Cophixalus amabilis, Kraus, Fred, 2012

Kraus, Fred, 2012, Papuan frogs of the genus Cophixalus (Anura: Microhylidae): new synonyms, new species, and a dichotomous key, Zootaxa 3559, pp. 1-36 : 27-30

Cophixalus amabilis , sp. nov.

Fig. 8 E, F, 16

Holotype. BPBM 37730 (field tag FK 14787), collected by F. Kraus along Upper Muniai Stream, below Bomagai Camp, Woodlark Island, 9.1216° S, 152.7486° E, 67 m, Milne Bay Province, Papua New Guinea, 13 October 2010.

Paratype (n = 8). BPBM 37740, same data as holotype, except collected 19 October 2010; BPBM 40010–13, same data as holotype, except collected 13 October 2011; BPBM 40014–15, PNGNM 24142, same data as holotype, except collected 17 October 2011.

Diagnosis. A species characterized by its unique combination of small size (male SV = 13.6–14.3 mm, female SV = 14.8–16.1 mm); tympanum hidden; finger discs smaller than toe discs (3rdF/4thT = 0.65–0.77); first finger of reduced size, but still elongate and functional, lacking a flattened disc and terminal groove; leg short (TL/SV = 0.42–0.48); snout short and broad (EN/IN = 0.79–0.87), shorter than or equal to eye diameter (SN/EY = 0.86–1.00); skin smooth; face and side black with pale blue flecks and spots; and forearms typically orange.

Comparisons with other species. Cophixalus amabilis differs from all other Papuan members of the genus except C. daymani , C. pictus sp. nov., and some C. kethuk in having the snout shorter than the eye, and it differs from all Papuan Cophixalus except C. cryptotympanum and C. pictus in having the tympanum hidden. It differs from each of these species except C. kethuk in having the finger discs smaller than the toe discs (3rdF/4thT = 1.2–1.4 in C. cryptotympanum , 1.3–2.0 in C. daymani , 1.3 in C. pictus ). Cophixalus kethuk differs in having basal webbing between the toes, which is lacking in C. amabilis . The color pattern of C. amabilis —in particular its black face and sides spotted with pale blue and its frequently orange forearms—is unique within the genus.

Description of holotype. An adult female with right-lateral incision. Head of modest width (HW/SV = 0.36), with steeply oblique, slightly swollen loreal region; canthus rounded, slightly convex when viewed from above ( Fig. 16 A); nostrils directed laterally, closer to tip of snout than to eyes; internarial distance larger than distance from naris to eye (EN/IN = 0.86, IN/SV = 0.095, EN/SV = 0.081); snout rounded when viewed from the side or from above ( Fig. 16 A, C), smaller than eye (SN/EY =0.95); eyes of moderate size (EY/SV = 0.13); eyelid approximately two-thirds width of interorbital distance; tympanum hidden ( Fig. 16 C). Dorsal, lateral, and ventral surfaces smooth; supratympanic fold absent. Fingers without webbing; relative lengths 3>4>2>1 ( Fig. 16 D). First finger small, with rounded tip but no expanded disc or circum-marginal groove; small expanded discs on remaining fingers but only F3 and F4 with circum-marginal grooves; third finger disc barely wider than penultimate phalanx (3rdF/SV = 0.028). Subarticular and metacarpal tubercles low and very poorly developed. Toes without webbing or fringes, bearing discs with terminal grooves; relative lengths 4>3>5>2>1 ( Fig. 16 E). Toe discs larger than those of fingers (3rdF/4thT = 0.65); disc of fourth toe approximately 1.5 times width of penultimate phalanx (4thT/SV = 0.043); disc of first toe same width as penultimate phalanx. Subarticular tubercles poorly developed; inner metatarsal tubercle low and circular, outer lacking. Hind legs short (TL/SV = 0.44).

In preservative, dorsum brown irregularly marked with dark brown ( Fig. 16 A); rear of thighs same. Sides and face dark brown flecked with pale gray; forearms pale straw yellow. Ventral surfaces brown spotted with pale gray ( Fig. 16 B). Iris black.

Measurements (in mm). —SV = 14.8, TL = 6.5, HW = 5.4, IN = 1.4, EN = 1.2, SN = 1.8, EY = 1.9, 3rdF = 0.41, 4thT = 0.63.

Variation. As for many frogs, females attain a larger size than males ( Table 11 ). Sample sizes are small, but, based on minimal overlap of mensural ranges between the sexes, there are tentative suggestions that males may have larger internarial distances, tympana, and finger discs than do females ( Table 11 ). In life, one paratype (BPBM 37740) is quite different to the holotype in dorsal pattern (compare Fig. 8 E vs. 8F), with the dark dorsal markings considerably more dissected and dispersed. The remainder of the paratypes are more like the holotype in generally having larger brown markings dorsally, although they always have a vague X-shaped blotch mid-dorsally in the scapular region. The orange forearms seen in the holotype ( Fig. 8 E) were less distinct in BPBM 37740 ( Fig. 8 E) and in a few of the other paratypes; in two specimens there is no pale area whatsoever on the upper arms, and these were also less distinct in life than those of the holotype. Pale lateral flecking on the body and face is evident in all specimens, and ventrally all paratypes are similar to the holotype.

Color in life. From field notes for holotype BPBM 37730 ( Fig. 8 E): “Dorsum brown with central orange diamond margined with black, forming a large X on the two posterior margins and a chevron on the anterior two. Dorsum with scattered blue-white punctations. Face and sides of body black with scattered blue-white flecks. Rear of thighs brown and dark brown with scattered blue-white flecks. Dark-brown chevron between eyes. Upper arms orange, lower arms brown and black. Iris metallic orange. All ventral surfaces charcoal gray densely flecked with blue white.” Field notes for paratype BPBM 37740 ( Fig. 8 F) state: “Dorsum metallic orange tan heavily maculated with dark brown, sides black flecked with blue white. Rear of thighs as dorsum, forearms copper orange. Venter dark gray flecked throughout with light blue gray. Iris dark brown with red rim around pupil.”

Call. This species calls at night from among leaf litter in lowland rainforest; the call sounds like a drawn-out, raspy snore. This description is based on 37 calls from a single frog.

The call is a single, highly pulsed note lacking harmonic structure and frequency modulation ( Fig. 17 A, C), averaging 1.12 ± 0.0131 s in length, and ranging from 0.97– 1.31 s in length. Calls were delivered at intervals averaging 10.5 ± 2.4733 s apart, and ranging from 1.8– 57.0 s apart. The number of pulses/call averaged 57.1 ± 0.6666 and varied from 50–66, and pulse rate average 50.9 ± 0.4259/s and varied from 43.5–54.9/s. Each note increases and decreases relatively evenly, giving the waveform a smoothly rounded, bilaterally symmetrical shape ( Figs. 10 C, 17A). Dominant frequency varied from 4460–5220 Hz and averaged 5080 ± 0.0219 Hz ( Fig. 17 B).

Etymology. The trivial epithet is a masculine Latin adjective meaning “lovely”.

Range. Known only from the type locality on Woodlark Island, Milne Bay Province, Papua New Guinea ( Fig. 2 ). Almost certainly endemic but widespread across Woodlark Island.

Ecological notes. This species inhabits mature lowland rainforest, with canopy heights at approximately 25– 35 m. All specimens were collected in a gully adjacent to a small, slow-moving stream in lowland primary rainforest or on its bounding ridgeline, usually in microhabitats of steep aspect. Animals were found nocturnally active on the forest floor and were moderately common but difficult to locate because they would typically terminate calling well before they could be closely approached.

Syntopic microhylids include Barygenys sp. nov., Cophixalus clapporum sp. nov., Copiula sp. nov., Genyophryne thomsoni , Hylophorbus myopicus , Mantophryne sp. nov., and Oreophryne sp. nov.

Figures

FIGURE 2. Map of southeastern New Guinea and adjacent islands showing type localities for Cophixalus ateles (filled star), C. sisyphus and C. nexipus sp. nov. (filled circle), C. verrucosus (stars), C. albolineatus sp. nov. (filled square), C. clapporum and C. amabilis (filled triangle), and an additional locality for C. albolineatus sp. nov. (open square). Five additional numbered localities from which call samples of C. verrucosus were obtained for this study are: 1 = Sudest Island, type locality for C. aimbensis; 2 = Cloudy Mts.; 3 = N slope of Mt. Simpson; 4 = W slope of Mt. Dayman; and 5 = Fane. Elevational contours are at 1000 m (light gray) and 1500 m (dark gray).

FIGURE 8. Portraits in life of (A) Cophixalus nexipus sp. nov., holotype BPBM 19323; (B) C. albolineatus sp. nov., paratype BPBM 18429; (C) C. clapporum sp. nov., paratype BPBM 37718; (D) C. clapporum sp. nov., paratype BPBM 37721; (E) C. amabilis sp. nov., holotype BPBM 37730; and (F) C. amabilis sp. nov., paratype BPBM 37740.

FIGURE 10. Expanded waveforms of (A) typical note of Cophixalus nexipus sp. nov., uncaptured animal, showing rectangular shape of amplitude envelope; (B) note from C. nexipus sp. nov. (BPBM 19232) showing left-handed skew in amplitude envelope common to this individual; and (C) typical note of C. amabilis sp. nov. (BPBM 15840).

FIGURE 16. (A) Dorsum, (B) ventrum, (C) side of head, (D) palmar view of right hand, and (E) plantar view of right foot of holotype of Cophixalus amabilis sp. nov. (BPBM 37730). Scale bars = 5 mm (A – C) and 1 mm (D, E).

FIGURE 17. (A) Waveform, (B) power spectrum, and (C) spectrogram of three calls of Cophixalus amabilis sp. nov. (BPBM 15840) recorded on Woodlark Island, 13 October 2011, air temperature 24.0 C.

Tables

TABLE 11. Mensural data for the type series of Cophixalus amabilis sp. nov. All are adult animals.

Character	Males (n = 4) mean range	Females (n = 5) mean range
SV (mm) TL/SV	14.0 13.6–14.3 0.45 0.44–0.48	15.2 14.7–16.1 0.44 0.42–0.46
EN/SV	0.081 0.077–0.086	0.079 0.074–0.082
IN/SV	0.097 0.093–0.101	0.093 0.087–0.095
SN/SV	0.13 0.12–0.13	0.13 0.12–0.14
TY/SV	0.060 0.058–0.064	0.054 0.044–0.061
EY/SV	0.15 0.14–0.15	0.14 0.13–0.15
HW/SV	0.39 0.38–0.39	0.38 0.36–0.39
HL/SV	0.34 0.34–0.35	0.33 0.32–0.34
3rdF/SV	0.031 0.031–0.032	0.028 0.027–0.030
4thT/SV	0.043 0.042–0.044	0.041 0.039–0.044
EN/IN	0.83 0.79–0.86	0.84 0.79–0.87
3rdF/4thT	0.74 0.72–0.77	0.68 0.65–0.71
HL/HW	0.88 0.87–0.89	0.86 0.82–0.91