Litoria bella, Mcdonald, Keith R., Rowley, Jodi J. L., Richards, Stephen J. & Frankham, Greta J., 2016

Mcdonald, Keith R., Rowley, Jodi J. L., Richards, Stephen J. & Frankham, Greta J., 2016, A new species of treefrog (Litoria) from Cape York Peninsula, Australia, Zootaxa 4171 (1), pp. 153-169 : 159-166

Litoria bella sp. nov.

Holotype: QM J74476 , adult male, from Lankelly Creek , 10 km NE of Coen, Cape York Peninsula, Queensland, Australia (13.8869º N; 143.2673ºE, 540 m asl; Fig. 1 ). Collected on 23 October 2000 by KRM.

Paratypes: QM J74466 –8, 74470, 74473–5, 74478, eight adult males from same locality and date as holotype. QM J38289 , adult male, from Little Stewart Creek , 19 km SE of Coen, Cape York Peninsula, Queensland, Australia (14.0776ºE, 143.3138º E: ~ 180 m asl), collected on 18 December 1978 . QM J39656 , adult male, from Coconut Creek , ~ 40 km North of Aurukun, Cape York Peninsula, Queensland, Australia (13.0082ºS, 141.7991ºE, ~ 40 m asl), collected 22 November 1981 . QM J46363 –4, two adult males, Double Point Road , Shelburne Station, Cape York Peninsula, Queensland, Australia (11.9666ºS, 142.9163º E, <50 m asl).

Etymology. The specific name “ bella ” (Latin), meaning pretty or lovely, is used as an adjective in reference to the beautiful coloration of this species.

Suggested common name. Cape York Graceful Treefrog.

Diagnosis. The new species is assigned to the genus Litoria based on the presence of a horizontally oriented contracted pupil and the absence of a palpebral reticulum (Zweifel 1958; Tyler & Davies 1978). Based upon molecular and morphological data the new species is closely related to Litoria auae , and it exhibits other characters typical of the L. gracilenta group: moderately small size (<50 mm SVL), green dorsum and a male advertisement call resembling a low-pitched growl ( Menzies 2006; Menzies & Tyler 2004). However it is distinguished from all congeners by the following combination of characters: size moderate (male body size 34.5–41.8 mm), dorsum near-immaculate green, venter orange, digits and webbing bright orange, lateral surfaces of the thigh bluish purple, no pale canthal stripe, bones white, and male advertisement call a finely pulsed single note with a pulse rate of 56– 64 pulses/s and dominant frequency of 2.6–2.8 kHz at 21.4ºC.

Description of holotype. Adult male, moderate body size (38.5 mm SVL; Fig. 3 ); head length equal to head width (101%); snout obtusely rounded in dorsal view and truncate in profile; canthus rostralis poorly defined; loreal region flat; interorbital region flat; nostrils oval, closer to tip of snout than eye; eyes moderately large (10% SVL), pupil oval, horizontal, tympanic rim slightly elevated relative to skin of temporal region, top margin obscured by supratympanic skin fold, tympanum 64% of eye diameter; vomeropalatines with two patches of teeth (one on each side) between internal nares ( Fig. 3 ). Vocal sac present; slightly raised supratympanic fold extending to just beyond level of axilla. Finger webbing does not extend to disks ( Fig. 3 C), relative length of fingers I <II <IV <III; tips of all fingers with well-developed disks with distinct circummarginal grooves, disks relatively wide compared to penultimate phalanx width (third finger disk 143% third finger width); subarticular tubercles indistinct; nuptial pads present on posteriodorsal surface of finger I. Relative length of toes I <II <V <III <IV; tips of toes with well-developed disks with distinct circummarginal grooves; disks slightly smaller than those of fingers (fourth toe disk 131% fourth penultimate phalanx width); toe webbing on fourth and fifth toe reaches base of disk, webbing between first and second toe reaches edge of terminal subarticular tubercle ( Fig. 3 D); subarticular tubercles indistinct, rounded; inner metatarsal tubercle low, oval; outer metatarsal tubercle absent. Tibia length moderately long (55% SVL). Skin of dorsal surfaces finely granular; ventral surfaces of body and thighs coarsely granular, finer on chest and under arms, smooth under shanks.

Colour of holotype in preservative. Dorsal ground colour uniform greyish green. Venter, upper arms, inner surface of lower arms, hands and feet including webbing pale yellowish orange. Upper thighs pale yellow with purplish brown wash. Iris pale yellow with black periphery.

Measurements (mm). Holotype: SVL 38.5, TIB 21.2, HL 13.8, HW 13.7, EYE 3.7, TMP 2.4, TEY 1.2, END 3.6, IND 3.4, 3FD 2.0, 4TD 1.7.

Colour in life. Recorded from images of the species from the Iron and McIlwraith Ranges ( Fig. 4 ). Dorsal surface bright green, with bright orange on the dorsal surface of the upper arms, fingers I–III, toes I–IV and distal end of finger IV and toe V, including webbing and toe-disks. Blueish purple inner and outer thighs with only thin strip of green along centre. Pale canthal stripe absent; paler yellowish along bottom of upper lip and along flanks. Ventral surfaces are orange, more yellowish along outer edges of limbs and belly. Iris bright yellowish gold with a network of fine darker gold reticulations; iris periphery black.

Variation. The type series exhibits little variation in colour or morphology, and specimens observed in life consistently exhibited the colours described above. The large variation in extent of dorsal spotting that is apparent in many other members of the L. gracilenta group is not apparent in L. bella . Adult males vary in size from ~ 34–41 mm but variation in morphological features is otherwise slight: measurements of the type series are shown in Table 4 .

continued.

Advertisement call. Call descriptions are based on the calls of two topoparatypes (QM J74467 and QM J74468 ), recorded at an air temperature of 24.1ºC within 0.3 m of calling sites ( Table 5; Fig. 5 ). The advertisement call of Litoria bella consists of a single note, although three of the eight recorded calls of QMJ 74467 were only separated by a short interval. The duration of each call varied from 1.42– 2.62 s and calls were separated by an interval of 0.88– 5.78 s. Each call had 89–156 uniformly spaced pulses repeated at a rate of around 60 pulses/s. Calls were amplitude modulated, increasing gradually to a peak at approximately 70% of the call duration (except for the three calls separated by a short interval). The dominant frequency was 2.6–2.8 Hz, but frequency increased over the duration of the call about 0.2 kHz, from 2.5–2.6 to 2.7–2.8 kHz.

Ecology. Litoria bella inhabits moist monsoon rainforest and vine thicket on hills and plains. The species has been observed breeding in ephemeral pools adjacent to permanent streams and observed (but not breeding) around ephemeral pools in gullies flowing into permanent streams. In October 2000, breeding was observed after a thunderstorm. Two pairs of frogs in inguinal amplexus (female QM J74465 and male QM J4466, and QM J74469 and QM J74470 ) laid spawn with 606 and 844 dorsally brown-pigmented eggs in clear jelly respectively.

Distribution and conservation status. Litoria bella is known from 5–560 metres elevation between Moa Island in the north and about 20 km south of Coen in the south ( Fig. 1 ). The species appears to be patchily distributed within the Cape York Peninsula Bioregion ( Sattler & Williams 1999), while Litoria gracilenta is restricted to the Wet Tropics, Brigalow Belt, Central Queensland Coast and South East Queensland Bioregions and the Eastern Australian Temperate Forests ( Sattler & Williams 1999). The southern-most location of the new species is separated by 220 km from the most northern record of Litoria gracilenta in the Endeavour Valley. Litoria bella is known to occur within at least three protected areas, the Kulla National Park (CYPAL), Kutini-Payamu (Iron Range) National Park (CYPAL) and the Oyala Thumotang National Park (CYPAL). Given its relatively broad distribution, no known threats, and its occurrence within at least three protected areas the species likely falls under the IUCN classification of Least Concern.

Litoria bella sp. nov. Litoria gracilenta

QM J74467 QM J74468 AMS R184768 AMS R184777

Measured 8 calls (3 double=5 sets) 6 calls (all single) 6 calls 6 calls

Call length (s) 1.94 (1.42–2.62) 2.34 (2.29–2.43) 2.06 (2.01–2.09) 2.20 (1.31–2.64) Intercall interval (s) 2.85 (0.88–4.54) 5.78 (5.05–5.78) 3.38 (2.62–4.49) 5.39 (4.18–7.33) Pulses 116.5(89–156) 140.8 (135–149) 180.2 (176–191) 183 (116–225) Pulse/s 60.6(55.8–64.0) 59.9(57.7–63.6) 85.7(85.7–93.0) 84.2(74.7–88.8) Dominant Frequency (Hz) 2.7 (2.7–2.8) 2.6 (2.6–2.7) 2.4 2.7 (2.6–2.8) Temperature (ºC) 24.1 24.1 21.8 21.7

Comparisons. From the eight species of the Litoria gracilenta group currently known, the new species may be distinguished by the combination of (1) male body size moderately large (34.5–41.8 mm SVL), (2) nearimmaculate green dorsum, (3) orange venter, (4) bright orange digits and webbing, (5), iridescent bluish purple lateral surfaces of thigh, (6) no pale canthal stripe, (7) white bones, and (8) a highly-pulsed, single-note, male advertisement call with a pulse rate of 56–64 pulses/s and dominant frequency of 2.6–2.8 kHz at 21.4ºC.

From L. auruensis , the new species further differs by lacking broad lateral fringes on fingers and toes (vs present in L. aruensis ), and in having white bones (versus green in L. aruensis ). It further differs from L. auae ( Fig. 6 A) by having a larger (although slightly overlapping) male body size (34.5–41.8 mm SVL vs 29.9–36.2 mm in 37 L. auae), smaller relative eye size (0.10–0.12 EYE/SVL vs 0.12–0.16 in L. auae ), bright orange webbing (vs golden yellow in L. auae ), immaculate dorsum in most individuals, with only a few small spots on the dorsum on five of 13 types (vs few to many small, scattered pale yellow spots in all but a few of the 40 types of L. auae ), bluish purple dorsal thigh coloration (vs yellow in L. auae ), no pale canthal stripe (vs indistinct yellow canthal stripe in L. auae ), relatively longer (although slightly overlapping) male advertisement call (1.42– 2.62 s at 24.1ºC vs 0.48– 1.78 s at 24ºC in L. auae ), and molecular divergence (see below). The new species differs from L. callista by having a larger male body size (34.5–41.8 mm SVL vs 31.5–34.5 mm in L. callista ), orange venter (vs yellow in L. callista ), bluish purple dorsal thigh coloration (vs orange in L. callista ), no pale canthal stripe (vs pale canthal stripe in L. callista ), bright orange webbing (vs yellow in L. callista ), and a male advertisement call of a longer duration (1.42– 2.62 s at 24.1ºC vs 0.045– 0.190 s at 24ºC in L. callista ), greater average number of notes per call (~117–141 vs 9.5 in L. callista ) and a higher dominant frequency (2.6–2.8 kHz at 24.1ºC vs 1.28–2.39 kHz at 24ºC in L. callista ). From L. elkeae , the new species differs by having a larger male body size (34.5–41.8 mm SVL vs 27.5–30.4 mm in L. elkeae ), immaculately green dorsum in most individuals (vs pale green with indistinct whitish dorsal spotting in L. elkeae ), orange venter (vs cream in L. elkeae ), no pale canthal stripe (vs white canthal stripe in L. elkeae ), and a male advertisement call with a single note with a relatively slow pulse rate (56–64 pulses/s at 24.1ºC vs a biphasic call with 80–101 pulses/s in L. elkeae ). From L. eschata , the new species differs by having an orange venter (vs yellow in L. eschata ), bluish purple dorsal thigh coloration (vs caramel brown in L. eschata ), a male advertisement call with a slower pulse rate (56–64 pulses/s at 21.4ºC vs 72–80 in L. eschata ) and higher dominant frequency (2.6–2.8 kHz at 24.1ºC vs 2.2–2.5 kHz in L. eschata ). From L. gracilenta ( Fig. 6 B–D), the new species differs by having an orange venter (vs white to yellow in L. gracilenta ), bluish purple dorsal thigh coloration (versus purplish red in L. gracilenta ), no pale canthal stripe (vs pale yellowish canthal stripe in L. gracilenta ), orange webbing (vs yellow in L. gracilenta ), bright golden iris with thick black iris periphery (vs brownish gold iris, often with blue or green at borders and a narrow black periphery in L. gracilenta ), a male advertisement call with fewer pulses (~120–140 at 24.1ºC vs ~180 pulses in L. gracilenta at 21.7–21.8ºC) and a slower pulse rate (~60 at 24.1ºC vs ~85 pulses/s in L. gracilenta at 21.7–21.8ºC), and molecular divergence (see below). From L. kumae , the new species differs by having a larger male body size (34.5–41.8 mm SVL vs 24–30 mm in L. kumae ), an orange venter (vs a venter that is white anteriorally and yellowish gold posteriorally in L. kumae ), bluish purple dorsal thigh coloration (vs reddish gold in L. kumae ) and no pale canthal stripe (vs pale canthal stripe in L. kumae ). From L. robinsonae , the new species differs by having a larger male body size (34.5– 41.8 mm SVL vs 28.3–28.7 mm in L. robinsonae ), orange webbing and digits (vs bluish-grey webbing with bluishgrey to translucent anterior digits) and no pale canthal stripe (vs pale canthal stripe in L. robinsonae ).

The new species differs from Litoria chloris ( Fig. 6 E) by having a smaller male body size (34.5–41.8 mm SVL vs> 45 mm), an orange venter (versus yellowish white in L. chloris ), orange webbing (vs yellow in L. chloris ), bright golden iris with thick black iris periphery (vs reddish-orange with thick black periphery in L. chloris ), a male advertisement call of a single, pulsed note of more than 1s duration (vs a multi-note call with each note <1s in duration in L. chloris ; see Fig 5 C), and molecular divergence (see below). The new species differs from Litoria xanthomera ( Fig. 6 F) by having a smaller male body size (34.5–41.8 mm SVL vs> 45 mm), bright orange webbing (vs yellow to pale orange-yellow in L. xanthomera ), bright golden iris with thick black iris periphery (vs reddishorange with thick black periphery in L. xathomera ), bluish purple dorsal thigh coloration (vs orange in L. xanthomera ), and a male advertisement call of a single, pulsed note of more than 1s duration (vs a multi-note call with each note <1s in duration in L. xanthomera ).

Tyler and Davies (1978) included the New Guinea species Litoria graminea and L. multiplica in their L. aruensis group. Litoria graminea and the closely related L. dux and L. sauroni are large (male SVL> 60 mm), robust canopy dwelling frogs with prominent white dermal ridges on the arms and legs and are restricted to New Guinea ( Richards & Oliver 2006). Litoria multiplica is a similar size to L. bella but has a prominent white bilobed dermal ridge around the vent, white dermal ridges around the knees and along the outer edge of the tarsus, and dark purplish black lateral spots or mottling ( Richards et al. 2009).

Sequence divergence. Uncorrected sequence divergences between L. bella and the two most morphologically similar species, L. gracilenta and L. auae , was 20.1–23.0% and 13.0–14.5% at the more rapidly evolving ND4 gene fragment analysed and 5.2–6.1% and 2.0% at the relatively conservative 16S gene fragment analysed. Uncorrected sequence divergences between L. bella and L. chloris was 20.5–21.5 % (ND4) and 4.8–5.0% (16S).

These values are comparable to those reported among other recognised Litoria species ( Mahony et al. 2001; Burns & Crayn 2006; Smith et al. 2013).

Figures

FIGURE 1. Localities of specimens and tissues of Litoria auae (pale yellow), Litoria bella sp. nov. (dark yellow), Litoria gracilenta (dark orange), and L. chloris (dark red) used in this study. DNA only = circle, specimen only = diamond, DNA and specimen = square. The type localities of the first three species are indicated by stars.

FIGURE 3. Holotype of Litoria bella sp. nov. (QM J 74476) in preservative (A) dorsal surface, (B) lateral view of head, (C) palmar surface of left hand, and (D) plantar surface of left foot.

FIGURE 4. Litoria bella sp. nov. in life. (A) female, (B) male showing ventral coloration, an (C) male showing thigh and webbing colouration from Iron Range, QLD, and (D) male QM J 65778 from McIlwraith Range, QLD, Australia.

FIGURE 5. Advertisement call of (A) Litoria bella sp. nov. recorded at 24.1 ºC, (i) waveform of relative amplitude over time of a single call of QM J 74468, (ii) waveform of relative amplitude over time and corresponding spectrogram (frequency over time) below over 40 s for QM J 74468, and (iii) waveform of relative amplitude over time and corresponding spectrogram (frequency over time) below over 40 s for QM J 74467. (B) Litoria gracilenta recorded at 21.7 – 21.8 ºC, (i) waveform of relative amplitude over time of a single call of AMS R 184768 (ii) waveform of relative amplitude over time and corresponding spectrogram (frequency over time) below over 40 s for AMS R 184768, and (iii) waveform of relative amplitude over time and corresponding spectrogram (frequency over time) below over 40 s for AMS R 184777. (C) Litoria chloris recorded at 21.8 ºC, (i) waveform of relative amplitude over time of a single call of AMS R 184770 (ii) waveform of relative amplitude over time and corresponding spectrogram (frequency over time) below over 40 s for AMS R 184770.

FIGURE 6. (A) Litoria auae from the Muller Range, Papua New Guinea; Litoria gracilenta from (B) Mareeba and (C) Kirrama, QLD, Australia, and (D) Richmond Range, NSW Australia; (E) Litoria chloris from Loadstone, NSW, Australia (AMS R 184770); and (F) Litoria xanthomera from Tully Gorge, QLD, Australia.

Tables

TABLE 4. Measurements (mm) of Litoria bella sp. nov. Abbreviations defined in text.

	QM J74476 * QM J46363	QM J39656	QM J38289	QM J74470	QM J74773	QM J74474
SVL	38.5 36.9	41.0	40.3	37.6	41.8	37.9
TIB	21.2 19.5	22.1	21.2	22.3	23.6	21.7
HL	13.8 12.0	14.2	13.2	13.5	13.5	13.6
HW	13.7 12.1	15.4	14.6	14.0	14.9	13.9
EYE	3.7 4.0	4.3	4.0	3.9	4.1	4.2
TMP	2.4 2.5	2.4	2.8	2.3	2.5	2.3
END	3.6 3.4	4.0	4.0	3.9	3.7	2.7
IND	3.4 2.7	3.0	3.0	3.3	3.4	2.9
TEY	1.2 1.4	1.5	1.2	1.2	1.3	1.4
3FD	2.0 1.8	2.6	2.3	2.1	2.1	2.3
3F	1.4 1.2	1.5	1.3	1.3	1.5	1.4
4TD	1.7 1.7	2.2	1.7	2.3	2.1	1.8
4F	1.3 1.3	1.6	1.2	1.4	1.2	1.6