Cyrtodactylus exercitus, Purkayastha & Lalremsanga & Litho & Rathee & Bohra & Mathipi & Biakzuala & Muansanga, 2022

Purkayastha, Jayaditya, Lalremsanga, Hmar Tlawmte, Litho, Beirathie, Rathee, Yashpal Singh, Bohra, Sanath Chandra, Mathipi, Vabeiryureilai, Biakzuala, Lal & Muansanga, Lal, 2022, Two new Cyrtodactylus (Squamata, Gekkonidae) from Northeast India, European Journal of Taxonomy 794, pp. 111-139 : 115-127

Cyrtodactylus exercitus sp. nov.

urn:lsid:zoobank.org:act:820A0B94-A800-4852-BB4A-A7BDF9D1156B

Figs 1–3A–C , 4 , 5B , 6 ; Tables 1–3

Diagnosis

Cyrtodactylus exercitus sp. nov. is a moderate-sized gecko (adult SVL 48.2–68.0 mm); 9–11 supralabials; 9–10 infralabials; dorsal tubercles are rounded, bluntly conical and feebly keeled in 21–24 longitudinal rows; 32–34 paravertebral tubercles between the level of the axilla and the level of the groin; 35–37 midventral scale rows; 11–15 precloacal pores in males; 16–17 subdigital lamellae under IV toe; no single row of transversely enlarged subcaudal scales; dorsal markings are dark brown, irregular blotches with a distinctive white posterior border; tail with alternating dark and light bands.

Differential diagnosis

Genetically, Cyrtodactylus exercitus sp. nov. is a sister taxon to the lowland species C. guwahatiensis , differing from each other by an uncorrected p-distance of 4.21%–4.25%, as in Fig. 2 and Table 2 . Morphological and meristic data are shown in Table 3 . Cyrtodactylus exercitus sp. nov. has been compared morphologically with all known members of the genus Cyrtodactylus within the khasiensis group. Morphologically, Cyrtodactylus exercitus sp. nov. is close to C. ayeyarwadyensis but differs from the latter by having greater TRL/SVL ratio (0.45–0.57.1, avg 0.51 in C. exercitus sp. nov. and 0.40 in C. ayeyarwadyensis ); in C. ayeyarwadyensis dorsum is with transverse rows of rectangular brown blotches vs W-shaped dorsal blotches in Cyrtodactylus exercitus sp. nov. Cyrtodactylus exercitus sp. nov. can be differentiated by having a smaller maximum adult size, SVL 68.0 mm maximum vs maximum adult size 81.7 mm in C. arunachalensis , 78.0 mm in C. ayeyarwadyensis , 77.0 mm in C. bapme , 72.5 mm in C. bengkhuaiai , 88 mm in C. brevidactylus , 79.78 mm in C. cayuensis , 96.2 mm in C. jaintiaensis , 80.0 mm in C. kazirangaensis , 81.1 mm in C. khasiensis , 72.0 mm in C. markuscombaii ( Darevsky, Helfenberger, Orlov & Shah, 1998) , 82.0 mm in C. martinstolli , 74 mm in C. mombergi , 78.2 mm in C. montanus , 72.0 mm in C. nagalandensis , 90.0 mm in C. tamaiensis , and 74.0 mm in C. urbanus . Cyrtodactylus exercitus sp. nov. has 11–15 PcP in males vs 7–8 PcP in C. aaronbaueri , 6–10 PcP in C. arunachalensis , 5–7 PcP in C. bengkhuaiai , 8–9 PcP in C. brevidactylus , 6–9 PcP in C. cayuensis , 10 PcP in C. himalayicus , 7 PcP in C. markuscombaii , 0–8 PcP in C. martinstolli , 8–10 PcP in C. montanus , 34–38 PcFP in C. karsticola , 26–39 PcFP in C. guwahatiensis , 29–37 PcFP in C. tripuraensis , 40 PcFP in C. tamaiensis , 16–29 PcFP in C. gansi ; 21–24 rows of feebly keeled tubercles in the dorsum vs 27–30 rows in C. brevidactylus , 16–20 rows in C. chrysopylos , 19–20 rows in C. jaintiaensis , 18 rows in C. mandalayensis , 14–15 rows in C. markuscombaii ,16–18 rows in C. nagalandensis and 19–21 rows in C. tripuraensis , 35–37 rows of scales between the ventrolateral folds vs 38 rows in C. arunachalensis , 47–49 rows in C. aunglini , 28–34 rows in C. cayuensis , 39–55 rows in C. chrysopylos , 30–35 rows in C. guwahatiensis , 33–34 rows in C. himalayicus , 40–42 rows in C. jaintiaensis , 37–43 rows in C. kazirangaensis , 32 rows in C. mandalayensis , 38–39 rows in C. markuscombaii , 57 rows in C. myaleiktaung , and 30–34 rows in C. urbanus . Cyrtodactylus exercitus sp. nov. has 16–17 subdigital lamellae beneath fourth toe vs 19–23 subdigital lamellae in C. aunglini and C. chrysopylos , 18–19 in C. brevidactylus , 10 in C. himalayicus and C. gansi , 19–22 in C. khasiensis and C. mombergi , 13 in C. martinstolli , and 18 in C. myaleiktaung . Cyrtodactylus exercitus sp. nov. has 9–11 paired dark blotches on the dorsum vs 7–8 C. gansi , 6–7 in C. kazirangaensis , 6 in C. myaleiktaung and 6–8 in C. urbanus . Cyrtodactylus exercitus sp. nov. can further be differentiated from C. agarwali and C. bapme by having a higher TRL/SVL ratio (min. 0.45 max. 0.57 avg. 0.51 vs min. 0.42 max. 0.48 avg. 0.45 in C. agarwali ; min. 0.43 max. 0.47 avg. 0.45 in C. bapme ). The presence of 32–34 rows of paravertebral tubercles between the level of axilla and groin separates Cyrtodactylus exercitus sp. nov. from C. aaronbaueri (36–39 rows), C. agarwali (34–38 rows), C. aunglini (36–45), C. bengkhuaiai (35–41), C. karsticola (34–39 rows), C. kazirangaensis (36–38), C. mombergi (35–42), C. montanus (37–43), C. nagalandensis (35–37) and C. septentrionalis (38–42 rows). Furthermore, Cyrtodactylus exercitus sp. nov. has small uniform scales on the underside of the tail, whereas C. cayuensis , C. khasiensis , and C. martinstolli have an enlarged median scale line.

Etymology

The specific epithet ‘ exercitus ’ is used as a noun in apposition in honour of the Indian army.

Suggested common name

Indian army’s bent-toed gecko.

Material examined

Holotype INDIA • adult ♂; Meghalaya state, Ri-Bhoi district, Umroi military cantonment area , within a small stretch of rocky caves; 25.689753°N, 91.949835°E; alt. 932 m; 3 Aug. 2021; Y. S. Rathee and J. Purkayastha leg.; rock substrata ( Fig. 7A ); GenBank accession number OK247679 ; MZMU2542 ( Figs. 3A , 4 , 5A ). Paratypes (n = 3) INDIA • adult ♀; same collection data as for holotype; MZMU2543 ( Figs 3B , 6 ) , • adult ♂; same collection data as for holotype; MZMU2544 ( Fig. 6 ) • adult ♂; same collection data as for holotype; GenBank accession number OK247680 ; MZMU2545 ( Figs 3C , 6 ) .

Description of holotype

Holotype is in generally good preservation condition ( Fig. 4 ). Adult male, SVL 68.0 mm.

HEAD. Head length slightly more than one-quarter of the snout to vent length (HL/SVL 0.29), longer than broad (HW/HL 0.63), somewhat depressed (HD/HW 0.59), and distinct from the neck; loreal region with granular scales; interorbital region is concave; canthus rostralis broadly rounded; snout is less than half of the head length (SO/HL 0.39), less than twice as long as the orbit diameter (OD/SO 0.56); scales on the forehead, canthus rostralis snout homogeneous. Scales from the posterior margin of the eyes to the nape are smaller than those of the forehead, somewhat blunt and juxtaposed; scales on forehead till the interorbital region without distinct tubercles. Orbit diameter is less than one-quarter of the head length (OD/HL 0.22) ( Fig. 4D ); pupil vertical with crenulate margins; superciliary scales are decreasing in size towards posterior of the eye; ear opening small (EL/HL 0.12) oval, obliquely orientated; eye to ear distance is shorter than the eye diameter (OE/OD 0.96). Rostrum slightly wider than long (RL/RW 0.89), partially divided dorsally by a weakly developed rostral groove; single enlarged supranasal on either side, separated by a single scale, little larger than enlarged scales on the snout; rostrum in contact with the first supralabials, nasals, supranasals and internasals; nostrils round, opening laterally orientated, three-fourth covered by the nasal pad, each nasal in broad contact with the rostral and surrounded by a supranasal, first supralabial, and three postnasals ( Fig. 4E ); mental wider than long (ML/MW 0.81), triangular; two well developed postmentals on either side, the inner pair less than twice the size of the outer pair (PMIIL/ PMIL 0.8); inner postmentals in contact with the mental, infralabial I, one outer postmental and two gular scales; outer postmental on each side is in contact with one inner postmental, infralabials I and II, and two to four gular scales; ten and eleven supralabials on each right and left side respectively, nine and ten infralabials on each right and left side respectively, infralabials II to IV bordered ventrally by a row of enlarged gular scales, largest anteriorly; gular region mostly covered with small granular scales except for a few rows bordering the mental, postmentals and infralabials which are larger, flat and juxtaposed ( Fig. 4F ).

BODY. Moderately slender; trunk length is half of the snout to vent length (TRL/SVL 0.53); dorsal scales heterogeneous, mostly rounded granular scales, intermixed with irregularly arranged, enlarged tubercles, bluntly conical and keeled throughout, becoming more keeled, conical and slightly smaller towards dorsolateral side and the flanks; largest on the pre sacral and sacral regions; tubercles extend posteriorly from the occipital region to beyond the tail base; tubercles on the nape are smaller than those on the dorsum; 22 mid-body rows of dorsal tubercles; 32 paravertebral tubercles between the level of the axilla and the level of the groin ( Fig. 4C ); ventral scales are larger than dorsals, smooth, cycloid, imbricate to subimbricate, smallest in the throat region gradually becoming enlarged, with largest being in the mid-abdominal region. Thirty-seven mid-ventral scale rows ( Fig. 4B ); fifteen precloacal pores in a continuous series with six pitted scales on the femoral region on the left and right sides interrupted by seven and six non pitted or pored scales, respectively ( Fig. 5A ). Scales posteriorly bordering the porebearing scale series are almost of the same size as the pore-bearing scales; three post cloacal tubercles on each side of the tail base.

LIMBS. Forearm (FL/SVL 0.16) and tibia (CL/SVL 0.18) short; digits laterally compressed, without a scansorial pad, strongly inflected at each joint, all bearing robust, recurved claws; subdigital lamellae transversely widened beneath the basal phalanx; basal lamellae 4–5–5–6–4 on the left manus, 5–5–6–6–5 on the left pes; distal lamellae (intervening rows of nonlamellar granular scales between basal and distal lamellae series in parentheses): 6(2)–8(1)–10(1)–10(1)–8(3) on the left manus, 7(0)–9(1)–10(1)–10(3)– 9(1) on the left pes; interdigital webbing absent from both manus and pes; relative length of digits: I <II <III <V <IV on the left manus, I <II <V <III <IV on the left pes; scales on the palms and soles are smooth, weakly raised, subimbricate; scales on the forelimbs are heterogeneous in size, comprising flat, subimbricate scales, ventral portion covered with heterogenous sized imbricate scales; scales on the hindlimbs are heterogeneous in size, dorsal surfaces of thighs and shanks with small granular scales, intermixed with scattered, enlarged, conical, keeled tubercles; strongly keeled tubercle on the tibia region; ventral surfaces of hindlimbs with enlarged, smooth, imbricate scales.

TAIL. Original, entire, gradually tapering from the base to the tip; dorsal caudal scales smooth, rounded, subimbricate, large at anterior region becoming smaller posteriorly; poorly developed tubercles limited to the anterior part of the tail. Ventral caudal scales much enlarged than the dorsal caudal scales; no transversely enlarged subcaudal plates.

COLOURATION IN LIFE. Dorsum of body grayish brown; head is primarily brown in colour with a few yellowish patches in the snout region and gray patches towards the posterior end of the head; supra ocular brownish yellow in colour. Nape has a white “W” streak with two dark brown blotches in it. Lateral surface of the post ocular region without any streak. The dorsal surface with nine pairs of dark brown vertebral blotches, each forming a “W” shaped pattern and have a distinct white border at the posterior surface of the dark brown “W” patterns ( Fig. 3A ). The ventral region is off-white in colour.

The tail has alternating light (13) and dark (14) bands. The first three dark bands are “W” shaped and the light bands are dirty white in colour.

COLOURATION IN PRESERVATIVE. The colour is pale in comparison to the live specimen. The dark spots on the dorsum have turned brownish-black ( Fig. 4 ).

Taxonomic remarks

Refer to Table no. 3 for meristic, morphometric and basic pholidosis variation within the type series of Cyrtodactylus exercitus sp. nov. The type series of C. exercitus sp. nov. is comprised of three males (two

adults (MZMU2542, MZMU2545) and a sub-adult (MZMU2544), and one female (an adult MZMU2543). Paratype MZMU2543 has visibly pitted scales (11) in its precloacal region.

Ecology and distribution

This species is only known from the type locality inside the Umroi army cantonment area. The type series was collected from a very small rocky patch within the cantonment area ( Fig. 7A ). All the individuals were collected just after dark from the crevices of the rock. During our survey, we could not find any Cyrtodactylus within the whole cantonment area except in this patch.

Figures

Fig. 1. Elevation map showing the type localities for the two newly described species of Cyrtodactylus and the congeners compared in this paper: 1. Cyrtodactylus exercitus sp. nov. (red star).2. C. siahaensis sp. nov. (blue star). 3. C. bengkhuaiai Purkayastha, Lalremsanga, Bohra, Biakzuala, Decemson, Muansanga, Vabeiryureilai, Chauhan & Rathee, 2021. 4. C. aaronbaueri Purkayastha, Lalremsanga, Bohra, Biakzuala, Decemson, Muansanga, Vabeiryureilai, Chauhan & Rathee, 2021.5. C. karsticolaPurkayastha, Lalremsanga, Bohra, Biakzuala, Decemson, Muansanga, Vabeiryureilai, Chauhan & Rathee, 2021. 6. C. agarwali Purkayastha, Lalremsanga, Bohra, Biakzuala, Decemson, Muansanga, Vabeiryureilai, Chauhan & Rathee, 2021. 7. C. montanus Agarwal, Mahony, Giri, Chaitanya & Bauer, 2018. 8. C. tripuraensis Agarwal, Mahony, Giri, Chaitanya & Bauer, 2018. 9. C. khasiensis (Jerdon, 1870). 10. C. jaintiaensis Agarwal, Mahony, Giri, Chaitanya & Bauer, 2018.11. C. guwahatiensis Agarwal, Mahony, Giri, Chaitanya & Bauer, 2018. 12. C. urbanus Purkayastha, Das, Bohra, Bauer & Agarwal, 2020. 13. C. septentrionalis Agarwal, Mahony, Giri, Chaitanya & Bauer, 2018.14. C. kazirangaensisAgarwal, Mahony, Giri, Chaitanya & Bauer, 2018. 15. C. nagalandensisAgarwal, Mahony, Giri, Chaitanya & Bauer, 2018. 16. C. arunachalensisMirza, Bhosale, Ansari, Phansalkar, Swant, Gowande & Patel, 2021.17. C. markuscombaii (Darevsky, Helfenberger, Orlov & Shah, 1998) and C. martinstolli Darevsky, Helfenberger, Orlov & Shah, 1998). 18. C. himalayicus (Annandale, 1906). 19. C. cayuensis Li, 2007. 20. C. tamaiensis (Smith, 1940). 21. C. ayeyarwadyensis Bauer, 2003. 22. C. mandalayensis Mahony, 2009.

Fig. 2. Maximum Likelihood phylogeny of the Cyrtodactylus khasiensis group; numbers at nodes represent bootstrap support (preceding the species name is the NCBI accession number).

Fig. 3. Cyrtodactylus exercitus sp. nov. in life (A. MZMU2542. B. MZMU2543. C. MZMU2545); Cyrtodactylus siahaensissp. nov.in life (D. MZMU2443.E. MZMU2444.F. MZMU2445.G. MZMU2446. H. MZMU2449. I. uncollected).

Fig. 4. Cyrtodactylus exercitus sp. nov., holotype (MZMU2542). A. Dorsal view. B.Ventral view. C. Details of dorsal pholidosis. D. Dorsal view of head. E. Lateral view of head. F. Ventral view of head.

Fig. 5. The arrangement of precloacal pores in A. Cyrtodactylus exercitus sp. nov., holotype (MZMU2542) B. Cyrtodactylus siahaensis sp. nov (MZMU2445).

Fig. 6. Type series of Cyrtodactylus exercitus sp. nov.

Fig. 7. Microhabitats showing the collection sites of our newly described species of Cyrtodactylus from Northeast India. A. Collection site of Cyrtodactylus exercitus sp. nov. in Umroi military cantonment area, Ri-Bhoi district, Meghalaya state. B–D. Collection sites of C. siahaensis sp. nov. in Siaha town, Siaha district, Mizoram state.