Euphlyctis kerala, Dinesh & Channakeshavamurthy & Deepak & Ghosh & Deuti, 2021

Dinesh, K. P., Channakeshavamurthy, B. H., Deepak, P., Ghosh, Avrajjal & Deuti, Kaushik, 2021, Morphological groupings within Euphlyctis (Anura: Dicroglossidae) and description of a new species from the surroundings of Thattekad Bird Sanctuary, Kerala, India, Zootaxa 4990 (2), pp. 329-353 : 335-344

publication ID	https://doi.org/ 10.11646/zootaxa.4990.2.7
publication LSID	lsid:zoobank.org:pub:CA6C0062-D733-4A3F-84C2-773481B81349
DOI	https://doi.org/10.5281/zenodo.5091927
persistent identifier	https://treatment.plazi.org/id/02B1DE04-C40C-4AAD-AC87-EF97673A4BF5
taxon LSID	lsid:zoobank.org:act:02B1DE04-C40C-4AAD-AC87-EF97673A4BF5
treatment provided by	Plazi
scientific name	Euphlyctis kerala
status	sp. nov.

Treatment

Euphlyctis kerala sp. nov.

( Table 1 View TABLE 1 , 2 View TABLE 2 ; Fig. 1 View FIGURE 1 , 2 View FIGURE 2 , 3 View FIGURE 3 , 4 View FIGURE 4 , 5 View FIGURE 5 , 6 View FIGURE 6 , 7 View FIGURE 7 , 8 View FIGURE 8 , 10 View FIGURE 10 )

Holotype: ZSI / WGRC /A/973, an adult male ( SVL, 32.1 mm) collected by B.H. Channakeshavamurthy and team on 13/10/2017 from the surroundings of the Thattekad Bird Sanctuary (N 10.1272, E 76.6840), Kerala. GoogleMaps

Paratypes: ZSI / WGRC /A/974 and ZSI / WGRC / A/975 two adult females ( SVL, 42.1 mm), collection details same as holotype .

Lineage diagnosis: Euphlyctis kerala sp. nov. is diagnosed phylogenetically as a member of larger ‘ Euphlyctis clade’ showing a sister relationship with E. aloysii (allopatric species) exhibiting a genetic divergence of 4.6 % for the 16S rRNA gene ( Table 4 View TABLE 4 ; Fig. 1 View FIGURE 1 ).

Field diagnosis: In the field Euphlyctis kerala sp. nov. is a member of morphological ‘ hexadactylus group’ sympatric in distribution with E. aff. cyanophlyctis (a ‘ cyanophlyctis group’ member) and allopatric in distribution with the phylogenetic sister species E. aloysii (a ‘ hexadactylus group’ member). The new species can be identified based on its combination of characters like male adult size small ( SVL, 30.7 to 32.1 mm) and medium sized females ( SVL, 36.2 to 42.1 mm); head length equal to head width; acutely pointed snout; snout equal to eye diameter; angled canthus rostralis with flat loreal region; inter orbital distance half of the upper lid width; distinct tympanum 68% of eye diameter; first finger equal to second finger; pre-pollex tubercle and supernumerary tubercles absent; hind limbs strongly overlap when folded at right angles to the body and tibio-tarsal articulation reaches front of eye; porous warts single row on either side; back of thigh with four white bands intervened with three dark chocolate bands. For the comparisons of Euphlyctis kerala sp. nov. with its sister lineage, sympatric and other congeners, see the comparison section below.

Geography: The species is known to have a restricted range of distribution in the south of Palghat gap, around the fresh water bodies in the surroundings of the Thattekad Bird Sanctuary, Kerala, India.

Description of Holotype (ZSI/WGRC/A/973) ( Fig. 3 View FIGURE 3 , 4 View FIGURE 4 , 5 View FIGURE 5 , 6 View FIGURE 6 ). A small sized skittering frog (SVL, 32.1 mm) with lean, elongated and squat body; head sub equal to head length (HW, 12.0 mm; HL, 13.7 mm); snout acutely pointed (SL, 5.0 mm) and sub equal to eye diameter (EL, 4.4 mm); canthus rostralis angled, loreal region flat, inter orbital space flat (IUE, 1.5 mm) half of the upper lid (UEW, 2.6 mm) and sub equal to internarial distance (IN, 1.5mm); distance between the back of eyes 1.6 times more than front of eyes (IFE, 5.1 mm; IBE, 8.6 mm); nostrils oval, on the lateral sides and nearer to tip of snout; symphysial knob moderate; tympanum distinct, visible below the supratympanic fold (TYD, 2.8 mm) and close to eye (TE, 0.8); vomerine ridges present, weak; tongue bifid without a papilla.

Fore arm robust (FLL, 5.8 mm), and shorter than hand (HAL, 9.3 mm); fingers thin without any dermal fringes, first finger (FL1, 3.2 mm) equal to second finger (FL2, 2.9 mm) and shorter than the third finger (TFL, 5.1 mm), tips blunt without any enlarged discs, webbing between fingers absent; subarticular tubercles moderate, rounded and pre-pollex tubercle and supernumerary tubercles absent.

Hind limbs short, strongly overlap when folded at right angles to the body and tibio-tarsal articulation reaches eye; femur length sub equal to tibia length (FL, 17.4 mm; TiL, 15.9 mm); foot length is 1.9 times tarsus length (FOL, 19.3 mm; TaL, 10.0 mm), relative toe length I<II<III<V<IV (FTL, 11.0 mm); inner toe minute (ITL, 2.5 mm), webbing complete, no phalanges free on toes; inner metatarsal tubercle (IMT, 1.4 mm) distinct, outer metatarsal tubercle, supernumerary tubercles and tarsal tubercle absent.

In preservative ( Fig. 4 View FIGURE 4 ), overall skin on the dorsum smooth uniform with few minute projected granular spots concentrated at the region of the vent; ventrally smooth on throat, belly, hands and back of thighs. Single row of porous warts on the lateral sides of the body.

Dorsum chocolate brown, thin straight single dorso-lateral line between the inter orbital space to vent; two lateral white bands from the front of the shoulder to groin; between the lateral white bands and the central thin line, light chocolate brown inverted ‘V’ shaped blotches leaving dark chocolate brown arrow headed markings on the back of the dorsum; below the two white lateral stripes brown band demarcating the ventral white skin and dorsal chocolate brown skin; upper surface of the forehand and hind legs without cross bands; back of thigh with four white bands intervened with three dark chocolate bands. Ventrally throat, chest and belly white; under surface of the forearm, hind leg mottled with brown.

In life ( Fig. 3 View FIGURE 3 ), dorsum dominated by green colour with brown background; mid dorsal thin white line, lateral two white bands prominent; inverted ‘heart shaped’ pattern on the dorsum due to background brown and upper green shades; single black band between two white bands at the back of thighs; tympanum region brown; stone black small patches at the region of supratympanic region, mouth commissure and groin. Eye diamond shaped, pupil black, iris golden brown.

Secondary sexual characters and sexual dimorphism: Males are smaller than females among the paired adults. In general females have grey spots on the entire ventral region ( Fig. 5 View FIGURE 5 ) when compared to males (cream white on throat, chest and belly).

Additional information from the paratypes (and other reference collections) and variations: Morphological data are given in Table 1 View TABLE 1 . All the males in the collections were ranging from 30.7 to 32.1 mm in SVL and females were ranging from 36.2 to 42.1 mm in SVL. In all the external morphological characters , holotype and paratypes were similar to the reference collections except for the colour characters for sexual dimorphism ( Fig. 5 View FIGURE 5 ).

Etymology: The new species is named after the western coastal state ‘Kerala’ of peninsular India which is home to the most number of endemic species of amphibians in India. The species epithet is treated as noun in apposition to the generic name. Suggested common name: ‘ Kerala skittering frog’.

Distribution and natural history: Euphlyctis kerala sp. nov. is known specifically from the freshwater bodies in the surroundings of Thattekad Bird Sanctuary, Kerala. The species is found to be locally common in the ponds adjacent to the river tributaries of the Periyar river in the lower elevations. More field explorations are needed in the low elevation freshwater bodies in the foot hills of the Western Ghats south of Palghat gap to decipher the exact range of distribution.

Comparisons. Euphlyctis kerala sp. nov. being a member of ‘ hexadactylus group’ can be easily distinguished from its congeners by a combination of characters like male adult size small (SVL, 30.7 to 32.1 mm) and medium sized females (SVL, 36.2 to 42.1 mm); head length equal to head width; acutely pointed snout; snout equal to eye diameter; angled canthus rostralis with flat loreal region; inter orbital distance half of the upper lid width; distinct tympanum 68% of eye diameter; first finger equal to the second finger; pre-pollex tubercle and supernumerary tubercles absent; hind limbs strongly overlap when folded at right angles to the body and tibio-tarsal articulation reaches front of eye; porous warts single row on either side; back of thigh with four white bands intervened with three dark chocolate bands.

The new species Euphlyctis kerala sp. nov. is compared with the sympatric species E. aff. cyanophlyctis based on the fresh collections and rest of the seven species based on the literature data of the respective species descriptions and other literature sources.

A multivariate Principal Component Analysis (PCA) was carried out with the new species (n=6) and the genetically confirmed sympatric populations of E. aff. cyanophlyctis (n=6) ( Fig. 6 View FIGURE 6 ). All the morphological measurements were size corrected by SVL. The PCA results suggested two different clusters on the scatter plot representing two different species Euphlyctis kerala sp. nov. (n=6) and E. aff. cyanophlyctis (n=6). For the combined data set for both males and females together, PC1 accounted for 44.8% variance (Eigen value of 13.4) and PC2 for 15.4% variance (Eigen value of 4.6) ( Fig. 6 View FIGURE 6 ). Although both the species cluster distinctly on the scatter plot of PCA, these two can be distinguished based on their morphological characters only (see morphological key).

Additionally, Euphlyctis kerala sp. nov. differs from E. aff. cyanophlyctis in having relatively smaller adult size SVL (mm) 37.0±4.5 (32.1 to 42.1), n=7 (vs. relatively larger SVL (mm) 46.0±10.8 (33.7 to 62.1), n=6); higher IN/ SVL ratio of 0.040 to 0.051, n=7 (vs. lower IN/SVL ratio of 0.018 to 0.032, n=6); higher MFE/SVL ratio of 0.292 to 0.332, n=7 (lower MFE/SVL ratio of 0.266 to 0.290, n=6); higher IUE/SVL ratio of 0.042 to 0.079, n=7 (lower IUE/SVL ratio of 0.033 to 0.039, n=6); lower IMT/SVL ratio of 0.040 to 0.050, n=7 (vs. higher IMT/SVL ratio of 0.051 to 0.064, n=6); first finger equal to second finger (vs. first finger longer than the second finger); hind limbs strongly overlap when folded at right angles to the body (vs. hind limbs just touches when folded at right angles to the body); porous warts single row on either side (vs. porous warts absent either side); back of thigh with four white bands intervened with three dark chocolate bands (vs. back of thigh with single white band); distribution restricted to lower elevations in the south of Palghat gap (vs. distribution in the lower elevations of both the north and south of Palghat gap).

The new species Euphlyctis kerala sp. nov. differs from the phylogenetic sister species E. aloysii in having a slightly smaller SVL up to 42.1 mm (vs. larger SVL up to 45.2 mm); head width equal to head length (vs. head wider than long); tympanum 62.5% to 69% of the eye diameter (n=5) (vs. tympanum sub equal to eye diameter (TYD, 2.6 to 4.5 mm; EL, 2.3 to 5.0 mm, n=24)); hind limbs strongly overlap when folded at right angles to the body (vs. hind limbs falls slightly apart when folded at right angles to the body); inner metatarsal tubercle distinct ( Fig. 8 View FIGURE 8 ) (vs. inner metatarsal tubercle indistinct ( Fig. 9 View FIGURE 9 )); supratympanic fold distinct and reaching the arm base ( Fig. 7D View FIGURE 7 , Fig. 8 View FIGURE 8 ) (vs. supratympanic fold thin and not reaching the arm base ( Fig. 7C View FIGURE 7 , Fig. 9 View FIGURE 9 )); back of thigh with four white bands intervened with three dark chocolate bands (vs. double white band at the back of thighs); in life dorsum with inverted ‘heart shaped’ pattern ( Fig. 3 View FIGURE 3 ) (vs. in life dorsum with large elliptical markings ( Fig. 7 View FIGURE 7 )); distribution restricted to south of Palghat gap in the Thattekad region of southern Western Ghats ( Fig. 10D View FIGURE 10 ) (vs. distribution restricted to north of Palghat gap in the Dakshin Kannada and Uttara Kannada region of central Western Ghats ( Fig. 10C View FIGURE 10 )).

Euphlyctis kerala sp. nov. differs from the sympatric congener E. karaavali in having smaller SVL up to 42.1 mm (vs. larger SVL up to 106.3 mm); head width equal to head length (vs. head wider than long); tympanum 68% of eye diameter (vs. tympanum 73% of eye diameter); back of thigh with four white bands intervened with three dark chocolate bands (vs. double white band at the back of thighs); only female ventral sides with light brown speckles (vs. adult male and female ventral side with brown reticulations); in life dorsum with inverted ‘heart shaped’ pattern ( Fig. 3 View FIGURE 3 ) (vs. dorsum with distinct elongated alternate stripe pattern ( Fig. 7 View FIGURE 7 )); distribution in the lower elevations to the south of Palghat gap, populations more towards the foot hills of the Western Ghats (away from the coastal belt) (vs. distribution from Uttara Kannada, Karnataka to Thiruvananthapuram, Kerala species populations more towards coastal region).

Euphlyctis kerala sp. nov. differs from the allopatric congener E. hexadactylus in having smaller SVL up to 42.1 mm (vs. larger SVL up to 130 mm); head width equal to head length (vs. head wider than long); back of thigh with four white bands intervened with three dark chocolate bands (vs. double white band at the back of thighs); tympanum 68% of eye (vs. tympanum 90% of eye); adult male ventral side without marking, adult female with small grey blotches (vs. ventral side without any reticulations); tibiotarsal articulation reaches front of eye (vs. tibiotarsal articulation reaches tympanum); in life dorsum with inverted ‘heart shaped’ pattern ( Fig. 3 View FIGURE 3 ) (vs. dorsum with distinct stripe pattern ( Fig. 7 View FIGURE 7 )); distribution in the lower elevations to south of Palghat gap (vs. distribution restricted to east coastal plains, Deccan plateau and foot hills of Eastern Ghats in India and Bangladesh).

Euphlyctis kerala sp. nov. differs from the allopatric congener E. cyanophlyctis in having smaller SVL up to 42.1 mm (vs. larger SVL up to 60.0 mm); head width equal to head length (vs. head wider than long); tympanum 68% of eye (vs. tympanum 85% of eye); nostrils nearer to snout tip (vs. nostrils nearer to front of eyes); hind limbs strongly overlap when folded at right angles to the body (vs. hind limbs falls slightly apart when folded at right angles to the body); inner metatarsal tubercle distinct (vs. inner metatarsal tubercle indistinct); back of thigh with four white bands intervened with three dark chocolate bands (vs. single white band at the back of thighs); in life dorsum with inverted ‘heart shaped’ pattern (vs. dorsum with irregular blotched pattern); distribution in the lower elevations to south of the Palghat gap (vs. distribution in the east coastal plains, Deccan plateau, eastern Indian plains and higher hill ranges of the central Western Ghats).

Euphlyctis kerala sp. nov. differs from the allopatric congener E. ehrenbergii in having smaller SVL up to 42.1 mm (vs. larger SVL up to 95 mm); head width equal to head length (vs. head wider than long); tympanum 68% of eye (vs. tympanum 60% of eye); in life dorsum with inverted ‘heart shaped’ pattern (vs. dorsum with irregular blotched pattern); distribution in the lower elevations of the south of Palghat gap, India (vs. distribution in the Arabian Peninsula).

Euphlyctis kerala sp. nov. differs from the allopatric congener E. ghoshi in having smaller SVL up to 42.1 mm (vs. larger SVL up to 60.0 mm); head width equal to head length (vs. head wider than long); snout acutely pointed (vs. snout rounded); tympanum 68% of eye (vs. tympanum 50% of eye); nostrils nearer to snout tip (vs. nostrils nearer to front of eyes); tibiotarsal articulation reaches the front of eye (vs. tibiotarsal articulation reaches tympanum); in life dorsum with inverted ‘heart shaped’ pattern (vs. dorsum with irregular blotched pattern); distribution in the lower elevations of the south of Palghat gap (vs. distribution in the Manipur region of north east India).

Euphlyctis kerala sp. nov. differs from the allopatric congener E. kalasgramensis in having larger SVL up to 42.1 mm (vs. smaller SVL up to 37.8 mm); head width equal to head length (vs. head longer than wide); back of thigh with four white bands intervened with three dark chocolate bands (vs. single white band at the back of thighs); in life dorsum with inverted ‘heart shaped’ pattern (vs. dorsum with irregular blotched pattern); distribution in the lower elevations of the south of Palghat gap, India (vs. distribution specifically from Bangladesh; in the Indian region locations bordering Bangladesh, West Bengal and Assam).