Onychodactylus kinneburi, Yoshikawa, Natsuhiko, Matsui, Masafumi, Tanabe, Shingo & Okayama, Takehito, 2013

Yoshikawa, Natsuhiko, Matsui, Masafumi, Tanabe, Shingo & Okayama, Takehito, 2013, Description of a New Salamander of the Genus Onychodactylus from Shikoku and Western Honshu, Japan (Amphibia, Caudata, Hynobiidae), Zootaxa 3693 (4), pp. 441-464 : 443-460

Onychodactylus kinneburi sp. nov.

(Japanese name: Shikoku-hakone-sanshou-uwo) (English name: Shikoku clawed salamander) ( Figs. 2 & 3 )

Synonymy: Salamandra unguiculata: Temminck & Schlegel 1838 , p. 123 (part)

Onychodactylus schlegeli: Duméril, Bibron & Duméril 1854 , p. 114 (part)

Onychodactylus japonicus: Stejneger 1907 , p.42 (part); Dunn 1923, p.506 (part); Kobayashi 1931, p. 709; Okada 1935, p. 575 (part); Sato 1934, p. 465; Sato 1939, p. 701 (part); Sato 1943, p. 288 (part); Nakamura & Uéno 1963, p.14 (part); Hoogmoed 1978, p. 96 (part); Poyarkov et al. 2012, p. 36 (part).

Onychodactylus japonicus (Subclade IV-B): Yoshikawa et al. 2008, p. 249.

Onychodactylus japonicus (Shikoku group): Yoshikawa et al. 2010a, p. 33; Yoshikawa et al. 2010b, p. 344.

Onychodactylus sp. Shikoku group: Yoshikawa & Matsui 2013, p. 9.

Holotype: KUHE 43194, an adult male from a small branch of Kuwaze River on Mt. Takanosu (133o16'E, 33o47'N, 1050 m a.s.l.) in Ino-cho (formerly Hongawa-mura), Kochi Prefecture, Japan, collected by T. Okayama and N. Yoshikawa on 19 May 2009.

Paratypes: A total of 54 specimens: 13 males and five females (KUHE 43060–43066, 43195–43200 and KUHE 43137, 43190–43193, respectively, all collected on 19 May 2009 by T. Okayama and N. Yoshikawa), and 12 males and 17 females (OMM-Am1–12 collected on 7 May 1993 and OMM-Am13–29 collected on 19 May 1993, respectively, all by T. Okayama) from the type locality, three males (KUHE 8330 on 21 June 1985 by S. Tanabe, KUHE 36934 on 8 October 2005 by M. Mori, and T3295 on 8 August 2005 by S. Tanabe, A. Tominaga, and S. Ichihara) and three females (KUHE 36933 on 8 October 2005 by M. Mori, T3062 on 8 August 2001 by S. Tanabe and S. Ichihara, and NSMT-H 0 1170 on 3 June 1957 by S. Uéno) from Mt. Tsurugi, Miyoshi-shi (formerly Higashi-iyayama-mura) Tokushima Prefecture, and one male (KUHE 18034 on 1 June 1994 by M. Matsui, S. Tanabe, and Y. Misawa) from Mt. Kuishi, Kochi-shi (formerly Tosayama-mura), Kochi Prefecture.

Referred specimens: See APPENDIX 1.

Etymology: The species epithet " kinneburi " is a noun derived from the Japanese “Kin-neburi”, a local name of this salamander on Ishizuchi Mountains (Kobayashi 1931; Sato 1934, 1943) meaning “Gold-licker”. Tanabe (2000) introduced origins of this local name suggested by a salamander collector on Ishizuchi Mountains: 1) Copperdiggers who found the salamanders considered that the salamanders came to underground to lick gold; 2) “Kin- (gold)” in the name of this salamander may be related to its coloration and the fact that dried specimens of this salamander were traded for medical purpose with higher price than those of the other salamanders in Ishizuchi Mountains. Sato (1934) noted that this salamander was collected by local people, who called individuals with vivid color as “Kin (gold)”, whereas those with relatively pale color as “Gin (silver)”. In any case, such local names seem to have derived from beautiful yellowish-orange coloration of the new species.

Diagnosis: The new species is assigned to a member of the genus Onychodactylus diagnosed by the following characters: lung absent; black horny claws present on tips of fingers and toes of breeding adults and larvae; vomerine teeth in two short, transverse, arch-shaped series; larvae with skin folds on posterior edges of limbs; breeding males with dermal flaps on posterior edge of hindlimb; black tubercles and asperities on palm and sole in breeding males and on sole in breeding females; breeding in flowing water under the ground; eggs large, pigmentless, small in number. It is further assigned to a member of the O. japonicus species complex that generally possessing a distinct dorsal stripe. Dorsal stripe yellow or yellowish-orange sharply defined on black background; body relatively large with mean SVL (±1SD) of 72.2± 4.3 mm and 78.4± 5.8 mm in males and females, respectively; tail longer than SVL in both sexes; lacking wedge-shaped dark marking on chest; ventrum pale white with weak pigments; presacral vertebrae including atlas usually 19; costal grooves 13; right and left vomerine tooth series usually continuous without gap, series tending to curve shallowly; vomerine teeth on one side of series usually 13–16.

Description of holotype: An adult male with SVL 75.0 mm ( Fig. 2 ); body thick; head oval and depressed, longer than wide; neck slightly narrower than head; snout rounded, projecting beyond lower jaw; nostril close to eye; eye large, shorter than snout, prominently protruded, laterally slightly beyond level of outer edge of upper jaw; gular fold posteroventrally to head; parotoid gland extremely developed, oval, ca. 1.6 times longer than wide, extending from angle of jaw to gular fold; postorbital groove obvious, running to parotoid gland; vomerine teeth in two transverse, shallowly curved arch-shaped series without gap in between ( Fig. 4 ); each series with 15 teeth; few dark pigments scattered around vomerine tooth series; forelimb thin, forearm slightly thicker than upper arm; relative length of fingers I<IV<II<III; hindlimb slightly longer and distinctly more robust than forelimb; tibia thicker than thigh; relative length of toes I<V<II<III<IV; secondary sexual characters obvious; dermal flap on posterior edge of hindlimb extremely developed; black horny claws on tips of fingers and toes; black tubercles and asperities on palm and sole; trunk elongated and cylindrical; indistinct middorsal groove from end of head to level of cloaca; well-developed 13 costal grooves on both sides of trunk; presacral vertebrae including atlas numbering 19; base of tail including around cloaca well swollen; cloaca longitudinal slit, length 11.6% SVL, with anterior one-third of its edge slightly swollen, forming inverse V-shaped skin fold; a series of small black spines lining along front edge of precloacal skin fold; tail long, 129% length of SVL, cylindrical at base, increasingly compressed posteriorly; posterior two-thirds of tail laterally compressed, extremely at tip, forming thin, finny shape; tip of tail rounded in lateral view; tail highest (11.7% SVL) near tip.

Color: In life, dorsum with distinct yellowish-orange marking from snout to near tip of tail; marking mottled on forehead, but becoming continuous behind eyes to form a stripe posterior to neck; stripe with wavy border and mostly sharply defined from black background ( Fig. 2 ); stripe partly interrupted on tail and narrowed toward tip; side of body black without spots, gradually fading toward whitish, unmarked ventral side; upper half of iris darkbrown, slightly mottled with gold, lower half uniformly dark-brown. In alcohol, dorsal yellowish coloration completely bleached quickly, and became whitish.

Measurements (in mm) and counts of the holotype: SVL 75.0, HL 17.2, HW 11.0, TAL 96.6, AGD 37.7, FLL (L) 20.4, FLL (R) 20.6, HLL (L) 21.6, HLL (R) 21.4, UEL (L) 4.6, UEL (R) 4.4, IOD 3.4, END (L) 2.0, END (R) 2.3, ICD 6.7, IND 5.3, SL (L) 6.0, SL (R) 6.1, CW 9.8, BTAH 8.3, BTAW 9.2, MTAH 8.5, MTAW 5.7.

Number of vomerine teeth 15 on both right and left series. Costal grooves 13 on both sides. Adpressed limbs overlapping by 0.5 costal folds. Number of presacral vertebrae including atlas 19.

Variation: The following description of variation is based on the maximum number of 36 adult males and 33 adult females obtained from Shikoku and Chugoku Mountains, including the type series. Morphometric data are summarized in Table 1 together with those of the reference species, O. fischeri , O. japonicus , O. nipponoborealis , and O. tsukubaensis .

Significant geographic variations between disjunct populations of Shikoku and Chugoku were detected: Chugoku populations significantly differed from Shikoku populations in having relatively shorter forelimb in males (26.1% vs. 27.5% in Shikoku), and in having smaller SVL (66.9± 3.8 mm vs. 79.1±5.0 mm in Shikoku), relatively shorter tail (93.1% vs. 105.3% in Shikoku), and larger eye (6.4% vs. 5.8% in Shikoku) in females. Males of Chugoku populations also tended to have smaller SVL (68.7± 1.9 mm) than Shikoku populations (72.6± 4.3 mm) but the difference was not significant.

When the two geographic groups were combined, males (72.2± 4.3 mm, n = 36) were significantly smaller than females (78.4± 5.8 mm, n = 33) in SVL (Table 1). In values relative to SVL, sexes significantly differed in the following characters: males had significantly longer tail, higher BTAH, wider BTAW, higher MTAH, wider MTAW, shorter trunk, shorter hindlimb, longer head, larger eye, and larger IND than females (Table 1). Males had significantly smaller number of vomerine teeth, and less frequent occurrence of short sub-branch of vomerine tooth series at the inner juncture (Table 3). Males had more robust hindlimb and posteriorly more projecting distal end of fibula than females.

Unlike non-breeding adults, the following characters appeared in breeding adults ( Figs. 5 & 6 ): dermal skin fold on posterior edge of hindlimb in males; black claws on digits in both sexes; black tubercles and asperities on palm and sole of males, and sole of females; parotoid gland well swollen in both sexes; cloaca well swollen in males; precloacal skin fold inverse V-shaped in males and inverse narrow U-shaped in females; black precloacal spine series in both sexes; tail laterally well compressed in both sexes, though more remarkable in males.

Number of costal grooves was usually 13, but varied from 12 to 14 (Table 2) and was sexually not significantly different. Both sexes were similar in the degree of overlap of fore- and hindlimbs (median = 0 fold). Number of presacral vertebrae including atlas was usually 19 but varied from 18 to 20. Sexes differed significantly in number of vomerine teeth (9 to 22, mean = 13.6± 3.2 in males and 8 to 25, 16.0± 3.8 in females; Table 3). Outer Outer branch of the vomerine tooth series was sometimes interrupted by postchoanal groove. Females more frequently had vomerine tooth series with the inner branch curving medially to form a short, anteriorly directed subbranch than in males (Table 3).

Color pattern in life was variable among individuals. Wide dorsal stripe or marking varies from straight, wavy, to continuous or discontinuous series of mottling. Color of dorsal stripe varied from orange, yellowish-orange to light yellow, while background color varied from gray-brown, dark-gray, to black. Border of dorsal stripe and background color was sharply defined, but was often partly obscured by merging with background, forming smooth gradation. Usually no markings were seen on lateral side, but sometimes small spots, that were same color of dorsal markings, were present. Lower half of iris was sometimes slightly mottled with gold.

Larva: Larvae immediately after hatching at stages of 54 to 55, which usually cannot be seen in open streams, 14.9–15.3 mm (15.1± 0.2 mm) in SVL and 27.0– 27.3 mm (27.1± 0.2 mm) in total length (TL), with large yolk, undeveloped spatulate limbs, and gray dorsum (see below); size of larvae seen in open streams (stages 66–70) 17.9–53.1 mm and 13.3–53.9 mm in SVL and TAL, respectively, with resultant TL of 32.9–105.3 mm; head rectangular and blunt at snout ( Fig. 7 ); eye slightly prominent; three pairs of short external gills; labial fold well developed at posterior half of upper jaw; caudal fin low but well-developed dorsally and ventrally; dorsal fin higher than ventral fin; origin of dorsal fin at level of posterior hindlimb to cloaca; ventral fin originating from around posterior half to two-thirds of tail; tail tip moderately rounded; skin fold on posterior edge of limb; surfaces of palm and sole with dark asperities; digits with acute and curved black claws.

Hatchlings in life with two color morphs, one dorsally yellowish-gray with black spots, and another black with sharply edged, wide stripe ( Fig. 7 G & H), and whitish and transparent ventrum; Premetamorphic larvae with orangish dorsal stripe or mottling extending posterior head to tail on black background ( Fig. 7 A–C); ventrally whitish or grayish without markings.

Comparisons: In comparing Onychodactylus kinneburi sp. nov. with the other congeneric species, some data were cited from Poyarkov et al. (2012) and Yoshikawa & Matsui (2013).

Onychodactylus kinneburi differs from the continental Onychodactylus species ( O. fischeri , O. koreanus , O. zhangyapingi , and O. zhaoermii ) in having a distinct wide dorsal stripe (vs. absent or indistinct in other species).

Onychodactylus kinneburi also differs from O. fischeri in having significantly smaller male SVL. SVL also tends to be smaller in female O. kinneburi , though not significant. In characters relative to SVL, O. kinneburi significantly differs from O. fischeri in having shorter tail in males (117.1% vs. 127.4% in O. fischeri ), shorter trunk in males (51.9% vs. 55.5% in O. fischeri ), longer forelimb (27.4% in males and 27.2% in females vs. 23.7% and 24.0%, respectively, in O. fischeri ), longer hindlimb (31.2% in males and 31.9% in females vs. 27.5% and 27.3%, respectively, in O. fischeri ), wider head (14.7% in males and 14.5% in females vs. 12.9% and 12.6%, respectively, in O. fischeri ), wider internarial space (7.3% in males and 7.0% in females vs. 5.7% and 5.4%, respectively, in O. fischeri : Table 1). Onychodactylus kinneburi is also significantly different from O. fischeri in having smaller number of presacral vertebrae (mode = 19 vs. mode = 21 in O. fischeri ) and costal grooves (mode = 13 vs. mode = 15–16 in O. fischeri : Table 2). Number of vomerine teeth in female O. kinneburi tends to be larger than O. fischeri , although it is not significant (Table 3).

From O. koreanus , O. kinneburi also differs in having larger SVL in both sexes, and shorter tail in males (117.1% vs. 128.7% in O. koreanus ), shorter and longer trunk in males and females, respectively (51.9% and 55.5%, vs. 55.7% and 48.1% in O. koreanus ), and narrower head (14.7% and 14.5% in males and females, respectively, vs. 16.9% and 15.8%, respectively, in O. koreanus ), all relative to SVL (n = 22 and 14 in males and females, respectively). Onychodactylus kinneburi also differs from O. koreanus in having smaller number of vomerine teeth in males (13.6±3.2 vs. 17.2±2.2 [n = 12] in O. koreanus ).

Other than possession (vs. absence) of dorsal stripe, O. kinneburi differs from O. zhangyapingi (n = 6 and 10 in males and females, respectively) in having larger SVL in both sexes, relatively shorter tail in both sexes (117.1% and 105.1% vs. 136.6% and 110.9% in males and females, respectively, in O. zhangyapingi ), shorter trunk in males (51.9% vs. 54.0% in O. zhangyapingi ), less vomerine teeth in males (13.6±3.2 vs. 16.9±0.9 [n = 6] in O. zhangyapingi ).

Similarly, from O. zhaoermii (n = 2 and 6 in males and females, respectively), O. kinneburi differs in having larger SVL, relatively shorter tail in males (117.1% vs. 136.8% in O. zhangyapingi ), larger numbers of presacral vertebrae (mode = 19 vs. mode = 17–18 in O. zhaoermii ) and costal grooves (mode = 13 vs. 11–12, in O. zhaoermii ), and more vomerine teeth in females (16.0±3.8 vs. 13.6±1.5[n = 6]in O. zhaoermii ).

Comparison of O. kinneburi with the other species in the O. japonicus species complex produced the following results (Tables 1, 2, 3 & 4). In SVL, O. kinneburi is significantly larger than O. japonicus , O. nipponoborealis , and O. tsukubaensis in both sexes except for male O. tsukubaensis .

In dimension relative to SVL, O. kinneburi significantly differs from O. japonicus in having longer hindlimb in females (31.9% vs. 30.6% in O. japonicus ), shorter snout (7.4% in both sexes vs. 7.8% in males and 7.7% in females in O. japonicus ), and narrower intercanthal space in males (8.8% vs. 9.1% in O. japonicus ). Onychodactylus kinneburi also differs from O. japonicus in having significantly larger numbers of presacral vertebrae (mode = 19 in both sexes vs. mode = 18 in males and 18−19 in female, in O. japonicus ) and costal grooves (mode = 13 in both sexes vs. mode = 12 in males and 13 in females, in O. japonicus ). Onychodactylus kinneburi shares sharply defined wide dorsal stripe on black background with topotypic (environs of Hakone) and sympatric (Chugoku Mountains) populations of O. japonicus , and this makes the two species not easily be distinguished only by dorsal coloration ( Fig. 8 ). However, O. kinneburi tends to differ from O. japonicus from these localities in color of dorsal stripe in life (yellowish in O. kinneburi vs. reddish in O. japonicus ). The most stable character to distinguish O. kinneburi from O. japonicus is the wedge-shaped dark marking on neck to chest ( Fig. 9 ), which is usually present in O. japonicus (present in 88.9%) but absent in O. kinneburi (absent in 97.7%: Table 4 ). Even in a sympatric locality, this character is quite effective as diagnostic character and the dark marking was presnt in all specimens of O. japonicus , but absent in all O. kinneburi specimens. In addition, O. kinneburi tends to be more whitish or less pigmented on ventral side than in O. japonicus , although the degree of pigmentation varies and overlaps in the two species.

From O. nipponoborealis , O. kinneburi significantly differs in having shorter tail in males (117.1% vs. 125.7% in O. nipponoborealis ), longer trunk in females (55.5% vs. 53.6% in O. nipponoborealis ), shorter hindlimb in males (31.2% vs. 33.5% in O. nipponoborealis ), narrower head in females (14.5%, respectively vs. 15.2% in O. nipponoborealis ), narrower chest (12.3% and 12.2% in males and females, respectively vs. 13.1% and 13.0% in O. nipponoborealis ), and shorter snout (7.4% in both sexes vs. 7.9% and 7.8% in males and females, in O. nipponoborealis ), all relative to SVL. Onychodactylus kinneburi also differs from O. nipponoborealis in having significantly larger numbers of presacral vertebrae (mode = 19 in both sexes vs. 18 and 19 in males and females, respectively, in O. nipponoborealis ) and costal grooves (mode = 13 in both sexes vs. 12 in both sexes in O. nipponoborealis ). Number of vomerine teeth in male O. kinneburi is tend to be smaller than O. nipponoborealis , although it is not significant (Table 3). In coloration, O. kinneburi with sharply defined yellowish-orange or yellow dorsal stripe or blotches with uniformly black background, and usually lacking silver dots on body, can be easily distinguished from O. nipponoborealis with ochre or brownish dorsal stripe of dusty dotted edge with dark-brown background, silver dots often seen on body. Dark marking on chest, usually absent in O. kinneburi tends to be present in O. nipponoborealis (65.2%: Table 4 ).

From O. tsukubaensis , O. kinneburi differs in having significantly longer tail (117.1% and 105.1% in males and females, respectively vs. 102.3% and 90.4% in O. tsukubaensis ), longer trunk in females (55.5% vs. 52.4% in O. tsukubaensis ), longer hindlimb in females (31.9% vs. 30.5% in O. tsukubaensis ), shorter and narrower head in females (21.7% and 14.5%, respectively vs. 23.3% and 15.6% in O. tsukubaensis ), narrower chest (12.3% and 12.2% in males and females, respectively vs. 13.1% and 13.4% in O. tsukubaensis ), all relative to SVL. Onychodactylus kinneburi also differs from O. tsukubaensis in having significantly larger numbers in both sexes of presacral vertebrae (mode = 19 vs. 18 in O.tsukubaensis ) and costal grooves (mode = 13 vs. 12 in O. tsukubaensis ). Number of vomerine teeth in both sexes tends to be smaller in O. kinneburi than in O. tsukubaensis , although the difference is not significant (Table 3). In coloration, O. kinneburi can also be easily distinguished from O. tsukubaensis with sharply defined ochre or reddish-brown dorsal stripe on grayish-brown background, and body usually with silver dots seen on. Dark chest marking, absent in O. kinneburi is possesed by about one-third (31.3%: Table 4 ) of O. tsukubaensis specimens.

At the larval stage, O. kinneburi looks very similar to O. japonicus and is hardly be distinguished from it. From larvae of O. tsukubaensis , O. kinneburi larvae differs in having longer tail ( Fig. 10 ) and different coloration (orangish dorsal stripe or blotches on uniformly black background vs. silvery dots and mottling on dark-brown body and light yellow dorsocaudal stripe in O. tsukubaensis ). Similarly, larval O. kinneburi differs in coloration from larval O. nipponoborealis that have only sometimes ochre or brownish dorsal stripe or markings on darkbrown background).

Karyotype: No karyotypic information is available for O. kinneburi .

Genetic characteristics: The new species corresponds to Subclade IV-B or Shikoku group of Yoshikawa et al. (2008, 2010a, 2012; Fig. 11 ). Based on the phylogeny derived from the mitochondrial cytochrome b gene, O. kinneburi is closest to and is the sister taxon to Onychodactylus sp. Kinki group ( Fig. 11 ), from which it differs by a large mean uncorrected p distance of 5.56% (5.08–5.87%: Yoshikawa et al., 2008).

Although O. kinneburi is geographically isolated in western Honshu and Shikoku Islands, no significant geographic genetic differentiation was found between these two areas ( Fig. 12 ), and intraspecific genetic variation in 615bp of mitochondrial cyt b gene is not high (up to 1.30% of uncorrected p-distance). This species is sympatric with O. japonicus in western Honshu, but the two species are reproductively isolated and genetically clearly distinct in both mtDNA (Yoshikawa et al. 2008; Fig. 12 ) and nuclear markers (Yoshikawa et al., 2010a).

Fecundity and natural history: Breeding season of O. kinneburi sp. nov. is middle May to middle June, when breeding adults arrive breeding sites near headstreams on upper parts of mountains. Breeding site and fecundity of O. kinneburi were amply reported by Sato (1943, as O. japonicus ), who obtained egg sacs on 21 May 1937 from a breeding site (1250 m a.s.l.) in Otonotaru Valley on Mt. Ishizuchi, Ehime Prefecture. According to his report, egg sacs were laid in completely dark places under a huge rock in the stream with water temperature of 6°C, where many breeding adults assembled. Egg sacs were attached under the rock and strongly adhered by gelatinous stalks that were up to 20 mm in length. Outer layer of egg sac was transparent, thick, and strong. Egg sacs were cylindrical or spindle in shape, in which eggs were arranged in a single row and two rows, respectively. Clutch size ranged from 7 to 15 (2– 12 eggs per egg sac), and eggs were large, with diameter of 5.0– 5.7 mm. They were completely whitish or yellowish white in color (Sato 1943). Clutch sizes of O. kinneburi we examined at the type locality ranged from 16 to 25 (mean±1SD = 20±2.7, n = 17), and were larger than those reported by Sato (1943). Number of eggs in one pair and a broken part of egg sacs of O. kinneburi , that we obtained in the wild on Mt. Kurokasa ( Fig. 13A : see below), was 10 and 11 (pair), and six (broken part). Diameters of 27 eggs in sacs ranged 4.7–5.9 mm (5.1±0.4), and seemed to vary among females (4.7–5.2 mm [4.9±0.1, n = 21] in the pair; 5.2–5.9 mm [5.7±0.3, n = 6] in the broken part). As Sato (1943) noted, the outer gelatinous layer of egg sac was elastic but very strong, and was difficult to be torn by hand. The egg sacs we obtained were cylindrical in shape (68.8 and 72.2 mm [pair] and 58.8 [broken part] long at the next day of finding), containing pigmentless, entirely yellowish colored eggs that were arranged in a single row ( Fig. 13A ). Very weak, longitudinal grooves could be seen on the surface of the egg sacs, and there were short whiptail-like structure on free ends of the egg sacs.

The breeding site where we found egg sacs of O. kinneburi was an underground stream near headstream (1400m a.s.l.) in Mt. Kurokasa, Miyoshi-shi, Tokushima Prefecture (on 10 June 2012). At the underground stream, water was cool (9.2°C) and abundant ( Fig. 13 B). Many small larvae with yolk (developmental stages of 66–68) and several breeding adults were found around the opening and inside of the underground stream. The egg sacs were found 160cm inside from the opening of the underground stream and were caught in the tree roots. The egg sacs lacked gelatinous stalks to adhere to the rock, and indicated that they had been flushed down from the actual oviposition site located in deeper portion inside the underground stream.

The egg sacs obtained were kept in the laboratory under the temperature of 11–12°C. As the result, three eggs hatched on 11 to 15 December 2012 ( Fig. 13 C) at stages of 54 to 55. For measurements of hatchlings, see “Larva” section.

Little is known on larval life history of O. kinneburi , but size of larvae found in open streams ranged from 32.9 to 105.3 mm. Tamura (2012) noted that many small larvae with a yolk in the stomach were found near the headstream in late May. We also found hatchlings with a yolk but well-developed clawed limbs (mean = 35.4± 1.5 mm in TL, n = 24) near headstreams in early June. They might have appeared in the open stream earlier, as known in the other species of the O. japonicus complex (Yoshikawa & Matsui 2013). Larvae dispersed downstreams and grew to metamorphose for two or more years (Sato 1943; Tamura 2012). Metamorphosis is reported to occur in late summer to early autumn (Tamura 2012). The size at metamorphosis is unknown, but seems to be around 100 mm or larger in TL. Metamorphosed juveniles disperse to inhabit forest floor around the stream.

Ecology of adults in the non-breeding season is little known, but they inhabit cool, humid, and well-forested mountains, as is the case in the other Onychodactylus species. The adults are often found under stones, rocks or logs on the forest floor far distant from streams. Shibata (1969) reported a case of predation by a snake Rhabdophis tigrinus .

In Chugoku Mountains, O. kinneburi sp. nov. and O. japonicus inhabit sympatrically. We observed breeding adults of both species around an identical underground stream (breeding site) in early June. We also found hatchlings of the two species coming out from the same underground streams, and larvae of the two species in a single stream. These observations suggest that breeding season and site of the two sympatric species are identical, despite their clear genetic isolation (Yoshikawa et al. 2010 a).

Range: Known from western Japan, mountains in Shikoku and several localities in Chugoku Mountains of western Honshu. In Shikoku, the new species is scatteredly distributed in mountain regions higher than 700 m a.s.l. (Okayama 2002), but is by now not known from Kagawa Prefecture located in northeastern part of the island. Known eastern limit in Shikoku is Mt. Tsurugi, Tokushima Prefecture, whereas southwestern limit is Uchiko-cho (formerly Oda-cho), Ehime Prefecture (Morikawa 1979; Uwa 2003; Fig. 1 ). In Chugoku Mountains of western Honshu, O. kinneburi sp. nov. occurs sympatrically with O. japonicus (Yoshikawa et al. 2008, 2010a). Known localities in Chugoku Mountains are separated into two disjunct areas, one is Kagamino-cho (formerly Okutsucho), Okayama Prefecture, and the other includes Mts. Jippo and Kanmuri, Hatsukaichi-shi (formerly Yoshiwamura), Hiroshima Prefecture, and Mt. Jakuchi, Iwakuni-shi (formerly Nishiki-cho), Yamaguchi Prefecture.

Conservation: At present, the new species is locally abundant, but its range is limited and fragmented. The new species is listed as O. japonicus on the Red Lists of Ehime, Kochi, and Tokushima Prefectures as Vulnerable, and populations are declining by recent disturbance of habitat such as deforestation, construction of roads and dams (Anonymous 2001; Okayama 2002; Uwa 2003). Because this species strongly depends on stability of open and underground streams, careful managements on its habitats and population monitoring are needed to maintain and/ or recover its population size. We propose that the new species to be designated as Near Threatened in the IUCN Red List.

Figures

FIGURE 1. Map of western Honshu and Shikoku showing sampling sites of Onychodactylus kinneburi sp. nov. (open star and inverse triangle) and O. japonicus (shaded circles) used in the morphological analysis. A star indicates type locality of the new species and black inverse triangles and black circles indicate other known localities of O. kinneburi and O. japonicus, respectively. A circle with “? ” indicates a locality where Onychodactylus population without exact species identification is recorded. For locality numbers, refer to Appendix 2.

FIGURE 2. Dorsal and ventral views of male holotype (A and B; KUHE 43194, SVL = 75.0 mm) and a female paratype of O. kinneburi sp. nov. (C and D; KUHE 43192, SVL = 81.1 mm). Scale bar indicates 20 mm.

FIGURE 4. Open mouth of holotype of O. kinneburi sp. nov. (KUHE 43194) showing the shape of vomerine tooth series. Scale bar indicates 1 mm.

FIGURE 5. Palmar (A) and tarsal (B) black tubercles and asperities seen on limbs of the male holotype (KUHE 43194) of O. kinneburi sp. nov. (in preservation). Scale bar indicates 10 mm.

FIGURE 6. Cloacae and tail-tips of the male holotype of O. kinneburi sp. nov. (A and C, respectively: KUHE 43194) and a female paratype (B and D, respectively: KUHE 43192) in breeding season (in preservation). Scale bars on cloacae and tails indicate 2 mm and 10 mm, respectively.

FIGURE 7. Dorsal views of premetamorphic (A – C), growing (D – F), and hatchling (G, H) larvae of O. kinneburi sp. nov. Scale bar indicates 10 mm.

FIGURE 8. Dorsal views of two Onychodactylus species sympatric in Chugoku Mountains (A-F) and a male topotypic specimen of O. japonicus from Hakone-machi, Kanagawa Pref. (G: KUHE 46612). Males (A-B: KUHE 40196 and 42851, respectively) and a female (C: KUHE 42853) of O. kinneburi sp. nov. Males (D-E: KUHE 41726 and 42852, respectively) and a female (F: KUHE 40197) of O. japonicus. Scale bar indicates 20 mm.

FIGURE 9. Comparison of dark marking on chest between two species of Onychodactylus. The male holotype from Shikoku (A: KUHE 43194) and a male from Chugoku Mountains (B: KUHE 42851) of O. kinneburi sp. nov. A male topotype specimen from Hakone-machi (C: KUHE 46612) and a male from Chugoku Mountains (D: KUHE 40195) of O. japonicus. Specimens of B and D were collected from nearly same localities. Arrows indicate dark marking on chest.

FIGURE 10. Relationships between SVL and relative length of tail (RTAL) in larvae of the four species of Onychodactylus; shaded inverse triangles: O. kinneburi sp. nov., RTAL = 0.48 SVL + 74.56, r ² = 0.4306; open circles: O. japonicus, RTAL = 0.59 SVL + 72.36, r ² = 0.7341; shaded squares: O. nipponoborealis, RTAL = 0.66 SVL + 66.04, r ² = 0.6126; closed triangles: O. tsukubaensis, RTAL = 0.19 SVL + 74.91, r ² = 0.1045.

FIGURE 11. An ML tree based on 1141 bp of mitochondrial cytochrome b gene (left) and a neighbor-joining tree based on 14 allozyme loci (right), modified from Yoshikawa et al. (2008) and (2010 a), respectively. Values at nodes indicate supports of 2000 and 1000 bootstrap replicates, respectively.

FIGURE 12. An ML tree based on 615 bp of mitochondrial cytochrome b gene. Values at nodes indicate supports of 1000 bootstrap replicates. Numbers in parenthesis indicate locality numbers shown in Appendix 2.

FIGURE 3. A male paratype of O. kinneburi sp. nov. (KUHE 43066) from the type locality in life.

FIGURE 13. A pair and half of egg sacs (A) and exterior of a breeding site (B) of O. kinneburi sp. nov. found in Mt. Kurokasa, Tokushima Prefecture. Arrows on (A) and (B) indicate the whiptail structure and the opening of underground stream, respectively. A larva of O. kinneburi immediately after hatching on 11 December 2012 (C). Scale bars in A and C indicate 10 mm.

Tables

TABLE 4. A table showing frequencies of presence or absence of the dark marking on chest (number followed by percentage in parenthesis) in five species of Onychodactylus. Bold numbers indicate modal values.

present	-	-	-	13 (72.2%)	27 (100%)	40 (88.9%)
indistinct	2 (3.2%)	-	2 (2.9%)	2 (11.1%)	-	2 (4.4%)
absent	61 (96.8%)	6 (100%)	67 (97.1%)	3 (16.7%)	-	3 (6.7%)