Litoria hunti, Richards, Stephen J., Oliver, Paul, Dahl, Chris & Tjaturadi, Burhan, 2006

Richards, Stephen J., Oliver, Paul, Dahl, Chris & Tjaturadi, Burhan, 2006, A new species of large green treefrog (Anura: Hylidae: Litoria) from northern New Guinea, Zootaxa 1208, pp. 57-68 : 59-65

Litoria hunti sp. nov.

( Figs 1 –4)

Type material

Holotype. SAMA R60716. Adult male with nuptial pads and vocal slits, calling when collected, Utai, Sanduan Province (141°35'E, 03°23'S), collected by Chris Dahl on 28/05/ 2004.

Paratypes. UPNG 10012, collected on 7/06/04; SAMA R60715, collected on 9/06/04; UPNG 10013 and SAMA R60714, collected on 11/06/04; all adult male specimens with vocal slits and nuptial pads, collected by Chris Dahl from the type locality.

Diagnosis

Litoria hunti can be distinguished from all other Litoria by a combination of (1) moderately large size (males 57.9–60.4 mm) (2) predominately green dorsal colouration (3) presence of a thin off white mandibular stripe not or marginally extending beyond the tympanum (4) possession of two clusters of nuptial excrescences on each thumb (5) presence of prominent off white dermal fold extending from outer edge of toe V, along the tarsus and across the heel (6) prominent off white dermal fold along arm (7) moderately robust build (HW/SVL 0.355–0.373) (8) moderately wide discs, especially on fingers (3FP/3FD 0.628–0.769) (9) iris without black pigmentation and (10) advertisement call a long guttural grunt lasting 0.7– 0.9 s

Description of holotype

Measurements are presented in Table. 1 . Moderately robust frog; head approximately as wide as long (HW/HL 1.017), wider than body in dorsal view; snout truncate in both dorsal and lateral aspect; labial region sloping and flared; loreal region moderately sloping and marginally concave; canthus rostralis indistinct, curved; nares much closer to tip of snout than to eyes, oriented laterally but marginally visible in both dorsal and anterior views.

Choanae large, roughly circular, separated by a distance approximately three times their width; vomerine teeth in bundles of 6–7 along the posterior ridge of two prominent elevations positioned medial to choanae. Eyes moderately small (EYE/SVL 0.110), protruding beyond head in both dorsal and lateral views, pupil horizontal. Tympanum moderately large (EAR/SVL 0.087), annulus distinct and raised, dorsal edge of tympanum obscured by supratympanic fold that extends from posterior edge of eye to axillary junction. In preservative body and legs smooth dorsally (slightly granular in life); ventrally throat, forelimbs and lower hindlimbs smooth, abdomen and upper portions of hindlimbs coarsely granular.

Arms robust; prominent off white dermal fold extending from halfway along finger IV, along carpus and around elbow; fingers with relative lengths III>IV>II>I; discs prominent with supramarginal grooves, significantly wider than penultimate phalanx (3FP/3FD 0.730); subarticular tubercles rounded, two on digits I and II, three (with medial tubercle distinctly larger than distal and proximal tubercles) on digits III and IV; supernumerary tubercles low, indistinct, present on most proximal phalanx of II–IV; single large low inner metacarpal tubercle. Nuptial excrescences in two clusters at the base of digit I, proximal cluster much longer than wide, distal cluster shorter and roughly as wide as long. All digits webbed, webbing reaching proximal subarticular tubercle between digits I–II, to distal end of penultimate phalanx on II and IV, and just beyond tubercle at base of penultimate phalanx on both sides of III; slight dermal fringes on all digits.

Legs moderately long (TL/SVL= 0.563); prominent off white dermal fold extending along tarsus from lateral edge of toe V across heel. Relative lengths of toes IV>III>V>II>I; discs expanded with circum­marginal grooves, significantly wider than penultimate phalanges (4TP/4TD 0.806); subarticular tubercles rounded, two on digits I and II, three on digits III and V, four on digit IV; numerous small indistinct round supranumerary tubercles visible on proximal phalanges of digits III–V; prominent ovoid inner metatarsal tubercle at base of digit I. All digits webbed, webbing extends to distal end of penultimate phalanx on inner edge of digit V, both sides of digit IV and outer edges of digits III, II and I, and to approximately halfway up penultimate phalanx on inner edge of digits III and II.

In preservative the dorsal surfaces of head, body, arms and thighs are pale greyish blue, with poorly defined patches of slightly darker blue on the head, dorsum and legs along one side of the body. Numerous tiny pigment spots are visible on dorsum under magnification; ventral surfaces largely off white, with bluish areas of varying intensity along the outer edge of the tarsus, toe V, on the arms just behind the elbow, and around the discs on both hands and feet.

Va r i a t i o n

Measurements for the type series are presented in Table 1 . The dorsal colour in preservative of the paratypes is the same as the holotype, with the exception of SAMA R60715 which is a significantly darker greyish blue. In two animals (SAMA R60714 and UPNG 10013) there is a line of brown pigment along the ventral edge of the lower jaw. The extent and intensity of the off white labial stripe varies, in some specimens it is very indistinct and does not extend beyond the edge of the jaw, while in others (including the holotype) it is more prominent and extends posteriorly to a distance approximately halfway across the tympanum. The dorsal surface of finger III and toe IV ranges from almost unpigmented to more than one half blue. In all animals the nuptial excrescences comprise two components, a long low posterior cluster and a rounded anterior cluster, however they sometimes merge, and both overall size and relative darkness varies; some of this variation is probably attributable to variation in reproductive condition.

Appearance in life

Based on photographs of a living specimen Litoria hunti has a relatively uniform pattern consisting of a leaf green dorsum and upper lateral zone, grading into orange­ish yellow lower lateral and ventral surfaces. In areas of integration between the two dominant colours, particularly on the mid­lateral surfaces there are a number of isolated green spots. The outer sides of the lower arms and all of the legs also leaf green. Dorsal surfaces of inner digits of both hands and feet are bright orange. Off­white labial, leg and arm stripes are clearly apparent. The eye has a distinctive orange­red outer rim, around an inner off white area that surrounds the pupil. The tympanum is largely green, except for a horseshoe shaped area of translucent skin.

Advertisement call

Twenty­three calls uttered by the holotype were analysed. The call is a single guttural grunt lasting 0.69– 0.9 s (mean 0.78 s, SD 0.05) and containing 109–154 pulses (mean 131.5, SD 16.22). Pulse pattern is unusual in that pulses are`clumped' in groups, most commonly of 3–4 pulses, rather than being uniformly distributed within the call (Figure 4). Energy is concentrated nearly equally in two major bands, at about 1900 hz and 900 hz. In 19 of 23 calls the dominant frequency is at 1787–2045 hz (mean 1926 hz, SD 70.8) but in four calls the lower frequency (885–915 hz) is dominant (mean 899.5, SD 12.26).

Natural history

Litoria hunti is an arboreal species that was normally heard calling from at least 5–8 m high in forest trees. The holotype was calling from just 1.5 m high in a swamp near Utai Village. This suggests that L. hunti breeds in lentic water bodies on or near the forest floor. The tok ples (local) name for this species is ‘Wowo’.

FIGURE 4. Wave form of a single call of Litoria hunti (holotype, SAMA R60716). Ta 26o C.

Distribution

Litoria hunti has been collected from the forests around Utai in Sandaun Province, Papua New Guinea. Two further specimens of a large green Litoria collected in the foothills of the Foya Mountains, Papua Province, Indonesia conform with this species in overall size, possession of a thin off white labial stripe, largely red iris and distinctive orange­yellow belly. Until these specimens are available for more detailed study we refrain from assigning them to L. hunti . Nonetheless it is likely that this new species has a broad distribution in the extensive lowland rainforests of northern New Guinea.

Etymology

Named in honour of the Hunt family of Adelaide in recognition of their generous support for research at the South Australian Museum.

Comparison with other species

The combination of large size and predominately green colouration make Litoria hunti superficially most similar to the New Guinea species Litoria infrafrenata and L. graminea . Litoria infrafrenata can be differentiated by its much larger adult size, less extensive webbing on fingers (generally not extending beyond the penultimate subarticular tubercle), much bolder labial stripe that extends beyond the posterior edge of the tympanum, and different call. The call of L. infrafrenata is a long series of double­notes ( De la Riva et al. 2004). Litoria graminea as it is currently recognised is a complex of at least three morphologically and acoustically similar species (Richards & Oliver in prep). Litoria hunti can be distinguished from all members of the Litoria graminea ‘group’ by having an off white white labial stripe, only moderately expanded discs (4FD/SVL 0.063–0.073 vs 0.069–0.084 in L. graminea group), smaller adult size (males 57.9–60.4 vs 63.7–73.0 mm) and a call consisting of a long guttural grunt lasting 0.7– 0.9 s (vs <0.5 s in L. graminea group).

There are a number of other medium to large, predominately green Litoria species in the Australopapuan region. Litoria caerulea is larger (to 80–100 mm; Tyler 1968), has a much broader head, prominent parotoid glands and lacks an off white labial stripe. Litoria multiplica has prominent, raised white dermal folds around the vent, a hidden tympanum, tends to have black ventral patterning, and is smaller (males 32.9–42.0 mm) ( Tyler 1968, pers obs). Members of the Litoria gracilenta group ( Litoria aruensis , Litoria auae , Litoria elkeae , Litoria gracilenta and Litoria kumae ) have a distinct canthal stripe running across the eyelid, lack dermal folds and white labial or leg stripes and are considerably smaller (males 24–38 mm SV; Tyler 1968, Menzies & Tyler 2004). Litoria sanguinolenta has halfwebbed hands, a flatter head and is also slightly smaller (males to 40 mm; Tyler 1968). The two Australian taxa Litoria chloris (Boulenger) and L. xanthomera Davies , McDonald & Adams are superficially similar but both lack an off white labial stripe and no or very indistinct off white dermal folds on the arms and legs. These two species have long, drawn­out finely pulsed calls with evenly spaced pulses, in contrast to the guttural grunt of L. hunti ( Davies, McDonald & Adams 1986).

Figures

FIGURE 1. Lateral view of head of holotype of Litoria hunti (SAMA R 60716). Scale bar = 10 mm.

Tables

TABLE 1. Measurements (mm) and key ratios for type series of five male Litoria hunti.

	SAMA R60716	SAMA R60715	SAMA R60714	UPNG 10013 UPNG 10012
SVL	58.4	58.4	60.4	57.9 58.9
EN EN/SVL	5.4 0.093	5.1 0.087	5.7 0.094	5.3 5.0 0.092 0.085
HW	21.3	21.1	21.5	21.0 22.0
HW/SVL EYE	0.365 6.4	0.361 7.1	0.355 6.5	0.363 0.373 6.7 6.8
EYE/SVL	0.110	0.122	0.108	0.116 0.115
TL TL/SVL	32.9 0.56	32.3 0.55	34.7 0.57	31.8 34.5 0.55 0.59
IN	5.0	5.2	5.4	5.2 5.7
IN/EN HL	0.926 21.0	1.020 20.9	0.947 22.6	0.981 1.140 20.7 20.8
HW/HL	1.017	1.010	0.951	1.014 1.055
EAR EAR/SVL	5.1 0.087	5.0 0.086	5.7 0.094	5.0 5.1 0.086 0.087
4TD	3.6	3.5	3.4	3.4 3.9
4TP 4TP/4TD	2.9 0.806	3.0 0.857	3.0 0.882	3.1 3.1 0.912 0.795
4TD/SVL	0.062	0.060	0.056	0.059 0.066
3FD 3FP	3.7 2.7	3.7 2.7	3.9 3.0	3.7 4.3 2.6 2.7
3FP/3FD	0.730	0.730	0.769	0.703 0.628
3FD/SVL	0.063	0.063	0.065	0.064 0.073