Sphaerotheca bengaluru, Deepak & Dinesh & Ohler & Shanker & Channakeshavamurthy & Ashadevi, 2020

Deepak, P., Dinesh, K. P., Ohler, Annemarie, Shanker, Kartik, Channakeshavamurthy, B. H. & Ashadevi, J. S., 2020, A new species of Sphaerotheca Günther, 1859 (Anura: Dicroglossidae) from the degraded urban ecosystems of Bengaluru, Deccan Plateau, India, Zootaxa 4885 (3), pp. 423-436 : 425-430

Sphaerotheca bengaluru sp. nov.

( Table 1 , 2 ; Figure 1–5 )

Holotype: ZSI / WRC /A/2284, an adult male ( SVL 47.3 mm) collected by Deepak and team on 14th July 2019 from a disturbed semi-urbanized agricultural site around Budumanahalli, (N 13.1876; E 77.5253, 850 msl), Bengaluru , Karnataka.

Paratypes: ZSI / WRC /A/2285, an adult male ( SVL 50.1 mm) collected by Deepak and team on 19th September 2019 from a disturbed semi urbanized agricultural site around Budumanahalli, (N 13.1973; E 77.5328, 850 msl), Bengaluru , Karnataka . ZSI / WRC /A/2286, an adult female ( SVL 55.5 mm) collected by Deepak and team on 18th September 2018 from a disturbed semi urbanized agricultural site around Budumanahalli, (N 13.1937; E 77.5299, 850 msl), Bengaluru , Karnataka .

Lineage diagnosis. Sphaerotheca bengaluru sp. nov. can be recognized phylogenetically as a member of the Sphaerotheca clade ( Fig. 2 ), showing a sister relationship to S. pashchima Padhye, Dahanukar, Sulakhe, Dandekar, Limaye & Jamdade, 2017 with which it is allopatric in distribution and has a high level of genetic divergence (4.8 % for the 16S rRNA fragment studied).

Morphological diagnosis. In the field Sphaerotheca bengaluru sp. nov. is sympatric with S. breviceps and can be distinguished in having a larger adult male size of SVL 48.9 mm (47.3 mm to 50.7mm), n=5 (vs. smaller adult male size SVL 30.4 mm (27.8 mm to 31.7mm), n=5); lower HL/ SVL ratio of 0.301 to 0.316, n=5 (vs. higher HL/ SVL ratio of 0.329 to 0.392, n=5); lower HW/ SVL ratio of 0.371 to 0.413, n=5 (vs. higher HW / SVL ratio of 0.421 to 0.466, n=5); lower IN/ SVL ratio of 0.060 to 0.078, n=5 (vs. higher IN / SVL ratio of 0.090 to 0.098, n=5); lower NE/ SVL ratio of 0.052 to 0.072, n=5 (vs. higher NE/ SVL ratio of 0.074 to 0.084, n=5); lower SL/ SVL ratio of 0.114 to 0.122, n=5 (vs. higher SL/ SVL ratio of 0.145 to 0.162, n=5); lower IUE / SVL ratio of 0.062 to 0.077, n=5 (vs. higher IUE / SVL ratio of 0.087 to 0.108, n=5); higher TYD / SVL ratio of 0.069 to 0.084, n=5 (vs. lower TYD / SVL ratio of 0.048 to 0.060, n=5); lower TE/ SVL ratio of 0.023 to 0.033, n=5 (vs. higher TE / SVL ratio of 0.041 to 0.058, n=5); lower FLL / SVL ratio of 0.177 to 0.218, n=5 (vs. higher FLL / SVL ratio of 0.219 to 0.274, n=5); lower FL/ SVL ratio of 0.386 to 0.428, n=5 (vs. higher FL / SVL ratio of 0.438 to 0.486, n=5); lower TiL/ SVL ratio of 0.360 to 0.394, n=5 (vs. higher TiL/ SVL ratio of 0.396 to 0.437, n=5); moderate webbing (I 0–1 II 1–1½ III 1–2 IV 2½–1 V) (vs. rudimentary webbing (I 1–2 II 1½–2½ III 2–3½ IV 4–2 V)); dorsum with specific banded colour pattern (vs. without specific banded pattern on the dorsum).

Sphaerotheca bengaluru sp. nov. can be distinguished from its probable phylogenetic sister species S. pashchima , in having a relatively larger adult male size of SVL 48.9 mm (47.3 mm to 50.7 mm) n=5 (vs. relatively smaller adult male size SVL 44.5 mm (40.8 mm to 55.7 mm) n=7); lower HL/ SVL ratio of 0.301 to 0.316, n=5 (vs. higher HL/ SVL ratio of 0.317 to 0.353, n=7); lower IN/ SVL ratio of 0.060 to 0.078, n=5 (vs. higher IN / SVL ratio of 0.088 to 0.112, n=7); lower SL/ SVL ratio of 0.114 to 0.122, n=5 (vs. higher SL/ SVL ratio of 0.135 to 0.158, n=7); tympanum about ½ the diameter of eye (vs. tympanum about ¾rd the diameter of eye); lower FLL / SVL ratio of 0.177 to 0.218, n=5 (vs. higher FLL / SVL ratio of 0.223 to 0.289, n=7); lower IMT / SVL ratio of 0.081 to 0.095, n=5 (vs. higher IMT / SVL ratio of 0.099 to 0.108, n=7); moderate webbing (I 0-1 II 1-1½ III 1-2 IV 2½-1 V) (vs. rudimentary webbing (I 1-2 II 1-3 III 2-3½ IV 3½-2 V)); type locality predominantly a disturbed urban habitat around Bengaluru (vs. type locality from Western Ghats and predominant distribution in the mid elevations of Western Ghats to Uttaranchal) .

Additionally, see the comparison section below for an updated morphological key to the ‘ breviceps group’ (after Dahanukar et al. 2017).

Occurrence and habitat. The new species is known from the mid-elevations of semi-urban agricultural lands of Budumanahalli, Arkere grama panchayath of Bengaluru which falls in the Deccan plateau region of India. This species is 700 km (aerial distance) from the type locality of its sister species S. pashchima which is one of the most widespread (from the Western Ghats to the foothills of Himalaya through Rajasthan) species of Sphaerotheca known from South Asia. In the field, Sphaerotheca bengaluru sp. nov. is sympatric with S. breviceps (type locality Tharangambadi, Tamil Nadu, India).

Description of holotype (ZSI/WRC/A/2284) ( Fig. 3A ). A moderate sized burrowing frog (SVL, 47.3 mm) with well built robust and stumpy body; head width more than head length (HW, 18.9 mm; HL, 14.2 mm); snout obtusely rounded (SL, 5.6 mm) sub-equal to eye diameter (EL, 6.4 mm); canthus rostralis bluntly angled, loreal region concave (caved in between the two raised eye balls), inter orbital space concave (IUE, 2.9 mm) less than upper eye lid (UEW, 4.8 mm) but equal to internarial distance (IN, 2.9 mm); distance between the back of eyes twice the distance in front of eyes (IFE, 6.7 mm; IBE, 14.0 mm); nostrils oval, nearer to the tip of snout than to eyes; tympanum distinct, almost half of the eye diameter visible below the sharply angled supratympanic fold (TYD, 3.3 mm) and close to the eye (TE, 1.1 mm); symphysial knob weak; vomerine ridges are closed place, left with 3 and right with 4 spiny tooth; tongue bifid without a papilla.

Fore arm robust and short (FLL, 10.3 mm) slightly shorter than the hand (HAL, 11.2 mm); finger short and thin without any dermal fringes, first finger (FL1, 4.8 mm) longer than the second (FL2, 3.1 mm) and subequal to the third finger (TFL, 5.5 mm), tips blunt without any enlarged discs, webbing between fingers absent; subarticular tubercles distinct, rounded and pre-pollex tubercle distinct, supernumerary tubercles absent.

Hind limbs short, just touching when folded at right angles to the body and tibio-tarsal articulation reaches the front of shoulders; femur length longer than tibia length (FL, 20.3 mm; TiL, 17.6 mm); foot length twice the length of tarsus (FOL, 20.7 mm; TAL, 8.5 mm), relative toe length I<II<V<III<IV (FTL, 10.7 mm); inner toe minute (ITL, 1.0 mm), webbing moderate (I 0–1 II 1–1½ III 1–2 IV 2½–1 V); inner metatarsal tubercle (IMT, 4.3 mm) distinct and sharp shovel shaped, outer metatarsal tubercle and supernumerary tubercles absent, tarsal tubercle prominent.

In preservative, entire dorsum slightly granulated with striped and blotched colour patterns. Head dorsally with a light cream triangle, forming the spear-shaped head of a light cream band extending from tip of snout to vent on mid-dorsum. On the head, on either side of canthus rostralis a cream band from the lower surface of eye to upper lip, a cream band from the back of eye towards the front of forearm through the anterior corner of tympanum and the mouth commissural region. On either side of the body, a cream band from the back of the eye above the supratympanic fold to the region of groin. On the dorsum, dark blackish brown blotches on the light brown background. Both the fore arm and hind limbs barred, front and back of thighs with cream reticulation pattern on dark brown ground. Ventral surface granular, region of throat light brown, belly and under surface of thighs cream white ( Fig. 4 ).

In life, entire dorsum dark brown with shades of orange and ornamented blotches with a clear pattern. A triangle, spear head shaped light orange band from tip of snout extending its tail to vent with a dorsolateral streak. On the head, on either side of canthus rostralis an orange cream band from the lower surface of eye to upper lip, an orange cream band from the back of eye towards the front of forearm through the anterior corner of tympanum and the mouth commissural region. On either side of the body, a bright cream orange band from the back of the eye above the supratympanic fold to the region of groin. On the dorsum, dark blackish brown blotches on the light brown background with light cream borders. Both the fore arm and hind limbs barred, front and back of thighs with yellow reticulation pattern on dark brown ground. Eye, diamond shaped pupil black, iris light golden yellow with fine blackish reticulations ( Fig. 3A ).

Secondary sexual characters. Among the amplected pairs, males are smaller than females ( Table 1 ) with light grey external vocal sac on throat ( Fig. 4B ) and glandular nuptial pad on the inner side of the first finger ( Fig. 4B ).

Additional information from paratypes, reference collections and variations. Paratypes and reference collections ranging for male SVL from 48.1 mm to 50.7 mm and female SVL from 50.1 mm to 55.5 mm. All the specimens were similar in other morphological characters and colour pattern; morphological data are given in Table 1 .

Etymology. The specific epithet is derived from the name ‘Bengaluru’, the type locality for the species and the species epithet is treated as a noun in apposition to the generic name. Suggested common name: “Bengaluru burrowing frog”.

Distribution and natural history. Sphaerotheca bengaluru sp. nov. is now known only from Budumanahalli village on the outskirts of Bengaluru with S. breviceps as its sympatric congener. During one of our visits in July 2019, only a few female individuals were seen emerging at night and feeding actively; during August 2019, both males and females were seen showing feeding activity at night with stray calls by males during light rain; during September 2019, male and females of Sphaerotheca bengaluru sp. nov. and S. breviceps were seen breeding actively next to temporary mud pools ( Fig. 5 ) during the northeast monsoon showers. Overall observations suggest that populations of both species are very limited around the type locality. Around temporary water bodies, 30 individuals were sighted in five visits. The absence of permanent water bodies and the burrowing nature of the species could explain their rarity around the type locality. The vegetation surrounding the type locality is primarily dominated by agroecosystems mixed with dry deciduous vegetation. Ponds and other water resources are seasonal and the area is under the influence of urban developmental activities. Additional sampling in the Deccan plateau is necessary to understand the range of distribution of the new species.

Comparisons. The distinct morphological characters like relative large size, robust body, head wider than long, rounded snout, inter orbital space less than upper eyelid, nostrils close to snout tip, distinct tympanum half of the eye diameter, sharply angled supratympanic fold, first finger longer than the second and sub equal to third finger, tibio-tarsal articulation reaches front of shoulders, moderate webbing, distinct inner metatarsal tubercle more than twice the inner to length and dorsum with a specific colour pattern, makes the identity of Sphaerotheca bengaluru sp. nov. unique from its 10 known congeners. The new species is compared in detail only with the known sympatric species S. breviceps and the probable phylogenetic sister species S. pashchima (see morphological diagnosis section above).

Additionally, the new species falls under the morphological ‘ breviceps group’ proposed by Dahanukar et al. (2017) and within the group, the new species can be identified morphologically using the following modified key of the ‘ breviceps group’.

* species included in the phylogenetic analysis

Figures

FIGURE 1. Map showing type localities of extant species of Sphaerotheca in South Asia.

FIGURE 2. Maximum Likelihood (ML) gene tree for species of Sphaerotheca based on 585 bp of mitochondrial 16S rRNA gene.

FIGURE 3. (A) Sphaerotheca bengaluru sp. nov. and (B) S. breviceps in life from the type locality.

FIGURE 4. Sphaerotheca bengaluru sp. nov. holotype in preservative (A) Dorsal view (B) Ventral view.

FIGURE 5. Habitat of Sphaerotheca bengaluru sp. nov. from the type locality, a degraded ecosystem of Bengaluru.