Hynobius kuishiensis, Tominaga & Matsui & Tanabe & Nishikawa, 2019

Tominaga, Atsushi, Matsui, Masafumi, Tanabe, Shingo & Nishikawa, Kanto, 2019, A revision of Hynobius stejnegeri, a lotic breeding salamander from western Japan with a description of three new species (Amphibia, Caudata, Hynobiidae), Zootaxa 4651 (3), pp. 401-433 : 419-430

Hynobius kuishiensis sp. nov.

(Japanese name: Iyoshima-sansyou-uwo)

(English name: Iyoshima salamander)

( Figs. 7 F–J, 8C, 9C, I)

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

Hynobius naevius (part, Shikoku local form): Sato, 1943: 206.

H. naevius (part, samples 8–10 in Group B): Tominaga et al. 2005a: 921–937.

H. naevius (part, samples 9–11 in Group B): Tominaga et al. 2005b: 1229–1244.

H. naevius (part, samples 8–9 of Clade 3 and sample 10 of Clade 4): Tominaga et al. 2006: 677–684.

H. yatsui (part): Tominaga & Matsui, 2008: 107.

H. stejnegeri (part): Matsui et al. 2017: 538.

Holotype: KUHE 18035 ( Fig. 7F ), an adult male from Mt. Kuishi , Kochi-shi (formerly Tosayama-mura), Kochi Prefecture (33 o 40’ N, 133 o 30’ E, alt. 1030 m a.s.l.) collected by M. Matsui, S. Tanabe, and Y. Misawa on 1 June 1994.

Paratypes: All from Mt. Kuishi , Kochi-shi (formerly Tosayama-mura), Kochi Prefecture: KUHE10205–10211 , six males and one juvenile by M. Matsui and T. Hayashi on 2 June 1989 ; KUHE 18036–18042 , five males, one female and one juvenile by M. Matsui, S. Tanabe, Y. Misawa on 1 June 1994 ; KUHE 24201 ( Fig. 8G, H ), 24202– 24204, two males and two juveniles by K. Nishikawa on 30-31 May 1998 ; T2118, one female by T. Okayama on 13 August 1990; T2707–T2709, one male and two females by M. Matsui, S. Tanabe, Y. Misawa, and K. Araya on 1 June 1994; T2960–T2961, two females from Mt. Okukuishi , Motoyama-cho, Kochi Prefecture by S. Tanabe and K. Nishikawa on 6 June 1999 .

Referred specimens: T1436, T1946–T1954, T2995 ( Fig. 7I, J ), T2016, T–2996-3001 from Mt. Ishizuchi, Kumakogen-cho (formerly Omogo-mura), Ehime Prefecture; T3487–3489 from Shikokuchuo-shi, Ehime Prefecture; KUHE 21712 , 21785 , T2689 ( Fig. 7K, L ), T 2956–2959 from Uchiko-cho (formerly Oda-cho), Ehime Prefecture ; T3338, T3370–3371, T3373, T3606–3608 from Mt. Takamaru , Kamikatsu-cho, Tokushima Prefecture .

Etymology: The specific name " kuishiensis " refers to Mt. Kuishi, the type locality of the species.

Diagnosis: A small-sized species (adult SVL 52–66 mm in males and 53–70 mm in females) within the lotic breeding Hynobius , breeding in montane underground streams; dorsum maculated with small to continuous brownish-white; limbs and tail long; tips of fore- and hindlimbs adpressed on body separated (overlap of -2.0 to -0.5 costal folds in males and -2.5 to - 0.5 in females); fifth toe well developed; ova large, pigmentless; egg sacs short and string-like, without distinct whiptail structure on free end; morphometrically most similar to H. tsrugiensis sp. nov., but with larger number of upper and lower jaw teeth, and vomerine teeth, relatively longer fifth toe, and reddish purple or dark blue ground color with small to continuous brownish-white dorsal marking of their trunk and tail.

Description of holotype (measurements in mm): Head-body small ( SVL 65.9); head oval and moderately depressed, distinctly longer (HL 15.1, 22.9% SVL) than wide (HW 11.3, 17.1%); 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 2.1, 3.2% SVL), shorter ( UEL 3.6, 5.5% SVL) than snout (SL 4.5, 6.8% 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 tooth series slightly wider ( VTW 3.4, 5.2% SVL) than long ( VTL 3.1, 4.6% SVL), vomerine tooth deep V-shaped, series nearly touching at midline ( Fig. 8C ), tongue broad, both sides free from mouth floor; fore- and hindlimbs long and thick (FLL 15.3, 23..2% SVL; HLL 18.6, 28.2% SVL); number of costal grooves between axilla and groin 13; depressed limbs separated by two costal folds; relative length of fingers I<IV<III<II, toes V<I<II=IV<III; fifth toe moderately developed (5TL 1.7, 2.6% SVL); cloaca longitudinal slit; genital tubercle on anterior cloaca absent; tail long ( TAL 45.3, 68.7% SVL), cylindrical at base and middle ( BTAW 7.5, 11.4% SVL; BTAH 6.9, 10.5% SVL, MTAW 6.0, 9.1% SVL; MTAH 7.2, 10.9% SVL), slightly compressed posteriorly, caudal fin never developed; tip of tail slightly sharpened in lateral view.

Additional Measurements and counts of the holotype: IND (3.5, 5.3% SVL); IOD (3.6, 5.5% SVL); AGD (34.2, 51.9% SVL); TRL (50.8, 77.1% SVL); MXTAH (7.2,10.9% SVL); 2FL (2.6, 4.0% SVL); 3FL (2.7, 4.1% SVL); 3TL (4.6, 7.0% SVL); UJTN (58); LJTN (59); VTN (52).

Color: In life, dark brown in dorsal ground color, with large discontinuous brownish-white markings ( Fig. 7F ). Underside of body lighter than dorsum with white marking. The ground color of ventral side dark gray with relatively small white markings. In preservative, dorsal and ventral ground color tending to fade.

Variation: This species includes two divergent mtDNA lineages, although their morphological and nuclear genomic differentiations are not distinct. Morphometric data are summarized in Tables 3 and 4 . Sexual size and morphometric dimorphism is obscure. Males tended to have slightly wider RHW (median=17.1% SVL) than in females (16.7% SVL). RFLL (median=23.8% SVL) and RHLL (29.3% SVL) in males are comparable to those of females (22.8% SVL and 29.2% SVL, respectively). Third toe was usually longer than the fourth like holotype. Fifth toe was almost always present and usually well developed, but a few individuals from the type locality had poorly developed fifth toe. Dorsal markings were usually smaller or large discrete ( Fig. 7F, G, K ) in individuals from most part of Shikoku (Shikokuchuo-shi, Motoyama-cho, Kochi-shi, Uchiko-cho, Kamikatsu-cho) but individuals from Mt. Ishizuchi, Ehime Prefecture usually have continuous brown markings on their dorsum ( Fig. 7I ).

Eggs and egg sacs: The egg sac morphology of Hynobius kuishiensis sp. nov. from Mt. Kuishi is shown in Fig. 9C . Egg sacs were string-like in shape with thin envelope, and lacked a distinct whiptail structure on the free end. The clutch size was small, ranging from 17–27 (mean ± SD =21.5 ± 3.9, n = 10). The average diameter of ova from one female was c.a. 6.0 mm. Both the animal and the vegetal poles were cream in color.

Larvae: SVL and TAL of a hatching larva from Mt. Kuishi were 10.6 mm and 7.9 mm, respectively. The hatched larvae often had balancers. SVL and TAL of each one fully grown larva from Mt. Kuishi at St. 63-65 of Iwasawa & Yamashita (1991) of the first year in early August were about 18 and 15 mm, head rounded in dorsal view ( Fig. 9I ); snout short and broadly rounded; eyes slightly protruded, inset from edge of head in dorsal view; labial fold indistinct; external gills developed; caudal fin higher than head; dorsal fin higher than ventral fin; origin of dorsal fin at middle of trunk; ventral fin originating from vent; tail tip weakly pointed; limbs short but slightly robust; claws on fingers and toes absent. In life, dorsum dark brown without marking; venter whitish and transparent; caudal fin transparent with small dots.

Range: Known from Mt. Ishizuchi, Saijo-shi and Kumakogen-cho, Ehime Prefecture; Iyomishima, Shikokuchuo-shi, Ehime Prefecture; Mt. Okukuishi, Motoyama-cho, Kochi Prefecture; Mt. Kuishi, Tosayama, Kochi-shi, Kochi Prefecture; Uchiko-cho (formerly Oda-cho), Ehime Prefecture; Mt. Takamaru, Kamikatsu-cho, Tokushima Prefecture ( Fig. 10 ). Hynobius kuishiensis sp. nov. seems to be sympatrically distributed widely with H. hirosei and Onychodactylus kinneburi but allopatrically distributed from H. tsurugiensis sp. nov.

Morphological Comparisons: Hynobius kuishiensis sp. nov. is differentiated from all 37 lentic breeding Hynobius species by having cylindrical tail at base and small number per clutch of large, unpigmented eggs. Hynobius kuishiensis sp. nov. ( SVL = 52.1–67.7 in males, 51.9–70.2 mm in females) is slightly larger than all the Taiwanese species although their ranges overlap (adult SVL usually 50–60 mm and less than 69 mm [ Lai & Lue 2008]). Hynobius kuishiensis sp. nov. differs from all the five Taiwanese species (data calculated from Lai & Lue 2008) in longer and wider head ( RHL 22.1–25.2% and RHW 15.2–18.8% vs. mean RHL = 18.3–23.9% and mean RHW = 15.0– 16.5%), longer forelimb and hindlimb ( RFLL =20.2–25.7% and RHLL =27.3 – 31.6% vs. mean RFLL = 19.1–25.0% and mean RHLL = 22.4–28.9%). Hynobius kuishiensis sp. nov. also differs from Taiwanese species in coloration.

Hynobius kuishiensis sp. nov. is also different from other lotic breeding congeners, including H. boulengeri , H. hirosei , H, shinichisatoi , H. ikioi , H. osumiensis , H. amakusaensis , H. kimurae , H. fossigenus , H. katoi , H. naevius , H. sematonotos , and H. oyamai by combination of the presence of small to continuous brownish-white dorsal markings, white ventral marking on the trunk, and smaller body size ( Matsui et al. 2004; Nishikawa & Matsui, 2014; Matsui et al. 2017; Okamiya et al. 2018; Tominaga et al. 2019). Hynobius kuishiensis sp. nov. is morphometirically similar to H. tsurugiensis sp. nov., but they differ in color with the former has usually with brownish-white dorsal markings whereas the latter with continuous bright yellow color on dorsum. Hynobius kuishiensis sp. nov. is similar to H. guttatus sp. nov. and H. stejnegeri in color, but has shorter vomerine teeth series and smaller number of vomerine teeth than the latter two.

Natural history: Breeding occurs from May to June, when egg sacs are attached to stones under the ground in the headwater of mountain streams. Larvae can metamorphose in early autumn without feeding like H. stejnegeri , H. guttatus sp. nov., and H. tsurugiensis sp. nov.

Figures

FIGURE 7. Dorsal and ventral views of male holotype (T2804) (A, B) of Hynobius guttatus sp. nov.; female holotype (T2096) (C) and a male paratype (T2873) (D, E) of H. tsurugiensis sp. nov.; male holotype (KUHE18035) (F) and a male paratype (KUHE24201) (G, H) of H. kuishiensis sp. nov. from Mt. Kuishi, Kochi Prefecture, a male specimen (T2995) (I, J) of H. kuishiensis sp. nov. from Mt. Ishizuchi, Ehime Prefecture, a male specimen (T2689) (K, L) of H. kuishiensis sp. nov. from Odamiyama, Uchiko-cho, Ehime Prefecture; and dorsal and ventral views of a male specimen (KUHE 28007) of H. stejnegeri (M, N) from Yamato-cho, Kumamoto Prefecture.

FIGURE 8. Vomerine teeth series of male holotype (T2804) of Hynobius guttatus sp. nov. (A); female holotype (T2096) of H. tsurugiensis sp. nov. (B); male holotype (KUHE18035) of H. kuishiensis sp. nov. (C); and a male specimen (KUHE 28007) of H. stejnegeri (D) from Yamato-cho, Kumamoto Prefecture.

FIGURE 9. Egg sacs of Hynobius guttatus sp. nov. (A) from Gifu Prefecture, H. tsurugiensis sp. nov., (B) from Mt. Tsurugi, H. kuishiensis sp. nov., (C) from Mt. Kuishi, and H. stejnegeri from Asakura-shi, Fukuoka Prefecture (D). Egg sacs A and D were laid in captive condition. Dorsal and lateral views of a full-grown larva (Stage 62–64) of Hynobius guttatus sp. nov. (E, F), H. tsurugiensis sp. nov. (G, H), H. kuishiensis sp. nov. (I), H. stejnegeri (J, K). Localities are same as those of egg sacs, respectively.

FIGURE 10. Map of western Japan showing distributional range of Hynobius stejnegeri and three new species. Range hatched by black: H.guttatus sp. nov.; range hatched by orange: H. tsurugiensis sp. nov.; range hatched by green: H. kuishiensis sp. nov.; range hatched by red: H. stejnegeri. Areas colored by brown and blue within the distributional range of H. kuishiensis sp. nov. indicate the ranges of the Ishizuchi-Kuishi lineage and the Oda lineage, respectively.

Tables

TABLE 4. Means±SD of SVL and medians of ratios of metric characters (R = %SVL), CG (L), CG (R), LO, UJTN, LJTN, VTN in female. First and 3rd quartiles are indicated in square brackets and ranges are shown in parentheses.

	Chubu-Kinki (n=32)	Tsurugi (n=16)	Ishizuchi-Kuishi (n=14)	Oda (n=9)	H. stejnegeri (n=63)
SVL	57.7±4.0	66.8±4.5	61.0±4.9	63.1±5.8	63.1±5.0
	(51.2–65.9)	(59.2–73.8)	(53.2–70.0)	(51.9–70.2)	(50.4–70.9)
RHL	23.8 [23.4–24.3]	22.6 [22.2–22.9]	23.8 [23.2–24.2]	23.2 [22.9–24.0]	23.1 [22.6–23.4]
	(22.0–24.9)	(21.5–23.8)	(22.4–25.2)	(22.5–24.3)	(21.3–24.7)
RHW	17.6 [17.1–18]	16.0 [15.7–16.7]	16.9 [16.3–17.4]	16.2 [15.6–16.7]	16.9 [16.5–17.3]
	(16.7–19.1)	(15.0–18.0)	(15.4–18.8)	(15.2–17.9)	(15.5–19.2)
RLJL	14.7 [14.5–15]	13.6 [13.3–14.1]	14.4 [13.9–14.8]	13.9 [13.4–14.3]	13.7 [13.5–14.3]
	(13.7–16)	(12.6–14.5)	(13.2–15.2)	(12.9–15.6)	(13.0–15.5)
RSL	6.7 [6.5–6.9]	6.6 [6.3–6.7]	6.7 [6.7–6.9]	6.5 [6.5–6.6]	6.3 [6.2–6.5]
	(6.3–7.2)	(6.1–6.9)	(6.4–7.2)	(6.3–7.1)	(5.8–6.9)
RIND	5.5 [5.3–5.6]	5.2 [5.1–5.4]	5.3 [5.0–5.5]	5.1 [5.0–5.1]	5.2 [5.0–5.4]
	(4.7–5.8)	(4.9–5.6)	(4.9–6.0)	(4.8–5.4)	(4.5–5.9)
RIOD	5.7 [5.5–5.8]	5.2 [5.1–5.4]	5.6 [5.3–5.8]	5.3 [5.1–5.3]	5.6 [5.3–5.7]
	(5.2–6.0)	(4.9–5.8)	(5.1–6.0)	(4.8–6.2)	(4.9–6.1)
RUEW	3.2 [3.1–3.3]	3.3 [3.1–3.4]	3.4 [3.1–3.4]	3.3 [3.2–3.4]	3.2 [3.0–3.3]
	(2.9–3.7)	(2.9–3.7)	(2.9–3.7)	(3.1–3.5)	(2.8–3.7)
RUEL	5.5 [5.4–5.7]	5.4 [5.3–5.7]	5.8 [5.5–5.9]	5.6 [5.3–5.6]	5.5 [5.4–5.8]
	(5.1–6.1)	(5.1–6.2)	(5.1–6.4)	(5.0–6.0)	(5.1–6.3)
RAGD	52.6 [51.8–53.3]	55.0 [54.3–55.3]	52.7 [51.2–53.5]	54.0 [53.5–55.1]	54.3 [53.3–55.3]
	(50.3–55.7)	(51.8–56.9)	(49.3–56.3)	(52.0–57.1)	(50.9–57.8)
RTRL	76.2 [75.7–76.6]	77.4 [77.1–77.8]	76.2 [75.8–76.8]	76.8 [76–77.1]	76.9 [76.6–77.4]
	(75.1–78.0)	(76.2–78.5)	(74.8–77.6)	(75.7–77.5)	(75.3–78.7)
RTAL	64.4 [62.2–66.2]	70.7 [68.8–71.4]	69.7 [66.8–72.8]	66.9 [63.7–68.5]	62.7 [60.5–63.8]
	(59.7–72.2)	(64.3–73.7)	(62.0–73.3)	(63.4–69.5)	(56.4–70.2)

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