Leptolalax botsfordi, Rowley, Jodi J. L., Dau, Vinh Quang & Nguyen, Tao Thien, 2013

Rowley, Jodi J. L., Dau, Vinh Quang & Nguyen, Tao Thien, 2013, A new species of Leptolalax (Anura: Megophryidae) from the highest mountain in Indochina, Zootaxa 3737 (4), pp. 415-428 : 418-425

Leptolalax botsfordi sp. nov.

Holotype: VNMN 0 3682, adult male, calling under leaf litter, 0.2 m from small trickle of water running through mossy rocks to a 1 m-wide cascading stream in upper montane forests on Mount Fansipan, Hoang Lien National Park, Lao Cai Province, Vietnam (22.3135º N, 103.7652º E, 2,815 m elevation; Figure 1 ). Collected at 19:35 h on 10 June 2012 by Jodi J. L. Rowley, Vinh Quang Dau, Sang Van Pham, Tu Van Tran, Su A Hang, and Di A Hoang. Paratypes: AMS R 176540 (adult female) climbing into mud hole in seep at 19:55 h, and AMS R 176534–176538 (five adult males), collected at same geographic locality and date as holotype. AMS R 176541 (adult female) and AMS R 176539 (adult male), collected on 11 June 2012, adjacent to a 2 m-wide, swift cascading stream in upper montane forest on Mount Fansipan, Hoang Lien Son National Park, Lao Cai Province, Vietnam at 22.3139º N 103.7654º E, 2,795 m elevation). All specimens were collected by Jodi J. L. Rowley, Vinh Quang Dau, Sang Van Pham, Tu Van Tran, Su A Hang, and Di A Hoang.

Etymology: Specific epithet is a patronym honouring Christopher Botsford, for his support of amphibian biodiversity conservation research and scientific capacity building in Asia.

Diagnosis: Assigned to the genus Leptolalax on the basis of the following characters: small (<~ 60 mm SVL) 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 botsfordi 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) medium SVL for the genus (29.1–32.6 mm in 7 adult males, 30.0– 31.8 mm in 2 females); (4) black markings on the flanks absent; (5) toes with rudimentary webbing and weak lateral fringing; (6) large pectoral glands (1.1–1.9 mm; 4–6% SVL) and femoral glands (2.4–4.3 mm; 7–14% SVL); and (7) an advertisement call with a dominant frequency of 2.6–3.2 kHz (at 14.0 ºC).

Description of holotype: Head width equal to head length; snout rounded in dorsal view and rounded in profile, projecting slightly beyond margin of the lower jaw; nostril equidistant between snout and eye; canthus rostralis indistinct, gently rounded; lores slightly concave; vertical pupil; eye diameter smaller than snout length; tympanum barely distinct, round, diameter smaller than that of the eye; tympanic rim elevated relative to skin of temporal region on ventral side only; vomerine teeth absent; pineal ocellus absent; vocal sac openings slit-like, located posterolaterally on floor of mouth in close proximity to the margins of the mandible; tongue long, wide, with broad, shallow notch at posterior tip; supratympanic ridge distinct, running from eye towards axillary gland, with raised tubercles. Tips of fingers rounded, slightly swollen; relative finger lengths I <II <IV <III; nuptial pad absent; subarticular tubercles absent; a large, round inner palmar tubercle distinctly separated from small, laterally compressed outer palmar tubercle; finger webbing and dermal fringes absent ( Figure 5 A). Tips of toes like fingers; relative toe length I <II <V <III <IV; subarticular tubercles absent, replaced by dermal ridges; large, oval inner metatarsal tubercle present, outer metatarsal tubercle absent; toe webbing rudimentary; narrow lateral fringes on all toes ( Figure 5 B). Tibia 46% of snout-vent length; tibiotarsal articulation reaches to middle of eye. Skin on dorsum shagreened; ventral skin smooth; pectoral gland large, oval, 1.5 mm diameter; femoral gland large, oval, approximately 3.4 mm diameter, on posteroventral surface of thigh, closer to knee than to vent; supra-axillary gland raised, 1.8 mm diameter. Ventrolateral glands just visible as small white dots forming an incomplete line anteriorally, barely visible in preservative.

Colour of holotype in life ( Figure 2 A–B): Dorsal surface dark brown with gold edging dorsolaterally; gold interorbital bar; very faint transverse dark brown bars on the dorsal surface of the thighs, tibia, tarsus, lower arms, fingers and toes. Supratympannic ridge and vertical bar at anterior tip of snout metallic copper. Flanks marbled metallic gold and pale brown. Ventral surfaces slightly transparent reddish brown with faint paler flecks most obvious on slightly darker throat and thighs. Supra-axillary gland white edged in pale copper; pectoral glands opaque white; femoral glands white ( Figure 2 D). Iris dark brownish gold with densely-packed minute, black reticulations throughout. Iris periphery lined with black. Sclera white.

Colour of holotype in preservative ( Figure 2 E–F): Dorsum dark brown; flanks marbled with paler brown; interorbital bar and dorsal surface of fingers and toes paler brown. Ventral surface of chest, belly, and thighs slightly mottled brown; throat dark brown speckled with white; arms and tibiotarsus mottled dark brown and cream. Macrogrands creamy white.

Measurements: Holotype: SVL 29.1, HDL 10.1, HDW 10.1, SNT 4.0, EYE 3.4, IOD 3.4, TMP 1.7, TEY 1.2, TIB 13.4, ML 7.4, PL 14.3, weight 2.4 g

Variation: Measurements of the type series are shown in Table 1 and representative photographs of paratypes are shown in Figures 2–4 . Specimens vary only slightly in the colour and extent of marbling on the dorsum; male AMS R 176537 was slightly paler pinkish brown in life. Males have more robust forearms than females (compare males in figures 4A and 4C with females in figures 4B and 4D).

Advertisement call: Call descriptions are based on the calls of the holotype, recorded at 14.0 ºC ambient temperature. Calls were of two distinct types ( Figure 6 ), the more frequent and higher amplitude clicking calls referred to here as ‘primary calls’, and low amplitude ‘rasps’ referred to as ‘secondary calls’. Primary calls were an average of 267 ms in duration and consistently comprised of three notes ( Table 2 , Figure 6 ). Calls were highly amplitude modulated, with amplitude peaking at the start of each note. Notes contained a variable number of pulses repeated at a highly variable rate (average ~86 pulses/s, range ~40–146 pulses/s). The number of pulses decreased from note one to note three, with notes two and three almost always containing 4 and 2 pulses respectively. The dominant frequency of the primary call was 2.6–3.2 kHz, and harmonics were weakly present at approximately 5.0–5.5 kHz. A fundamental frequency was not visible. Primary calls were repeated at a rate of approximately 1.3 calls per second, and had an average intercall interval of 0.5 s. Secondary calls were an average of 299 ms in duration and consisted of a single note with 14–19 irregularly-spaced pulses ( Table 2 , Figure 6 ). Secondary calls were of less amplitude than primary calls, and not strongly amplitude modulated. The dominant frequency of the secondary call was slightly higher than the primary call (2.8–3.4 kHz). Due to background noise in the recording, full analysis of secondary calls was not possible. To the human ear, the advertisement call of L. botsfordi sp. nov. is a weak chirping, similar to an orthopteran.

Ecology: All specimens of Leptolalax botsfordi sp. nov. were found in upper montane forest between 2,795– 2,815 m elevation on Mount Fansipan ( Figure 7 A). The climate of Mount Fansipan is almost temperate, with an average temperature of about 15 ºC (range -3–20 ºC), with frequent freezing in the coldest months (Nguyen & Harder 1996). The mountain has 3,500 mm of rain and 2–3 snow days per year, and no dry months (Nguyen & Harder 1996; Nguyen et al. 2000). In addition to the heavy rainfall, fog is common and evaporation rates low (Nguyen 1998). Several males were heard faintly calling under leaf litter adjacent to a small stream ( Figure 7 B) and females were located whilst moving towards calling males. The species was very difficult to locate, even when calling. During surveys conducted within the same week at lower elevations (1,355–2,240 m) on Mount Fansipan and surrounding habitat in Hoang Lien National Park and Sa Pa, District, Leptolalax botsfordi sp. nov. was not detected, although the two other Leptolalax species known from Mount Fansipan and surrounds (Bourret 1937; Ohler et al. 2000), L. bourreti and L. pluvialis , were common.

Distribution: Leptolalax botsfordi sp. nov. is only known from relatively near the summit of Mount Fansipan, northern Vietnam. Mount Fansipan is the highest point in Indochina (3,143 m), and part of the Hoang Lien Son Mountain Range, which extends south from the Ailao Shan mountains in China, the south-easternmost extension of the Himalayan chain. The actual distribution of the new species is unknown but may extend along the range northwest through Lao Cai and Lai Chai provinces and into Yunnan Province in China, or southeast further into Vietnam. However, there are only a handful of small, isolated areas along the range above 2,700 m until approximately 250 km further north in Yunnan Province.

Comparisons: In having supra-axillary and ventrolateral glands, L. botsfordi sp. nov. differs from the southern species L. arayai , L. dringi , L. fuliginosus , L. fritinniens , L. gracilis , L. hamidi , L. heterops , L. kajangensis , L. kecil , L. maurus , L. melanolecus , L. pictus and L. solus (all of which are considered to belong in the subgenus Leptolalax ; Delorme, Dubois, Grosjean, and Ohler, 2006).

Leptolalax botsfordi sp. nov. is distinguished from all species in the genus except for L. applebyi , L. bidoupensis , and L. melicus by having a dark brownish red ventral surface with white speckling ( L. aereus , L. alpinis , L. arayai , L. bourreti , L. dringi , L. firthi , L. fuliginosus , L. fritinniensis , L. gracilis , L. hamidi , L. khasiorum , L. lateralis , L. liui , L. minimus , L. nahangensis , L. nokrekensis , L. oshanensis , L. pelodytoides , L. pictus , L. playcephalus , L. solus , L. sungi , L. tamdil and L. tuberosus have mostly white or pale grey/brown venters, with or without dark spots or mottling; L. croceus has a bright orange belly; L. pluvialis has a dirty white/grey venter with dark brown/grey marbling, and uniform pale dirty white/grey throat with pale speckling only around the margins; L. melanoleucus and L. ventripunctatus display large patches of distinct brown/black and white marbling, L. heteropus has a grey venter, speckled with black; L. maurus has a black or dark grey brown venter, with indistinct small light areas, and L. kecil has a uniformly dark venter with large, dark orange pectoral glands).

From the three species with dark reddish brown ventral surfaces, L. botsfordi sp. nov. differs by having a SVL of 29.1–32.6 mm in 7 adult males, 30.0– 31.8 mm in 2 females ( L. applebyi males 19.6–22.3 mm, females 21.7– 25.9 mm; L. bidoupensis males 23.6–24.6 mm, females 29.2–29.4 mm; L. melicus males 19.5–22.7 mm), and in having only faint white spotting (versus dense white spotting or marbling on the belly). Body size also distinguishes the new species from the smaller L. alpinus (26.3 mm), L. croceus (males 22.2–27.3 mm), L. kecil (males 19.3–20.5 mm, female 25 mm), L. khasiorum (24.5–27.3 mm), and L. pluvialis (males 21.3–22.3 mm), and the larger L. bourreti (male 36.2 mm), L. eos (males 33.1–34.7 mm), L. gracilis (males 34.3–39.0 mm, females 42.4–49.3 mm), L. kajangensis (males 34–35 mm), L. nahangensis (male 40.8 mm), L. platycephalus (male 35.1, female 46 mm), L. sungi (males 48.3–52.7 mm, females 56.7–58.9), and L. tamdil (male 32.3 mm, female 31.8 mm).

An absence of black markings on the flanks further distinguishes the new species from L. alpinus , L. applebyi , L. bidoupensis , L. bourreti , L. oshanensis , L. fuliginosus , L. frittianensis , L. gracilis , L. hamidi , L. heteropus , L. kecil , L. melanoleucus , L. melicus , L. nokrekensis , and L. pelodytoides . In having toes with rudimentary webbing and weak lateral fringing, L. botsfordi sp. nov. can also be readily differentiated from L. alpinis , L. firthi , and L. liui , which have wide lateral fringing on toes, and from L. pelodytoides , which has more extensive webbing and wide lateral fringes between toes. In addition, Leptolalax botsfordi sp. nov. has large pectoral glands (1.1–1.9 mm; 4–6% SVL) and femoral glands (2.4–4.3 mm; 7–14% SVL). The femoral glands in particular are the most prominent of all Leptolalax species measured by us (see Appendix I; femoral glands 2–8% SVL).

The advertisement call of L. botsfordi sp. nov. is unique among congeners with known calls. In having a call with a dominant frequency of 2.6–3.2 kHz (at 14.0 ºC), L. botsfordi differs from all but L. bidoupensis , L. croceus , L. fuliginosus , L. gracilis , L. heteropus , L. kecil , L. melanoleucus , L. melicus , L. solus and L. tuberosus ( L. aereus 6.2–7.9 kHz at 22.4–25.7 ºC; L. alpinus ~6.7 kHz at 16 ºC; L. applebyi 4.0–4.3 kHz at 21.5 ºC; L. arayai 5.4–5.8 kHz at 17.4 ºC; L. dringi 7–7.5 kHz at 24.3 ºC; L. hamidi 7.0 kHz at 22.9 ºC; L. liui 5.3 kHz; L. oshanensis 4.4–4.6 kHz, 14 ºC, recorded from c. 40 km from type locality of L. oshanensis ; L. pictus 6.8–7.2 at 19–22 ºC; L. firthi 5.6– 6.4 kHz at 18.3–21.2; L. fritinniensis 7.3–9.2 at 24.3–24.9 ºC). Although frequency can vary with temperature, differences among species of the scale reported here are unlikely to be attributed to temperature alone. From L. bidoupensis , the call differs in having variable note types and in the number of notes per call (1 or 3 versus 6–9), from L. croceus in the number of notes per call (1 or 3 versus 4–5), L. fuliginosus in the number of notes per call (1 or 3 versus 6–9), L. gracilis in the number of notes per call (1 or 3 versus 3–4), L. heteropus in the number of notes per call (1 or 3 versus 6–9), L. kecil in having variable note types and in the number of notes per call (1 or 3 versus 4), L. melanoleucus in the number of notes per call (1 or 3 versus 3–4), L. melicus in the number of notes per call (1 or 3 versus 4–11), L. solus in the number of notes per call (1 or 3 versus 4–8) and L. tuberosus in the number of notes per call (1 or 3 versus 1 single pulsed call). In lacking strong frequency modulation, the call of L. botsfordi sp. nov. differs from L. dringi and L. hamidi .

Figures

FIGURE 1. Type locality of Leptolalax botsfordi sp. nov. on Mount Fansipan, northern Vietnam.

FIGURE 2. Leptolalax botsfordi sp. nov. (A) dorsal and (B) ventral view of adult male holotype VNMN 0 3682 in life, (C) ventral view of gravid female paratype AMS R 176540 in life, (D) posterior view of adult male holotype VNMN 0 3682 in life, showing large femoral glands in (not to scale), (E) dorsal and (F) ventral view of adult male holotype VNMN 0 3682 in preservative, and (G) ventral view of adult female paratype AMS R 176540 in preservative. Scale bars = 5 mm.

FIGURE 5. Palmar surface of (A) left hand and (B) right foot of adult male holotype Leptolalax botsfordi sp. nov. VNMN 0 3682. Scale bar = 1 mm.

FIGURE 6. Advertisement call of Leptolalax botsfordi sp. nov. holotype VNMN 0 3682 (A) 14 s waveform of relative amplitude (Rel. amp.) over time for 16 “ primary ” calls, (B) waveform and (C) corresponding spectrogram of single representative “ secondary ” call expanded from first section shown in A, and (D) waveform and (E) corresponding spectrogram of single representative “ primary ” call expanded from second section shown in A; all recorded at an ambient air temperature of 14.0 ºC.

FIGURE 7. Habitat of Leptolalax botsfordi sp. nov. (A) View of Mount Fansipan and surrounding mountains, Lao Cai Province, Vietnam. (B) Microhabitat of calling male L. botsfordi sp. nov. at ~ 2,800 m elevation.

Tables

TABLE 1. Measurements (mm) of Leptolalax botsfordi sp. nov. Abbreviations defined in text.

	VNMN 03682*	AMS R 176534	AMS R 176535	AMS R 176536	AMS R 176537	AMS R 176538	AMS R 176539	AMS R 176540	AMS R 176541
SEX	Male	Male	Male	Male	Male	Male	Male	Female	Female
SVL	29.1	32.6	29.5	30.4	28.7	28.8	30.5	31.8	30.0
HDL	10.1	10.7	10.4	10.1	10.3	10.8	10.5	11.0	10.2
HDW	10.1	10.9	10.4	10.6	11.0	10.3	10.6	10.5	10.3
SNT	4.0	4.2	3.8	4.1	4.2	4.3	4.1	4.7	4.3
EYE	3.4	2.9	3.2	3.4	3.0	2.8	2.8	3.5	2.9
IOD	3.4	-	3.0	3.2	3.5	3.1	3.3	3.0	3.4
TMP	1.7	1.8	1.4	1.8	1.5	1.8	2.0	1.8	1.7
TEY	1.2	1.6	1.6	-	1.6	1.4	1.5	1.2	1.5
TIB	13.4	14.2	13.5	14.3	13.6	14.5	15.0	14.1	15.1
EN	1.9	2.2	1.9	2.0	2.1	2.4	2.3	2.1	2.1
IN	3.1	2.9	2.8	2.9	2.8	3.0	2.8	3.0	3.0
NS	1.9	2.0	2.1	2.1	1.9	2.0	1.9	2.2	2.1
ML	7.4	7.5	6.9	7.9	7.3	7.4	8.3	7.8	8.1
PL	14.3	14.4	13.2	14.1	14.8	14.3	15.2	14.5	15.0
HDL/HDW	1.00	0.99	1.00	0.95	0.94	1.04	0.99	1.05	0.99
HDL/SVL	0.35	0.33	0.35	0.33	0.36	0.37	0.34	0.35	0.34
TIB/SVL Weight in life (g)	0.46 2.4	0.44 2.8	0.46 2.2	0.47 2.5	0.47 2.4	0.50 2.7	0.49 2.3	0.44 3.0	0.50 2.3

TABLE 2. Measurements of advertisement call parameters for adult male holotype (VNMN 03682) of Leptolalax botsfordi sp. nov. recorded at 14.0 ºC ambient temperature. Parameter values are given as means (and ranges).

	Primary call	Secondary call
Number of calls measured	10	5
Call duration (ms)	267 (239–303)	229 (194–283)
Call repetition rate (calls/s)	1.3
Intercall interval (ms)	536 (406–1028)
Notes/call	3	1
Dominant frequency (kHz)	3.0 (2.6–3.2)	3.1 (2.8–3.4)
Pulses/note
Note 1	10.8 (7–15)	15.8 (14–19)
Note 2	4.1 (4–5)
Note 3	2.4 (1–4)