Platymantis sulcatus, 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 : 17-24

Platymantis sulcatus sp. nov.

Figs. 1 B–D, 2B, E

Holotype. BPBM 22192 (field no. FK 10941), adult male, collected by F. Kraus 11.3 km NNW Marmar, 5.42868ºS, 151.45654ºE, 850 m, East New Britain Province, New Britain Island, Papua New Guinea, 2 March 2005.

Paratypes. Papua New Guinea: New Britain Island: East New Britain Province: same data as holotype but 28 February 2005 ( BPBM 22184); 9.0 km NNW Marmar, 5.4473ºS, 151.46307ºE, 865 m, 23 February 2005 ( BPBM 22189), 28 February 2005 ( PNGNM 24025); 2.6 km NNW Marmar, 5.49895ºS, 151.4893ºE, 517 m, 9 March 2005 ( BPBM 22222), 10 March 2005 ( BPBM 22193).

Diagnosis. A small species of Platymantis (males to 21.6 mm and 0.8 g) with relatively short snout (EN/ IN = 0.81–0.91); small eye (EY/SN = 0.82–0.89); long, parallel dorsal skin ridges ( Fig. 1 C, D); fingertips only slightly flattened and barely expanded ( Fig. 2 B); first finger slightly longer than the second; dorsal surface of snout smooth, without warts; abdomen with reticulate pattern in which the granules are largely white and their interstices brown; rear of thighs with largely clear straw (orange in life) patch distally that may have a few brown flecks; tubercles of plantar and palmar surfaces lighter than surrounding skin; and call consisting of

Comparisons with other species. Platymantis sulcatus may be easily distinguished from most other Platymantis of the Bismarck and Solomon Islands. From P. adiastolus , P. browni , P. guppyi , P. m a c ro s c e l e s, P. mamusiorum , P. nakanaiorum , P. neckeri , P. n e x i p u s, P. rhipiphalcus , and P. schmidti the new species differs in having discs of the fingers poorly developed and scarcely wider than the penultimate phalanges (vs. considerably wider than penultimate phalanges); from P. acrochordus in its smaller size and in lacking (vs. having) sharply pointed fingertips; from P. aculeodactylus in having dorsal ridges and in lacking (vs. having) sharply pointed fingertips; from P. macrops and P. p a r k e r i in having the first finger slightly longer (vs. shorter) than the second; from P. boulengeri , P. gilliardi , P. magnus , P. myersi , P. papuensis , P. solomonis , and P. w e b e r i by its much smaller adult size (males to 34 mm in P. gilliardi , 64 mm in P. magnus , 69 mm in P. m y e r s i, 44 mm in P. papuensis , 49 mm in P. solomonis , 40 mm in P. w e b e r i; males unknown in P. boulengeri but females to 80 mm). Platymantis sulcatus is most similar in size and general appearance to P. mimicus and P. akarithymus , especially to the latter. From P. mimicus , P. sulcatus may be distinguished by its smaller size (males to 40 mm SVL in P. mimicus ), first finger slightly longer than the second (vs. distinctly longer in P. mimicus ), relatively smaller eye (EY/SN = 1.04–1.11 in P. m i m i c u s), shorter snout (EN/IN = 0.97 in P. mimicus ), and long (vs. short) dorsal ridges

From Platymantis akarithymus , P. sulcatus differs in its smaller adult size (males to 25.4 mm and 1.7 g in P. akarithymus ), shorter snout (EN/IN = 0.89–1.08 in P. akarithymus ), long dorsal ridges (short in P. akarithymus ), absence of warts on dorsal surface of snout (prominent in P. akarithymus ), abdomen with reticulate pattern in which the granules are largely white and their interstices brown (straw with scattered brown punctations in P. akarithymus ), rear of thighs with light-colored patch distally that is orange in life (area heavily and uniformly dusted with brown in P. akarithymus ), tubercles on feet and hands lighter color than surrounding skin (same color in P. akarithymus ), call consisting of a series of 3–5 rapid, mostly unpulsed clicks produced in groups of up to seven calls (vs. a call consisting of a single, nasal note produced at irregular intervals in groups of up to 31 calls in P. akarithymus ), and behavior of calling during dusk and just after dark (vs. diurnally in P. akarithymus ).

Description of holotype. An adult male with left lateral incision and liver removed. Vocal slits present. Head wide (HW/SV = 0.42), wider than long (HW/HL = 1.03), with oblique loreal region; canthus rostralis rounded, concave when viewed from above; nostrils small, directed laterally, much closer to tip of snout than to eyes; internarial distance wider than distance from naris to eye (EN/IN = 0.87); snout slightly rounded when viewed from side, acutely rounded when viewed from above; eyes large (EY/SV = 0.15); eyelid approximately equal to width of interorbital distance; tympanum distinct, fairly large (TY/SV = 0.089) but smaller than eye (TY/EY = 0.61), with a distinct annulus. Supratympanic fold short, not well-differentiated from pustules immediately behind. Dorsal surfaces granular with series of long ridges; first pair of these arrayed immediately to either side of vertebral column, extending from anterior plane of eyes to mid-body; second pair lateral to this, extending from behind center of eyes to level of hindlimb insertion, most prominent of series; third pair lateral to these, again prominent, dorsolateral, extending from lateral margin of eyes to level of hindlimb insertion; a weakly raised ridge (right side) or series of ridges (left side) between these last two pairs of prominent ridges. Sides with small pustules. Ventral surfaces generally smooth but granular on abdomen. Fingers unwebbed, relative lengths 3>1>2>4; tips flattened but bearing terminal grooves only on third finger, only slightly wider than penultimate phalanges ( Fig. 2 B). Subarticular and metacarpal tubercles well-developed. Toes unwebbed, bearing flattened discs with terminal grooves, except on first toe, which is slightly flattened but lacks terminal groove; relative lengths 4>3>5>2>1. Toe discs larger than finger tips but only slightly wider than penultimate phalanges ( Fig. 2 E). Subarticular tubercles well-developed; inner metatarsal tubercle small and oval, outer a raised circular cone; entire plantar surface covered by rows of small supernumerary tubercles. Hind legs moderately long (TL/SV = 0.49).

Color in preservative. Dorsal ground color medium brown with narrow tan mid-dorsal stripe extending from tip of snout to above vent. Second pair of long dorsal ridges outlined in black for most of length; dorsolateral pair slightly lighter brown than remainder of dorsum. Subtending each dorsolateral ridge posteriorly is an elongate black blotch. A series of indefinite black blotches or mottling extends posteriorly from behind eye to mid-body. Face with large brown blotches along maxilla and lighter blotch anterior to eye; snout darker; another series of brown blotches along mandibular margin. Tympanum blotched with dark brown on upper third and with annulus largely margined in dark brown. Iris silver with minute black punctations. Chin, throat, and chest with dirty white ground color heavily clouded with dark brown. Each granule of abdomen dirty white, with interstices margined in brown, imparting impression of series of dirty white spots. Overall appearance of venter is two-toned, with chin, throat, and chest appearing darker than the abdomen. Front, back, and lower surfaces of thighs with pale orange cast, densely flecked with brown below but with sparser brown flecking or punctations anteriorly and posteriorly. Dorsal surfaces of thighs and shanks with three irregular dark brown bands on a lighter brown ground color. Palmar and plantar surfaces brown; subarticular, metacarpal, and metatarsal tubercles dirty white. Each small plantar tubercle dirty white, giving plantar surfaces a speckled appearance.

Measurements (in mm). SV = 19.1, TL = 9.4, HW = 8.0, HL = 7.8, IN = 2.3, EN = 2.0, SN = 3.4, EY = 2.8, TY = 1.7, FD = 0.53, TD = 0.69.

Variation. The range of mensural variation in the samples is not large ( Table 1 ). The most significant morphological variation is in the development of the dorsal ridges and in color pattern. Two of the paratypes (BPBM 22222, FK 10885) have elongate, parallel dorsal ridges similar to the holotype but these are narrower and not as elevated, also being four on each side. Two others (BPBM 22189, 22193) also have series of elongate ridges but these are not so uniformly or extensively developed, with several of the rows being reduced to series of shorter ridges or pustules. The last specimen (BPBM 22184) has the ridges least developed of all, with the dorsolateral pair fairly well developed but with the dorsal pairs reduced to an irregular scattering of low, elongate pustules.

Two paratypes (BPBM 22193, FK 10885) are colored dorsally and laterally largely as the holotype except that there is less or no black margining of the dorsal ridges. Two specimens (BPBM 22184, 22222) have the mid-dorsal region distinctly lighter than the lateral regions, giving the appearance of a broad dorsal stripe ( Fig. 1 B, D). In one of these specimens (BPBM 22222) the dorsum is medium brown; in the other dirty white with an elongate, vertebral smudge of black. In both specimens, the two-toned appearance results from the increased melanization of the lateral surfaces and its heightened contrast with the dorsal coloration. The final specimen (BPBM 22189) is olive green mottled dorsally and laterally with dark brown ( Fig. 1 C). All paratypes agree with the holotype in having the chin, throat, and chest darker than the abdomen and in having the abdominal coloration consisting of a network of white granules; the chin and throat of BPBM 22222 are darker than in the remaining specimens. The orange flush on the thighs is present in all specimens but is most densely suffused with brown in FK 10885. All specimens have the speckled appearance to the plantar surfaces, but the contrast is least obvious in BPBM 22222.

Color in life. In life, BPBM 22189 was noted to have a dorsum mottled brown and olive green with a short tan line extending posteroventrally from the corner of mouth ( Fig. 1 C); light gray and tan iris; orangered groin, front of thighs, and rear of thighs; gray venter heavily flecked with light gray and with charcoal gray on chin. Specimen BPBM 22184 ( Fig. 1 B) was noted to have: “Broad orange-brown dorsal band, darker vertebrally, narrowly bordered below by black. Sides dark purple-brown. Iris bright medium brown. Venter light gray, dusted with darker gray between granules of abdomen, flecked with dark gray on chin and throat. Bright orange-red patch in groin and on rear of shanks. Rear of thighs mottled light and dark brown.”

Call. Platymantis sulcatus exhibited a very narrow window of calling activity. Animals began calling just before dark and quit calling soon after dark; total calling activity was rarely more than one hour per night. Males could also be heard calling occasionally for a few minutes just before dawn. Frogs called perched on small fallen limbs and were never more than a few cm above the forest floor; one animal was found calling under leaf litter.

We recorded 45 complete calls from two individuals, BPBM 22189 and 22192 ( Figs. 5–7 ; Tables 3 , 4 ). All but six of the calls consisted of a train of 2–6 similar, unpulsed notes. The exceptions, all from BPBM 22192, consisted of a single, unpulsed call note. The call notes from both individuals were remarkably constant, with a mean duration of 13 ms (range 9–23; n = 169) ( Fig. 6 ; Table 3 ). The overall acoustic impression of the call was that of rapid plinking with a small hammer.

The calls of BPBM 22189 were organized into three groups of six or seven calls each ( Fig. 7 A, B). In the three complete call groups that we recorded from BPBM 22189, the first call in each group invariably consisted of three notes. The second call consisted of three notes in one call group and included four notes in the other two call groups. The third call consisted of four notes in all three call groups. All subsequent calls included five notes (e.g., Fig. 5 ). The first call in the group was invariably the fastest, with a mean repetition rate of 10.3 notes/s. The second three-note call in the first group had a repetition rate of 9.7 notes/s. The remaining 16 four- and five-note calls had a mean repetition rate of 8.1 notes/s (range 7.4–9.7). The mean duration for three-note calls was 0.210 (range 0.202-0.219). This increased to 0.359 for the four-note calls (range 0.355–0.365) and to 0.527 for five-note calls (range 0.426–0.526).

The mean interval between calls in a group for BPBM 22189 was 2.3 s. This interval was greatest between the first and second calls with a mean of 3.7 s (range 2.1 – 5.3; Fig. 7 B). Interval length then progressively declined through the fourth or fifth call and stabilized at ~1.7– 1.8 s. The repetition rates of calls in a group averaged 0.38 calls/s (range 0.33 – 0.43; n = 3).

The call sequence for BPBM 22192 was somewhat different ( Fig. 7 C). This individual called 25 times over a 155-second recording period at intervals ranging from 0.2 to 16.6 s. Twenty-two of the calls were issued in seven groups. One of the call groups had seven calls, one had five, and the rest had two or three calls. The three calls that were not in a group were issued at 10- or 11-second intervals over a 30-second sequence. Each of these latter three calls included three notes. The calls that included two or more notes (n = 39) were delivered at a mean repetition rate of 9.8 notes/s (range 7.4 – 14.1).

The cadence of calls within a calling group for BPBM 22192 was similar to that of BPBM 22189 but direct comparison was difficult because most call groups included only two or three calls. In the call group from BPBM 22192 having seven calls (at the end of the sequence in Fig. 7 C), the interval between the first and second calls (2.0 sec) was the longest interval in the group, as in the call groups of BPBM 22189. However, the intervals between the remaining calls did not progressively decline (as in BPBM 22189) but ranged from 1.2 to 1.6 s throughout the call. In addition, the number of notes reached a peak in the middle rather than the end of the call sequence. The first call in the group had four notes. This increased to five in the next two calls and then to six in the fourth call. It declined to five notes and then to four notes before increasing again to five in the final call.

The mean dominant frequency across notes for the calls of BPBM 22189 was 3320 Hz (range of note means 3210–3410, Table 4 ). The call notes had significant harmonic development with subsidiary peaks at ~1800 and 4400 Hz ( Fig. 5 B). The mean dominant frequency across notes for BPBM 22192 was somewhat higher, 3490 Hz (range 3010–3700, Table 4 ). The dominant frequency in both individuals tended to increase over the course of each call ( Table 4 ). This increase was roughly 150 Hz in BPBM 22189 and more than twice that in BPBM 22192.

The interval between call groups ranged from 36 to 46 s for BPBM 22189 and from 13 to 37 s for BPBM 22192.

The call of Platymantis sulcatus is more complex than that of the morphologically similar P. akarithymus but has the same basic elements. It differs from P. akarithymus in having fewer calls per call group (1–7 calls vs. 10–31 in P. akarithymus ), in having a greater number of notes per call (1–6 notes vs. 1 in P. akarithymus ), a shorter call note (13 ms vs. ~ 53 in P. akarithymus ), and notes that are mostly unpulsed (vs. pulsed in P. akarithymus ).

Ecological notes. Platymantis sulcatus is an inhabitant of leaf-litter in primary and old secondary rainforests from at least 520–865 m elevation. The species 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. n e x i p u s, P. s c h m i d t i, and the new species whose description follows.

Etymology. The masculine Latin adjective “ sulcatus ” means “furrowed” and refers to the appearance produced by the series of long, parallel dorsal ridges in members of this species.

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 5. (A) Waveform, (B) power spectrum, and (C) spectrogram of the call of Platymantis sulcatus, BPBM 22189, from 9.0 km NNW Marmar, East New Britain Province, Papua New Guinea; recorded 23 Feb 2005 at 2145 h, air temperature 21.2 ºC.

FIGURE 6. Waveform of the fourth call note from Fig. 5 A.

FIGURE 7. (A) Complete waveform of the recorded call sequence for Platymantis sulcatus, BPBM 22189, from 9.0 km NNW Marmar, East New Britain Province, Papua New Guinea; recorded 23 Feb 2005 at 2145 h, air temperature 21.2 ºC, (B), waveform of the last recorded call group of BPBM 22189, (C) complete waveform of the recorded call sequence of BPBM 22192 from 11.3 km NNW Marmar, East New Britain Province, Papua New Guinea; recorded 0 2 March 2005 at 1835 h, air temperature 22.6 ºC.

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.

Tables

TABLE 3. Duration of call notes and internotes of Platymantis sulcatus, in s, analyzed sequentially. BPBM 22189 was recorded 23 February 2005 at 9.0 km NNW Marmar, at 2145 h and 21.2 ºC; BPBM 22192 was recorded 2 March 2005 at 11.3 km NNW Marmar, at 1835 h and 22.6 ºC.

					Call Note/Internote Number
Specimen		1 Note	Internote	2 Note	3 4 Internote Note Internote Note	Internote	5 Note	Internote	6 Note
BPBM 22189	Mean Min Max	0.012 0.010 0.014	0.105 0.075 0.133	0.013 0.011 0.014	0.103 0.013 0.108 0.014 0.092 0.011 0.011 0.013 0.113 0.014 0.124 0.015	0.129 0.121 0.146	0.014 0.013 0.015	- - -	- - -
	n	20	20	20	20 20 16 16	11	11	-	-
BPBM 22192	Mean Min	0.012 0.010	0.093 0.074	0.012 0.009	0.091 0.013 0.095 0.014 0.075 0.010 0.080 0.011	0.106 0.098	0.014 0.014	0.126 0.126	0.015 0.015
	Max	0.023	0.132	0.015	0.132 0.014 0.111 0.015	0.121	0.015	0.126	0.015
	n	25	18	19	17 18 13 13	6	6	1	1

TABLE 4. Dominant frequency (Hz) of call notes for Platymantis sulcatus. Collecting data as for Table 3.

			Call Note No.
Specimen	1	2	3 4	5	6
BPBM 22189	Mean 3210 Min 3010	3330 3100	3360 3380 3350 3350	3360 3350	- -
	Max 3350	3440	3530 3530	3440	-
BPBM 22192	n 20 Mean 3340	20 3580	20 16 3650 3690	11 3590	- 3700
	Min 3010	3100	3100 3530	3010	3700
	Max 3700 n 25	3780 19	3780 3780 18 13	3700 6	3700 1