–0.22 (0.21); 4DW/SVL 0.034–0.047 (0.039); 3DW/4DW 1.14–1.44 (1.33). Comparison of sexes: Based on field measurements ( Table 2 ), females are generally larger (e.g. average SVL 22.6 vs. 19.9), have proportionally larger finger discs, and are bulkier (i.e. heavier relative to SVL). Colour pattern in preservative: Generally as for holotype – light brown background with areas of darker brown smudging and mottling. Other specimens are dark brown with darker mottling or smudged areas. Consistent features on most specimens are: grey/brown triangle on snout, grey on eyelids, dark W-shaped mark or shoulders; pale lumbar ocelli marked behind by dark patch, dark irregular band/s above axilla on lateral surfaces, dark band from snout through eye and along supratympanic fold; generally dark band on wrist, pale dots at base of finger and toe pads, dark mottling on hindlimbs and lateral surfaces. Ventral surfaces variable: evenly pale cream (N = 3), brown with white flecking (N = 3) or grey brown (N = 1). Undersides of limbs pale to dark brown with white mottling, tubercles and pads generally pale.

Measurements of live individuals. Table 2 presents measurements for 83 males and 5 females in the field.

Colour pattern in life. As for C. australis sp. nov.

Call. A finely pulsed ‘beep’ ( Fig. 3 B) of the characteristics outlined in Table 2 .

Comparison. Only likely to be confused with other rainforest microhylids. Cophixalus hinchinbrookensis sp. nov. can be distinguished from these species (except C. australis and C. hinchinbrookensis sp. nov.) by the presence of large, truncated finger pads and by the mating call, which is a finely-pulsed ‘beep’ rather than a call with obvious pulses or notes. Cophixalus hinchinbrookensis sp. nov. is phenotypically similar to C. australis and C. hinchinbrookensis sp. nov.. There are multivariate differences in mating call and morphology between these three species (Hoskin et al. 2011) but they cannot be identified based on any single known phenotypic trait in the field ( Table 2 ). Calls of C. hinchinbrookensis sp. nov. are of relatively high pitch, short duration, low pulse number and slow pulse rate ( Table 2 ; Fig. 3 ; Hoskin et al. 2011). Males and females of C. hinchinbrookensis sp. nov. are generally smaller and less bulky (i.e. lighter relative to SVL) frogs and have proportionally smaller finger discs ( Table 2 ; Hoskin et al. 2011). Cophixalus hinchinbrookensis sp. nov. can be reliably identified by genetics, representing a divergent monophyletic lineage for both mtDNA and nDNA loci (Hoskin et al. 2011). For 16S mtDNA, the SNPs presented in Table 3 and the GenBank sequences listed below can be used for identification. Cophixalus hinchinbrookensis sp. nov. can be readily identified in the field by being restricted to Hinchinbrook Island ( Fig. 1 ), where it is the only Cophixalus .

Genetics. Cophixalus hinchinbrookensis sp. nov. is the ‘Hinchinbrook Island’ lineage referred to in Hoskin et al. (2011). Two representative 16S mtDNA sequences for this species from near the type locality are JF743704 and JF743756 (GenBank accession numbers).

Distribution. Cophixalus hinchinbrookensis sp. nov. is restricted to Hinchinbrook Island, a large island off the coast of north-east Queensland ( Fig. 1 ). The species has been recorded around Mt Diamantina and Mt Bowen, from 300 m elevation to the highest point on the island, the summit of Mt Bowen (1120 m).

Habitat and habits. Cophixalus hinchinbrookensis sp. nov. inhabits rainforest, montane heath and rocky areas. The mid and high elevations of Hinchinbrook Island consist of a mosaic of low, dense heath in exposed areas, rainforest in the sheltered gullies, and exposed rock. Cophixalus hinchinbrookensis sp. nov. is abundant throughout these habitats. The species has not been recorded from the extensive areas of lowland rainforest on the island. The only other frog species recorded during surveys in the higher elevations of Hinchinbrook Island were Litoria serrata and a species of stoney creek frog for which species identity was not determined with certainty ( Litoria jungguy or L. wilcoxii ). Cophixalus hinchinbrookensis sp. nov. males call during and following wet weather. Males call from ground-level to about 2 m above the ground. Calling sites include rocks, tree trunks, stems of saplings and vines, thick tangles of ferns or other low vegetation, and dead leaf litter caught amongst low vegetation. The most common calling position is facing head upwards on a vertical stem approximately 50 cm off the ground. Females are rarely encountered at night. A gravid female was observed following a male uttering a lead call in amongst rocks to a probable nest site. Adults of both sexes, sub-adults and egg clutches were readily found under granite rock slabs. As for all Australian microhylids ( Zweifel 1985; Hoskin 2004), the species is a terrestrial breeder, with small clutches of large eggs ( Fig. 2 D). Recorded clutch sizes range from 3– 15 eggs (average = 8 eggs, N = 10). A male was usually found in close proximity to each clutch (e.g. Fig 2 D), sometimes straddling it. In a number of instances a single male appeared to be attending two clutches of different developmental stage. In one case, multiple clutching appeared to involve 3 clutches. A male was found calling beside a hollow in a small tree stem approximately 1.5 m above the ground. Inside the hollow was a clutch of 10 unpigmented early-stage eggs, a clutch of 15 eggs of mid development, and 2 metamorphs. During the day the male was found sheltering inside the hollow with the egg clutches.

Figures

FIGURE 1. Phylogeny (A) and distributions (B) of C. australis sp. nov., C. hinchinbrookensis sp. nov. and C. ornatus. (A) Maximum likelihood tree constructed from 513 bp 16 S mtDNA. The phylogeny shows the relationship between C. ornatus, C. australis sp. nov. and C. hinchinbrookensis sp. nov. The tree also shows the three subgroups within C. australis sp. nov.: Mt Bartle Frere region (BF), Lowland (L) and Southern (S). Numbers at major nodes are Bayesian posterior probabilities. (B) Map of the Wet Tropics region of north-east Australia and an enlargement of the Atherton Tablelands-Mt Bartle Frere region. The coloured dots show the most common mtDNA lineage at each site, with dot colour matching the phylogeny. The site numbers match the locality details in Table 1. This figure is modified from Figs 3 and C 1 in Hoskin et al. (2011).

FIGURE 2. Photos of: (A) the holotype of C. australis sp. nov. (QMJ 43655); (B) C. australis sp. nov. in life, Mt Hypipamee (photo: Conrad Hoskin); (C) the holotype of C. hinchinbrookensis sp. nov. (QMJ 44166); (D) C. hinchinbrookensis sp. nov. in life, Hinchinbrook Island (photo: Alex Anderson); (E) the holotype of C. ornatus (R 222); (F) C. ornatus in life, Kuranda (photo: Conrad Hoskin).

FIGURE 3. A single representative call of: (A) C. australis sp. nov., Tully Falls, 750 m a. s. l., 18 ° C; (B) C. hinchinbrookensis sp. nov., Mt Diamantina, Hinchinbrook Island, 770 m a. s. l., 19 ° C; (C) Cophixalus ornatus, Butchers Ck, 715 m a. s. l., 18.5 ° C. These calls were selected because they are from similar altitudes and temperatures, and because they fall near the group centroid of variation within each species from analyses in Hoskin et al. (2011). Waveforms display amplitude (y - axis) against time (x - axis, seconds); Spectrograms display call frequency (y - axis) and intensity (degree of shading) against time (x - axis, seconds).