Microhyla sholigari Dutta & Ray 2000

Redescription of Microhyla sholigari Dutta & Ray, 2000

Figure 2 a–j; 3 and Table 4.

Suggested common name: Sholiga narrow-mouthed frog

Voucher specimens: BNHS 5968–5969, 2 ex., adult females, collected near the kitchen of ATREE field station (11.9879° N, 77.1433° E, elevation 1177 m) within BRTTR, Chamarajanagara District, Karnataka State, collected by KVG, HP, RRS and NAA, 14th October 2012; BNHS 5970–5972, 3 ex., adult males, BNHS 5973– 5974, 2 ex., adult females, courtyard of Bisle Community Hall (12.7192° N, 75.6915° E, elevation 837 m), Bisle Village, Sakleshpura Taluk, Hasana District, Karnataka State, collected by VKK, 13th July 2015.

Diagnosis. Dutta & Ray (2000) provided a diagnosis on a subadult female individual (ZSI A9061). A comprehensive diagnosis is provided here based on an adult male individual of Microhyla sholigari and it can be distinguished from all other congeners in the Indian subcontinent by the following suite of characters: (i) A very small sized adult frog (male: 15.9–16.2 mm, N = 3 and female: 16.5–19.2 mm, N = 4); (ii) snout pointed in dorsal and ventral view with indistinct canthus rostralis, snout protrudes beyond mouth in ventral view; (iii) tongue oval with complete margin lacking a lingual papilla; (iv) tympanum indistinct; (v) head wider than long; (vi) skin smooth on dorsum and venter; (vii) throat buff colored with brown pigmentation; (viii) reduced webbing in feet, reaching proximal tubercle on the fourth toe on the inside; (ix) disc on fingers with circum-marginal groove, cover notched distally and disc on toes with circum-marginal groove, cover bifurcate distally.

Differential diagnosis. Microhyla sholigari is compared with congeners from India, namely M. berdmorei, M. butleri, M. chakrapanii, M. heymonsi, M. laterite, M. ornata, M. pulchra and M. rubra. Microhyla sholigari differs from M. berdmorei in size (SVL, male: 15.9–16.2 mm, female: 16.5–19.2 mm vs. male: 25–28 mm, female: 27–45 mm); webbing in feet (reaching proximal tubercle on fourth toe on the inside vs. full webbing); number of pulse per call (64–72 vs. 3–9) and dominant frequency (3375–3704 Hz vs. 1500–1800 Hz). Microhyla sholigari differs from M. butleri in size (SVL, male: 15.9–16.2 mm, female: 16.5–19.2 mm vs. male: 21–23 mm, female: 23–26 mm); snout (pointed vs. rounded); webbing in feet (reaching proximal tubercle on fourth toe on the inside vs. nearly half); number of pulse per call (64–72 vs. 6–7) and dominant frequency (3375–3704 Hz vs. 1200–4500 Hz). Microhyla sholigari differs from M. chakrapanii in size (SVL, male: 15.9–16.2 mm, female: 16.5–19.2 mm vs. male: 22 mm); snout (pointed vs. rounded) and discs on finger (present vs. absent). Microhyla sholigari differs from M. heymonsi in size (SVL, male, 15.9–16.2 mm vs. 21.5–24.4 mm); no lateral band from snouth to groin vs. a continuous dark lateral band from the end of the snout to the groin and number of pulse per call (64–72 vs. 11–17). Microhyla sholigari differs M. laterite in vocal sac (cream with sparse brown pigmentation vs. purplish black); webbing in feet (reaching proximal tubercle on fourth toe on the inside vs. reaching distal tubercle on fourth toe on the inside); dorsal pattern (strongly constricted vs. less constricted) and number of pulse per call (64–72 vs. 90– 126). Microhyla sholigari forms a sister relationship with M. laterite and a detailed comparison is provided in Seshadri et al. (2016). Microhyla sholigari differs from M. ornata in size (SVL, male, 15.9–16.2 mm vs. 18–21 mm); discs on fingers and toes (present vs. absent); vocal sac (cream with sparse brown pigmentation vs. greyish black) and number of pulse per call (64–72 vs. 8–14). Microhyla sholigari differs from M. pulchra in size (SVL, male: 15.9–16.2 mm, female: 16.5–19.2 mm vs. male: 35 mm); discs on fingers and toes (present vs. absent) and webbing in feet (reaching proximal tubercle on fourth toe on the inside vs. nearly half). Microhyla sholigari differs from M. rubra in size (SVL, male, 15.9–16.2 vs. 25.8–29.6 mm); discs on fingers and toes (present vs. absent); vocal sac (cream with sparse brown pigmentation vs. black) and number of pulse per call (64–72 vs. 15–21).

Description of an adult male (Voucher No. BNHS 5970, Fig. 2, all measurements in mm). A small sized adult (SVL = 16.2 mm), head wider than long (HW = 4.9; HL = 3.9). Snout acute in both dorsal and ventral views, upper jaw protrudes slightly in ventral view. Snout acuminate in lateral profile, 1.5 times longer the eye length (SL = 2.4; EL = 1.6). Canthus rostralis rounded. Loreal region concave. Interorbital space sloping towards snout, 2.28 times larger than upper eyelid width, and wider than internarial distance (IUE = 2.0; UEW = 0.9; IN = 1.4). The distance between posterior margins of eyes 1.84 times that of anterior margins (IBE = 4.2; IFE = 2.3). Nostrils rounded, without flap, closer to the tip of snout than to eye (NS = 1.1; EN = 1.3). Symphysial knob present, weak. Tongue relatively large, oval, free at base, margin entire. Lingual papillae absent. Vomerine teeth absent. Tympanum indistinct, moderate supratympanic fold. Single subgular vocal sac with a pair of openings at the base of lower jaw without skin folds. Eyes small (EL = 1.6), pupil-rounded.

Forelimb shorter than hand (FLL = 3.2; HAL = 4.3). Dermal fringe present on fingers. Webbing between fingers absent. Relative lengths of fingers I<II<IV<III (FIL = 1.2; FIIL = 2.1; FIIIL = 2.9; FIVL = 2.4). Finger tips with disc (FD1 = 0.4, FD2 = 0.5, FD3 = 0.5, FD4 = 0.5; FW1 = 0.4, FW2 = 0.5, FW3 = 0.4, FW4 = 0.4). Circummarginal grooves present, notched distally. Palmar tubercles well developed and distinct. Outer tubercle divided in two. Subarticular tubercles distinct (finger: i = 1, ii = 1, iii = 2, iv = 2) and rounded. Supernumerary tubercles present. Nuptial pad absent. Hindlimbs moderately long, touch when folded at right angles to body. Shank 3.8 times longer than wide (ShL = 9.6; TW = 2.5), longer than thigh length (TL = 8.6) and shorter than foot length (FOL = 9.8). Heel to tip of fourth toe (TFOL = 13.9) about 2.46 times longer than fourth toe length (TIVL = 5.6). Relative toe length I<II<III<V<IV (TIL = 1.0; TIIL = 1.6; TIIIL = 3.3; TIVL = 5.6; TVL = 3.1). Toe tips dilated (TD1 = 0.3, TD2 = 0.4, TD3 = 0.4, TD4 = 0.5, TD5 = 0.4; ToW1 = 0.3, ToW2 = 0.4, ToW3 = 0.4, ToW4 = 0.5, ToW5 = 0.3). Circum-marginal grooves present on toes bifurcated distally. Webbing reduced (MTTF = 4.5, MTFF = 5.0, TFTF = 4.8, FFTF = 4.9). Inner and outer metatarsal tubercle distinct. Inner metatarsal tubercle elongated (IMT = 1.5) and larger than the rounded outer metatarsal tubercle (OMT = 0.4). Supernumerary tubercles and tarsal tubercle present (toe: i = 1, ii = 1, iii = 2, iv = 3—3rd weak, v = 2—2nd weak).

Skin texture in preservative. The skin on the snout, inter orbital space and sides of head smooth; Dorsum smooth, interspersed with tubercles increasing in intensity towards vent; Dorsal surface of forelimb and hind limb smooth with tubercles on the upper arm, thigh, shank, and foot. The skin on ventral side smooth, throat shagreened.

Color in preservative. Dorsal coloration pale brown. Tubercles pale red. Forelimbs reddish brown with black cross bands. Tympanic region greyish black. Flanks with a black band are starting above the shoulder and terminating just before the groin. Anterior part of the thigh with a distinct black band starting from knee and terminating short of the groin. Dorsal surface of hind limbs brownish with black cross bands. Vent with a black triangular marking. Anterior and posterior portions of pupil black. Throat buff colored with brown pigmentation. Ventral region pale cream colored. Tarsus to the tip of toes brownish with pale buff colored webbing.

Color in life. Overall pale brown with contrasting black markings on dorsum, hands, feet and flanks. Dark trifoliar pattern on dorsum from the back of the eye to vent. Pattern towards the vent appears like hilt-guard of a sword. Vocal sac buff colored. Iris golden yellow with brown mottling. Pupil black. Ventral parts pale cream. Reddish tubercles on the dorsum (Fig. 3).

Variations. Sexes dimorphic, female larger than male (SVL: male, 15.9–16.2 mm, N = 3; female: 16.5–19.2 mm, N = 4); Subgular vocal sac present in males.

Ecology and natural history observations. Microhyla sholigari is encountered commonly around human settlements, open areas in forests, and ponds. In general, they inhabit areas with dense grass clumps and vocalize between 18:00 h to about 23:00 h between June and October. They breed in shallow water bodies and possibly streams. They have overlapping calls with other M. sholigari individuals and with ground crickets.

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Advertisement calls description. Calls of M. sholigari were recorded on 11th June 2016, between 21:00 h and 23:45 h at Bisle, 12.7192° N, 75.6915° E, elevation 837 m. The air temperature was 23.4 ± 0.06° C and relative humidity of 94.33 ± 0.58%. Advertisement calls sound like ‘Zeeeeee…..Zeeeee…..Zeeeee…’ and are heard as a chorus. Calls of M. sholigari had 52–67 pulses (Mean ± SE, 62.92 ± 3.86; N = 13) in each call. Average dominant frequency was 3596.08 ± 98.46 Hz (range: 3375–3704) and call duration was 0.76 ± 0.04 s (range: 0.65–0.81 s). A single call with a duration of 0.76 s is given in Figure 4. A video clip of advertisement call of M. sholigari is at https://youtu.be/Zx7qQ8T75U8.

Geographic range extension and IUCN status. We encountered this species in localities in Western Ghats including one locality in the outskirts of the city of Bengaluru (Shivanalli), which is outside the Western Ghats boundary (Fig. 1, Table 1). From the type locality, the new range of M. sholigari extends to about 284 km to the north-west. The localities vary from forests inside protected areas to open fallow land outside of the Western Ghats. The geographic extent of occurrence as determined from the minimum convex hull was 28,304.6 km 2. This species is locally abundant (> 50 calling male individuals/ 100 m 2 were observed at Bisle, BRTTR and Shivanalli). There is however, limited information on population size, fluctuation and trends, the number of individuals and generation length. M. sholigari being widespread, does not occur in any one geographically and distinct ecological location. Additionally, there appear to be no sub-population effects as indicated by the low genetic divergence between the two locations sampled in this study (Table 3). In light of the extended geographic range, this species no longer meets the requirements to be classified as Endangered under the criteria of B1ab(iii) or any other category, and thus, we suggest down-listing M. sholigari to Least Concern (LC) instead.