Leptolalax pallidus, Rowley & Tran & Le & Dau & Peloso & Nguyen & Hoang & Nguyen & Ziegler, 2016

Rowley, Jodi J. L., Tran, Dao T. A., Le, Duong T. T., Dau, Vinh Q., Peloso, Pedro L. V., Nguyen, Truong Q., Hoang, Huy D., Nguyen, Tao T. & Ziegler, Thomas, 2016, Five new, microendemic Asian Leaf-litter Frogs (Leptolalax) from the southern Annamite mountains, Vietnam, Zootaxa 4085 (1), pp. 63-102 : 87-90

Leptolalax pallidus sp. nov.

Figs. 8A , 11 .

Holotype. UNS 0 0 510, adult male, calling on plant leaf 0.1 m from ground, 1 m from 2–3 m wide rocky stream in evergreen forest, Bidoup Nui Ba National Park, Lam Dong Province, Vietnam . (12.1520 º N, 108.695º E; 1644 m elevation, Fig. 1 , 9E ). Collected at night on 27 June 2011 by Dao T. A. Tran and Duong T. T. Le.

Paratypes. UNS 0 0 512, AMS R 177657, ZFMK 96599 , three adult males collected on 26 July 2011 in in evergreen forest in Bidoup Nui Ba National Park , Lam Dong Province, Vietnam (12.1519º N, 108.6940º E; 1681 m elevation) . UNS 0 0 511, AMS R 177659, ZFMK 96598 , three adult males collected on same date and location as holotype. AMS R 177658, collected on 27 June 2011 at same location as holotype. All specimens were collected by Dao T. A. Tran and Duong T. T. Le

Etymology. The specific name “ pallidus ”, meaning pale, is used as an adjective in reference to the paler coloration and less distinct markings of this species, particularly in preservative, compared to other species in the group.

Diagnosis. Assigned to the genus Leptolalax on the basis of the following characters: small size, rounded finger tips, the presence of an elevated inner palmar tubercle not continuous to the thumb, presence of macroglands on body (including supra–axillary, pectoral, femoral and ventrolateral glands), the absence of vomerine teeth, the presence of tubercles on eyelids, and anterior tip of snout with pale vertical bar ( Dubois 1983; Lathrop et al. 1998; Delorme et al. 2006). Leptolalax pallidus sp. nov. is distinguished from its congeners by a combination of (1) supra–axillary and ventrolateral glands present; (2) dark brownish red ventral surface with faint white speckling; (3) small SVL for the genus (24.5.1– 27.7 mm in 8 adult males), (4) toes lacking webbing and lateral fringes; (5) tibia length 45–51% of SVL in males; (6) pectoral gland 3.4–6.7% of SVL in males, (7) tuberculate skin texture on dorsum, (8) iris copper in upper half, gold in lower half; (9) distinct black supratympanic line absent, (10) an advertisement call with 4–7 notes with the short introductory note encompassing a quarter of each call and only one note in non-introductory notes.

Description of holotype. Head width slightly subequal to head length; snout truncate in dorsal view and in profile, projecting slightly beyond margin of the lower jaw; nostril closer to snout than to eye; canthus rostralis indistinct, gently rounded; lores sloping; pupil vertical; eye diameter smaller than snout length; tympanum indistinct, round, diameter smaller than that of the eye; tympanic rim slightly elevated relative to skin of temporal region; vomerine teeth absent; pineal ocellus absent; vocal sac openings small, located posteriolaterally on floor of mouth; tongue wide with broad, shallow notch at posterior tip; supratympanic ridge distinct, running from eye to axillary gland. Tips of fingers rounded, very slightly swollen; relative finger lengths I <IV <II <III; nuptial pad absent; subarticular tubercles absent except at base of finger IV; a large, round inner palmar tubercle distinctly separated from small, laterally compressed outer palmar tubercle; finger webbing and dermal fringes absent. Tips of toes like fingers; relative toe length I <II <V <III <IV; subarticular tubercles absent, replaced by dermal ridges, distinct on base of toes II and III; large, oval inner metatarsal tubercle present, outer metatarsal tubercle absent; toe webbing rudimentary; lateral fringes absent. Tibia 51% of snout–vent length; tibiotarsal articulation reaching to anterior edge of eye. Skin on dorsum coarsely shagreened; ventral skin smooth; pectoral gland oval, 1.7 mm diameter; femoral gland oval, approximately 1.0 mm diameter, on posteroventral surface of thigh, closer to knee than to vent; supra–axillary gland oval, raised, 1.5 mm diameter. Ventrolateral glands discernible on right side only.

Colour of holotype in life. Dorsal surface brown with slightly darker interorbital bar with pale brown patches anteriorly and posteriorly; faint dark W-shaped marking between axilla ( Fig. 11A ). Darker brown line along supratympanic ridge, terminating above axilla, encompassing most of tympanum; transverse dark brown bars on dorsal surface of thighs, tibia, tarsus, lower arms, fingers and toes; elbows and upper arms paler brown; numerous, small dark brown spots on sides from groin to axilla. Dark brownish ventral surface with white speckling on ventral surfaces of throat, chest and belly, more sparse on legs and arms. Supra-axillary gland copper; femoral glands white; pectoral glands white, ventrolateral glands white. Iris copper in upper half, gold in lower half, black reticulations throughout.

Colour of holotype in preservative. Dorsum relatively uniform medium brown with darker interorbital bar and slightly paler posterior to this; dorsal surface of brachium, fingers and toes paler brown, dark brown/black banding on dorsal surface of tibiotarsus, antebrachium, hands and feet ( Fig. 8A ). Elbows and upper arms pale brown. Ventral surface medium brown with faint white speckles. Macroglands creamy white.

Measurements (mm). Holotype: SVL 25.2, HDL 9.4, HDW 9.2, SNT 3.9, EYE 3.4, IOD 3.2, TMP 1.7, TEY 1.4, TIB 13.0, EN 2.5, IN 2.6, NS 1.2, ML 6.8, PL 12.6.

Variation. Measurements of the type series are shown in Tables 5–6 and representative photographs of paratypes are shown in Fig. 11 . All specimens have a degree of darker brown patterning (mostly marbling but also some spots) on the dorsum and dark banding on the tibiotarsus and antebrachium, hands and feet, but both are more pronounced in UNS00512, AMS R 177657 and UNS00511. ZFMK 96599 has faint dark brown spots evenly distributed around tubercles on dorsum. UNS00510–00512 have more distinctly pale elbows in preservative. Size and distribution of white speckles on the venter varies a little between specimens, more clumped on chest in AMS R 177659 and ZFMK 96598. Skin texture less tuberculate in preservative than in life.

Advertisement call. Call descriptions are based on the calls of three individuals, recorded at 14.0–21.4 ºC ambient temperature. Calls were an average of 673 ms in duration and consisted of 4–7 notes (Table 7, Fig. 6A ). Short introductory notes of low relative amplitude were present in all calls. Introductory notes were 22–26% of the call duration, contained up to 63 pulses. Non-introductory notes invariably contained a single pulse. Amplitude peaked towards the middle of the call. Notes were repeated an average of 6.8 notes/s. The average dominant frequency was 2.5 kHz. Harmonics were weakly present at ~7.3 kHz, and a fundamental frequency was not visible. To the human ear, the advertisement call of L. pallidus sp. nov. consists of a squelch followed by clicking.

Ecology. All specimens of Leptolalax pallidus sp. nov. were found in evergreen forest in Bidoup Nui Ba National Park between 1644–1681 m elevation. Males were located on the forest floor, on leaf-litter or rocky crevices and clay holes in the banks of a dry stream. Fig 9E .

Distribution. Leptolalax pallidus sp. nov. is only known from Gia Rich mountain in Bidoup Nui Ba National Park, only about 5 km from L. bidoupensis . The two species occur in continuous forest, with no obvious current biogeographic barrier between them.

Comparisons. Leptolalax pallidus sp. nov. differs from all other Leptolalax species in mainland Southeast Asia on the basis of morphology, and from all congeners in the region for which comparable data is available on the basis of molecular and acoustic data.

The new species differs from L. aereus by ventral coloration and iris coloration, from L. bourreti by ventral coloration, male body size, absence of black supratympanic line, skin texture and iris coloration, from L. botsfordi by male body size, absence of black supratympanic line, iris coloration and relative male body weight (0.42–0.50 versus 0.75–0.94 g /mm), from L. croceus by ventral coloration and iris coloration; from L. eos by ventral coloration, male body size, iris coloration and lateral fringes on toes; from L. firthi by ventral coloration, absence of black supratympanic line, iris coloration and lateral fringes on toes; from L. fuliginosus by ventral coloration, male body size, skin texture and iris coloration; from L. heteropus by ventral coloration, male body size, skin texture and absence of black supratympanic line; from L. kecil by ventral coloration, male body size, absence of black supratympanic line and iris coloration; from L. melanoleucus by ventral coloration, body size, absence of black supratympanic line, skin texture and iris coloration; from L. minimus by ventral coloration, skin texture and male body size; from L. nahangensis by ventral coloration, male body size, skin texture, absence of black supratympanic line and iris coloration; from L. nyx by ventral coloration, skin texture and absence of black supratympanic line, from L pelodytoides by ventral coloration and absence of black supratympanic line; from L. platycephalus by ventral coloration and male body size; from L. pluvialis by ventral coloration, body size, skin texture and absence of black supratympanic line; from L. solus by ventral coloration, absence of black supratympanic line, skin texture and iris coloration; from L. sungi by ventral coloration, male body size and iris coloration; from L. tuberosus by ventral coloration, presence of black supratympanic line, iris coloration and skin texture; from L. ventripunctatus by ventral coloration, absence of black supratympanic line, skin texture and iris coloration; and from L. zhangyangpingi by ventral coloration, male body size, skin texture and iris coloration. See Table 8 for details.

From members of the L. applebyi group, L. pallidus sp. nov. differs by at least one morphological character (all following morphometric differences refer to males only). The new species differs from L. applebyi by having a significantly larger and non-overlapping male body size (Wilcoxon post-hoc Z=3.4, p<0.001), larger relative tibia length (Wilcoxon post-hoc Z=2.7, p=0.006), larger relative head width (Wilcoxon post-hoc Z=2.5, p=0.011), larger relative diameter of the eye (Wilcoxon post-hoc Z=2.3, p=0.024), larger relative pectoral gland size (Wilcoxon post-hoc Z=3.0, p=0.002), indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. applebyi ) and tuberculate skin texture (versus mostly smooth in L. applebyi ). L. pallidus sp. nov. differs from L. bidoupensis by having a significantly larger body size (Wilcoxon post-hoc Z=2.7, p=0.006), larger relative tibia length (Wilcoxon post-hoc Z=3.0, p=0.002), larger relative tympanum size (Wilcoxon post-hoc Z=2.0, p=0.041), dark brown iris (versus reddish upper and silver below), indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. bidoupensis ) and tuberculate skin texture (versus mostly smooth in L. bidoupensis ). L. pallidus sp. nov. differs from L. melicus by having a significantly larger and non-overlapping male body size (Wilcoxon post-hoc Z=-3.3, p<0.001), larger length between eye and tympanum (Wilcoxon post-hoc Z=-3.0, p=0.003), indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. applebyi ) and tuberculate skin texture (versus mostly smooth in L. melicus ). L. pallidus sp. nov. differs from L. pyrrhops by having a significantly smaller and non-overlapping male body size (Wilcoxon post-hoc Z=3.2, p=0.002), smaller relative diameter of the eye (Wilcoxon post-hoc Z=3.2, p=0.002), indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. pyrrhops ) and tuberculate skin texture (versus only slightly shagreened in L. pyrrhops ). L. pallidus sp. nov. differs from L. ardens sp. nov. by having a significantly larger body size (Wilcoxon post-hoc Z=-3.8, p<0.001), larger relative tympanum diameter (Wilcoxon post-hoc Z=-2.7, p=0.007), indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. ardens sp. nov) and tuberculate skin texture (versus mostly smooth in L. ardens sp. nov). L. pallidus sp. nov. differs from L. kalonensis sp. nov. by having a significantly smaller body size (Wilcoxon post-hoc Z=3.0, p=0.002), larger relative tympanum diameter (Wilcoxon post-hoc Z=-3.1, p=0.002), indistinct, brown supratympanic line (versus distinct black supratypmanic line in most L. kalonensis sp. nov) and tuberculate skin texture (versus mostly smooth in L. kalonensis sp. nov). L. pallidus sp. nov. differs from L. maculosus sp. nov. by having indistinct, brown supratympanic line (versus distinct black supratypmanic line in L. maculosus sp. nov) and tuberculate skin texture (versus mostly smooth in L.

maculosus sp. nov). L. pallidus sp. nov. differs from L. tadungensis sp. nov. by having a significantly larger relative tibia length (Wilcoxon post-hoc Z=-3.1, p=0.002), larger relative distance between the eye and tympanum (Wilcoxon post-hoc Z=-2.4, p=0.019), indistinct, brown supratympanic line (versus distinct black supratympanic line in L. maculosus sp. nov) and tuberculate skin texture (versus mostly smooth in L. maculosus sp. nov). See Table 4 and Fig. 4 .

The male advertisement call of L. pallidus sp. nov. differs from all members of the L. applebyi group. The call of L. pallidus sp. nov. differs from L. applebyi in call duration, having a relatively long, pulsed introductory note, having one pulse in non-introductory notes, and by average note repetition rate and average dominant frequency. L. pallidus sp. nov. differs from L. bidoupensis in call duration, in having a distinct, pulsed introductory note, and by average note repetition rate and perhaps average dominant frequency (non-overlapping but similar values); from L. melicus in call duration, number of pulses in the introductory note, average note repetition rate and average dominant frequency; from L. pyrrhops in call duration, average number of pulses in introductory note, average note repetition rate and potentially by dominant frequency; from L. ardens sp. nov. differs by call duration, number of pulses in the introductory note, note repetition rate and dominant frequency; from L. kalonensis sp. nov. in average call duration, average number of pulses in the introductory note and average note repetition rate; from L. maculosus sp. nov. in average call duration number of notes per call, and having a distinct introductory note; from L. tadungensis sp. nov. in average call duration, average duration of introductory note, and note repetition rate. See Table 7 and Figs. 5–6 .

Leptolalax pallidus sp. nov. differs from all species within the L. applebyi group by>4.7% divergence at the 16S gene fragment examined. Interspecific variation in three L. pallidus sp. nov. collected from <200 m apart was 0%.

Figures

FIGURE 1. Map showing the localities where specimens in the Leptolalax applebyi group were collected in Cambodia and Vietnam. Colours of localities assigned based on molecular lineages. Paler areas are higher elevation. Dark grey lines show country boundaries, pale grey lines show watershed boundaries and blue lines show rivers.

FIGURE 4. Morphometric variation and differentiation among adult male frogs in the Leptolalax applebyi group. Boxplots of (A) SVL, (B) relative tibia length (TIB / SVL), (C) relative pectoral gland size (PEC / SVL) and (D) relative tibia length (TIB / SVL) of adult males in each molecular lineage. For all boxplots, horizontal lines within each box represent the median and boxes encompass the 75 th and 25 th quartiles.

FIGURE 5. Advertisement calls of species in the Leptolalax applebyi group minus L. pyrrhops (i) 10 s waveform of relative amplitude (Rel. amp.) over time, (ii) waveform and (iii) corresponding 2 s spectrogram of representative call expanded from first section shown in i for (A) L. applebyi holotype AMS R 171703, (B) L. bidoupensis paratype UNS 00101 / AMS R 173135, (C) L. melicus holotype MVZ 258198, and (D) L. ardens sp. nov. paratype UNS 00534 / AMS R 176466. For ambient temperatures during recordings, see Table 4.

FIGURE 6. Advertisement calls of species in the Leptolalax applebyi group minus L. pyrrhops (i) 10 s waveform of relative amplitude (Rel. amp.) over time, (ii) waveform and (iii) corresponding 2 s spectrogram of representative call expanded from first section shown in i for (A) L. pallidus sp. nov. holotype UNS 00510, (B) L. kalonensis sp. nov. paratype IEBR A. 2014.21, (C) L. maculosus sp. nov. holotype UNS 0 0 513, (D) L. tadungensis sp. nov. AMS R 177666. For ambient temperatures during recordings, see Table 4.

FIGURE 8. Dorsal and ventral views of holotypes of (A) L. pallidus sp. nov. UNS 00510, (B) L. kalonensis sp. nov. IEBR A. 2014.14, (C) L. maculosus sp. nov. UNS 00513, (D) L. tadungensis sp. nov. UNS 00516. Scale bar = 5 mm.

FIGURE 9. Calling sites and representative habitats of species in the Leptolalax applebyi group. (A) L. ardens sp. nov., (B) L. kalonensis sp. nov., (C) L. maculosus sp. nov.. (D) stream in Kon Ka Kinh National Park, Gia Lai Province, where L. ardens sp. nov. males were observed 1 - 2 m from stream, calling under leaf-litter, (E) downstream from dry section of stream in Bidoup Nui Ba National Park, Lam Dong Province, where L. pallidus sp. nov. were observed calling, (F) dry stream bed in Song Luy Watershed Forest, Binh Thuan Province, where calling L. kalonensis sp. nov. were collected, and (G) dry stream bed in Ta Dung Forest, Dak Nong Province, where L. tadungensis sp. nov. were calling and collected.

FIGURE 11. Leptolalax pallidus sp. nov. in life (A) male holotype UNS 0 0 510, (B) male paratype AMS R 177657 (C) male paratype UNS 0 0 512, (D) ventral surface male paratype UNS 0 0 512.