Hynobius sematonotos, Tominaga & Matsui & Nishikawa, 2019

Tominaga, Atsushi, Matsui, Masafumi & Nishikawa, Kanto, 2019, Two new species of lotic breeding salamanders (Amphibia, Caudata, Hynobiidae) from western Japan, Zootaxa 4550 (4), pp. 525-544 : 530-533

Hynobius sematonotos n. sp.

(Japanese name: Chugoku-buchi-sanshou-uwo)

( Figs. 4A, B , 5A , 6A , 7A, B .)

Pseudosalamandra naevia: Tago 1931: 170 –180, pl. XX. (part).

Hynobius naevius: Abe 1922: 329 –330 (part).

Hynobius naevius (part, standard type): Sato 1943: 198 –217.

Hynobius naevius (part Group A): Tominaga et al. 2005a: 921; Tominaga et al. 2005b: 1229, fig. 7C.

Hynobius naevius (part Chugoku subclade in Clade 2): Tominaga et al. 2006: 677.

Holotype: KUHE 30218 ( Fig. 4A, B ), an adult male from Nojiyama , Higashi-hiroshima-shi (formerly Fukutomicho), Hiroshima Prefecture (34 o 30’31”N, 132 o 43’06”E, alt. 722 m) collected by A. Tominaga and S. Ikeda on 30 April 2002.

Paratypes: KUHE 30219 collection data same as the holotype , KUHE 34694 , 34695 from the type locality by A Tominaga and S. Okada on 4 May 2004 .

Referred specimens: KUHE 30268–30274 from Nichinan-cho, Tottori Prefecture; KUHE 6905–6911, 6988, 6992–6993, 6995 from Jinsekikogen-cho, Hiroshima Prefecture; KUHE 11037–11047 from Geihoku-cho, Hiroshima Prefecture: KUHE 11066–11067, 17812, 30276–30279, 30281–30283, 30921–30932 from Hatsukaichishi, Hiroshima Prefecture; KUHE 30193–30200 from Hagi-shi, Yamaguchi Prefecture.

Etymology: The specific name sematonotos is a compound noun in apposition derived from Greek words, semato-, meaning marking, and notos, meaning dorsum, referring to marked dorsum of the new species.

Diagnosis: A medium-sized species (adult SVL 58–81 mm in males and 70–82 mm in females) within the lotic breeding Hynobius , breeding in montane streams; dorsum maculate in adults; limbs and tail long; tips of fore- and hindlimbs adpressed on body scarcely meeting (overlap of -2.0 to -0.5 costal folds in males and -2.0 to -1.0 in females); fifth toe well developed; ova large, pigmentless; egg sacs short and crescent-like, without distinct whiptail structure on free end; most similar to sp. B and H. naevius , but with smaller body size, large number of LO, small number of upper and lower jaw teeth, and vomerine teeth, relative size to SVL in larger upper eyelid width and length, shorter trunk length, relatively longer hindlimb, shorter fifth toe length, shallower vomerine teeth series, and grayish white dorsal marking of their trunk. Hynobius sematonotos n. sp. genetically closer to H. hirosei and H. katoi than to H. naevius and Hynobius sp. B, however, H. sematonotos n. sp. has large marking on dorsum and has medium SVL compared to other two genetically close species.

Description of holotype (measurements in mm): Head-body small (SVL 64.9) but robust; head oval and moderately depressed, distinctly longer (HL 15.3, 23.6%SVL) than wide (HW 11.5, 17.7%SVL); snout rounded, slightly projecting beyond lower jaw; nostril close to snout tip; labial fold absent; eye large, prominently protruded, slightly inset from edge of head in dorsal view; upper eyelid well developed (UEW 2.0, 3.1%SVL), shorter (UEL 3.8, 5.9%SVL) than snout (SL 4.6, 7.1%SVL); gular fold distinct, curving slightly anteriorly; parotoid gland evident, extending from angle of jaw to gular fold; postorbital grooves distinct, branching posterior to angle of jaw, one short and running down to lower jaw, the other long and posteriorly to parotoid gland; vomerine teeth series slightly wider (VTW 3.9, 6.1%SVL) than long (VTL 2.6, 3.9%SVL), vomerine teeth shallow V-shaped, series nearly touching at midline ( Fig. 5A ), tongue broad, both sides free from mouth floor; fore- and hindlimbs long and thick (FLL 16.9, 24.8%SVL; HLL 19.4, 29.8%SVL); number of costal grooves between axilla and groin 13; depressed limbs separated by one costal fold; relative length of fingers I<IV<III<II, toes I<V<II<IV<III; fifth toe well developed (5TL 1.3, 2.0%SVL); cloaca longitudinal slit; genital tubercle on anterior cloaca absent; tail short (TAL 45.3, 69.8%SVL), cylindrical at base (BTAW 6.7, 10.3%SVL; BTAH 6.1, 9.4%SVL), increasingly compressed posteriorly, caudal fin poorly developed posteriorly; tip of tail rounded in lateral view.

Additional Measurements and counts of the holotype: IND (3.7, 5.7%SVL); IOD (3.7, 5.7%SVL); AGD

(33.8, 52.1%SVL); TRL (49.6, 76.4%SVL); MTAW (5.0, 7.7%SVL); MXTAH (7.1, 10.9%SVL); MTAH (7.1,

10.9%SVL), 2FL (2.4, 4.2%SVL); 3FL (2.1, 3.8%SVL); 3TL (4.2, 7.2%SVL); UJTN (72); LJTN (70); VTN (41). Color: In life, the dorsum varying from reddish- to bluish- purple in ground color, with discontinuous, grayish-

to brownish-white markings ( Fig. 4A ). Underside of body lighter than dorsum with light white marking. The ground color of ventral side becoming reddish to bluish gray with relatively large markings varying from palewhite to white ( Fig. 4B ). In preservative, dorsal and ventral ground color tending to fade.

Variation: Morphometric data are summarized in Table 1. Males tended to have relatively wider head (HW, median=17.8%SVL) than in females (17.0%SVL). Males had relatively longer forelimb (median=24.3%SVL) and hindlimb (median=30.4%SVL) than in females (median=21.3%SVL and 27.7%SVL, respectively). Separation of limbs was greater in females (median=1.5 folds) than in males (median=1.0 fold). Males had relatively longer (median=75.7%SVL) and higher (median=11.5%SVL) tail than in females (median=69.8%SVL and 9.9%SVL, respectively). Third toe was usually longer than fourth like holotype. Fifth toe was almost always present. Combined series of vomerine teeth tended to be wider in males (VTW/VTL, median=142.5%) than in females (median=129.4%). Body size was usually larger in eastern populations (from Mimasaka-shi [formerly Katsutacho], Okayama Prefecture to Un’nan-shi [formerly Daito-cho], Shimane Prefecture) than those in western populations (from Higashi-hiroshima-shi, Hiroshima Prefecture to Shimonoseki-shi [formerly Toyota-cho], Yamaguchi Prefecture) ( Tominaga et al. 2005b).

Eggs and egg sacs: The egg sac morphology of Hynobius sematonotos n. sp. is shown in Fig. 6A . Egg sacs are crescent in shape with slightly thin envelope, and lacks a distinct whiptail structure on the free end. The clutch size is small, ranging from 11–39 (mean ± SD =21.5 ± 8.0, n = 46). The diameter of ova from three females ranges from 4.7–5.5 (mean ± SD = 5.2 ± 0.2, n = 10) mm, 4.9–5.5 (mean ± SD = 5.1 ± 0.22, n = 10) mm, and 5.7mm (n=1). Both the animal and the vegetal poles are cream in color.

Larvae: Fully grown larvae (n=8) at St. 61–63 (median = 62) of Iwasawa and Yamashita (1991) of the first year in late July to early September had SVL ranging from 19.7–24.8 (mean ± SD = 22.1 ± 1.7) mm and total length of 38.5–50.0 (mean ± SD = 43.1 ± 3.9) mm, head rounded in dorsal and lateral views ( Fig. 7A, B ); snout short and broadly rounded; eyes slightly protruded, inset from edge of head in dorsal view; labial fold distinct at half of upper jaw; external gills developed; caudal fin higher than head; dorsal fin higher than ventral fin; origin of dorsal fin at half of trunk; ventral fin originating from vent; tail tip weakly pointed; limbs slender; claws on fingers and toes absent. In life, dorsum light brown with marking; venter whitish and transparent; large black marking; golden dots scattered on tail fin. In preservative, dorsal coloration tending to fade and golden dots fading to white.

Range: Known from mountain regions from Okayama Prefecture to Yamaguchi Prefecture, Chugoku district, Western Japan ( Fig. 1 ). Hynobius sematonotos n. sp. seems to be largely parapatrically distributed with H. kimurae but sometimes co-occur with H. kimurae and/or H. nebulosus in Chugoku district.

Morphological Comparisons: Hynobius sematonotos n. sp. is distinct from all 30 lentic breeding Hynobius species with having cylindrical tail at base and small number of large unpigmented eggs per clutch. Hynobius sematonotos n. sp. is also distinct from all Taiwanese species by larger body size (adult SVL usually 50–60 mm and less than 69 mm [ Lai & Lue 2008]) and different coloration.

Hynobius sematonotos n. sp. is also different from other lotic breeding congeners, including H. hirosei and H. katoi , by the presence of grayish white ventral and dorsal marking on the trunk. Hynobius sematonotos n. sp. is also distinguished from H. hirosei by smaller body size (58.1–81.5 mm vs. 73.3–103.3 mm in H. hirosei ), relatively shorter head length (RHL: 21.8–24.8%SVL vs. 23.8–28.6%SVL in H. hirosei ), relatively smaller upper eyelid width (RUEW: 2.8–3.8 vs. 3.3–4.7 in H. hirosei ), relatively longer trunk length (RTRL: 75.2–78.2%SVL vs. 72.0– 76.3%SVL in H. hirosei ), and relatively smaller vomerine teeth series width (RVTW: 4.6–6.0%SVL vs. 5.0– 7.7%SVL in H. hirosei ) ( Nishikawa et al. 2007). Hynobius sematonotos n. sp. is also distinct from H. katoi by larger body size (58.1–81.5 mm vs. 53.8–66.1 mm in H. katoi ), relatively shorter head length (RHL: 21.8– 24.8%SVL vs. 24.0–25.2%SVL in H. katoi ), relatively larger head width (RHW: 16.2–19.3%SVL vs. 14.8– 16.7%SVL in H. katoi ), and relatively longer trunk length (RTRL: 75.2–78.2%SVL vs. 74.8–76.0%SVL in H. katoi ) ( Matsui et al. 2004).

Hynobius sematonotos n. sp. is most similar to Hynobius sp. B and H. naevius morphologically, but H. sematonotos n. sp. is distinguished from Hynobius sp. B by smaller body size, small number of upper and lower jaw teeth, and vomerine teeth, relatively larger upper eyelid, shorter trunk, longer hindlimb, shorter fifth toe, shallower vomerine teeth series, and grayish brown dorsal marking of their trunk and tail. Hynobius sematonotos n. sp. is also distinguishable from H. naevius by smaller body size, larger numbers of LO, smaller number of vomerine teeth, relatively longer snout length, larger upper eyelid, shorter trunk, longer limbs, and shallower vomerine teeth series, and presence of grayish white dorsal marking on the trunk and tail.

Natural history: Breeding occurs from April to June, when egg sacs are attached to stones under the water in mountain streams with the maximum width of 2 m. Some overwintered larvae can be found in spring.

Conservation: Populations in Soryo-cho, Shobara-shi, Hiroshima Prefecture are protected by the local government as a natural monument.

Figures

FIGURE 1. Map of western Japan and distributional range of Hynobius naevius and two new species. Range filled by oblique lines: distributional range of H. naevius; range filled by horizontal line: distributional range of H. sematonotos n. sp.; range filled by vertical lines: distributional range of H. oyamai n. sp. Closed symbols: sampling locality used in this study. Closed triangle: supposed type locality and sampling locality of topotypic specimens of H. naevius. Closed star: type locality of H. sematonotos n. sp. Closed diamond: type locality of H. oyamai n. sp.

FIGURE 4. Dorsal and ventral views of male holotype (KUHE 30218) of Hynobius sematonotos n. sp. A, B), male holotype (KUHE 27267) of Hynobius oyamai n. sp. (C, D), and supposed topotypic male specimen (KUHE 28637) of H. naevius from Tara-cho, Saga Prefecture. Scale bar shows 50 mm.

FIGURE 5. vomerine teeth series of male holotype (KUHE 30218) of Hynobius sematonotos n. sp. (A), male holotype (KUHE 27267) of Hynobius oyamai n. sp. (B), and supposed topotypic male specimen (KUHE 28637) of H. naevius (C) from Taracho, Saga Prefecture. Scale bar indicates 1 mm.

FIGURE 6. Egg sacs of Hynobius sematonotos n. sp. from Shobara-shi, Hiroshima Prefecture (A) and egg sacs of Hynobius oyamai n. sp. from Yamaga-shi, Kumamoto Prefecture (B). Scale bar in (B) shows 5 cm.

FIGURE 7. Dorsal (A) and lateral (B) views of a full-grown larva (Stage 62) of Hynobius sematonotos n. sp. from Higashihiroshima-shi, Hiroshima Prefecture (type locality). Dorsal (C), lateral (D), and ventral (E) views of a full-grown larva (Stage 63) of Hynobius oyamai n. sp. from Kitakyushu-shi, Fukuoka Prefecture (type locality). Scale bar shows 10 mm.