Paedophryne verrucosa Kraus,

Kraus, Fred, 2011, At the lower size limit for tetrapods, two new species of the miniaturized frog genus Paedophryne (Anura, Microhylidae), ZooKeys 154, pp. 71-88 : 76-81

Paedophryne verrucosa Kraus, sp. n. Figs 2C, D4

Holotype.

BPBM 37747 (field tag FK 15516), alcohol specimen, adult male, collected by F. Kraus and local villagers at Sota, SE slope Mt. Dayman, 9.7580°S, 149.1822°E, 1860 m, Milne Bay Province, Papua New Guinea, 27 March 2011.

Paratype.

(n = 11). BPBM 37745-46, same data as holotype; BPBM 37743, same data as holotype, except female collected 23 March 2011; BPBM 37744, same data as holotype, except collected 26 March 2011; BPBM 37748-50, PNGNM 24121-22, same data as holotype, except collected 28 March 2011; BPBM 37751-52, same data as holotype, except females collected 29 March 2011.

Diagnosis.

A minute microhylid (male SV = 8.1-8.9 mm, female SV = 8.8-9.3 mm) with highly pustulose dorsal skin and plantar surfaces; a relatively short leg (TL/SV = 0.37-0.42); short and broad snout (EN/SV = 0.067-0.080, IN/SV = 0.108-0.123, EN/IN = 0.60-0.70); wide head (HW/SV = 0.38-0.44), fifth toe distinctly shorter than second; relatively large discs on third and fourth toes (4thT/SV = 0.044-0.055); and a light-brown dorsum and sides flecked with black.

Comparisons with other species.

Paedophryne verrucosa differs from all other members of the genus in its warty plantar surfaces and in having the fifth toe distinctly shorter than the second; it further differs from Paedophryne kathismaphlox in its smaller size (male SV = 8.1-8.9 mm in Paedophryne verrucosa , 10.1 mm in Paedophryne kathismaphlox ; female SV = 8.8-9.3 mm in Paedophryne verrucosa , 10.4-10.9 mm in Paedophryne kathismaphlox ), more heavily warty dorsal skin, shorter snout (IN/SV = 0.108-0.123 in Paedophryne verrucosa , 0.087-0.099 in Paedophryne kathismaphlox ; EN/SV = 0.067-0.080 in Paedophryne verrucosa , 0.78-0.80 in Paedophryne kathismaphlox ), larger discs on third and fourth toes (4thT/SV = 0.044-0.055 in Paedophryne ver rucosa , 0.032-0.037 in Paedophryne kathismaphlox ), in having the lateral surfaces the same color as the dorsum (lateral surfaces sharply darker than dorsum and punctated with pale gray in Paedophryne kathismaphlox ), and in generally lacking a colored patch below anus (tan in one specimen of Paedophryne verrucosa , burnt-orange patch below anus in all Paedophryne kathismaphlox ). The new species further differs from Paedophryne oyatabu in its smaller size (female SV = 8.8-9.3 mm in Paedophryne verrucosa , 11.3 mm in Paedophryne oyatabu ), heavily warty dorsal skin (smooth in Paedophryne oyatabu ), shorter snout (EN/SV = 0.067-0.080 in Paedophryne verrucosa , 0.062 in Paedophryne oyatabu , IN/SV = 0.108-0.123 in Paedophryne verrucosa , 0.097 in Paedophryne oyatabu ), larger discs on third and fourth toes (4thT/SV = 0.044-0.055 in Paedophryne verrucosa , 0.031 in Paedophryne oyatabu ), dorsum brown with black flecks (brown with two darker scapular chevrons in Paedophryne oyatabu ); it further differs from Paedophryne dekot in its heavily warty dorsal skin (smooth in Paedophryne dekot ), shorter leg (TL/SV = 0.37-0.42 in Paedophryne verrucosa , 0.45-0.46 in Paedophryne dekot ), wider head (HW/SV = 0.38-0.44 in Paedophryne verrucosa , 0.37-0.38 in Paedophryne dekot ), and light-brown dorsum flecked with black (dorsum brown or red-brown with dorsolateral black triangular blotches in Paedophryne dekot ).

Description of holotype.

An adult male with vocal slits. Head wide (HW/SV = 0.43, Fig. 3A), with steeply oblique loreal region; canthus rostralis rounded, straight when viewed from above; nostrils directed anterolaterally, closer to tip of snout than to eyes; internarial distance much larger than distance from naris to eye (EN/IN = 0.60, IN/SV = 0.112, EN/SV = 0.067); snout somewhat pointed, sharply rounded when viewed from the side or from above (Fig. 4A, C); eyes moderately large (EY/SV = 0.13; EY/SN = 1.0, Fig. 4C), pupil horizontal; eyelid more than half width of interorbital distance; tympanum indistinct and small (TY/SV = 0.056), visible only when skin dries slightly, hidden posterodorsally. Skin granular and highly pustulose dorsally, granular to slightly pustulose ventrally; supratympanic fold absent. Fingers unwebbed, flattened; F1 very reduced in size; relative lengths 3>2=4>1 (Fig. 4D); discs absent. Subarticular and metacarpal tubercles absent; plantar surfaces granular to slightly pustulose. Toes unwebbed; T3 and T4 with flattened discs and terminal grooves; disc of T4 not wider than penultimate phalanx. Second and fifth toes reduced in size, with round tip and no disc; T1 a vestigial nub; relative lengths of toes 4>3>2>5>1 (Fig. 4E). Subarticular and metatarsal tubercles absent, but plantar surfaces heavily pustulose. Hind legs rather short (TL/SV = 0.38, Fig. 4A). Tongue elongate, straplike, anterior one-third attached to floor of mouth.

In preservative, uniform dark brown above, lighter on sides, where many granules are light brown. Face dark brown with few pale-brown spots. Ventral surfaces and front and rear of thighs pale brown heavily flecked with dark brown, the latter most heavily concentrated on chin and throat. Iris black.

Measurements (in mm).-SV = 8.9, TL = 3.4, HW = 3.8, HL = 2.9, IN = 1.0, EN = 0.6, SN = 1.2, EY = 1.2, TY = 0.5, 4th T = 0.49.

Variation.

Females attain larger size and have smaller tympana than males (Table 1). Mensural variation in the sample is slight, and important differences are not obvious between the sexes.

In preservative, most specimens are somewhat lighter than the holotype, varying to medium brown dorsally, in which case a few small black blotches are evident. Three specimens directly fixed in alcohol each exhibit a pale gray-brown dorsum with a pair of black scapular blotches and a pair of black lumbar blotches, with a smaller mid-dorsal black blotch between the lumbar blotches. This pattern is evident in life in some specimens (Fig. 2D). Ventral coloration can be lighter in overall tone than seen in the holotype due to presence of fewer dark-brown flecks. Both tan and black spots may also occur sparsely in the ventral pattern. Three specimens have a pale-gray patch below the anus.

Color in life.

Field notes for paratype BPBM 37743 (Fig. 2C): "Brown with black flecks; warty. Face and venter black with light-gray flecks, posterior of abdomen brown. Rear of thighs brown, each with one large black spot." For paratype BPBM 37745 (Fig. 2D): "Dark brown with black markings, some tan flecks posteriorly and on legs, tan patch around anus. Venter charcoal gray and light gray." BPBM 37746 was light brown above with two black scapular triangles and no light anal patch. Its chin, throat, and chest were charcoal gray and its abdomen brown with light-gray punctations and dark-gray flecks. BPBM 37747 was dark brown above and also lacked a light-colored anal patch. Its venter was charcoal gray with light-gray flecks. BPBM 37748 was dorsally as for BPBM 37745 and ventrally as for BPBM 37746 and also lacked an anal patch. PNGNM 24121 was brown and black above and gray flecked with light brown below; PNGNM 24122 tan with black flecks above and gray with light-brown flecks below; BPBM 37749 also brown and black above and light and dark gray below.

Call.

The advertisement call of the holotype was recorded. Each call is a single drawn-out pulsed note given in a long train, with call trains varying from 67-102 s in the two series recorded by me. To the human ear, each call sounds like a quick drag of a finger over a comb. Calls are brief, with average duration varying from 1.210-1.652 s between animals and ranging from 0.712-1.942 s overall (Table 2, Fig. 5). Calls are given at a rate of 0.19-0.46 notes/s, with faster rates at higher temperatures (Table 2). Intervals between calls were longer than the calls themselves and were shorter at higher temperatures, averaging 1.093 s (range 0.897-3.876 s) at 14.9°C, and longer at colder temperatures, averaging 3.694 s (range 1.824-11.655 s) at 19.4°C (Table 2). Calls are highly pulsed, with 15-36 pulses/call, each pulse lasting 0.032-0.066 s (Table 2), and they increase and decrease in maximum amplitude gradually, with maximum amplitude sustained over most of the call duration (Fig. 5A). The power spectrum was rather broad, with a dominant frequency varying from 6510-7890 Hz (Fig. 5B).

Etymology.

The species name “verrucosa” is a Latin adjective meaning "full of warts".

Range.

Known only from the southeastern slope of Mt. Suckling near the saddle where it joins Mt. Dayman to the southeast, Milne Bay Province, Papua New Guinea.

Ecological notes.

Paedophryne verrucosa inhabits leaf litter on the floor of primary mid-montane rainforest, seeming to prefer the lower slopes of steep hillsides. Canopy at the type locality was approximately 35 m high; understory was dense, with fallen trees, Nastus , and melastomes common. This mid-montane forest begins at approximately 1200 m elevation, so Paedophryne verrucosa seems likely to inhabit forest down to that elevation.

This species typically called at dusk, even continuing through the deafening period of cicada calling at approximately 1800-1830 h, but calling ceased soon after dark. It also frequently called before dawn, and occasional individuals were heard to call briefly in mid-morning. It was not heard by me to call on days lacking rain.

All three females contained two enlarged, well-yolked, cream-colored eggs and approximately a dozen small white oocytes.