Agasthyagama edge, Das & Pal & Narayanan & Subin & Palot & Rajkumar & Deepak, 2024

Das, Sandeep, Pal, Saunak, Narayanan, Surya, Subin, K., Palot, Muhamed Jafer, Rajkumar, K. P. & Deepak, V., 2024, Discovery of a new species of kangaroo lizard (Squamata: Agamidae: Agasthyagama) from the southern Western Ghats of India, Vertebrate Zoology 74, pp. 151-168 : 151

Agasthyagama edge sp. nov.

Figures 6 , 7 , 8 , 9 , 9B, Table 2

Holotype.

ZSI/WRC/R/1165, an adult male (SVL 42.5 mm) (Fig. 6 ) collected from roadside disturbed tropical semi-evergreen forest patch in Kulamavu, Idukki district, Kerala, India (9.814150°N, 76.889926°E; 808 m a.s.l) by Sandeep Das, Muhamed Jafer Palot and K. Subin on 29 October 2021

Paratypes.

ZSI/WRC/R/1166, ZSI/WRC/R/1167 (adult males) collection details same as holotype and ZSI/WRC/R/1168 and ZSI/WRC/R/1169 (adult males), ZSI/WRC/R/1170 (adult female) collected by the same team on the same day as the holotype from a similar disturbed forest patch (9.845741°N, 76.942100°E; 856 m a.s.l) on the roadside near to Kuyilimala bus stop, Idukki District, Kerala, India which is approximately seven km aerial distance from the holotype locality; ZSI/WRC/R/1171, ZSI/WRC/R/1172 (adult males), ZSI/WRC/R/1173 (subadult male) collected near Uppukunnu Government Tribal School, Idukki District (9.845061°N, 76.881476°E; 636 m) by Muhamed Jafer Palot and Sandeep Das on 25 July 2017. BNHS 3222 and BNHS 3223 (subadult males) collected by Muhamed Jafer Palot and Sandeep Das, on 26 July 2017 from Idukki.

Comment.

There are no previous records of Agasthyagama from the mountains in Idukki district. Sivagiri hills according to a map provided by Smith (1935) is on the Eastern slopes of the Western Ghats immediately north of the Shencotta/ Shencottah gap.

Etymology.

The species is named after the Zoological Society of London’s EDGE of Existence Program who supported SD and RKP, and several early career conservation researchers across the globe in their projects on evolutionarily distinct species. EDGE is an acronym for Evolutionarily Distinct and Globally Endangered. The specific epithet “edge” is a patronym as a noun in apposition. We suggest common name "northern kangaroo lizard" and വടക ൻ ക ംഗാരു ഒ ാന്ത് (vadakan kangaroo oanth) as a regional Malayalam name.

Diagnosis and comparison.

A small-sized agamid (SVL 30-42.5 mm; n = 11) lizard characterised by the presence of heterogenous dorsolateral scales, oriented backwards, small overlapping scales with larger often trihedral scales; larger scales roughly forming 5 or 6 chevron shaped ridges on mid dorsum from nuchal region to above cloaca; strongly keeled enlarged scales randomly scattered laterally, 76-82 rows of scales around midbody; head with unequal keeled scales, supraciliary Agasthyagama edge sharp; a small antehumeral pit present, tympanum concealed; nuchal and dorsal crests absent; ventral scales strongly keeled, larger than lateral scales, 73-80 ventrals from mentum to cloaca; gular scales at the mid-line nearly equal to the adjacent scales; males with a small dewlap, 32-35 scales from mentum to last dewlap scale; limbs slender, covered with larger keeled scales; 4th digit on pes much longer than others, 5th digit on pes much reduced. Uniform olive-brown body, with lighter, enlarged scales laterally, mid dorsum paler; breeding males with pale peach to grey mid dorsum; dewlap in breeding males with pale bluish-white centre flanked by reddish-brown stripe.

Agasthyagama edge sp. nov. is the second species from the recently recognised genus Agasthyagama . It is superficially similar to A. beddomii in overall shape, size and colour but can be distinguished by combination of the following characters: 49-58 dorsal scales from behind occiput to above cloacal ending (vs. 60-67 dorsal scales in A. beddomii ) and 32-35 dewlap ventral scales in males (vs. 37-44 dewlap ventral scales in males of A. beddomii ). Additionally, dewlap stripe in breeding males of A. edge sp. nov. grey brown from mentum, gradually forming a brick-red elongated circle with pale bluish-white scales at the centre (vs. darker stripe with brick-red circle bordered with bright yellow scales on the outside and with a bright yellow to orange blotch at the centre in breeding males of A. beddomii ).

Description of the holotype (ZSI/WRC/R/1165).

The holotype is generally in good condition; hemipenis everted, exposed and visible on both sides when viewed dorsally (Fig. 3A ). Tail entire, curved towards the left; head slightly tilted towards the left a small incision of ca. 4 mm to extricate tissue, are artefacts of preservation. An adult male (SVL: 42.5 mm), morphometric and meristic data are summarised in Table 2. General habitus moderately compressed. Head moderately large (HL/SVL = 0.30), elongate (HW/HL = 0.63), maximum height less than maximum width, not depressed (HH/HL = 0.58). In profile, snout pointed, steeply tapering to a pointed tip; snout moderately long (SO/HL = 0.43), longer than orbital diameter (OD/SO = 0.73). Orbit large (OD/HL = 0.31); pupil round, eyelids covered with small rounded scales, a single row of scales bordering eyelids slightly elongate; four supraciliaries on each side, elongate, similar in size, with single anterior most supraciliary smallest. Canthals and supraciliaries imbricate, laterally forming a distinctly protruding supraorbital ridge. Rostral rectangular, approximately three times wider (1.6 mm) than high (0.6 mm), bordered by seven scales including first supralabial. Nostrils circular, positioned in upper half of a single roughly pentagonal nasal shield; nasal bordered by seven scales on each side, including one prenasal, one supranasal, two postnasals, with two subnasals and the first supralabial on left side, and three subnasals on right side; separated on both sides from rostral by prenasal (Fig. 6D ). Supralabials roughly rectangular, more or less equal-sized, posterior-most being longest, bordered above by a row of scales starting behind prenasal; eight supralabials on the left, nine on the right side. Loreal region with irregularly arranged, flat to partially keeled scales; scales surrounding orbit, small, granular. Scales on postorbital and temporal region heterogeneous in shape and size, flat. Dorsal forehead and snout scales heterogeneous in size, weakly tubercular at the edges, becoming keeled on the supraorbital region and rear of the head. Scales on occipital region heterogeneous in shape and size; smaller scales weakly tubercular, larger ones with distinct keels. Parietal eye oval, longitudinally oriented, partially visible through a roughly rhomboid parietal which is subequal in size to contacting scales, with much smaller posteriorly. Single small spinose scale along the upper posterior temporal region, another small sharply keeled, partly spinose scale in the post tympanic region on each side; tympanum concealed. Mentum subpentagonal, longer than wide, slightly narrower than rostral; bordered laterally by a first infralabial and posteriorly by a pair of elongated postmentals, subequal in length to the mentum but do not contact each other, bordered posteriorly by a row of two enlarged chin shields, postmental pairs flat; 10 infralabials on each side. Remaining gular scales imbricate to subimbricate, subequal in size, partially keeled scales towards the side while central gular scales strongly keeled. Posterior gular region with enlarged, flat, strongly keeled, pointed, imbricate scales; anterior gular scales smaller, subimbricate; all gular scales directed posteromedially except a few median rows which are directed posteriorly. A small but distinct gular pouch present up to anterior to the forelimb insertion (Fig. 6E ). Ventral scales larger than scales on posterior gular region, enlarged, flat, strongly keeled, pointed, imbricate, fairly homogenous; arranged in regular longitudinal rows directed posteriorly, 34 scales from mentum to last dewlap scale, 40 scales from posterior end of dewlap to cloacal opening. (Fig. 6E ). Nuchal and dorsal crest absent (Fig. 6C ). Scales on the nuchal region are smaller, less than half the size of those on the interorbital region, imbricate, strongly keeled. Body slender, relatively long (TrL/SVL = 0.40); 79 rows of scales around midbody; dorsal scale row with 53 scales, five transverse chevron shaped marking directed backwards from back of neck until groin along the vertebral region composed of three or four larger, sharply keeled trihedral dorsal scale rows on either side, separated by smaller dorsal scales; scales on flanks heterogeneous, smaller than those on back, oriented posteroventrally, partially keeled, intermixed with scattered larger, strongly keeled scales (Fig. 7B ). Fore and hindlimbs relatively slender, tibia short (CL/SVL = 0.33); digits moderately long, ending in strong, elongate, slightly recurved claw; inter-digital webbing absent; subdigital lamellae entire, bi-mucronate, 14 subdigital lamellae on digit IV of manus and 17 subdigital lamellae on digit IV of pes including claw sheath; relative length of digits on manus 4> 3> 2> 5> 1, of pes 4> 3> 2> 1> 5. Fore and hindlimbs covered above and below with regularly arranged, enlarged, pointed, strongly keeled scales. Tail moderately long (TL/SVL = 1.86), entire, base swollen, uniformly covered with similar sized, keeled, pointed, regularly arranged, backwardly directed imbricate scales; subcaudal scales keeled, weakly pointed near base, becoming pointed posteriorly.

Colour in life.

Uniform dull olive-brown body with slightly darker head, few light and darker enlarged scales scattered laterally; mid dorsum paler, forming a broad pale peach band from behind the head continuing till above tail, flanked by a thin almost broken stripe, most prominent above shoulder and above groin where it turns orangish (Fig. 9 A, B , 10B ). Body colouration paler towards lower flanks and much darker near the shoulder and around the antehumeral pit region, laterally continuing to the orbit. Head laterally darker with a pale white, roughly triangular patch from behind nasal plate extending below the midorbit; another narrow, conical pale stripe from posteroventral margin of orbit extending to the last labials; nasal shield darker followed by small alternating dark speckles on the supralabials, labials white to pale grey, interrupted by darker speckles. Head above uniform with a dark brown transverse band across the forehead, connecting supraorbitals. Abdomen pale off-white to buff in colour with few brown speckles on some scales. Forelimbs and hindlimbs darker suffused with alternating bands, a distinct pale peach band across upper arm of forelimb and a narrow light band just below elbow on the dorsal side; hind limbs with alternating light and dark brown bands, a distinct pale white to buff marking at the knee junction; digits roughly banded with light and dark markings. Tail uniform darker with few obscure lighter patches laterally, roughly forming dark and light bands towards latter half of the tail. Gular region with a central dark brown stripe starting from posterior half of the mentum, gradually becoming elongated brick red stripe abruptly ending at posterior half of neck, the latter half of stripe forming an elongated oval shape with a row three to four bluish-white scales (Fig. 2 ). Throat scales along both sides of the stripe pale bluish-white, all the way till anterior junction of forelimbs, roughly speckled with small brown spots.

Colour in preservative.

Entire dorsal surface of the body from the back of the head extending onto the tail, between the dorsolateral keels is pale creamy white, dorsal surface of the head pale brown, supraorbital stripe distinct. Lateral surface of head pale brown followed by darker brown marking below eye, narrow stripe from posterior end of eye distinct, pale creamy white. Body laterally uniform dark brown, speckled with few light grey to white scales. Limbs pale grey with darker blotched towards the digits. Abdomen, underside of limbs and tail dirty white intermixed with darker scales. Throat stripe brown with pale creamy white scales at the centre. Scales adjacent to the stripe buff to creamy white.

Variation.

Morphometric and meristic data for the type specimens is presented in Table 1. The adult paratypes include nine male specimens ranging from 30-41.1 mm in SVL and one female specimen (ZSI/WRC/R/1170) with an SVL of 33.7 mm (Fig. 8 ). The paratypes agree with the holotype (ZSI/WRC/R/1165) in general morphology and scalation except for the following characters: 76-82 rows of scales around midbody; 49-58 rows of dorsal scales from behind occiput to above cloacal ending; male paratypes with 32-35 dewlap ventral scales; 13-15 subdigital lamellae under fourth finger, 17-22 subdigital lamellae under fourth toe; 9 or 10 supralabial and 8-10 infralabial scales. The female paratype, ZSI/WRC/R/1170 agrees with the holotype in overall scalation except that it lacks the small dewlap, has 78 ventral scales from mentum to cloaca and tail base not swollen. In colouration overall darker reddish brown, vertebral band paler, not as prominent as in males; head overall darker with a distinct creamy white stripe from below the eye till posterior end of labials; supraorbital band distinct, flanked by a narrow creamy white stripe; five distinct black chevron shaped transverse band, pointed backwards; abdomen pale buff, throat reddish brown with medial stripe; tail darker greyish brown. The male paratypes generally similar to the holotype in colouration. Subadults (ZSI/WRC/R/1173, BNHS 3222 and BNHS 3223) overall paler with darker markings on vertebral region, stripes on head lighter cream to buff.

Natural History and Distribution.

Agasthyagama edge sp. nov. is currently known only from the type locality and its vicinity and appears to be relatively common in the type locality (Fig. 10A ). The habitat type at the type locality is evergreen forests. All records of this species are between 636-835 m elevation. In most of our surveys between 2016-2022 a minimum of 20 and a maximum of 50 individuals were sighted within a three-kilometre stretch within two hours of search. A greater number of individuals were encountered during March-May months. In disturbed habitats like roadside vegetation, and plantation areas, the numbers were smaller compared to undisturbed vegetation types. Males had a creamy throat patch during the breeding months of March to May (Fig. 3 ). Young ones were observed during June and July.

Figures

Figure 2. Maximum likelihood phylogeny for Agasthyagama and its three sister genera using the concatenated 16 S and ND 2 genes. Numbers on internal branches are Bayesian posterior probability / ML bootstrap support values. See Appendix 1 for data sources. Inset images of the two Agasthyagama species showing differences in throat coloration and pattern.

Figure 3. Asulcal view of hemipenis: A Agasthyagama edge sp. nov. (Holotype ZSI / WRC / R / 1165); B A. beddomii (FMNH 217760). Photographs by Saunak Pal and V. Deepak.

Figure 6. Holotype of Agasthyagama edge sp. nov. (ZSI / WRC / R / 1165): A dorsal, B ventral view of body; C dorsal, D lateral, E ventral view of head. Scale bars 10 mm. Photographs by Saunak Pal.

Figure 7. Scales on trunk of holotype of Agasthyagama edge sp. nov. (ZSI / WRC / R / 1165): A dorsal view, B lateral view, C ventral view. Scale bars 10 mm. Photographs by Saunak Pal.

Figure 8. Paratype series of Agasthyagama edge sp. nov.: A dorsal view, B ventral view. Image not to scale. Photographs by Saunak Pal.

Figure 9. Agasthyagama edge sp. nov. in life: A uncollected adult male from Kulamavu, Idukki; B uncollected female from the same locality. Photographs by Sandeep Das.

Figure 10. A Habitat at the type locality of Agasthyagama edge sp. nov. in Kulamavu, Kerala, India. B In-situ image of an uncollected female in its habitat at the type locality. Photographs by Sandeep Das.