Leptolalax tadungensis, 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 : 96-99

Leptolalax tadungensis sp. nov.

Figs. 8D , 14 .

Holotype. UNS 00516, adult male, in dry stream in evergreen forest in Ta Dung Nature Reserve , Dak Nong Province, Vietnam (11.8350º N, 108.0081º E, 1262 m elevation, Fig. 1 , 9G ). Collected on 13 July 2010 by Dao T. A. Tran, Vinh Q. Dau, and Huy D. Hoang.

Paratypes. AMS R 177666 and ZFMK 96601, two adult males, collected on same date and locality as holotype. UNS00515, AMS R 177661, AMS R 177662, ZFMK 96602 and ZFMK 96603 , five adult males collected on 17 July 2010 in Ta Dung Nature Reserve , Dak Nong Province, Vietnam (11.8388º N, 107.8945º E, 720 m elevation) . UNS 0 0 526 and UNS 0 0 527, two adult males, collected on 17 July 2011 in Ta Dung Nature Reserve , Dak Nong Province, Vietnam (11.8561º N, 108.0371º E, 1932 m elevation) ; UNS 0 0 517 adult female, collected at same site on 16 July 2011. Specimens were collected by Dao T. A. Tran and Huy D. Hoang.

Etymology. Specific epithet “ tadungensis ” is in reference to the type locality of the species, Ta Dung Nature Reserve.

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 tadungensis 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 white speckling; (3) small/medium SVL for the genus (23.5–26.0 mm in eight adult males, 32.1 mm in one female); (4) toes lacking webbing and lateral fringes; (5) tibia length 43–48% of SVL in males; (6) pectoral gland 3.3–5.4% of SVL in males, (7) smooth dorsum, (8) iris dark gold, (9) distinct black supratympanic line present, (10) an advertisement call with 4–7 notes with the first, introductory note encompassing less than a tenth of each call.

Description of holotype. Head width less than head length; snout rounded in dorsal view and slightly truncate in profile, projecting slightly beyond margin of the lower jaw; nostril closer to snout than eye; canthus rostralis indistinct, gently rounded; lores straight; vertical pupil; eye diameter smaller than snout length; tympanum distinct, 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 slit–like, 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; a large, round inner palmar tubercle separated from a much smaller, 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; large, oval inner metatarsal tubercle present, outer metatarsal tubercle absent; toe webbing rudimentary, slight lateral fringes present. Tibia 47% of snout–vent length; tibiotarsal articulation reaches snout. Skin on dorsum smooth; ventral skin smooth; pectoral gland oval, 1.0 mm diameter; femoral gland small, oval, approximately 0.6 mm diameter, on posteroventral surface of thigh, closer to knee than to vent; supra–axillary gland oval, raised, 1.0 mm diameter. Ventrolateral glands indistinct.

Colour of holotype in life. Dorsal surface dark brown; very faint transverse darker brown bars on the dorsal surface of the thighs, tibia, tarsus, lower arms, fingers and toes. Black line along supratympanic ridge, terminating above axilla, encompassing posterodorsal half of tympanum; anteroventral half paler brown; transverse dark brown bars on dorsal surface of thighs, tibia, tarsus, lower arms, fingers and toes; elbows and upper arms slightly paler, brownish copper; numerous, small darker brown spots on sides from groin to axilla. Dark brown ventral surface with fine white speckling on ventral surfaces of throat, chest, belly, legs and arms; most dense on chest. Supraaxillary gland copper; femoral glands white; pectoral glands white. Iris copper, fine black reticulations throughout.

Colour of holotype in preservative. Dorsum uniform dark brown with scattered small black blotches on flanks and larger black spot on groin; fine black banding on dorsal surface of tibiotarsus, antebrachium, hands and feet ( Fig. 8D ). Ventral surface medium brown with only very faintly visible, fine white speckling. Macroglands white.

Measurements (mm). Holotype: SVL 24.9, HDL 9.4, HDW 8.9, SNT 3.8, EYE 2.9, IOD 3.4, TMP 1.6, TEY 0.9, TIB 11.7, EN 2.2, IN 2.2, NS 1.7, ML 6.0, PL 10.4.

Variation. Measurements of the type series are shown in Tables 5–6 and representative photographs of paratypes are shown in Fig. 14 . Little variation in dorsal colouration. Single female specimen UNS 0 0 527 is paler in colour with a more truncate snout. The white speckling on venter is more distinct in UNS 0 0 527, UNS00517, and AMS R 177661, forming small blotches in UNS 0 0 527, and UNS00517; the dorsolateral line is more distinct and less broken in these specimens. UNS 0 0 526 and UNS00517 have a slightly shagreened skin texture in preservative, possibly an artefact of preservation (with these specimens being better preserved).

Advertisement call. Call descriptions are based on the calls of four individuals, recorded at 12.9–22.3ºC ambient temperature. Calls were an average of 291 ms in duration and consisted of 4–7 notes (Table 7, Figure 6D ). Introductory notes were very short and quite similar to non-introductory notes, comprising only 3–9% of the call duration, and were indistinctly pulsed. Non-introductory notes contained 1–4 pulses. Notes were repeated an average of 14.3 notes/s. The average dominant frequency was 2.8 kHz. Harmonics were weakly present at ~6.3, 13.2, 16.6 kHz, and a fundamental frequency was not visible. To the human ear, the advertisement call of L. pallidus sp. nov. is a short raspy chirp, similar to an orthopteran.

Ecology. All specimens of Leptolalax tadungensis sp. nov. were found in evergreen forest in Ta Dung Nature Reserve between 720–1932 m elevation ( Fig. 9H ). All frogs were found calling during rainy conditions. Frogs collected at the type locality were in underground rocky crevices. Individuals collected on Ta Dung Mountain (~ 1930 m elevation) were calling from the ground or under leaf litter.

Distribution. Leptolalax tadungensis sp. nov. is only known from Ta Dung Nature Reserve, Dak Nong Province, Vietnam. The greatest distance between known localities for the species is 15.7 km.

Comparisons. Leptolalax tadungensis 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 presence of distinct black supratympanic line, from L. bourreti by ventral coloration, from L. botsfordi by male body size, from L. croceus by ventral coloration, presence of black supratympanic line, iris coloration and skin texture; from L. eos by ventral coloration, male body size, presence of black supratympanic line and lateral fringes on toes; from L. firthi by ventral coloration, iris coloration, skin texture and lateral fringes on toes; from L. fuliginosus by ventral coloration and iris coloration; from L. heteropus by ventral coloration and iris coloration; from L. kecil by ventral coloration, male body size and iris coloration; from L. melanoleucus by ventral coloration and iris coloration; from L. minimus by ventral coloration; from L. nahangensis by ventral coloration and male body size; from L. nyx by ventral coloration; from L pelodytoides by ventral coloration; from L. platycephalus by ventral coloration and male body size; from L. pluvialis by ventral coloration and male body size; from L. solus by ventral coloration 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 and skin texture; from L. ventripunctatus by ventral coloration and iris coloration; and from L. zhangyangpingi by ventral coloration, male body size and iris coloration. See Table 8 for details.

From members of the L. applebyi group, L. tadungensis sp. nov. differs from all species 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 greater body size (Wilcoxon post-hoc Z=3.6, p=0.001), greater relative diameter of the eye (Wilcoxon post-hoc Z=2.5, p=0.013), and greater relative pectoral gland size (Wilcoxon posthoc Z=2.9, p=0.004). L. tadungensis sp. nov. differs from L. bidoupensis by having a significantly smaller relative head width (Wilcoxon post-hoc Z=-2.1, p=0.032), smaller relative distance between eye and tympanum (Wilcoxon post-hoc Z=-2.1, p=0.032), and gold iris (versus reddish upper and silver below in L. bidoupensis ). L. tadungensis sp. nov. differs from L. melicus by having a significantly larger body size (Wilcoxon post-hoc Z=3.5, p=0.001), and smaller relative tibia length (Wilcoxon post-hoc Z= -2.3, p=0.019). L. tadungensis sp. nov. differs from L. pyrrhops by having a significantly smaller body size (Wilcoxon post-hoc Z= -3.4, p=0.001), smaller relative tibia length (Wilcoxon post-hoc Z= -3.2, p=0.002), smaller relative distance between eye and tympanum (Wilcoxon post-hoc Z=-3.1, p=0.002) and smaller relative diameter of the eye (Wilcoxon post-hoc Z= -3.3, p=0.001). L. tadungensis sp. nov. differs from L. ardens sp. nov. by having a significantly larger body size (Wilcoxon post-hoc Z= 3.4, p=0.001) and smaller relative tibia length (Wilcoxon post-hoc Z= -3.0, p=0.003). L. tadungensis sp. nov. differs from L. pallidus sp. nov. by having smaller relative tibia length (Wilcoxon post-hoc Z= -3.1, p=0.002), smaller relative distance between eye and tympanum (Wilcoxon post-hoc Z= -2.4, p=0.019), a black supratympanic line (versus no black supratypmanic line in L. pallidus sp. nov) and mostly smooth skin texture (versus tuberculate in L. pallidus sp. nov). L. tadungensis sp. nov. differs from L. kalonensis sp. nov. by having a significantly smaller body size (Wilcoxon post-hoc Z= -3.3, p=0.001) and smaller relative tibia length (Wilcoxon post-hoc Z= -3.4, p=0.001). L. tadungensis sp. nov. differs from L. maculosus sp. nov. by having a significantly smaller relative tibia length (Wilcoxon post-hoc Z= -2.5, p=0.013). See Table 4 and Fig. 4 .

The male advertisement call of L. tadungensis sp. nov. differs from all species in the L. applebyi group. The call of the new species differs from L. applebyi in dominant frequency; from L. bidoupensis in having an introductory note present and in dominant frequency; from L. melicus in relative length of introductory note and dominant frequency; from L. pyrrhops by dominant frequency; from L. ardens sp. nov. by relative length of introductory note; from from L. pallidus sp. nov. by call duration and relative length of introductory note; from L. kalonensis sp. nov. by relative length of introductory note; from L. maculosus sp. nov. by call duration, number of notes per call, distinctness of introductory note and different relative duration of introductory note. See Table 7 and Fig. 5–6 .

Leptolalax tadungensis sp. nov. differs from all species within the L. applebyi group by>6.3% divergence at the 16S gene fragment examined. Interspecific variation in four L. tadungensis sp. nov. collected from up to ~ 15 km apart was 0.0–0.2%.

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 14. Leptolalax tadungensis sp. nov. in life (A) topotypic male (B) male paratype UNS 0 0 515 (note the black supratympanic fold and upper tympanum).