Leptobrachium masatakasatoi

Anh Van Pham, Dzung Trung Le, Cuong The Pham & Son Lan Hung Nguyen, 2016, Two additional records of megophryid frogs, Leptobrachium masatakasatoi Matsui, 2013 and Leptolalax minimus (Taylor, 1962), for the herpetofauna of Vietnam, Revue suisse de Zoologie 123 (1), pp. 35-43 : 38-40

Leptobrachium masatakasatoi Leptolalax minimus

Sex males (n = 7) females (n = 5) males (n = 3) females (n = 7) tympanum indistinct ( TYD 2.8-4.0 mm in males and 3.5- 4.0 mm in females); tympanum-eye distance (TYE 2.4- 3.1 mm in males and 2.7-3.2 mm in females); vomerine teeth absent; tongue heart-shaped, notched posteriorly; vocal openings absent.

Forelimb long (FLL 38.2-43.7 mm in males and 39.8- 49.2 mm in females), forearm (LAL 17.0- 18.8 mm in males and 17.0-22.0 mm in females), longer than the hand length (HAL 12.0- 14.5 mm in males and 12.3- 15.7 mm in females); relative finger lengths II<IV<I<III; fingers without dermal fringe, free of webbing; tips of fingers rounded, slightly swollen; subarticular tubercle indistinct, 1:1:2:2; palmar tubercles two, oval; nuptial pads absent.

Hindlimb slender, long (HLL 64.0- 72.6 mm in males and 64.0- 78.8 mm in females); foot longer than tibia (TL 19.0-22.0 mm in males and 19.7-24.8 mm in females; FOT 19.8-23.7 mm in males and 20.0- 25.6 mm in females); tibiotarsal articulation reaching to posterior margin of tympanum when limb adpressed along body; relative toe lengths I<II<V<III<IV; tips of toes slightly swollen; webbing formula I1–1II1 – 1III 1 –2IV2–1 V; inner metatarsal tubercle distinct, shorter than length of toe I (IMT 2.6-3.2 mm in males and 2.7-3.7 mm in females; ITL 4.4-5.4 mm in males and 4.0- 5.4 mm in females); subarticular tubercles indistinct, 1: 1: 2: 3: 2. Skin. Dorsal surface with fine network of ridges, tubercles present in the posterior region of sacrum, more distinct in anterior part of vent; upper lip without spines in males; supratympanic fold present, from posterior edge of eye to axilla; flanks granular; throat and chest asperities; belly and ventral surfaces of limbs smooth except for granular thigh.

Coloration in life. Dorsal surface light brown or brownreddish, with dark spots on medial side of upper eyelid, distinct or indistinct in some individual, back with irregularly black spots; supratympanic fold edged in black below; flanks light brown reticulated with large black spots; anterior part of thigh with large dark spots; dorsal limbs light brown with dark crossbars; ventral surface with irregular brown and cream markings.

Acoustic properties ( Fig. 3 ): Calls emitted by the male (IEBR A.2015.19) from Sop Cop NR were recorded at a temperature of 8oC and a relative humidity of 83%. The calls were composed of a single pulsed note, lasting for 0.161- 0.244 s (0.199 ± 0.019; n = 27), repeated at a rate of 1.115-1.218 calls/s (1,166 ± 0,073; n = 2) and inter-call intervals of 0.259- 1.184 s (0.61 ± 0.277; n = 24). Each note consisted of multipulse. Frequency band of calls ranged between 0.224 and 2.015 kHz (from 0.314 ± 0.05 to 1.771 ± 0.145; n = 26). The dominant frequency, presenting at about 0.861-1.206 kHz (1.097 ± 0.098; n = 26). Rise time of calls (mean CV = 9.31%), call repetition rate (mean CV = 6.23%), inter-call interval (mean CV = 45.35%) and dominant frequency (mean CV = 8.87%) were the most stereotyped properties. Time of calls, call rate, and dominant frequency can be considered static properties, while inter-call interval can be considered dynamic properties. In comparison with other species of Leptobrachium from Vietnam, advertisement calls of L. masatakasatoi intensively overlap with those of L. leucops and L. pullum in both temporal and spectral properties (Stuart et al., 2011; Tran, 2013). All three species emit calls of a single pulsed note, with a dominant frequency at around 1.0 kHz ( L. masatakasatoi 0.861-1.206 kHz, L. leucops 1-1.6 kHz, and L. pullum 0.99-1.38 kHz).

Calling behavior: Calling males were found on stream banks in the secondary forest. The smallest distance in between two calling individuals was from 1 to 2 m. This species is quite sensitive for surrounding disturbances such as light or sounds. The calling individuals stayed silence for a long time when they recognized disturbances.

Ecological notes: Specimens of L. masatakasatoi were found on the edge of small streams and on forest paths between 20:00 and 24:00. The surrounding habitat was evergreen forest of small hardwood and shrub at elevations between 1000 and 1670 m.

Distribution: This species was previously known only from Laos (Matsui, 2013).

Figures

Fig. 3. Advertisement call of Leptobrachium masatakasatoi (IEBR A. 2015.19, adult male). (a) A 0.8 - sec waveform of relative amplitude. (b) Corresponding 0.8 - sec spectrogram.