Gekko asahi Matsukoji, Cao, Poyarkov, Okamiya, Xu & Yuan sp. nov.

Figs 4, 5, 6, 7, Table 2, Suppl. material 1: table S 6.

Chersonymy:

Gekko sp. — Morita (1987); Morita (1988); Matsuo et al. (1988); Matsuo and Ejima (1988); Tokunaga (1988); Matsuo and Ejima (1989 a); Matsuo and Ejima (1989 b); Sengoku (1989); Shibata (1990); Matsuo (2019).

Gekko sp. 1 — Okamoto and Toda (2022).

Gekko sp. 2 — Cao et al. (2026).

Gekko sp. A — Jono (2016); Okamoto et al. (2025).

Holotype.

• SPMN -HP 003810 (Field NO. TMR-65, adult male) from Nakadori Island, Shinkamigoto Town, Nagasaki Prefecture, Kyushu District, Japan (32.8611°N, 129.0756°E; 3 m asl.), collected by Seiji Tsujita on January 08, 2024.

Paratypes

(N = 9, Nagasaki and Kagoshima Prefectures, Japan). • SPMN -HP 003811 (Field NO. TMR-69, adult female) from the same locality of the holotype, collected by Seiji Tsujita; • SPMN -HP 003812 (Field NO. TMR-85, adult male) from Okinoshima Island, Noko Town, Hirado City, Nagasaki Prefecture (33.1921°N, 129.3567°E; 2.5 m asl.) collected by Tomoya Matsukoji on September 23, 2024; • SPMN -HP 003813 (Field NO. TMR-104, adult male) from Hirado Island, Noko Town, Hirado City, Nagasaki Prefecture (33.1815°N, 129.3502°E; 3 m asl.), collected by Tomoya Matsukoji on September 23, 2024; • SPMN -HP 003814 (Field NO. TMR-117, adult male) from Kashiyama Town, Nagasaki City, Nagasaki Prefecture (32.8061°N, 129.7375°E; 2.5 m asl.), collected by Tomoya Matsukoji, Masahiro Nagano, Yusuke Fuji on November 04, 2024; • SPMN -HP 003815 (Field NO. TMR-148, adult female) from Kasasa Town, Minamisatsuma City, Kagoshima Prefecture (31.4213°N, 130.1815°E; 2 m asl.), collected by Tomoya Matsukoji on July 07, 2025; • SPMN -HP 003816 (Field NO. TMR-149, adult male) from Nagashima Island, Nagashima Town, Kagoshima Prefecture (32.1609°N, 130.1082°E; 5 m asl.), collected by Tomoya Matsukoji on July 07, 2025; • SPMN -HP 003817 (Field NO. TMR-161, adult female) from Shimo-Koshiki Island, Satsumasendai City, Kagoshima Prefecture (31.6361°N, 129.6996°E; 5 m asl.), collected by Tomoya Matsukoji on July 05, 2025; • SPMN -HP 003818 (Field NO. TMR-163, adult female) from Naka-Koshiki Island, Satsumasendai City, Kagoshima Prefecture (31.8005°N, 129.8424°E; 2 m asl.), collected by Tomoya Matsukoji on July 05, 2025; • SPMN -HP 003819 (Field NO. TMR-167, adult female) from Kami-Koshiki Island, Satsumasendai City, Kagoshima Prefecture (31.8778°N, 129.8599°E; 50 m asl.), collected by Tomoya Matsukoji on July 05, 2025.

Additional specimens

(N = 15): • TMR-62 (adult male), • TMR-70 (adult female) from the same locality and date of the holotype, collected by Seiji Tsujita; • TMR-86, • TMR-88 (adult male), • TMR-96 and • TMR-97 (adult female) from the same locality and date of the paratype SPMN -HP 003812; • TMR-106 (adult female) from the same locality and date of the paratype SPMN -HP 003813, • TMR-119 (adult female) from the same locality and date of the paratype SPMN -HP 003814; • TMR-169, • TMR-197 (adult female) and • TMR-190 (adult male) from the same locality and date of the paratype SPMN -HP 003819; • TMR-170 (adult female), • TMR-173 and • TMR-196 (adult male) from the same locality and date of the paratype SPMN -HP 003817; • TMR-183 (adult male) from the same locality and date of the paratype SPMN -HP 003818.

Etymology.

The specific epithet “ asahi ” is treated as an indeclinable noun in apposition. It is derived from the Japanese word “ 朝日 ” (あさひ, asahi), meaning “ morning sun ” or “ rising sun ”. The name refers to the slightly faint yellow to light orange-red coloration present on the body and limbs, as well as the bright reddish yellow to pale golden-yellow coloration of the ventral surface of the new species, which resembles the warm hue of the early morning sunlight. For the common names, we suggest “ West Japanese Gecko ” in English, “ ニシヤモリ ” (Nishi-yamori) in Japanese, “ 晨曦壁虎 ” (che ́ n xi ̄ bì hǔ) in Chinese, and “ Западнояпонский геккон ” (Zapadnoyaponskiy gekkon) in Russian.

Diagnosis.

Gekko asahi sp. nov. can be diagnosed from other Japonigekko species by the following unique combination of characters: (1) a moderate body size (SVL reaches up to 73.85 mm in males and 73.96 mm in females); (2) 6–9 supralabials and 6–8 infralabials; (3) internasal scales absent; (4) two postmentals; (5) 14–18 preorbitals; (6) 34–44 interorbital scales; (7) 158–189 ventral scales between the mental and the cloacal slit; (8) 127–158 midbody scale rows; (9) 32–45 ventral scale rows; (10) prominent dorsal tubercles present from the posterior head through the neck to the anterior portion of the tail, arranged in 12–16 rows at midbody and numbering 17–23 tubercles along a longitudinal line on the dorsum between the limb insertions; (11) subdigital lamellae 8–11 on finger I, 9–14 on finger IV, 9–12 on toe I, and 10–18 on toe IV; (12) webbing absent; (13) 6–9 precloacal pores in males, absent in females; (14) one postcloacal tubercle on each side, with the midpoint of the tubercle distinctly concave in some male individuals; (15) in life, the dorsum is predominantly yellowish-gray, with 8–9 indistinct pale yellowish-brown rounded patterns, and venter is pale golden-yellow in color.

Description of the holotype

(Fig. 4, Suppl. material 1: table S 6). An adult male with original tail. Size medium, SVL 60.69 mm; body slender and trunk relatively elongate, AG 25.49 mm, AG / SVL ratio 0.42.

Head depressed, noticeably longer than wide, and clearly separated from the neck, HL 15.18 mm, HW 12.24 mm, HH 6.6 mm, HL / SVL ratio 0.25, HW / SVL ratio 0.2, HW / HL ratio 0.81, HH / HL ratio 0.43. Snout obtuse, round anteriorly, SE 7.03 mm, SE / HL ratio 0.46. Relatively longer, NE 5.45 mm, NE / HL ratio 0.4. EE 5.71 mm, EE / HL ratio 0.38. EL 2.9 mm, EL / HL ratio 0.19; pupil vertical, featuring crenulated edges. IND 2.1 mm, IND / HL ratio 0.14. OD 5.07 mm, OD / HL ratio 0.33.

Rostral approximately rectangular in shape, wider than the high. Nares oval, rounded by the rostral, 1 st supralabial, one distinctly enlarged supranasal and three slightly enlarged nasals posteriorly; internasals absent. Preorbitals 15, preorbital region deeply concave; interorbital scales between the anterior corners of eyes 37; supralabials 7 / 7; infralabials 6 / 6. Mental pentagonal, wider than long, and slightly narrower than the rostral; postmentals two, enlarged, twice as long as wide, touching the mental and the first infralabial on both sides and three gular scales posteriorly. Tubercles are enlarged and strongly elevated, present on the lateral surfaces of the head behind the eyes.

Dorsal scales smooth, round to oval, granular, and juxtaposed. Tubercles distinctly raised, irregularly arranged, extending from the posterior part of the head to the anterior one-third of the tail, forming approximately 13 rows at midbody, and with 19 tubercles along a longitudinal line on the dorsum between the limb insertions. Ventrolateral fold present, without tubercles; ventrals slightly larger than dorsals, smooth, imbricate, and largest in middle of belly; ventral scale rows at midbody 38; scale rows around midbody 137; ventral scales in a row between mental and cloacal slit 174; precloacal scales enlarged, but no enlarged scales on thighs; precloacal pores six (Figs 4 H, 5 A); postcloacal tubercles 1 / 1, large, with the midpoint of each tubercle distinctly concave. Dorsal scales of tail flat and smooth, irregular in size, with a few tubercles present on the anterior one-third of the tail; subcaudals small at the base, distinctly enlarged beyond the swollen portion, and arranged in a longitudinal row.

Forelimbs and hindlimbs well-developed; dorsal surface of the upper forelimb lacks tubercles, whereas the lower forelimb bears tubercles; the hindlimbs have tubercles across the entire dorsal surface. No webbing between the fingers and toes; digits moderately dilated; fingers and toes II – IV clawed; claws laterally compressed, extending beyond the terminal lamellae; no webbing between fingers and toes; subdigital lamellae undivided, 8 on finger I (left), 9 on finger IV (left), 10 on toe I (left), and 15 on toe IV (ledt); relative length of fingers and toes I <II <V <III <IV.

Coloration of the holotype in life.

In life, the ground color on the dorsal surface of the head was yellowish gray, extending from the snout and eyelids to the posterior margin of the head. The dorsal ground color of the body was grayish brown, bearing eight indistinct, pale yellowish-brown rounded blotches from the neck to the base of the tail. These blotches were aligned along the vertebral region and became progressively smaller toward the tail. Large, irregularly arranged scales scattered along the dorsal surfaces from below the eyelids to the tail base and onto the limbs were grayish white. The dorsal ground color of the tail was yellowish gray, with nine irregular brown crossbands bordered by indistinct dark brown scales. The dorsal surfaces of the limbs were yellowish gray to yellowish brown, becoming reddish toward the toes.

Ventrally, the entire body was predominantly yellow, with the head being particularly bright reddish yellow. The ground color on the ventral surface of the head was reddish yellow, whereas that of the body, limbs, and tail was pale golden yellow. Sparse, irregular, and narrow grayish-brown patches occurred along both sides of the ventral surfaces of the body and limbs, as well as at the base of the tail.

Coloration of the holotype in preservation.

In preservative (Fig. 4), the ground color on the dorsal surfaces of the head, body, and limbs turned gray. The eight indistinct pale yellowish-brown rounded blotches on the dorsum became slightly obscured, and the nine irregular brown crossbands on the tail also became more indistinct. The ventral surfaces faded to an ivory color, and the grayish-brown patches along the ventral body, limbs, and tail base faded to a pale grayish-brown.

Variation.

The main morphological characters of Gekko asahi sp. nov. are summarized in Suppl. material 1: table S 6. The species exhibits no evident sexual dimorphism in morphometric ratios, scale counts, or coloration. The longest known male measures SVL 73.85 mm (TMR-86); and the female measures SVL 73.96 mm (SPMN -HP 003811). SPL 7–9, IFL 6–9; large and slender towards the tip. IS absent; almost the same size. PO 14–18; preorbital region deeply concave. PM 2; common to all individuals. IOS 34–44; large towards the eyelids. Dorsal scales smooth, round to oval, granular and juxtaposed, SMC 158–189, SR 127–158. LRT 12–16; tubercles irregularly arranged, extending from the posterior part of the head to the anterior part of the tail, especially head has tubercles on the side surface of the head behind the eyes. PVT 17–23; present on dorsal surfaces. VS 32–45; venter slightly larger than dorsum, smooth, imbricate, and largest in middle of belly; precloacal scales enlarged, but no enlarged scales on thighs. PP 6–9 in males (Fig. 5), situated at the distal of each scale; PP absent in females. PAT one on each side, with the midpoint of the tubercle distinctly concave in some male individuals; in females, the postcloacal tubercles are smaller and less distinct. Dorsal scales of tail flat and smooth, irregular in size, with a few tubercles present on the anterior part of the tail; subcaudals small at the base, distinctly enlarged beyond the swollen portion, and arranged in a longitudinal row.

Forelimbs and hindlimbs well-developed; dorsal surface of the upper forelimb lacks tubercles, whereas the lower forelimb bears tubercles; the hindlimbs have tubercles across the entire dorsal surface. No webbing between the fingers and toes; digits moderately dilated; fingers and toes II – IV clawed; claws laterally compressed, extending beyond the terminal lamellae; LF 1 8–11; LF 4 9–14; LT 1 9–12; LT 4 10–18.

Main characters of the pattern in life

(Fig. 6, 7). In life, the ground color on the dorsal surfaces of the head, body, limbs, and tail varies among individuals, ranging from gray to grayish brown, yellowish gray, yellowish brown, or dark brown. From the neck to the base of the tail, there are 8 to 9 indistinct pale yellowish-brown rounded blotches, and the tail bears 8 to 11 irregular brown crossbands bordered by indistinct dark brown scales. The ventral surfaces of the body are generally pale reddish yellow to pale yellowish-gold in life, and females tend to show a more vivid yellowish tint. In individuals with autotomized and regenerated tails, the regenerated portion is yellowish brown or brown, with numerous irregular brown or dark brown stripes.

Main characters of the pattern in preservation.

In preservative, the coloration of the paratypes also resembled that of the holotype. The ground color on the dorsal surfaces of the head, body, limbs, and tail turned grayish white to gray. The indistinct pale yellowish-brown rounded blotches on the dorsum became further obscured, and the irregular brown crossbands on the tail also became more indistinct.

Distribution and ecology.

Gekko asahi sp. nov. is currently known only from offshore islands and peninsulas of Nagasaki and Kagoshima Prefectures, Japan (Fig. 1, Suppl. material 1: Suppl. material 1: table SS 1). Its distribution includes the Hirado Islands (Hirado Island, Nakano-shima Island, Oitoku Island, Okinoshima Island, Toyaku Island); the Goto Islands (Fukue Island, Hisaka Island, Naru Island, Kaba Island, Mae Island, Kuro Island, Aka Island, Wakamatsu Island, Nakadori Island); the Danjyo Islands (Meshima Island, Oshima Island); Kuro Island; Enoshima Island; Oshima Island; Kakinoura Island; Matsu Island; Ohiki Island; Ike Island; and the Nishisonogi Peninsula in Nagasaki Prefecture. In Kagoshima Prefecture, the species occurs on the Koshiki Islands (Kami-Koshiki Island, Naka-Koshiki Island, Naka Island, Shimo-Koshiki Island), the Uji Islands, the Kusagaki Islands, and the Satsuma Peninsula (Morita 1987, 1988; Matsuo et al. 1988; Matsuo and Ejima 1988, 1989 a, 1989 b; Tokunaga 1988; Sengoku 1989; Shibata 1990; Matsuo 2019).

Sympatry has been recorded with G. hokouensis on Nakadori Island, Kami-Koshiki Island, Naka-Koshiki Island, and the Satsuma Peninsula (Matsuo 2019; Chiba and Chiba 2024), with G. japonicus on Hirado Island, Okinoshima Island, Fukue Island, Nakadori Island, Kakinoura Island, the Nishisonogi Peninsula, Kami-Koshiki Island, and the Satsuma Peninsula (Matsuo 2019; Chiba and Chiba 2024), and with G. yakuensis on the Satsuma Peninsula (Okamoto et al. 2025).

The species is nocturnal and inhabits primarily coastal rocky shores (Fig. 8), but also occurs on the walls of coastal buildings at elevations of 2–50 m asl. On inhabited islands where invasive geckos such as Gekko japonicus and G. hokouensis have not yet established, Gekko asahi sp. nov. is commonly observed both in rocky coastal areas and on nearby building walls. However, on uninhabited islands or inhabited islands where invasive geckos are established, it appears to prefer rocky coastal habitats exclusively (Chiba and Chiba 2024; see Discussion below). Females lay two eggs within rock crevices in relatively dry, sunlit sites during May and June (Matsuo 2005; Matsui and Mori 2021). Communal nesting is common, and numerous eggs may occur in a single crevice (Matsuo and Ejima 1988). Seasonal microhabitat preferences include sunny rocky areas in early spring, cool shaded crevices in midsummer, and deep rock crevices for overwintering (Matsuo 2005). The diet consists mainly of insects and wharf roaches, though predation on small mollusks has been reported (Matsui and Mori 2021). On the Koshiki Islands, multiple ant heads were detected in the feces of several individuals. In the wild, few individuals possess intact tails, and many have undergone autotomy at least once. Compared with its sister species G. kaiyai, which exhibits strong aggressiveness and rarely autotomizes its tail (Zhang et al. 2023), Gekko asahi sp. nov. may display tail autotomy more frequently.

Comparisons.

The main characteristics that distinguish Gekko asahi sp. nov. from other species of the subgenus Japonigekko are summarized in Table 2. Based on both morphological and molecular evidence, Gekko asahi sp. nov. is closely related to G. kaiyai and G. hokouensis. However, morphological comparisons and analyses revealed their differences (Fig. 3; Suppl. material 1: table S 4). In particular, both males and females of Gekko asahi sp. nov. are significantly larger (p <0.05) than those of G. hokouensis (mean SVL 64.4 ± 4.85, N = 12 in males; mean SVL 70.6 ± 5.43, N = 13 in females in Gekko asahi sp. nov. vs. mean SVL 55.1 ± 7.07, N = 3 in males; mean SVL 58.2 ± 4.43, N = 8 in females in G. hokouensis). Male Gekko asahi sp. nov. have greater HH / SVL (0.098 ± 0.007 vs. 0.087 ± 0.005) and FLL / SVL (0.122 ± 0.004 vs. 0.114 ± 0.008), but smaller IND / SVL (0.037 ± 0.002 vs. 0.042 ± 0.001) than in G. hokouensis (see Suppl. material 1: table S 4). Female Gekko asahi sp. nov. have smaller HW / SVL (0.199 ± 0.004 vs. 0.206 ± 0.007) and EL / SVL (0.056 ± 0.003 vs. 0.064 ± 0.004) than in G. hokouensis (see Suppl. material 1: table S 4).

Gekko asahi sp. nov. is also larger than G. kaiyai both in males (mean SVL 64.4 ± 4.85; N = 12 vs. 57.9 ± 4.09; N = 11) and females (mean SVL 70.6 ± 5.43; N = 13 vs. 62.0 ± 4.10; N = 4) (see Suppl. material 1: table S 4). As compared to males of G. kaiyai, Gekko asahi sp. nov. males have greater SE / SVL (0.12 ± 0.003 vs. 0.08 ± 0.005) and EE / SVL (0.087 ± 0.005 vs. 0.075 ± 0.005), but smaller AG / SVL (0.43 ± 0.01 vs. 0.46 ± 0.02), HW / SVL (0.20 ± 0.005 vs. 0.22 ± 0.009), and HL / SVL (0.23 ± 0.01 vs. 0.26 ± 0.006). Females of Gekko asahi sp. nov. have smaller HW / SVL (0.19 ± 0.004 vs. 0.21 ± 0.007), but greater HH / SVL (0.096 ± 0.007 vs. 0.085 ± 0.008), SE / SVL (0.115 ± 0.005 vs. 0.077 ± 0.005), EE / SVL (0.084 ± 0.003 vs. 0.077 ± 0.004), and EL / SVL (0.056 ± 0.003 vs. 0.051 ± 0.002) than females of G. kaiyai.

In addition, Gekko asahi sp. nov. can be distinguished from G. kaiyai by having more SR (127–158 vs. 99–121), more IO (34–44 vs. 22–33); and in life, ventral surface of body pale reddish yellow, pale yellow, or pale yellowish-gold (vs. creamy white). And it can be distinguished from G. hokouensis by having fewer SPL (7–9 vs. 10–14), more IO (34–44 vs. 30–33), dorsal surfaces of both fore- and hindlimbs bearing tubercles (vs. lacking tubercles), and in life, ventral surface of body pale reddish yellow, pale yellow, or pale yellowish-gold (vs. creamy white).

In comparison with the other two sympatrically occurring species, Gekko japonicus and G. yakuensis, Gekko asahi sp. nov. can be distinguished from G. japonicus by having fewer PAT (1 vs. 3–5), dorsal surface of hindlimbs bearing tubercles (vs. lacking tubercles), and in life, ventral surface of body pale reddish yellow, pale yellow, or pale yellowish-gold (vs. creamy white). It can be further distinguished from G. yakuensis by having fewer SPL (7–9 vs. 12–13), and dorsal surfaces of both fore- and hindlimbs bearing tubercles (vs. lacking tubercles).

By having SPL 7–9, Gekko asahi sp. nov. can be easily distinguished from G. aaronbaueri Tri, Thai, Phimvohan, David & Teynié, 2015, G. adleri, G. bonkowskii Luu, Calame, Nguyen, Le & Ziegler, 2015, G. canhi Rösler, Nguyen, Van Doan, Ho, Nguyen & Ziegler, 2010, G. chinensis, G. cib, G. kwangsiensis Yang, 2015, G. liboensis Zhou, Liu & Li, 1982, G. liui Zhou, Zhou, Wang, Li, Zhang, Li, Shen, Liu & Rao, 2025, G. melli Vogt, 1922, G. nadenensis Luu, Nguyen, Le, Bonkowski & Ziegler, 2017, G. palmatus Boulenger, 1907, G. paucituberculatus Wang, Qi, Zhou & Wang, 2024, G. prep Zhou, Chen, Liu, Li, Qi, Li & Peng, 2025, G. scientiadventura Rösler, Ziegler, Vu, Herrmann & Böhme, 2004, G. shibatai Toda, Sengoku, Hikida & Ota, 2008, G. similignum, G. tesselatus Xu, Ma, Cai, Qi, Matsukoji, Poyarkov, Sun, Jiang & Peng, 2025, G. thakhekensis Luu, Calame, Nguyen, Le, Bonkowski & Ziegler, 2014, G. truongi Phung & Ziegler, 2011, G. vertebralis Toda, Sengoku, Hikida & Ota, 2008, and G. wenxianensis Zhou & Wang, 2008, (vs. 13–14 in G. aaronbaueri, 10–15 in G. adleri, 12–14 in G. bonkowskii, 14 in G. canhi, 10–14 in G. chinensis, 10–12 in G. cib, 10–12 in G. kwangsiensis, 11 in G. liboensis, 11–13 in G. liui, 10–13 in G. melli, 12–14 in G. nadenensis, 11–15 in G. palmatus, 11 in G. paucituberculatus, 14 in G. prep, 12–14 in G. scientiadventura, 10–13 in G. shibatai, 12–14 in G. similignum, 10 or 11 in G. tesselatus, 12–14 in G. thakhekensis, 13–15 in G. truongi, 10–15 in G. vertebralis, and 12 in G. wenxianensis).

In addition, by having IO 34–44, Gekko asahi sp. nov. can be easily distinguished from G. alpinus Ma, Shi, Shen, Chang & Jiang, 2024, G. auriverrucosus Zhou & Liu, 1982, G. fengshanensis Huang, Wang, Qi, Song, Huang, Wang & Mo, 2025, G. jinjiangensis Hou, Shi, Wang, Shu, Zheng, Qi, Liu, Jiang & Xie, 2021, G. khunkhamensis Sitthivong, Lo, Nguyen, Ngo, Khotpathoom, Le, Ziegler & Luu, 2021, G. scabridus Liu & Zhou, 1982, G. sengchanthavongi Luu, Calame, Nguyen, Le & Ziegler, 2015, G. swinhonis, G. taibaiensis Song, 1985, and G. tawaensis (vs. 22–28 in G. alpinus, 26–27 in G. auriverrucosus, 22–27 in G. fengshanensis, 20–24 in G. jinjiangensis, 31–32 in G. khunkhamensis, 30 in G. scabridus, 28–32 in G. sengchanthavongi, 23–24 in G. swinhonis, and 28 in G. taibaiensis and G. tawaensis).

Finally, by the absence of webbing between the fingers and toes, Gekko asahi sp. nov. can be easily distinguished from G. guishanicus Lin & Yao, 2016, G. ichangensis Cao, Sucharitakul, Tie, Suwannapoom, Yan & Chomdej, 2025 and G. subpalmatus Günther, 1864 (vs. webbing present).