MZB Amph.32873 (SJR[JCUNQ]4141), adult male, ~2090 m altitude, unnamed mountain range, Derewo River Basin, Papua Province, Indonesia, (3.4416°S, 136.4738°E), collected by Stephen Richards and Djoko Iskandar, 4^th April 1998.

SAMA R72334–5 (SJR[JCUNQ]4142, 4144), MZB Amph.32874 (SJR[JCUNQ]4152) all adult males, MZB Amph.32872 (SJR[JCUNQ4140]) adult female, same locality and collectors as holotype, between 4–5 April 1998.

A species of Litoria that can be distinguished from all congeners by the following unique combination of characters: moderate size and strong sexual size dimorphism (4 adult males 30.4–31.8 mm SVL, one adult female 48.9 mm SVL); snout moderately long (EN/IN 0.69–0.80), with sharply acuminate tip and with concave dorsal surface; canthus rostralis nearly straight, sharply defined; limbs moderately long (TL/SVL 0.55–0.60); finger webbing moderate, not extending beyond third phalanx between Finger 3 and Finger 4; toe webbing extensive, extending to penultimate phalanx between all digits except Toe 1 and Toe 2; dorsal skin relatively smooth with scattered small tubercles; heel with 2–3 distinct conical tubercles; vomeropalatines prominent; vocal slits present in males; dorsal colouration predominately light to mid-brown with scattered darker-brown spots and or blotches; venter largely buff with little to no pattern; and advertisement calls produced in series of 5–7 calls, each comprising a single short note that is unpulsed or slightly pulsatile but may become longer, with discrete pulses, in terminal calls of the series.

Adult male with vocal slits and pale-brown nuptial pads. Body moderately slender, limbs long (TL/SVL 0.60), head moderately wide (HW/SVL 0.34), slightly longer than wide (HL/SVL 0.34, HL/HW = 1.04). Vomerine teeth in two small but prominent clumps, each approximately 0.5 mm in diameter. Tongue large, broadly oval; lateral margins with distinct indentations, posterior margin with deep notch; vocal slits laterally in floor of mouth, extending from near angle of jaws to about one third distance to front of jaw. Snout protruding distinctly beyond lower jaw, tip sharply acuminate in both dorsal and lateral views, only slightly less so in lateral view, dorsal surface of snout distinctly concave (Figs 1, 2A). Canthus rostralis nearly straight, sharply defined (Fig. 2B); loreal region steeply sloping, slightly concave in dorsal view; nostrils slightly closer to tip of snout than to eyes; internarial distance greater than distance from external naris to eye (EN/IN 0.73, IN/SVL 0.12, EN/SVL 0.086). Eyes large (EYE/SVL 0.13), prominent, protruding in dorsal and ventral views; pupil horizontal, pigmentation on nictitating membrane restricted to narrow band along dorsal edge. Tympanum small (TYM/SVL 0.04), less than half diameter of eye (TYM/EYE = 0.35), annulus poorly defined, particularly on right side, dorsal ~1/3 obscured by moderately thick, slightly curved supratympanic ridge.

Figure 1. 

Type series of Litoria hastula sp. nov. showing distinctly acuminate snout tip and marked sexual size dimorphism: A dorsal view and B ventral view. Smaller males from top left to bottom right are: MZB Amph.32873 (holotype); SAMA R72334, SAMA R72335, MZB Amph.32874. Much larger female on far right is MZB Amph.32872. Tags on the specimens are field numbers. Scale bar = 10 mm.

Figure 2. 

Details of holotype of Litoria hastula sp. nov. MZB Amph.32873: A lateral view of head; B dorsal view of head; C heels with conical tubercles, D ventral view of hand, and E) ventral view of foot.

Skin of dorsum and dorsal surfaces of limbs smooth except for scattered low, indistinct tubercles (Fig. 1); skin on throat and chest loose, folded and with patches of low granules; abdomen coarsely granular; patch of low, pale buff tubercles extends posteriorly from behind and below eye, under lower edge of tympanum to axilla. Ventral surfaces of forelimbs smooth with scattered tubercles; ventral surfaces of thighs coarsely granular proximally, becoming less so distally, with patch of large pale buff tubercles below vent; tarsus and tibia smooth ventrally. Low, pale buff tubercles form indistinct ridge along outer edge of forearm; heels both with one enlarged, conical and two smaller but distinct tubercles (Fig. 2C); eyelids with two prominent and several smaller conical tubercles dorsally.

Fingers moderately long with prominently expanded terminal discs (3FD/3FP 1.85; 3FD/SVL 0.08) with distinct circum-marginal grooves (Fig. 2D); relative lengths of fingers 3>4>2>1, subarticular tubercles unilobed. Webbing moderate, reaching halfway to subarticular tubercle at base of penultimate phalanx on inside of Finger 4; to tubercle at base of ultipenultimate phalanx before continuing as narrow flange to subarticular tubercle at base of penultimate phalanx on outside of Finger 3; in a narrow basal flange between fingers 2 and 3; and absent between fingers 1 and 2. Hand with indistinct round (0.6 mm diameter), unpigmented outer, and oval (1.5 mm long) inner metacarpal tubercles. Narrow pale-brown nuptial pad on first finger low, granular, extending 2.5 mm along outer edge of Finger 1, wider proximally than distally, distal ~25% angled at nearly right angles across base of thumb. Toes with expanded terminal discs with terminal grooves (Fig. 2E), disc on Toe 4 slightly narrower than on Finger 3 (3FD/4TD 1.14). Webbing between toes reaches to proximal edge of subarticular tubercle at base of penultimate phalanges on both sides of Toe 4, nearly to base of disc on all other toes except Toe 1 where it reaches only to subarticular tubercle at base of penultimate phalanx; relative lengths of toes 4>5>3>2>1. Inner metatarsal tubercle oval, small (1.3 mm long) but prominent; outer metatarsal tubercle absent (Fig. 2E).

Dorsal base colouration mottled varying shades of light brown, patterned with scattered darker-brown maculations across snout, back and limbs, with larger indistinct darker-brown blotches on hindblimbs and posterior portion of torso (Fig. 1A). Dark colouration of eyeball visible through dorsal skin of orbital. Ventral surfaces buff, largely unpatterned except for dense light-brown maculations on outer edges of lower forelimbs and lower hindlimbs (Fig. 1B).

Measurements and proportions of males in the type series show relatively limited variation (Table 1), and all have similar extents of webbing on the hands and feet and conspicuous conical tubercles above the eyes and on the heel. Dorsal base colouration varies from light to medium brown, and the amount and extent of darker-brown maculations and blotching varies from a few blotches on the hindlimbs, to darker patches forming broad bands across the torso and forelimbs (Fig. 1A). Base colouration of venter is always buff, generally without pigmentation (Fig. 1B). When compared against the holotype, paratype SAMA R72335 has tubercles below vent larger and more elongate, lateral margins of tongue less emarginate, and vomerine teeth that are somewhat less conspicuous. Paratype SAMA R72334 has lateral margins of tongue that are smooth and a narrower and straighter supratympanic fold. Paratype MZB Amph.32874 is noticeably darker brown on the dorsum, and the pale tubercles along outer edge of forearm are more conspicuous.

The single female paratype, MZB Amph.32872, is considerably longer than the males, more robust in body form and has a less acute snout tip (Fig. 1A) but does not show obvious differences in ratios or proportions from the males (Table 1). Compared to males, the ventral surfaces of the female paratype show more extensive dark-brown blotches and maculations across the limbs, torso and throat (Fig. 1B).

The following description of colour in life is based on images of three different paratypes (Fig. 3). Dorsal and lateral surfaces of male paratype SAMA R72334 light brown, with variable amounts of medium-brown mottling and small dark-brown spots (Fig. 3A). Female paratype with dorsal pattern comprising extensive areas of dark-green pigmentation across head, torso and limbs (Fig. 3C) and ventral colouration buff with numerous dark-brown maculations that in some areas coalesce to form indistinct spots (Fig. 3D). Hidden surfaces of thighs of SAMA R72335 dark orange with extensive dark-brown spots and flecks (Fig. 3B). Iris predominately light brown, with extensive thin darker-brown reticulations.

Figure 3. 

Colouration of Litoria hastula sp. nov. in life: A lateral view of adult male paratype SAMA R72334; B hidden coloration in thighs of male paratype SAMA R72335; C lateral view of adult female paratype MZB Amph.32872; D ventral view of adult female paratype MZB Amph.32872. All photographs by S.J. Richards.

We analysed two call series produced by SAMA R72335 at an air temperature of 16.4° C. Calls were recorded against a background of loud rushing water. The first series contained seven calls and lasted six seconds, and the second series, separated from the first by 23 seconds, lasted 3.4 seconds and contained five calls (Fig. 4). Inter-call intervals for both series were relatively uniform (0.58–1.03 s, mean 0.78, SD 0.16, n = 10). Dominant frequency was 2530–2730 Hz (mean 2650, SD 67.4, n = 12). Length of individual calls in Series 1 increased substantially from 0.06 s in the first call to 0.35 s in the last call, and calls 5–7 in this series were characterized by increasingly pulsatile structure and subdivision into groups of variably well-defined pulses (Fig. 4). In contrast, call length in Series 2 increased only slightly during the series, from 0.071 s in Call 1 to 0.091 s in Call 5. Excluding calls 5–7 in Series 1, call length for all calls combined was 0.06–0.09 s (mean 0.07, SD 0.01, n = 9).

Figure 4. 

Two complete advertisement call series produced by paratype of Litoria hastula sp. nov. SAMA R72334, top = waveform, bottom = spectrogram. Time between the two call series has been shortened to allow comparisons.

Latin, “little spear’, combining spear “hasta” with the diminutive suffix “-ula” in reference to the elongate and sharply pointed snout of the species.

Litoria hastula sp. nov. is known only from the type locality in the mountains of Papua Province, Indonesia (Fig. 5). The habitat at this locality consisted of very mossy wet mid-montane rainforest at about 2000 m a.s.l (Fig. 6A). The type series was collected on vegetation along a fast-flowing stream in very rugged and steep terrain (Fig. 6B) where males called from leaves at night. The single female paratype is gravid and contains numerous large (2.4–2.6 mm) yellow eggs. Nine species of frog were collected at the type locality, including three other species of torrent-breeding pelodryadid treefrogs (Litoria angiana, L. fuscula and L. cf. pratti), four species of microhylid frogs in the genus Oreophryne and the limnodynastid frog Lechriodus platyceps (Richards et. al. 2000).

Figure 5. 

Known distribution of Litoria hastula sp. nov. in Indonesia (red star) and L. dorsivena in western Papua New Guinea (blue circles).

Figure 6. 

Details of habitat at the type locality for Litoria hastula sp. nov.: A dense and very mossy mid-montane forest, and B small fast-flowing rocky stream. The type series was collected from low vegetation along this stream at night. All photographs by S.J. Richards.

Litoria hastula sp. nov. is currently only known from a single locality. However, large areas of suitable habitat at similar elevations remain in nearby areas. This species also occurs at elevations around which Batrachochytrium dendrobatidis has devastated communities of ecologically similar Litoria in Australia, and is predicted to be very sensitive to this frog pathogen. Given the species’ poorly known distribution and that threats are poorly understood, we recommend that this species be considered as Data Deficient at this stage.

The combination of predominantly brown dorsal colouration, canthus rostralis sharply defined and straight, snout tip pointed in dorsal view, moderate webbing on fingers, and moderate size (adult male SVL 30–35 mm) readily distinguishes Litoria hastula sp. nov. from all other non-torrent-breeding Litoria in New Guinea. It differs from all species we currently ascribe to the genus Nyctimystes (most of which are also torrent-breeders) in these same characters, in having a horizontal (versus vertical) pupil, and in lacking palpebral venation.

In comparison to other torrent-breeding Litoria from New Guinea, Litoria hastula sp. nov. is smaller than L. angiana, L. arfakiana, L. becki, L. macki, L. oenicolen, L. spartacus, L. spinifera and L. wollastoni (max male SVL < 35mm versus >35mm); and further differs from L. arfakiana, L. becki, L. macki, L. oenicolen, L. spinifera and L. wollastoni in having moderately extensive webbing between fingers 2 to 4 (versus absent, or at most a thin basal strip between fingers 3 and 4); from L. angiana in having a snout that is sharply pointed in dorsal and lateral profile (versus slightly pointed in dorsal profile only); from L. macki, L. spartacus and L. spinifera in having a predominately brown dorsum (versus mottled green and brown) and in lacking prominent tubercles along the legs and much of the body (versus spiniform and/or conical tubercles prominent and widespread on body and/or limbs).

Litoria hastula sp. nov. is larger than L. amnicola, L. brongersmai, L. megalops, L. napaea, L. rara and L. rivicola (male SVL >30 mm versus <25 mm); and further differs from L. amnicola, L. brongersmai and L. napaea in having prominent vomerine teeth (versus indistinct and detectable only as slight bumps) and prominent heel tubercles (versus absent); from L. megalops in having webbing on the hand (versus absent), canthus rostralis relatively straight in dorsal profile (versus curved), and in its smaller eye (EYE/SVL 0.13 versus 0.14–0.17); from L. rivicola by it smooth dorsal skin (versus strongly tuberculate); and from L. rara by its sharply pointed snout in dorsal and lateral views (versus rounded). Litoria hastula sp. nov. is slightly larger than L. scabra (male SVL 30.4–31.8 versus 23.6–27.2.1, female SVL 48.9 versus 27.2–30.6 mm), and further differs in having a relatively smooth dorsum (versus covered in distinct tubercles), relatively straight canthus rostralis (versus curved) and pointed snout tip in dorsal and lateral views (versus rounded and truncate).

Litoria hastula sp. nov. differs from five similar-sized (max male SVL between 30–40 mm) torrent-breeding taxa (L. bulmeri, L. fuscula, L. micromembrana, L. modica and L. pratti) in having moderately extensive finger webbing that extends to the third phalanx on fingers 2, 3 and 4 (versus at most basal webbing between fingers 3 and 4) and in having a sharply pointed snout and relatively straight canthus rostralis (versus typically rounded snout and curved canthus rostralis). It further differs from the sympatric L. fuscula in having prominent vomerine teeth (versus indistinct and detectable only as slight bumps), dorsum light brown with dark-brown spots and blotches (versus dark brown with no obvious pattern), and in having small conical tubercles on the heel (versus no tubercles).

Litoria hastula sp. nov. is most similar to Litoria dorsivena, a species known from about 700 km to the east in the Telefomin and upper Strickland River areas of Papua New Guinea (Fig. 5) but differs from that taxon in its slightly larger size (male SVL 30.4–31.8 versus 27.2–29.1, female SVL 48.9 versus 41.0–48 mm); proportionately longer snout (EN/IN ratio 0.71–0.80 versus 0.57–0.65); more angular canthus rostralis and more sharply pointed snout (Fig. 7); dorsal surface of snout concave (versus not obviously concave); dorsum with only sparse tubercles (versus tubercles scattered across the dorsum); and in having at least two moderately prominent conical tubercules on the heel (Fig. 2C) (versus one).

Figure 7. 

Comparison of head profile of a male paratype of Litoria dorsivena SAMA R7907 (left) and holotype of Litoria hastula MZB Amph.32873 (right). Note much more sharply pointed tip of snout on Litoria hastula sp. nov.

Material of Litoria dorsivena collected from localities in the Muller Range (5.657°S, 142.305°E,~1600 m a.s.l.) and Upper Strickland River region (5.288°S, 142.494°E, ~1100 m a.s.l.) (Richards and Dahl 2011) (Fig. 5) extends the range of this species approximately 80 km east of the type locality at Telefomin. The specimen from the Muller Range (SAMA R65133) is a subadult female. In contrast the collections from the Upper Strickland region comprise four adult males, allowing us to present new information on the colouration and variation in adult males of this species. In life (Fig. 8A–C) and preservative (Fig. 8D) these frogs are predominately light brown on the dorsum, with dark-brown spotting and blotching of greatly varying extent. The canthus rostralis is highlighted by either a sharp boundary between dark-brown lateral colouration on the snout and paler-brown dorsal colouration (Fig. 8A) or by a thin yellowish-brown canthal stripe (Fig. 8B). The venter and hidden surfaces of limbs have a buff base colouration, overlain with light orange on the posterior portion of torso and most of the hindlimbs and groin, and sparse to dense patches of light-brown maculations (Fig. 8C). Iris is predominately silvery grey, with light-brown vermiculations and dark-brown blotching across the ventral half.

Figure 8. 

Colour variation and habitats details for male Litoria dorsivena from Tualapa in the upper Strickland River basin, Hela Province, Papua New Guinea: A SAMA R72320; B SAMA R72321; C SAMA R72321 ventral surfaces; D preserved samples (SAMA R72321–4) illustrating variation in dorsal pattern; and E swift-flowing stream habitat in the upper Strickland River region. All photographs by S.J. Richards.

Summary measurements of the new adult male Litoria dorsivena specimens are presented in Table 2 along with newly obtained measurements of the female holotype (SAMA R7901) and five male paratypes (SAMA R7907–7911). Measurements of the newly documented specimens agree closely with those taken from the type series and confirm that males of this species are consistently smaller than males of L. hastula sp. nov. (see above and Table 2). The specimen from the Muller Range (SAMA R65133) is a subadult female with an SVL of 32.9 mm).

The new specimens from Tualapa in the upper Strickland River basin were collected from trees along a large torrential stream with a rocky substrate flowing through relatively undisturbed lower montane forest at an altitude of 1,100 m a.s.l. (Fig. 8E). Although we did not observe reproduction in the field, examination of two adult females in the type series of L. dorsivena revealed that they contain large yellow eggs typical of torrent-breeding Litoria in New Guinea. SAMA R7904 (SVL 45mm) had eggs approximately 2 mm in diameter and SAMA R7903 (SVL 46 mm) had eggs between 1.4–1.6 mm in diameter.

Menzies and Zweifel (1976) reported specimens of L. dorsivena in the paralectotype series of L. arfakiana, which was collected from the Arfak Mountains and stored in the Museo Civico di Storia Naturale (MSNG). One of us (SJR) has examined this material. None of these specimens from far western New Guinea identified as L. dorsivena overlap the size range of either the type series of L. dorsivena, additional material confirmed by us to be L. dorsivena or L. hastula; and the snouts of the MSNG material identified by Menzies and Zweifel are much more bluntly rounded than those of both L. dorsivena and L. hastula sp. nov. On this basis we consider that neither species is represented in this series, and the specific status of this far western material is unresolved.