Platymantis latro, Richards, Stephen J., Mack, Andrew L. & Austin, Christopher C., 2007

Richards, Stephen J., Mack, Andrew L. & Austin, Christopher C., 2007, Two new species of Platymantis (Anura: Ceratobatrachidae) from the Admiralty Archipelago, Papua New Guinea, Zootaxa 1639, pp. 41-55 : 47-52

Platymantis latro sp. nov.

( Figs 1 –6)

Holotype: SAMA R62819, Adult male, Chachuau Camp near Tulu 1 Village, Manus Island, Papua New Guinea, (2o01.089' S, 146o47.807' E; 20 m a.s.l.) collected by S.J. Richards on 8 June 2002.

Paratypes: UPNG 10051, SAMA R62820, adult females, same location as holotype, collected by S.J. Richards on 7 June 2002; SAMA R62824– 5 adult females, Tingau Village, 27 km south-west of Lorengau, Manus Island (02 o 05.76S, 147o 06.33E; 296 m a.s.l.), collected by C. Austin on 28 August 2001; SAMA R62826 adult female, Natnewai Camp, Manus Island (2o10.053'S, 147o15.09'E; 150 m a.s.l.) collected by A. Mack on 29 April 2001.; SAMA R62827, adult female, Penchal Village, Rambutyo Island, Manus Province (02o 19.70S, 147o 46.00E; 58 m a.s.l.), collected by C. Austin on 3 September 2001; SAMA R62828– 9 adult males, Salami Village, Los Negros Island, Manus Province (02o 02.46S, 147 o 24.24E; 5 m a.s.l.) collected by C. Austin on 28 August 2001; UPNG 10052–4, SAMA R62821–3, adult males, Lorengau, Manus Island (2o01.870' S, 147o15.593'E; 5–10 m a.s.l.), collected by S. Richards on 4 June 2002.

Diagnosis. A moderately large Platymantis (males 32.0– 38.3 mm, females 52.4–58.3 mm) distinguished from congeners in the Papuan region by a combination of very short legs (TL/SVL 0.46–0.50), small terminal discs on digits, reduced dorsal folds, a dark loreal stripe, and a biphasic advertisement call consisting of an introductory “rattle” followed by a single musical pulse.

Description of holotype. Adult male with vocal slits, calling when collected. Head longer than wide (HL/ HW 1.06), canthus rostralis straight, well defined; loreal region oblique, slightly concave; nares closer to snout than eye, oriented postero-laterally; snout rounded in lateral view, broadly rounded in dorsal view; tympanum moderately large (TYM/EYE 0.64), annulus low but distinct, obscured by curved supratympanic fold dorsally; vomerine teeth in two prominent clumps between and posterior to choanae; tongue oval, deeply bifid posteriorly. Snout minutely roughened; eyelids with numerous low tubercles and one large, rounded tubercle; skin finely granular dorsally and laterally; a series of low, longitudinal folds on dorsum, the most prominent being lyrate and starting behind each eye, converging towards the mid-dorsum at a point above the arms. A long dorso-lateral fold begins lateral to, and overlaps (by 4 mm), the prominent pair of dorsal folds, terminating above groin; additional short folds between orbits, on mid-dorsum, and laterally. Anterior one third of throat granular, remainder of throat and chest smooth, abdomen granular posteriorly. Limbs short (TL/SV 0.48); relative lengths of fingers 3>2>1>4; subarticular tubercles prominent, fingers unwebbed; tips of digits slightly wider than penultimate phalanx, with shallow circum-marginal grooves. Relative length of toes 4>3>5>2>1; subarticular tubercles prominent, heavily pigmented; toes with trace of basal webbing; tips of digits expanded with deep circum-marginal grooves; toe discs larger than finger discs (3FD/4TD 0.73).

Dorsally brown, paler creamy brown laterally with scattered darker brown patches; a narrow, pale brown mid-vertebral line from snout to vent diverges above vent and continues along dorsal surface of thigh and tibia, and posterior edge of tarsus. A broad dark brown loreal stripe extends from tip of snout, through eye and tympanum, terminating at a point above arm insertion. Loreal stripe forms sharp boundary with dorsal snout colouration along canthus rostralis. Patches of dark brown pigment form bars on lower lip, bars across arms and fingers, and faint dark bands across thighs and tibiae. Hidden surfaces of legs heavily and unevenly pigmented with dark brown, anterior of thighs and knees with large brown patches. A triangular patch of dark brown pigment encloses vent. Additional dark brown patches enclose short sections of dorso-lateral folds, including those in inter-orbital space, on mid-dorsum, and laterally. Ventrally cream, with dense brown stippling on throat.

Measurements of the holotype: SV 38.3; TL 18.2 HW 15.5; HL 16.5; EN 4.1; IN 4.1; EYE 5.3; TYM 3.4; 4TD 1.1; 4TP 0.6; 3FD 0.8; 3FP 0.7; 1FD 0.75.

Variation. Variation in measurements and proportions of the paratypes are presented in Table 1 . Males are 32.0– 38.3 mm, females 52.4–58.3 mm SV. Dorsal colouration is rather uniform, all frogs being a shade of pale to dark brown. In several paratypes the intensity of dorsal and lateral pigmentation is variable, producing a mottled pattern. The dark loreal stripe and extremely short limbs are consistent features of the paratype series. In some specimens the narrow dorsal folds are conspicuously paler than the background colour, but in others the dorsal colouration is uniform. Pale spots may be present along the upper and lower lips, and the intensity of pigmentation on the throat is variable. Two paratypes have the thin, pale mid-vertebral stripe exhibited by the holotype.

Advertisement call. The vocalization of P. latro sp. nov. is normally a single biphasic note lasting about 0.5 s and normally consisting of a series of 10–20 short, irregularly spaced pulses followed by one long, musical pulse. Inter-pulse interval of short pulses varies from 0.004– 0.071 s. ‘Short’ pulses last 0.0027– 0.023 s and ‘long’ pulses are 0.037– 0.115 s ( Table 3 ). Energy in the short pulses is broadly distributed but energy in long pulses is concentrated in a narrow frequency band (Fig. 6). Notes are produced at approximately two-second intervals and are uttered singly or, occasionally, in couplets or triplets. The call structure of P. l a t ro is similar to that of other species of the Platymantis papuensis ‘group’ in the New Guinea region in that notes have an initial pulsed ‘segment’ followed by an unpulsed terminal ‘segment’ (e.g. Zweifel 1969). However the calls (= notes) differ dramatically from those of all morphologically similar species in the region ( P. adiastolus , P. admiraltiensis sp. nov., P. cryptotis , P. papuensis , P. s c h m i d t i and P. w e b e r i) in that they are presented individually rather than in series, and individual notes are more than twice the length of notes produced by these species (0.5 s vs <0.2 s; Zweifel 1969, Menzies 1982, Günther 1999, Brown et al. 2006, Richards unpublished data). As a result the acoustic impression is of a harsh rattle followed by a musical ‘ping’, quite unlike the ‘yapping’ or ‘rattling’ sound produced by the other species. Advertisement call parameters are presented in Table 3 and a call is illustrated and compared with the call of P. admiraltiensis and P. papuensis in Figure 6.

FIGURE 6. Advertisement calls of A. Platymantis admiraltiensis sp. nov. holotype (SAMA R62799), B. P. papuensis (recorded on Biak Island, the type locality for this species), and C. P. l a t ro sp nov. holotype (SAMA R62819) recorded at air temperatures of 28, 25.2 and 27o C respectively.

Comparison with other species. The size, general habitus, small finger and toe discs, dorsal folds, and biphasic note structure of the advertisement call of P. latro sp. nov. suggest affinities with the informal P. papuensis ‘complex’. It differs from all other species in this group by its conspicuous dark loreal mask, extremely short legs (TL/SV = 0.5) and advertisement call structure ( Table 3 ). Platymantis adiastolus , P. admiraltiensis sp. nov., P. c r y p t o t i s, P. papuensis , P. schmidti , and P. w e b e r i have advertisement calls consisting of a repetitive train of short notes consisting, in full sequences, of many notes ( Zweifel 1969, Menzies 1982, Günther 1999, Brown et al. 2006) and having individual notes lasting less than 0.2 s. These calls contrast strikingly with the single-note calls of P. l a t ro sp. nov. that last for 0.5 s (see ‘Advertisement call’ above for a more detailed comparison of vocalisations). Two other Platymantis in the New Guinea region, P. boulengeri and P. rhipiphalcus , exhibit a conspicuously darkened loreal region. P. boulengeri is a much larger species (to ~ 70 mm) with a very broad head (HW/SV 0.44–0.49 vs 0.36–0.40 in P. l a t ro) and it and the smaller P. rhipiphalcus (females to 41.5 mm) can be distinguished from P. latro by having a fan-shaped series of dorsal skin folds (absent in P. latro ).

Etymology: A noun in apposition from the Latin meaning ‘robber’, referring to the dark loreal face-mask of this species.

Distribution. Presently known from Manus, Los Negros, Rambutyo and Pak Islands in the Admiralty Archipelago, Papua New Guinea ( Figure 7 ).

Natural history. Males called from exposed or semi-exposed positions in forest litter, or from the base of grass tussocks in disturbed garden habitats, at night after heavy rain. No frogs were observed calling from elevated sites. This species occurred in micro-sympatry with P. admiraltiensis sp. nov., and calling males of the two species were frequently spaced less than 50 cm apart. Like that species, P. l a t ro sp. nov. persists in large numbers in heavily degraded habitats, including grassy paddocks in the centre of Lorengau Town. Given its tolerance of habitat degradation and its wide distribution on Manus and surrounding islands we recommend that the conservation status of this species be listed as ‘Least Concern’ using the criteria of the Global Amphibian Assessment.

Figures

FIGURE 1. Lateral view of heads of A. Platymantis admiraltiensis sp. nov. holotype (SAMA R 62799) and B. P. latro sp. nov. holotype (SAMA R 62819) showing distinct lateral band of P. latro sp. nov. Scale = 10 mm.

FIGURE 7. Map of Manus and surrounding islands showing locations discussed in the text.