Sphaerotheca varshaabhu, Deepak & Dinesh & Nag & Ohler & Shanker & Prasad & Ashadevi, 2024

Deepak, P., Dinesh, K. P., Nag, K. S. Chetan, Ohler, Annemarie, Shanker, Kartik, Souza, Princia D, Prasad, Vishal Kumar & Ashadevi, J. S., 2024, Discovery and description of a new species of burrowing frog Sphaerotheca Günther, 1859 (Anura: Dicroglossidae) from the suburban landscapes of Bengaluru, India, Zootaxa 5405 (3), pp. 381-410 : 392-398

Sphaerotheca varshaabhu sp. nov.

urn:lsid:zoobank.org:act:C88C6AFA-9889-4E3E-A2CD-816FDA5481FD

( Table 1–3 and Figure 6–7 )

Holotype: ZSI/WRC/A/2571 (Fig. 6,7), an adult male ( SVL 35.2 mm) collected by P. Deepak and team on 24 th July, 2020 from the disturbed suburban agro ecosystems of Budumanhalli ( N 13.1973; E 77.5328, 850 msl), Bengaluru , Karnataka.

Paratypes: ZSI/WRC/A/2572 , an adult male (SVL 36.8 mm) collected by P. Deepak and team on 19 th September, 2019 and ZSI/WRC/A/2573 , an adult male (SVL 34.0 mm) collected by P. Deepak and team on 24 th July, 2020 location details same as holotype .

Lineage separation ( Fig. 2 ): Sphaerotheca varshaabhu sp. nov. can be assigned phylogenetically to the genus Sphaerotheca . The new species is part of a clade of species including S. breviceps and S. cf. breviceps [swani]. The new species has 3.9% uncorrected pairwise genetic distance to S. breviceps and 3.6 % to 4.1 % genetic distance to S. cf. breviceps [swani] for 16S rRNA.

Geography: So far, the species is known from a restricted range of distribution in a few pockets around the Bengaluru, Karnataka, India (predominantly Deccan Plateau). Based on our current knowledge of its distribution, Sphaerotheca varshaabhu sp. nov. is geographically separated from its the phylogenetic sister species S. breviceps which is found in the eastern part of southern India ( Fig. 11 ) and S. cf. breviceps [swani], which is distributed from Nepal to Central India.

Morphological diagnosis: Sphaerotheca varshaabhu sp. nov. can be identified in the field based on the following combination of morphological characters. A medium-sized burrowing frog ( SVL ranging from 33.7 mm to 41.1 mm) with a robust stocky body; head slightly wider than the head length; snout rounded, snout length sub equal to eye diameter; nostrils near to snout tip; tympanum rounded and almost half the diameter of the eye; first finger longer than the second finger; hind limbs short, when adpressed to body tibiotarsal articulation reaching tympanum; webbing moderately ( Deepak et al. 2020a) developed (I 0–1 II ½–1 III 1–2 IV 2–1 V); inner metatarsal tubercle shovel-shaped and longer than inner toe; tibiotarsal tubercle present; dorsal surface of the skin glandular with raised glandular tubercles and overall skin colour light chocolate with brown blotched pattern interspersed with raised small orange granules ( Fig. 3 ). In the field, there are no confusing sympatric congeners reported ( S. bengaluru is the known sympatric congener which is morphologically distinct in body colour and striped pattern).

Description of the holotype (ZSI/WRC/A/2571) ( Fig. 6–7 )

A moderate-sized burrowing frog (SVL 35.2 mm) with a robust, stocky body; with head width slightly wider than head length (HW 14.1 mm; HL 12.0 mm); snout rounded (SL 4.3 mm) and sub equal to eye diameter (EL 5.7 mm); canthus rostralis slightly angled, loreal region concave; inter orbital space (IUE 2.6 mm) sub equal to the upper eyelid (UEW 3.2 mm) and sub-equal to inter narial distance (IN 2.2); distance between the back of eyes twice the distance in front of eyes (IFE 5.9 mm; IBE 11.1 mm); nostrils oval, nearer to the tip of snout than to eyes (NE 2.7 mm); distinct tympanum, almost half of the eye diameter visible below the curved supratympanic fold (TYD 2.6 mm) and close to the eye (TE 1.2 mm); symphysial knob weak; vomerine ridge weak; tongue bifid without a papilla.

Forearm stout and shorter (FLL 7.4 mm) compared to the hand (HAL 9.2 mm); fingers short and narrow without dermal fringes, first finger (FL1 3.6 mm) slightly larger than the second finger (FL2 3.0 mm) and shorter than the third finger (TFL 4.5 mm) with blunt tips, without any enlarged discs, webbing absent between fingers; subarticular tubercles distinct, rounded and pre-pollex tubercle distinct, supernumerary tubercles absent.

Hind limbs short, falling apart when folded at right angles to the body and tibiotarsal articulation reaches tympanum; femur length (FL 16.6 mm) longer than tibial length (TiL 14.0 mm); foot length (FOL 17.0 mm) twice the size of tarsal length (Tal 7.6 mm), relative toe length I<II<V<III<IV (FTL 9.1 mm); inner toe minute (ITL 0.9 mm), webbing moderately developed (I 0–1 II ½–1 III 1–2 IV 2–1 V); inner metatarsal tubercle (IMT 3.3 mm) distinct and sharp shovel shaped, distinctly longer than inner toe; prominent tarsal tubercle present.

The skin on dorsum smooth with regularly set glandular tubercles; flanks with dense glandular tubercles; abdomen and groin granular.

Colour in life, light chocolate and brown blotched pattern on dorsal body surface with raised small orange granules ( Fig. 6 ). Fore and hind limbs with distinct dark brown transversal bands. Entire ventral side of the body whitish, except the region of the vocal sacs which is blackish in adult males.

In preservative ( Fig. 7 ), the entire dorsum is covered with dark blotches outlined by black markings; glandular granules whitish. Forelimb grey and creamish and hindlimb lighter grey than dorsum with dark brown bands. Creamy white bars on the upper lip. Back of supra tympanic fold is creamy white.A small creamy white spot present between the eyes, V-shaped brown marking above the spot, in between the eyes. Inverted V-shaped brown marking on dorsum in the region between forelimbs and a creamy white spot at the intersection of the marking. Tubercles on the flank region are creamy white on a dark brown background. Venter pale creamy white in colour. Vocal sacs black. Ventral side of the limbs and groin light brown.

Secondary sexual characters: Males are smaller than females among amplecting pairs. During the breeding season, males have a blackish vocal sac on the throat ( Fig. 7A, 7B ) and an inconspicuous light brown nuptial pad on the first finger.

Variations among paratypes and other referred collections: The morphological data for the paratypes and other referred collections are given in Table 2 ; males SVL range from 33.7 mm to 36.8 mm; a single female measured SVL 41.1 mm. All the specimens collected are similar to the holotype description in colour pattern.

Etymology: The specific epithet is derived from the Sanskrit name ‘Varshaabhu’, (Varshaa, rain; Bhu, taking birth) signifying the breeding activity of the species only during the rains. The species epithet is treated as a noun in opposition to the generic name. Suggested common name: “Varshaa burrowing frog”.

Occurrence and natural history ( Fig. 8 ): Sphaerotheca varshaabhu sp. nov., is currently known from the agro-horticultural regions of Budumanhalli village, Bengaluru. S. bengaluru is the only sympatric congener in its known distribution range. During our anuran surveys in 2019 and 2020, we encountered calling males during the peak northeast monsoon period (October to December). Feeding and breeding activities of both the species of Sphaerotheca were seen during the northeast monsoon and calling males were observed during torrential rains. There are no permanent water bodies around the study area and the species were found to breed in temporary muddy puddles. No activity was observed for the two species between the intermittent showers.

Advertisement call: ( Fig. 12 ; Table 5 ): The advertisement calls of Sphaerotheca varshaabhu sp. nov. ( Fig. 12 , fourth from top: A&B; Table 5 ) are long and pulsatile. The call repetition rate is low and inter-call interval is high. The call duration is long. The calls had a mean duration of 823.15 ± 95.21 ms (742–928.60 ms) with a mean pulse rate of 128.16 ± 6.18 pulses/s (119.53–134.24 pulses/s) and mean of 104.75 ± 7.93 pulses per call (98.00–115.00 pulses/call). The call repetition rate was 0.53 ± 0.08 calls/min (0.44–0.58 calls/min). The mean dominant frequency was 3649.88 ± 41.23 Hz (3617.58–3703.71 Hz). We heard the similar advertisement calls from two more calling males of S. varshaabhu sp. nov. in the surroundings. Also, we heard the calls of S. bengaluru occurring in same habitat at same time that S. varshaabhu sp. nov. was calling. S. varshaabhu sp. nov. and S. bengaluru are syntopic. Further observations are needed to confirm partitioning in their calling microhabitat.

Figures

FIGURE 2. Mitochondrial 16S rRNA gene based Maximum Likelihood (ML) tree for the species of Sphaerotheca Günther.

FIGURE 3. Sphaerotheca breviceps (ZSI/WRC/A/1546) dorsal, ventral, tarsal region and webbing diagram from the topotypic collections of Padhye et al. (2017).

FIGURE 6. Sphaerotheca varshaabhu sp. nov. in life from the type locality A. male; B. female.

FIGURE 7. Sphaerotheca varshaabhu sp. nov. holotype (ZSI/WRC/A/ 2571) dorsal, ventral, tarsal region showing tarsal tubercle and webbing diagram.

FIGURE 8. Habitat of Sphaerotheca varshaabhu sp. nov. from the type locality.

FIGURE 11. Map showing known approximate range of distribution for the recognized species of Sphaerotheca Günther, 1859 and an unnamed lineage from south Asia.

FIGURE 12. Schematic illustrations of advertisement calls of Sphaerotheca bengaluru (recorded in Budumanhalli; calling site air temperature: 21 °C), Sphaerotheca maskeyi (data from Prasad et al. (2020)), recorded in Panna Tiger Reserve; calling site air temperature: 28.5 — 29.8 °C), Sphaerotheca cf. breviceps [swani] (recorded in Nawadih, Koderma; calling site air temperature: 27.4 °C), and Sphaerotheca varshaabhu sp. nov. (recorded in Budumanhalli; calling site air temperature: 21 °C). A represents — oscillograms and B represents —spectrogram (FFT size = 1024 pts, Hanning window, 43.1 Hz resolution).