Platymantis bufonulus, Kraus, Fred & Allison, Allen, 2007

Kraus, Fred & Allison, Allen, 2007, Two new species of Platymantis (Anura: Ranidae) from New Britain, Zootaxa 1485, pp. 13-32 : 24-29

Platymantis bufonulus sp. nov.

Figs. 1 E, F, 2C, F

Holotype. BPBM 22188 (field no. FK 11173), adult male, collected by F. Kraus 2.6 km NNW Marmar, 5.49895ºS, 151.4893ºE, 517 m, East New Britain Province, New Britain Island, Papua New Guinea, 8 March 2005.

Paratypes. Papua New Guinea: New Britain Island: East New Britain Province: 11.3 km NNW Marmar, 5.42868ºS, 151.45654ºE, 850 m, 28 February 2005 ( BPBM 22185–86); 11.8 km NNW Marmar, 5.4255ºS, 151.45337ºE, 800 m, 1 March 2005 ( BPBM 22187, PNGNM 24026).

Diagnosis. A small species of Platymantis (males 15.4–21.4 mm) lacking vocal slits and with expanded discs on toes but not fingers, blunt fingertips no wider than penultimate phalanges, first finger longer than second, head wide (HW/SV = 0.42–0.46), dorsum densely covered with tuberculate warts but lacking elongated ridges ( Fig. 1 E, F), an unpatterned mud-brown dorsum, and a three-note, frequency-modulated advertisement call that sounds like a dog’s squeaky toy.

Comparisons with other species. Platymantis bufonulus is readily distinguished from P. adiastolus , P. browni , P. guppyi , P. macrosceles , P. mamusiorum , P. nakanaiorum , P. neckeri , P. nexipus , P. rhipiphalcus , and P. s c h m i d t i in lacking (vs. having) expanded finger discs; from P. acrochordus in its smaller size and in lacking (vs. having) sharply pointed fingertips; from P. aculeodactylus in having tuberculate skin and in lacking (vs. having) sharply pointed fingertips; from P. m a c ro p s and P. parkeri in having the first finger longer (vs. shorter) than the second; from P. adiastolus , P. boulengeri , P. gilliardi , P. magnus , P. m y e r s i, P. papuensis , P. solomonis , and P. w e b e r i in its much smaller size; and from P. akarithymus , P. m i m i c u s, and P. s u l c a t u s in lacking elongated ridges on the dorsum. The absence of vocal slits and presence of a highly tuberculate, unpatterned mud-brown dorsum is unique among Platymantis from the Bismarck and Solomon islands. Among Platymantis from the Bismarck Archipelago the wide head is equalled only by P. boulengeri , P. n e x i - pus, and P. s u l c a t u s.

Description of holotype. An adult male with left lateral incision and liver removed. Vocal slits absent. Head wide (HW/SV = 0.44), wider than long (HW/HL = 1.04), with oblique loreal region; canthus rostralis rounded, largely straight but slightly concave immediately behind nares when viewed from above; nostrils small, directed laterally, much closer to tip of snout than to eyes; internarial distance slightly less than distance from naris to eye (EN/IN = 1.04); snout truncate when viewed from side, acutely rounded when viewed from above; eyes large (EY/SV = 0.16); eyelid equal to width of the interorbital distance; tympanum distinct, large (TY/SV = 0.12) but smaller than eye (TY/EY = 0.71), with a distinct annulus. Supratympanic fold composed of a series of connected pustules. Dorsal and lateral surfaces extremely rugose; skin granular with dense, irregular array of small, largely rounded warts. Ventral surfaces granular. Fingers unwebbed, relative lengths 3>4=1>2; tips rounded, without discs or terminal grooves, no wider than penultimate phalanges ( Fig. 2 C). Subarticular and metacarpal tubercles extremely pronounced. Toes unwebbed, bearing discs with terminal grooves on toes 2–4; toe 1 slightly flattened but lacking disc and terminal groove; toe 5 rounded and lacking disc and terminal groove; relative lengths 4>3>2>5>1. Toe discs larger than fingertips, barely wider than penultimate phalanges ( Fig. 2 F). Subarticular tubercles well-developed; inner metatarsal tubercle large and oval, outer a small circular cone; entire plantar surface covered by rows of small supernumerary tubercles. Hind legs short (TL/SV = 0.44).

Color in preservative. Dorsum uniformly dark gray with pair of small, obscure black spots present in suprascapular region; tympanum medium brown, contrasting with dorsum. Iris silver, densely stippled with black punctations. Rear of thighs with a suffusion of dark brown or gray over a light brown ground. Venter dirty white on granules with interstices brown, producing a network of white spots across entire surface, with brown increasing in extent under thighs and predominating under shanks and tarsi. Palmar and plantar surfaces dark gray-brown with subarticular, metacarpal, and metatarsal tubercles dirty white.

Measurements (in mm). SV = 21.4, TL = 9.5, HW = 9.5, HL = 9.1, IN = 2.3, EN = 2.4, SN = 3.8, EY = 3.5, TY = 2.5, FD = 0.48, TD = 0.66.

Variation. The range of mensural variation in the samples is minor ( Table 1 ). Degree of dorsal rugosity varies slightly, with one or two specimens having slightly smoother dorsa than the holotype. Color pattern is remarkably uniform but two specimens are slightly lighter in dorsal color than the holotype, being medium brown-gray instead of dark gray. In these specimens, there is little contrast between the dorsal color and that of the tympana and the small black suprascapular spots are more distinct. Three paratypes have some sparse white flecking on the plantar surfaces.

Color in life. In life, BPBM 22185 was noted to have a uniformly dark brown dorsum, venter darkly flecked, and no red in groin or shanks. FK 10919 had the dorsum mud-brown and ventrum dark gray with light gray flecks. BPBM 22188 was noted to have the iris pale gray-green ( Fig. 1 E). BPBM 22187 had a slightly yellow cast to the brown dorsum ( Fig. 1 F).

Call. The call is a quiet, infrequent 3-note squeak. The first note is difficult to discern and the overall impression of the call is similar to that produced by a dog’s squeeze toy, or a short cough or sneeze, sounding vaguely like a nasal “ah ha”. The species calls from under or on top of leaf litter on the forest floor. Males call infrequently and often shift location between calls, making them difficult to locate.

We recorded five calls from two frogs (BPBM 22185 and one uncaptured). These calls averaged 325 ms in duration (range 269–342, Table 5 , Fig. 9 ). Each note of the three-note call was distinctly different. The first note consisted of an unpulsed click that averaged 17 ms in duration (range 16–19 ms, Fig. 10 A). This was followed by a pause ranging from 41–91 ms ( Table 5 ). The second note was about three times longer than the first and averaged 44 ms in duration (range 41–49 ms, Fig. 10 B). This note was unpulsed in the uncaptured individual and had 2–3 pulses in BPBM 22185. In this latter individual the initial pulses were consistently brief (~3 ms) and the last pulse was consistently long (~37–40 ms). This was followed by a pause ranging from 50–121 ms ( Table 5 ). The third note ( Fig. 10 C), which is evenly pulsed, averaged 73 ms in duration in BPBM 22185 (range 70–75) and was 104 ms long in the uncaptured frog ( Fig. 9 C). The pulses were roughly similar in duration (~3 ms). The mean number of pulses for the third note produced by BPBM 22185 was 26 (range 25–27). The call of the uncaptured individual had 43 pulses in the third note.

The frequencies of the three notes varied ( Fig. 9 C). The dominant frequency of the first note averaged 1560 Hz (range 1200–2060). In our recordings, this note was generally, but not always, well tuned. Its frequency was consistently modulated and generally dropped by 500–700 Hz from the beginning to the end of the note.

The second note had a higher pitch and was always well tuned. It had an average dominant frequency of 2910 (range 2840–3010) and was slightly modulated. The frequency generally increased by about 200 Hz around one-third to two-thirds of the way through the note and then slowly declined to the starting frequency by the end of the note.

The third note had a dominant frequency of 1810 Hz (range 1720–1890) and had a trill-like quality due to the pulsing. There was also modest frequency modulation, with an increase in dominant frequency of ~300– 700 Hz from the beginning to the end of the note.

The power spectrum for the overall call generally had two peaks ( Fig. 9 B), one at 1890 Hz, which coincided with the first and third notes, and the other at 3010 Hz, which coincided with the second note.

Ecological notes. This species is an inhabitant of leaf litter in primary and old secondary rainforests, being found by us in both ravine bottoms and on hill slopes. Its elevational range extends from at least 520– 850 m. Platymantis bufonulus is syntopic with Platymantis adiastolus , P. akarithymus , P. boulengeri , P. browni , P. gilliardi , P. m a c ro s c e l e s, P. nexipus , P. s c h m i d t i, and P. s u l c a t u s.

Etymology. The name is a noun in apposition created by appending the masculine diminutive suffix “- ulus”, meaning “somewhat like”, to the generic name Bufo , in reference to this species’ superficial similarity in appearance to a small toad.

Range. Known only from the southern slopes of the Nakanai Mts. in the vicinity of the western end of Jacquinot Bay, New Britain ( Fig. 8 ).

Figures

FIGURE 1. Portraits of (A) Platymantis akarithymus, male, BPBM 22203; (B) Platymantis sulcatus, male, BPBM 22184; (C) P. s ul catu s, male, BPBM 22189; (D) P. sulcatus, male, BPBM 22222; (E) P. bufonulus, male, BPBM 22188; and (F) P. bufonulus, male, BPBM 22187. Photos by F. Kraus.

FIGURE 2. Palmar surface of hand for (A) Platymantis akarithymus (BPBM 22205); (B) holotype of Platymantis sulcatus (BPBM 22192); (C) holotype of Platymantis bufonulus (BPBM 22188); (D – F) plantar surface of foot for same specimens.

FIGURE 8. Map of eastern New Britain showing the collecting localities for Platymantis described in this study. Asterisk indicates the range of collecting localities extending from 2.6 – 11.8 km NNW Marmar.

FIGURE 9. (A) Waveform, (B) power spectrum, and (C) spectrogram of the call of Platymantis bufonulus, BPBM 22185, from 11.3 km NNW Marmar, East New Britain Province, Papua New Guinea; recorded 28 February 2005 at 2030 h, air temperature 22.5 ºC.

FIGURE 10. (A). Waveform of the first note in the call of Platymantis bufonulus BPBM 22185 from 11.3 km NNW Marmar, East New Britain Province, Papua New Guinea; recorded 28 February 2005 at 2030 h, air temperature 22.5 ºC, (B), second note of same call, (C) third note of same call.

Tables

TABLE 5. Call characteristics of Platymantis bufonulus. BPBM 22185 was recorded 28 February 2005 at 11.3 km NNW Marmar, at 2030 h and 22.5 ºC; the uncaptured individual was recorded 2 March 2005 at same location, at 1900 h and 22.6 ºC. Dom. Freq. = dominant frequency

Specimen	Call		Note 1	Internote 1 Note 2
		Duration (s)	Dom. Freq.(Hz)	Duration (s) Duration (s) Dom. Freq. (Hz)
BPBM 22185	A	0.017	2060	0.089 0.044 2840
"	B	0.017	1550	0.091 0.041 3010
"	C	0.016	1550	0.084 0.045 2920
"	D	0.019	1200	0.091 0.041 2920
Uncaptured 1	A	0.017	1460	0.049 0.049 2840