Xenorhina woxvoldi, Günther & Richards, 2021

Guenther, Rainer & Richards, Stephen, 2021, Description of six new species of Xenorhina Peters, 1863 from southern Papua New Guinea (Amphibia, Anura, Microhylidae), Zoosystematics and Evolution 97 (2), pp. 355-382 : 355

Xenorhina woxvoldi sp. nov.

Holotype.

SAMA R71646 (SJR10249), adult male, from southern edge of Karius Range, Hela Province, Papua New Guinea (5.9911°S, 142.6707°E; 1,368 m a.s.l.), collected on 07-02-2008 by S.J. Richards.

Paratype.

ZMB 91133 (SJR 10311), adult male, same collection details as for holotype.

Diagnosis.

This species of Xenorhina is characterised by the unique combination of: small to medium-size (males 28.7-30.1 mm SUL); vomeropalatines each with one moderate-sized vomerine spike; legs short (TL/SUL 0.36 in two specimens); all fingers and toe 1 without expanded discs, toes 2-5 with weakly expanded discs (T4D/SUL 0.038-0.040); eye-naris distance smaller than internarial distance (END/IND 0.80-0.91); tympanum slightly larger than eye (TyD/ED 1.11 in two specimens). Dorsal surfaces bluish-brown in life, ventral surfaces dark orange with irregular whitish and greyish spots. Advertisement calls uttered in series lasting 3-5 s, calls per series 13-19, call length 37-84 ms, repetition rate 4.0-4.5 calls/s.

Description of the holotype.

Measurements are summarised in Table 6 , a dorsolateral view in life is shown in Fig. 15a and ventral surfaces in life in Fig. 15b . Head broader than long (HL/HW 0.75); snout acuminate from above, protruding in profile; loreal region oblique, no canthus rostralis; nostrils near tip of snout, directed more laterally than dorsally, visible from above, but not from below; eye-naris distance less than internarial distance (END/IND 0.90); tympanum visible in life and preservative, its diameter slightly larger than eye (TyD/ED 1.11); tongue very broad; vomerine spikes triangular, moderately large; prepharyngeal ridge narrow with four denticles; supratympanic fold well-developed, not reaching eye or insertion of fore leg (Fig. 15a ); shank short (TL/SUL 0.36); fingers moderately short, not webbed; tips of all fingers with circum-marginal grooves, not or only marginally wider than penultimate phalanges, relative lengths of fingers 3> 4> 2> 1 (Fig. 15c ); all toe tips with circum-marginal grooves, those on toes 2-4 clearly wider than penultimate phalanges, those on toe 1 and toe 5 scarcely wider than penultimate phalanges; toes not webbed, relative lengths 4> 3> 5> 2> 1 (Fig. 15d ); plantar, palmar and subarticular tubercles barely visible; body laterally with some distinct tubercles in life, barely visible in preservative; dorsal surfaces of extremities, middle of dorsum and all ventral surfaces smooth; tip of snout with several tiny pimples.

In life, dorsal surface of head, body and extremities a mixture of grey-brown and copper-brown (RAL 8004) (Fig. 15a ); lower flanks uniform greyish with bluish hue and off-white dots and streaks; semicircular lumbar spot present, but only vaguely defined; a distinct whitish mid-dorsal line extends on to rear of thighs and on shanks and tarsi, then as broken line on to abdomen and chest; dorsal and ventral surfaces of fingers and toes and palmar surfaces orange; plantar surfaces a mixture of irregular light grey, dark grey and orange spots. Ventral surfaces of throat, chest, abdomen and extremities orange-brown (RAL 8023) with irregular light grey spots (Fig. 15b ); most tubercles on flanks and extremities with whitish tips; snout tip light grey with tiny dark grey spots; outer margin of iris blackish and inner margin gold-orange, with some integration of colours at their margins.

In preservative, dorsal surfaces changed from copper-brown to mahogany-brown (RAL 8016), that of ventral surfaces from orange-brown to ivory (RAL 1014). Dorsal surfaces of fingers and toes also become ivory coloured. Lumbar spots no longer visible.

Morphological variation.

All body measurements and body ratios of holotype and paratype are similar (Table 6 ). In life, dorsal surfaces of paratype a mixture of lighter and darker brown and reddish areas, with reddish components more restricted than in holotype. Colours of flanks and dorsal surfaces of fingers and toes and colour and extent of mid-dorsal line (extending on to hind limbs and abdomen) as for holotype. Ventral surfaces more yellow and light grey spotting more extensive, in paratype. Dorsal surfaces in preservative slightly paler than holotype, ventral surface with more extensive pale brown reticulation.

Distribution and ecological notes.

Xenorhina woxvoldi sp. nov. is known only from one location at an altitude of 1,368 m a.s.l. on the southern fringe of the Karius Range in Hela Province, Papua New Guinea (Fig. 16 ), where males called from within the humus layer in lower montane rainforest during late afternoon and early evening.

Vocalisation.

Two call series from the holotype (SAMA R71646) and one from the paratype (ZMB 91133), recorded at air temperatures of 18-19.5 °C, were analysed. Call is a single unpulsed, piping note produced in discrete series. Call series last 2.9-4.8 s (mean 3.7 s, n = 3) and contain 13-19 calls (mean 5.7 calls, n = 3) produced at a rate of 4.0-4.5 calls/s (mean 4.3 calls/s, n = 3). Call length is 37-84 ms (mean 75.1 ± 8.3 ms, n = 47) and call intervals last 137-250 ms (mean 172.4 ± 28.4 ms, n = 44). Calls are of approximately equal length throughout a series (first call may be shorter) with approximately equal intervals (intervals between first two and last two calls of a series may be slightly longer). Volume of each call increases during course of call series, but rise in pitch is marginal. Calls start abruptly at maximum amplitude, which then decreases gradually until end of call (Fig. 17a ). All calls have harmonic structure with 4-5 harmonics between 0.7 and 3.2 kHz (Fig. 17b ). First harmonic clearly dominant, with peak at 0.8 kHz (Fig. 17c ). Third harmonic often with more energy than second. Frequency of calls weakly modulated with slight reduction during course of call.

Etymology.

The specific epithet Xenorhina woxvoldi is the Latinised patronymic adjective in genitive singular derived from the family name Woxvold. It is in gratitude of the junior author to Iain Woxvold for the many years of friendship, camaraderie and shared adventures in remotest New Guinea.

Comparisons with other species.

We compare Xenorhina woxvoldi sp. nov. with all congeners of a similar size (SUL ~ 25-35 mm) that have a single spike on each vomeropalatine.

Xenorhina fuscigula differs from Xenorhina woxvoldi sp. nov. by having an internarial distance shorter (IND/SVL 0.054-0.064 vs. 0.066-0.070), eye-naris distance greater (END/SVL 0.064-0.074 vs. 0.056-0.060), END/IND ratio higher (1.00-1.36 vs. 0.80-0.90), ventral surfaces pale with dark reticulation (vs. orange with light grey spots) and calls produced singly (vs. produced in rapid series of 13-19 calls).

Xenorhina huon has eye-naris distance greater (0.073-0.103 vs. 0.056-0.060), END/IND ratio higher (1.00-1.27 vs. 0.80-0.90), eyes larger (ED/SVL 0.070-0.091 vs. 0.060-0.066), head wider (HW/SVL 0.35-0.47 vs. 0.30-0.34) and ventral surfaces with dark flecking (vs. ventral surfaces with light flecking in life and pale brown reticulation in preservative).

Xenorhina lacrimosa is larger (SUL 34.3-41.0 mm vs. 28.7-30.1 mm), has shanks longer (TL/SUL 0.42-0.46 vs. 0.36 in both known Xenorhina woxvoldi sp. nov.), fourth toe longer (T4L/SUL 0.42-0.49 vs. 0.41-0.42), head longer (HL/SUL 0.27-0.30 vs. 0.25 in both known Xenorhina woxvoldi sp. nov.), eye-naris distance greater (END/SUL 0.073-0.099 vs. 0.056-0.060) and advertisement calls longer (141-231 ms vs. 37-84 ms) with lower repetition rate (0.20-0.27 vs. 4.0-4.5 calls/s).

Xenorhina mehelyi has hind legs longer (TL/SVL> 0.42 vs. 0.36), eye-naris distance greater (END/SVL 0.076-0.096 vs. 0.056-0.060), END/IND ratio higher (1.12-1.50 vs. 0.80-0.90), eyes larger (ED/SVL 0.067-0.079 vs. 0.060-0.066), ventral surfaces with dark mottling (vs. no dark mottling) and calls longer (on average140 ms vs. 75 ms) with inter-call intervals also longer (on average 1500 ms vs. 172 ms).

Xenorhina schiefenhoeveli has eye-naris distance greater (END/SVL 0.077 vs. 0.056-0.060), END/IND ratio higher (1.16-1.21 vs. 0.80-0.90), eyes larger (ED/SVL 0.071-0.081 vs. 0.060-0.066), ventrum cream, with reticulated brown (vs. orange-red with whitish flecking); calls longer (~ 100 ms vs. mean of 75 ms), uttered in very long series of more than 100 calls (vs. 13-19 calls) with repetition rate about 2 calls/s (vs. 4.0-4.5 calls/s).

Xenorhina subcrocea has hind legs longer (TL/SVL> 0.46 vs. <0.40), ratio of END/IND much larger (1.26-1.41 vs. 0.80-0.90), ventral surfaces with dark reticulation (vs. with whitish flecking) and mid-dorsal line absent (vs. distinct dorsal line present).

Xenorhina tumulus has eye-naris distance greater (0.073-0.081 vs. 0.056-0.060), END/IND ratio higher (1.11-1.28 vs. 0.80-0.90), ventral surfaces in life pinkish, mottled with brown (vs. orange-brown with no brown mottling) and call intervals within series 300-400 ms (vs. 137-250 ms).

Xenorhina wiegankorum appears to be larger (five males 32.0-35.7 mm vs. two males 28.7-30.1 mm SUL), has hind legs much longer (TL/SUL 0.44-0.47 vs. 0.36 in two specimens), has toes longer (T4L/SUL 0.45-0.47 vs. 0.41-0.42), fingers longer (F3L/SUL 0.188-0.213 vs. 0.174-0.189), END/IND ratio higher (1.19-1.37 vs. 0.80-0.90) and a different advertisement call (see description of X. wiegankorum , this paper).

Xenorhina zweifeli is larger (SVL 33.2-38.0 vs. 28.7-30.1), with internarial distance smaller (IND/SVL 0.052-0.063 vs. 0.066-0.070), eye-naris distance larger (END/SVL 0.071-0.085 vs.0.056-0.060), END/IND ratio higher (1.17-1.47 vs. 0.80-0.90); ventral colour pattern of dark brown flecks on a cream ground in preservative (vs. pale brown flecks on ivory-coloured ground) and call consisting of a single note (vs. 13-19 calls produced in distinct series.

Figures

Figure 15. Holotype (SAMA R 71646) of X. woxvoldi sp. nov. in life: (a) Dorsolateral view; (b) Ventral view; (c) Volar view of right hand; (d) Thenar view of right foot.

Figure 16. Map of Papua New Guinea showing the known distributions of X. thiekeorum sp. nov. (blue circle), X. wiegankorum sp. nov. (yellow triangles) and X. woxvoldi sp. nov. (red square). Arrows indicate the type localities.

Figure 17. (a) Oscillogram, (b) Spectrogram and (c) Amplitude spectrum of the last five calls of a series containing 15 calls from the holotype of Xenorhina woxvoldi sp. nov.