Cyrtodactylus khambui sp. nov.

Holotype. Adult male (CDZMTU502), collected from Dharan Basecamp Area, Sunsari District, Koshi Province, Nepal (26.8364° N, 87.2983° E, WGS 84, elevation 628 m asl) by Asmit Subba on 01 August 2023.

Paratypes. CDZMTU501 (male), CDZMTU503 (female), CDZMTU504 (male), CDZMTU505 (male), same data as holotype.

Etymology. The species-specific epithet is a patronym for Prof. Dr. Kalu Ram Rai Khambu, the first Nepali scholar to obtain a Ph.D. in herpetology and who has predominantly worked in eastern Nepal where the new species was discovered. We name the new species after Prof. Khambu to honor his contributions to herpetofaunal systematics and conservation in Nepal.

Suggested common name. Khambu’s bent-toed gecko

Diagnosis. Cyrtodactylus khambui sp. nov. can be diagnosed based on the following characters: (1) smallsized Cyrtodactylus, SVL 51.05–60.63 (2) tail long, TL 1.04–1.19% SVL; (3) head moderately proportioned and relatively flat HW 63.42%−60.79% HL, HD 38.7%−33.3% HL; (4) mid ventral scales 35−45; (5) ventral folds present; (6) dorsal pholidosis on trunk heterogeneous, consisting of rounded scales intermixed with feebly keeled scales; (7) ventral scales slightly larger than dorsals, semicircular, smooth, slightly upward directed; (8) supralabials 8−11; (9) infralabials 8−10; (10) 8–10 precloacal pores present; (11) precloacal femoral (PcFP) and precloacal groove absent; (12) four transverse series of dark dorsal crossbands parallel to the body axis (n = 4); (13) mid dorsal line absent (Table 2 & 3).

Comparisons. Cyrtodactylus khambui sp. nov. can be distinguished from all regional congeners by the following combination of characters: moderate body size (maximum SVL 60.6 mm versus <65 mm in C. annapurnaensis, C. bhupathyi, C. chamba, and C. himalayicus, and> 80 mm in C. cayuensis, C. chitwanensis, C. fasciolatus, and C. martinstolli); wider interorbital distance (IO/HW 0.52–0.66 versus 0.29–0.45 in C. nepalensis and 0.42–0.45 in C. martinstolli; p <0.05); fewer total lamellae under the fourth toe (TLamT4 15–18 versus 17–24 in C. martinstolli, 19–21 in C. karanshahi, 22–24 in C. chitwanensis, and 19.5–22 in C. makwanpurgadhiensis; p <0.05); four parallel dorsal crossbands (versus vertical crossbands in C. annapurnaensis, C. chitwanensis, C. karanshahi, and C. makwanpurgadhiensis); absence of a mid-dorsal line (versus presence in C. chitwanensis and C. nepalensis); seven to nine dorsal crossbands anterior to the hindlimb insertions (versus six dorsal crossbands in C. nepalensis); 30–31 tubercles in paravertebral rows (PVT) (versus 49–58 in C. kamengensis); presence of 8–10 precloacal pores in males (versus three or four in C. annapurnaensis, 5 in C. chamba, and absent in C. gubernatoris, C. chitwanensis and C. nepalensis); and an original tail length exceeding the snout–vent length (SVL) (versus shorter in C. lawderanus).

Description of the holotype. Holotype well preserved, with a small ventral and right ventrolateral axillary incision made for tissue collection (Fig. 5). Head comparatively large (HL/SVL 0.32), moderately narrow (HW/ HL 0.58), dorsoventrally depressed; neck distinct, occipital region broad; snout tip rounded in both dorsal and lateral view; loreal region partially convex; canthus rostralis indistinct, slight bulge at ear hole region; interorbital space slightly flat; a longitudinal furrow on dorsal surface of the snout; snout short (SE/HL 0.39); nostril elliptical posterolateral directed; eye moderately large (ED/HL 0.20); ear opening slightly oval and oblique; head scales heterogenous, snout region and loreal region scales comparatively larger than interorbital, posterior occipital region, granular, juxtaposed; upper eyelid scales comparatively similar in shape and size across the region; smooth granules with comparatively same size scale in interorbital and heterogenous in occipital region with outwardly directed conical shaped scales; rostral wider (2.7 mm) than deep (1.4 mm), partially divided by weakly developed rostral groove above, in contact with nostrils, supranasals, internasal and supralabials I; approximately same size enlarged supranasal on either side, separated by pentagonal shaped internasal, approximately same size as enlarged snout scales; nostril-bean shaped, posteriorly half covered by nasal pad, laterally oriented, enclosed on either side with rostral, supranasals, supralabial I and three postnasals; three rows of scales separated orbit from supralabials; mental wider (2.4 mm) than long (1.6 mm), triangular, in contact with postmentals and infralabials I; postmentals two, well developed on either side, inner postmentals longer (0.9 mm) than wide (0.5 mm), bordered by mentals, infralabials I, outer postmentals, and three gular scales on each side; supralabials 10 /9 (right/left) up to angle of jaw and 8 th /7 th (right/left) at midorbital; nine infralabials at angle of jaw and seven at midorbital region on both sides, scale size decreases towards the jaw point.

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Body slender and relatively long (BW/SVL 0.19) and (TRL/SVL 0.59), with ventrolateral folds; dorsal scales heterogenous consisting of rounded granules blended with feebly keeled shaped, extending beyond tail base; ventral scales slightly larger than dorsals, smooth, slightly upward directed; mid ventral scales 39; enlarged paravertebral tubercles 30; gular scales homogenous; precloacal pores eight continuous series, precloacal femoral pores (PcFP) and precloacal groove present.

Forelimbs and hindlimbs average long; LAL/SVL 0.14; CL/SVL 0.17; limbs slender with recurved claws; distal phalanges laterally compressed; basal unpaired lamellae separated from distal by single enlarged lamella at inflection; lamellae beneath digit; basal lamella series; (5-5-5-5-6 left manus, 7-6-5-6-8 left pes), (4-6-6-6-6 right manus, 7-6-4-5-8 right pes); distal lamellae series: (9-10-12-12-9 left manus, 12-13-14-12-10 left pes), (9-10-12- 13-10 right manus, (12-14-13-11-10 right pes); digit length relative—manus: IV (4.6)> III (4.3)> V (3.7)> II (3.5)> I (2.5); pes: IV (5.4)> V (4.8)> III (4.6)> II (4.1)> I (2.6); tail length 57.2 mm; width 5.0 mm; slender, tapering; seven segmented dorsal bands; dorsal scales small, juxtaposed basally; ventral scales large, weakly keeled, extending up to 13 segments; subcaudal scales subimbricate, heterogeneous, smooth to keeled; one conical and blunt post-cloacal spur on each side; tail base slightly constricted.

Coloration in preservative. Dorsal region heterogenous, composed of light cream, brownish gray, and dark tan hues, with light brown ground coloration with four irregular continuous transverse marking from occipital regions up to the posterior hindlimbs, lateral transverse lines comparatively fainter than mid-dorsal one; tail dorsum similar to trunk pattern, featuring eight irregular light cream-colored bands; subcaudal coloration light cream with faint brown spots on the posterior portion of tail. Occipital markings separated from post-orbital streak, extends up to the nasals. The dorsum of head uniform faint brownish grey, interrupted only by irregular dark brown patches above the orbits. Limbs mottled with faint brown irregular markings on both forelimbs and hindlimbs. The ventral side of body and limbs display light cream tones with some deeper browns or grays (artefact of preservation).

Coloration in life. Dorsal ground color pinkish brown with four darker, irregular transverse bands nearly parallel to the mid-dorsal (vertebral) line. An additional 7–9 irregular crossbars occur on the dorsum anterior to the hindlimb insertions; these crossbars tend to fuse between the forelimb insertions and the nape. Lateral region adorned with small white dots. Occipital markings are separated from post-orbital streak, which continues up to nares. Head dorsum unicolored except for indistinct dark markings anterior to orbits. Limbs mottled with faint brown markings, flanks with irregular light and dark markings. Ventral region off-white, extending from abdomen to the base of the tail. Tail coloration continuous with the dorsum on the proximal half, becoming conspicuously white toward the tip. The proximal portion of the tail bears five light-brown transverse bands; the distal portion shows three darker transverse bands set on a white background, which become more pronounced toward the tail tip (Fig. 6).

Variation. The type series (holotype CDZMTU502; paratypes CDZMTU501, CDZMTU503 – CDZMTU505) shows the following morphometric variation: SVL 51.05–60.63 mm (holotype 51.05 mm, paratypes 52.08–60.63 mm); trunk length (TRL) (holotype 30.19 mm, paratypes 32.64–37.80 mm); axilla–groin length (AGL) (holotype 19.46 mm, paratype 19.5–27.00 mm). No notable variation is observed in meristic or morphometric characters within the type series (Tables 3 & 4). Compared to the holotype (CDZMTU502), the four paratypes (CDZMTU501, CDZMTU503 – CDZMTU505) show minor but consistent variation in coloration, patterning, and tail condition (Fig. 7). Paratypes CDZMTU501 and CDZMTU505 are more uniformly earthy-toned on the dorsum, lacking the heterogeneous mix of light cream, brownish-gray and dark tan seen in the holotype; by contrast, CDZMTU503 and CDZMTU504 more closely resemble the holotype in dorsal coloration (Fig. 7). Similarly, CDZMTU501 and CDZMTU505 lack the series of 7–9 irregular cross-bars anterior to the hindlimb insertions that occur in the holotype and in CDZMTU503 – CDZMTU504, and their tails bear only faint brown bands rather than the distinct light-cream bands and stronger distal contrast exhibited by the holotype. The occipital region of CDZMTU501 and CDZMTU505 is an even earthy tone without brown patches, whereas the holotype shows faint brownish-gray with irregular brown patches. Limbs of CDZMTU501 and CDZMTU505 are essentially the same color as the dorsum, whereas the holotype and CDZMTU502 – CDZMTU504 have limbs mottled with faint brown irregular markings. In preservative, the ventral surfaces of CDZMTU501 and CDZMTU505 appear somewhat more yellowish compared with the light-cream venter with occasional deeper brown or gray markings in the holotype and CDZMTU502 – CDZMTU504. Two paratypes (CDZMTU503 and CDZMTU504) retain original, complete tails marginally longer than SVL (TL/ SVL = 1.12 and 1.13, respectively); the original tails of CDZMTU501 and CDZMTU505 were detached, and when measured separately yield TL/ SVL values of 1.14 and 1.16, respectively, but these values should be treated cautiously because detachment/regeneration can affect length measurements.

Distribution and natural history. Cyrtodactylus khambui sp. nov. is a scansorial gecko found on the northern and southern slopes of the Churia Hills in Sunsari District, Nepal (Fig. 8). The species occupies diverse microhabitats; individuals were observed on the walls of an abandoned building in the mixed-forest Dharan basecamp area (CDZMTU501, CDZMTU502), on the wall of waterfall (CDZMTU505) and on small branches in the Sal-dominated Panchakanya Forest and mixed forest near Vedetar (CDZMTU503, CDZMTU504, Fig. 8).

Surveys conducted from 2023 to 2025 indicated that the species is nocturnal and an adept climber, occurring at elevations range of 600 to 1800 m asl. All individuals were recorded during evening and night surveys (17:30– 23:30), with no detections during daytime searches. Local density appears relatively high, with up to six individuals encountered per hour. Sympatric lizards at the holotype type and paratype localities included Hemidactylus frenatus Duméril&Bibron,1836, Hemidactylus garnotii Duméril&Bibron1836,and Calotes cf. versicolor (Daudin 1802).