Choerophryne epirrhina, Iannella, Amy, Oliver, Paul & Richards, Stephen, 2015

Iannella, Amy, Oliver, Paul & Richards, Stephen, 2015, Two new species of Choerophryne (Anura, Microhylidae) from the northern versant of Papua New Guinea’s central cordillera, Zootaxa 4058 (3), pp. 332-340 : 333-336

Choerophryne epirrhina sp. nov.

( Figs 1 A, 2)

Holotype. SAMA R67920 (Field No. SJR 12687), adult male, calling when collected, un-named camp in upper Sepik River basin, West Sepik Province, Papua New Guinea (4°39.185’S, 141°43.448’E; 850 m a.s.l.), collected by S. Richards 01/12/2009.

Paratopotype. Field No. SJR 12684, adult male, with same locality and collector details as holotype. To be deposited in PNGNM.

Diagnosis. A moderately small Choerophryne (SUL 14.9–15.0 mm) with a projecting and elongated snout (OHG/SUL 0.09–0.10); moderately long legs (TL/SUL 0.41); expanded discs up to 1.7 times width of penultimate phalanx on all digits of hands and feet except the first; and advertisement call consisting of 3–4 (normally 4) distinctly pulsed notes repeated at a rate of 2.2–2.3/s and comprising 27–31 pulses produced at a rate of 117–141/s.

Comparison with other species. Choerophryne epirrhina sp. nov. differs from all congeners previously included in the genus Albericus by having a distinctly projecting snout comprising an extension of the nasal bones and the alary processes of the premaxillae. From other long-nosed Choerophryne it differs in the following characters: it is smaller (SUL 14.9–15.0 mm), than C. longirostris , C. microps , C. nigrescens and C. proboscidea (SUL> 15 mm), and further differs from these species in lacking an expanded disk on the first finger. Choerophryne epirrhina sp. nov. is larger than C. allisoni and C. burtoni (SUL <14.1 mm) and further differs from these species in having a much longer snout (OHG/SUL 0.09–0.10 vs. <0.06) and tibia (TL/SUL 0.41 vs. <0.37). Choerophryne epirrhina sp. nov is slightly larger than C. gracilirostris (SUL 14.9–15.0 vs. 13.5–14.7) and has a wider snout ( IND /SUL 0.066–0.070 vs. 0.052–0.062). It is slightly larger than C. arndtorum (SUL 11.2–14.8) and has a longer snout (SL/SUL 0.23–0.24 vs. 0.19–0.22).

Choerophryne epirrhina sp. nov. overlaps in size with C. rostellifer (male SUL 14.0– 16.8 mm) and the geographically disjunct C. amomani (11.8–15.1 mm) and C. bryonopsis (15.0– 17.9 mm). It differs from C.

amomani and C. bryonopsis in lacking an expanded disk on the first finger, having a longer snout (OHG/SUL 0.09–0.10 vs. 0.06–0.07 and 0.05–0.06 respectively), and smaller eye diameter (ED/SUL 0.09–0.10 vs. 0.11–0.13 for both C. amomani and C. bryonopsis ). Morphologically, this species is difficult to distinguish from C. rostellifer but it has a different call and is also genetically divergent (see below). Key diagnostic features of long-nosed Choerophryne found on the central cordillera of New Guinea are summarised in Table 2 .

In having calls normally containing four notes C. epirrhina sp. nov. differs from C. allisoni (5–6 notes), C. amomani (1–2 notes), C. bryonopsis (1 note), C. burtoni (5–6 notes), C. microps (5–9 notes), C. nigrescens (6–10 notes) and C. proboscidea (3 notes). Choerophryne arndtorum produces four-note calls, but the notes are shorter (0.13– 0.18 s vs 0.20– 0.25 s) and produced at a faster rate (2.7–3.4/s vs. 2.0–2.3/s). Choerophryne gracilirostris makes 3–5-note calls with shorter notes (0.014–0.042 vs. 0.20– 0.25 s) produced at a much faster rate (7.2–13.3/s vs. 2.0–2.3/s). Choerophryne longirostris and C. rostellifer also sometimes make four-note calls; but C. longirostris notes are much longer (0.45–0.52 vs. 0.20– 0.25 s) and produced at a much slower rate (0.69 vs. 2.0–2.3/s); C. rostellifer notes are much shorter (0.066–0.085 vs. 0.20– 0.25 s) and produced at a much faster rate (~7/s vs 2.0– 2.3/s).

Description of holotype. Adult male with a short ventral incision on right side, liver removed, and measurements (in mm) of: SUL 14.9; TL 6.1; HW 5.1; HL 5.3; ED 1.5; END 2.5; IND 1.0; SL 3.4; OHG 1.4; F1D 0.4; F3D 0.7; T1D 0.3; T4D 0.8. Head rather narrow (HW/SUL 0.34), canthus rostralis weakly defined and smoothly rounded, loreal region very slightly concave. Snout narrow, acute and projecting well beyond anterior rictus of lower jaw (OHG 1.4 mm), tip rounded in dorsal and lateral profiles, ventral surface of tip with a broad, unpigmented medial ridge, clearly defined anteriorly and becoming shallow and indistinct towards anterior rictus of the upper jaw. Nares oval, narrowing slightly posteriorly, located close to tip of snout, oriented ventrolaterally and not visible in dorsal view; internarial distance moderately large (IN/SUL 0.066). Eye rather small (ED/SUL 0.099), transverse diameter less than length of snout, pupil horizontal. Tympanic annulus visible along the ventral and anterior edges of tympanic membrane, not visible dorsally or posteriorly. Urostyle projecting slightly beyond vent. Dorsum relatively smooth except for a very faint vertebral ridge extending from snout tip to urostyle tip; scattered tubercles across flanks, densest anteriorly; venter smooth.

Fingers moderately long, with distinct circum-marginal grooves, relative lengths III>IV>II>I, finger I more than half length of II, fingers II–IV with distinctly expanded discs up to 1.6 times width of penultimate phalanx, finger I without disk and with only faint circum-marginal groove; subarticular tubercles, metacarpal tubercules and webbing absent. Legs moderately long (TL/SUL 0.41). Toes moderately wide, relative lengths IV>V≥III>II>I, toe I just over half length of II, all toes except I with small terminal discs up to 1.2 times width of penultimate phalanx and with circum-marginal grooves; metatarsal tubercles and webbing absent. Toe discs wider than finger disks (F3/ T4 0.91).

In preservative, ground colour of dorsum buff with dense dark grey-brown maculations, slightly denser anterior to the tympana, lending the head an overall darker appearance. Dorsum dominated by a longitudinally oriented, medium-brown, medially constricted blotch, wider posteriorly than anteriorly and with prominent but weakly defined darker brown edging. Inguinal region with a pair of indistinct dark-brown lumbar ocelli, each containing a distinct pale-cream medial spot. Vent bordered laterally and dorsally by a dark-brown arc, urostyle tip pale buff. Exposed dorsal and lateral surfaces of limbs pale buff, with extensive tan maculations and dark-brown blotches forming transverse bands at the midpoints of the thigh, shank, foot, forearm and hand, giving an overall barred appearance. Dorsal surfaces of hands and feet pale buff with extensive pale-brown flecking and darkerbrown blotches around the base of the distal phalanges. Venter and ventral surface of limbs pale buff with fine tan maculations. Palmar and plantar surfaces largely unpigmented except for scattered light-tan speckling.

Variation. Measurements for the type series are given in Table 1 . The paratype is of similar dimensions to the holotype, but has a slightly longer snout (OHG/SUL 0.10 vs. 0.094). Tuberculation of the flanks is sparser than on the holoype, and the slope of the loreal region is straight (vs. slightly concave). Like the holotype, the paratype also has a medium-brown dorsal blotch with darker-brown edging and distinct pale-cream inguinal spots, limbs with dark-brown transverse bands, and ventral colouration of pale buff with extensive tan speckling. Internal oral features of the holotype are not visible so those of the paratype are presented here: tongue oval, slightly bifurcated at tip; two curved prepharyngeal ridges present, vomerine teeth absent, vocal slits present slightly anterolateral to base of tongue.

Appearance in life. Photographs in life ( Figure 1 A) of the holotype taken at night show a greater degree of contrast between light and dark-brown dorsal and ventral areas than is evident in preservative. Dorsum grey, with dense brown and orange maculations (giving an overall brownish-grey appearance), overlain with darker-brown blotching and numerous smaller grey spots. Ventral surfaces tinged blue-grey, with scattered pale-grey blotches; belly and ventral surface of the snout overlain with extensive orange flecking; similar flecking is present but less dense on the throat and thighs. Iris black with small bronze flecks, pupil horizontal with a thin reddish-orange border. Dorsal surfaces of torso and legs with numerous pale-grey tubercles of heterogeneous size (less conspicuous in preservative).

Advertisement call. Ten calls produced by the holotype were analysed, including nine consecutive calls produced in an uninterrupted series. A single complete call from the holotype is presented in Figure 2 A. The series of nine calls lasted 79.2 seconds and was produced at a rate of 0.1 calls/s. Energy was focused in two major frequency bands, one at around 3,000 hz and the other at around 3,800 hz. In seven of the ten calls analysed the dominant frequency was between 3692 and 3884 hz (mean = 3829 hz, SD = 71.4), while in the remaining three calls the dominant frequency was 2942–3037 hz (mean = 2999 hz, SD = 50.7). Calls contained 3–4 notes (nine of 10 calls had 4 notes) and were 1.13– 1.70 s long (mean = 1.5, SD = 0.15), but this narrowed to 1.53– 1.70 s (mean = 1.59, SD = 0.05) when the only 3-note call was excluded from analysis. Note length was similar both within and between calls, ranging from 0.20– 0.25 s (mean = 0.22, SD = 0.01; n = 39), and notes were produced at a rate of 2.0–2.3/s (mean = 2.22, SD = 0.07; n = 10 calls). Notes contained 27–31 pulses produced at a rate of 117–141 pulses/s (mean = 127.8, SD = 6.51; n = 20 notes).

Etymology. From the Greek, epirrhinos, meaning ‘long-nosed’.

Natural history and distribution. Choerophryne epirrhina sp. nov. is known from one location in primary foothill rainforest on the northern side of Papua New Guinea’s central cordillera at an altitude of 850 m. Males were calling after rain at night, from within curled leaves that were accumulated at the base of shrubs, within 20 cm of the ground. Given the extent of suitable habitat in the area, this species probably has a broad distribution along the northern slopes of the central cordillera. Choerophryne epirrhina sp. nov. and Choerophryne rostellifer are also very similar in external appearance, and some specimens from elsewhere on the central cordillera referred to the latter species ( Kraus & Allison 2001) may also actually represent the former.

Figures

FIGURE 1. (A) Choerophryne epirrhina sp. nov. holotype SAMA R 67920 in life and (B) Choerophryne grylloides sp. nov. holotype SAMA R 67921 in life.

FIGURE 2. Advertisement calls (A) Choerophryne epirrhina sp. nov. (SAMA R 67920) recorded at 23.5 ° C and (B) Choerophryne grylloides sp. nov. (SAMA R 67921) recorded at 23.5 ° C. Top = waveform, bottom = spectrogram, left = power spectrum.

Tables

TABLE 1. Summary of measurements (mm) for Choerophryne epirrhina sp. nov. and Choerophryne grylloides sp. nov.

Reg#	SAMAR67920	PNGNM	SAMAR67921	SAMAR67928
Species	HOLOTYPE C. epirrhina sp. nov.	PARATYPE C. epirrhina sp. nov.	HOLOTYPE C. grylloides sp. nov.	Referred specimen C. grylloides sp. nov.
Sex SUL TL	Male 14.9 6.1	Male 15.0 6.1	Male 12.5 5.3	Male 11.7 6.0
F1D F3D T1D	0.4 0.7 0.3	0.4 0.8 0.4	0.1 0.5 0.3	0.2 0.4 0.3
T4D HL HW	0.8 5.3 5.1	0.8 5.3 5.1	0.6 4.2 4.3	0.6 4.0 3.6
SL ED OHG	3.4 1.5 1.4	3.6 1.4 1.5	2.9 1.3 1.1	2.7 1.3 1.0
END IND	2.5 1.0	2.5 1.1	1.9 0.9	1.9 0.8