Xenorhina pohleorum, Günther & Richards, 2021
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publication ID |
https://dx.doi.org/10.3897/zse.97.59696 |
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publication LSID |
lsid:zoobank.org:pub:FB92F5DF-7FC7-4F01-A1DD-8E85B6F5FE67 |
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persistent identifier |
https://treatment.plazi.org/id/91F9054A-3CF0-4672-8A86-F64F6A2BA7AA |
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taxon LSID |
lsid:zoobank.org:act:91F9054A-3CF0-4672-8A86-F64F6A2BA7AA |
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treatment provided by |
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scientific name |
Xenorhina pohleorum |
| status |
sp. nov. |
Xenorhina pohleorum sp. nov.
Holotype.
SAMA R71644 (SJR 14202), adult male, from Rentoul River, Western Province, Papua New Guinea (6.4355°S, 142.5615°E; 380 m a.s.l.), collected on 11-08-2014 by S.J. Richards and K. Aplin.
Paratype.
SAMA R60217 (SJR 3223), adult male, Darai Plateau, Gulf Province, Papua New Guinea (7.1295°S, 143.6134°E; 435 m a.s.l.), collected on 1-08-2003 by S.J. Richards.
Diagnosis.
This species of Xenorhina is characterised by the unique combination of: small size (SUL of two adult males 20.3 and 21.2 mm); vomeropalatines each with a single moderately developed triangular vomerine spike; legs of medium length (TL/SUL 0.44 in both specimens); all fingers without and all toes with, expanded terminal discs; tips of all fingers and toes with circum-marginal grooves, all grooves extending at least partly along digits; head short (HL/SUL 0.26 in both specimens); eye-naris distance greater than internarial distance (END/IND 1.33 in both specimens); dorsal surfaces in life brown-beige (RAL 1011) or grey-brown; ventral surfaces ivory-white with extensive pale brown (RAL 8025) reticulation; mid-dorsal line and lumbar spots absent; advertisement calls uttered in series lasting 4-9 s, containing 10-30 “piping” calls, each 56-93 ms duration with repetition rate of 2.5-3.6 calls/s.
Description of the holotype.
Measurements are summarised in Table 3 View Table 3 . Body squat (Fig. 6a View Figure 6 and b View Figure 6 ), head broader than long (HL/HW 0.83); snout short (HL/SUL 0.26), strongly acuminate from above and below, protruding in profile; tongue broad, only its lateral edges and posterior lobes free; prepharyngeal ridge with few tiny denticles; vomerine spikes triangular and of moderate size; loreal region oblique, canthus rostralis absent; nostrils near tip of snout, directed more laterally than dorsally, visible from above, but not from below; eye-naris distance significantly greater than internarial distance (END/IND 1.33); tympanum nearly as large as eye (TyD/ED 0.92); supratympanic fold weakly expressed, not reaching eye or insertion of fore leg; shank moderately long (TL/SUL 0.44); fingers moderately short, not webbed, all fingers without and all toes with expanded terminal discs; circum-marginal grooves on all fingers and all toes, extending at least partly along most digits; head short (HL/SUL 0.26); eye-naris distance greater than internarial distance (END/IND 1.33); tympanum slightly larger than half the size of eye (TyD/ED 0.59); relative lengths of fingers 3> 4 = 2 = 1 (Fig. 6c View Figure 6 ); toes not webbed, relative lengths 4> 3> 5> 2> 1 (Fig. 6d View Figure 6 ); plantar and palmar tubercles, as well as subarticular tubercles, not clearly demarcated, with the exception of small, but prominently raised inner metatarsal tubercle (Fig. 6d View Figure 6 ). Dorsolateral surfaces of body and dorsal surfaces of shanks with some tubercles, more conspicuous in life than in preservative; ventral surfaces smooth; tip of snout lighter than surrounding skin, with some tiny depressions.
In life, dorsal surfaces brown beige (RAL 1011); lumbar spots and mid-dorsal line absent; tubercles with whitish apices concentrated on upper flanks; lower flanks, lateral surfaces of head and anterior hind limbs off-white with conspicuous fawn (RAL 8007) reticulum; snout tip window grey (RAL 7040); iris blackish with few golden specks (Fig. 6a View Figure 6 ); ventral surfaces pearl-white (RAL 1013) with dusky pink (RAL 3014) reticulum and irregular pearl-white spots; throat dusky pink with only a few whitish spots (Fig. 6b View Figure 6 ).
In preservative, ground colour of dorsal surfaces of head, back and hind limbs fawn brown (RAL 8007) with some inconspicuous darker areas; head less densely pigmented than adjacent neck; ground colour of dorsal surfaces of fore limbs and anterior hind limbs beige (RAL 1001) with conspicuous terra-brown strikes and reticula; rear of thighs predominantly terra-brown with a few whitish spots below and small blackish area around vent; ventral surfaces fawn-brown with conspicuous pearl-white spots; throat and middle of chest least spotted.
Morphological variation.
Measurements and body ratios of paratype are similar to holotype (Table 3 View Table 3 ). Dorsal surfaces more tubercular in life (Fig. 7 View Figure 7 ), but in preservative, lateral surfaces with fewer tubercles; colour of dorsal surfaces in life a mixture of indistinct lighter and darker grey-brown flecks, lower lateral surfaces of body and upper arms beige-brown (RAL 8024) with off-white spots and ventral surfaces beige-brown with off-white spots. Dorsal surfaces in preservative beige with signal brown (RAL 8002) spots, stripes and reticula; ventral surfaces in preservative paler than holotype, light ivory (RAL 1015) with scarcely visible brownish network.
Distribution and ecological notes.
Xenorhina pohleorum sp. nov. is known from two localities approximately 140 km apart in the lowland rainforests of Gulf and Western Provinces in south-central Papua New Guinea (Fig. 8 View Figure 8 ), where males called from under the litter or within the humus layer, at night during rain.
Vocalisation.
Advertisement call is a single short, unpulsed and melodic “piping” note and is always uttered in series. Call length and inter-call interval are variable, but call intervals are always much shorter than the interval between call series. Due to some differences in call features, we analysed five call series from the holotype (SAMA R71644) recorded at an air temperature of 24 °C separately from seven call series produced by the paratype (SAMA R60217) at an air temperature of 22 °C. Call series produced by the holotype last 3.6-8.8 s (mean 5.8 ± 1.8 s) and contain 13-28 calls (mean 18.2 ± 5.6) produced at a rate of 2.55-3.61 calls/s (mean 3.22 ± 0.41, n = 5). Call length is 56-93 ms (mean 74.5 ± 8.5 ms, n = 91) and length of call intervals is 139-528 ms (mean 253.4 ± 71.7 ms, n = 86). Calls start abruptly at maximum or almost maximum amplitude which then decreases at an irregular rate until end of call (Fig. 9a View Figure 9 ). Fundamental and dominant frequencies are at 1.5 kHz and the only upper harmonic (at 3.0 kHz) has much less energy (Fig. 9b View Figure 9 and 9c View Figure 9 ). Frequency of calls is weakly modulated with a slight increase over the duration of the call. A number of calls were uttered in exact antiphony with calls from an unvouchered specimen (Fig. 9d View Figure 9 and 9e View Figure 9 ).
Calls of the paratype (SAMA R60217) are similar to those of the holotype, but call series generally contain fewer calls (10-15, mean 12.9 ± 1.77, n = 7, vs. 13-28 mean 18.2; see above) and so are shorter (3.4-5.4 s, mean 4.6 ± 0.72 s, n = 7 vs. 3.6-8.8 s, mean 5.8 ± 1.8 s), although there is some overlap. Calls of the paratype are also slightly longer (66-98 ms, mean 88.4 ± 4.8 ms, n = 89 vs. 56-93 ms, mean 74.5). Other structural parameters of calls from the paratype fall within the range produced by the holotype: inter-call intervals 234-408 ms (mean 290.0 ± 31.1 ms, n = 83) and mean repetition rate 2.73-3.0 calls/s (mean 2.83 ± 0.10, range, n = 7). Calls of the holotype do not show the typical increase in volume and pitch that is typical of the series produced by the paratype. However, the holotype was calling within a group of closely adjacent males and exhibited antiphonal calling behaviour (Fig. 9d View Figure 9 and 9e View Figure 9 ). It cannot be discounted that the slight differences noted between calls of holotype and paratype were a result of their different calling situations (alone vs. within a chorus).
Etymology.
The specific epithet Xenorhina pohleorum is the Latinised patronymic adjective in genitive plural derived from the family name Pohle. It is to recognise a very long-lasting friendship of the senior author with Sybille and Claus Pohle from Berlin.
Comparisons with other species.
We compare Xenorhina pohleorum sp. nov. with all congeners of a similar size (SUL 18-25 mm) that have a single spike on each vomeropalatine.
Xenorhina anorbis has hind legs shorter (TL/SVL <0.38 vs.> 0.38) and fingers and toes without expanded terminal discs (vs. enlarged discs on all toes in Xenorhina pohleorum sp. nov.).
Xenorhina brachyrhyncha has legs longer (TL/SVL 0.46-0.49 vs. twice 0.44), head longer (HL/SVL 0.30-0.32 vs. twice 0.26) and broader (HW/SVL 0.35-0.38 vs. 0.31-0.32), with END/IND ratio lower (1.06-1.13 vs. 1.31-1.33).
Xenorhina lanthanites has expanded disc only on 4th toe (vs. on all toes), head broader (HW/SVL 0.35-0.37 vs. 0.31-0.32), eyes larger (ED/SUL 0.071-0.081 vs. 0.057-0.064), END/IND ratio lower (0.94-1.20 vs. 1.31-1.33) and advertisement call series much longer (up to more than one minute vs. less than 10 seconds).
Xenorhina mehelyi appears to be much larger (SVL 20.7-35.2 mm vs. 20.3-21.2 mm); although the sex (or state of maturity) of previously reported specimens is unknown, with a male SUL of 20.3-21.2 mm, it is unlikely that Xenorhina pohleorum sp. nov. of either sex will approach the upper size limit reported for X. mehelyi . Xenorhina mehelyi also has eyes larger (ED/SVL 0.067-0.079 vs. 0.057-0.064) and different advertisement calls. Mean call interval 1.5 s, (vs. 0.25 s) and mean call rate 0.60 calls/s (vs. 3.2 calls/s); calls are also longer (mean 140 ms vs. 74.5 ms) and have a much lower dominant frequency (0.88 kHz vs. 1.5 kHz) ( Blum and Menzies 1989).
Xenorhina perexigua is smaller than Xenorhina pohleorum sp. nov. (males 16.7 mm vs. 20.3-21.2 mm SUL). Some body ratios also differ (Tables 2 View Table 2 and 3 View Table 3 ), but sample sizes are too small for robust comparisons. However, substantial differences in advertisement calls support recognition of Xenorhina pohleorum sp. nov. as a distinct species: calls of Xenorhina perexigua sp. nov. are shorter (29-42 ms vs. 56-93 ms), there are more calls/series (28-31 vs. 10-28 calls) and inter-call intervals are shorter (101-195 ms vs. 139-528 ms), so the call rate is twice as fast in Xenorhina perexigua sp. nov. (6.8-6.9 calls/s vs. 2.6-3.6 calls/s). The substantially greater call rate of Xenorhina perexigua sp. nov. (double that of Xenorhina pohleorum sp. nov.) cannot be attributed to differences in temperature because the recording temperature for the former was lower than that of latter, which should reduce, not increase, the call rate.
Xenorhina schiefenhoeveli (Blum & Menzies, 1989) is larger (SVL 26.7-30.7 mm vs. 20.3-21.2 mm) and its call series lasts more than 100 s (vs. not more than 10 s in Xenorhina pohleorum sp. nov.), with call intervals of more than 700 ms (vs. <528 ms).
Xenorhina tumulus (Blum & Menzies, 1989) is larger (male SVL more than 26.0 mm vs. less than 22.0 mm), has ventral surfaces of toes with striped pattern (vs. absent) and abdomen partly pink or red (vs. pearl-white with dusky pink reticulum and irregular pearl-white spots); and supratympanic ridge is absent (vs. present). Advertisement calls of X. tumulus differ in, amongst other characters, having a much lower dominant frequency (0.9 kHz vs. 1.5 kHz). Xenorhina tumulus is known only from an elevation of about 1500 m a.s.l. in the Adelbert Range, an isolated mountain range near the north coast of Papua New Guinea, while Xenorhina pohleorum sp. nov. is known only from altitudes of around 400 m on the southern side of New Guinea’s central cordillera.
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