Cobitis takenoi, Nakajima, Jun, 2016

Nakajima, Jun, 2016, Cobitistakenoi sp. n. (Cypriniformes, Cobitidae): a new spined loach from Honshu Island, Japan, ZooKeys 568, pp. 119-128 : 121-125

Taxon classification Animalia Cypriniformes Cobitidae

Cobitis takenoi sp. n. Figs 3, 4, 5, Table 1

Cobitis takenoi 'Tango tetraploid form’ of Cobitis striata : Takeno et al. 2010: 108, fig. 2; Cobitis sp. 5: Nakajima et al. 2012: 92, fig. 3e; Cobitis sp.: Hosoya 2013: 331; Cobitis sp.: Kawase 2015: 181.

Type materials.

Holotype: KPM-NI 31994, 60.4 mm standard length (SL), male, Tango District, Kyoto Prefecture, Honshu Island, Japan; collected by K. Tominaga on 17 Apr. 2010. Paratypes: 10 specimens, all from same locality as the holotype: TKPM-P 7363, 7364, 53.2-67.5 mm SL, male and female, same data as holotype; KPM-NI 31995-31999, 49.4-70.5 mm SL, 3 males and 2 females, collected by J. Nakajima on 12 Nov. 2010; KUN-P 45133, 57.7 mm SL, male, collected by K. Tominaga on 5 Jul. 2014; JNC 188, 189, 58.6-60.6 mm SL, 2 males, same data.

Diagnosis.

Maxillary barbel short, more of the same eye diameter; lamina circularis in adult males simple and roundish; USP narrow; PMN 14; line L5 organised in 11-17 oblong or ovoid blotches out of spawning season, and lines L3 and L5 in adult male well-developed longitudinal obvious stripes during spawning season; upper and lower spot at caudal base not connected; tetraploid.

Description.

Dorsal-fin rays iii, 7; anal-fin rays iii, 5; pectoral-fin rays i, 7-8; pelvic-fin rays ii, 6; caudal-fin rays 8+8. Body elongate, laterally compressed. Head and snout elongated. Interorbital space narrow, convex. Eye relatively large. Caudal peduncle relatively compressed. Mouth small, inferior, arched with fleshy lips; lower lip divided with 2 well-developed lobes; upper lip with transverse wrinkles on the surface. Barbels, 3 pairs, first on rostorum, second on maxilla, third on maxillomandibula; each barbel well-developed, length of maxillary barbel short, same as the eye diameter; the length of the rostral and maxillary barbels shorter than that of mandibular barbel (Fig. 4a). Lateral line short, reaching the pectoral-fin base. PMN 14. Very small cycloid scales on the trunk. Suborbital spine two-pronged and incurved; length of the outer spine one-third of that of the inner spine (Fig. 4b). First branched ray of the pectoral fin longer than rest (Fig. 4c); pectoral fin in adult males longer than that in females. USP narrow (Figs 4c, d, see also Fig. 6). Lamina circularis at the base of the pectoral fin in adult males simple and roundish (Fig. 4d). Dorsal-fin base equidistant from the base of the caudal fin and the top of the snout. Pelvic-fin origin below the second or third branched dorsal fin ray. Anal fin not reaching the caudal-fin base. Margin of anal and dorsal fins slightly roundish. Caudal fin slightly roundish. Abdominal vertebrae 22 (21-23); caudal vertebrae 20 (19-21); total vertebrae 42 (40-44) ( Takeno et al. 2010). Largest recorded specimens 65.5 mm SL in male and 84.9 mm SL in female ( Takeno et al. 2010).

Colouration.

Body yellowish white with dark brown pigmentation in fresh. A clear streak running from the tip of the snout to the occiput, crossing to the eye. Upper part of the head covered with amorphous spots; opercle and snout covered with amorphous patterns. Caudal and dorsal fins with 3-4 arcuate bars. Anal fin pigmented along fin rays. Upper spot at caudal base jet-black, size comparable to the eye diameter, lower spot at the caudal base relatively inconspicuous and small; upper and lower spots at the caudal base not connected. Male out of spawning season (Figs 3a, 5b). Body pigmentation organised in 1 dorsal and 4 lateral lines. Line L1 consisting of a series of 11-16, saddle or oval shaped blotches. Line L2 formed by a longitudinal jugged line or convex semicircular spots or chained small angular blotches, only present on dorsal part of body. Line L3 formed by a sharp longitudinal line or narrow dotted line, reaching to the post-dorsal body, with intermissive posterior part. Line L4 formed by narrow web like line or dots, reaching to dorsal body. Line L5 organised in 11-17 blotches from the upper part of the pectoral fin to the caudal-fin base; blotches roundish, frequently oblong or ovoid. Male in the spawning season (Fig. 5a). Line L4 not visible or formed by faint longitudinal line. Lines L3 and L5 well developed, forming longitudinal obvious stripes from the upper part of the pectoral-fin base to the caudal-fin base, often intermissive posterior part of L3. Female (Fig. 3b). Similar to males out of spawning season.

Sexual dimorphism.

Males having a roundish lamina circularis at the base of the pectoral fins; females do not. Generally, the body size of females larger than that of males. Lines L3 and L5 of adult males well developed, forming longitudinal obvious stripes during the spawning season; females do not.

Ploidy.

Tetraploid ( Takeno et al. 2010).

Etymology.

The specific name is dedicated to Mr. Makoto Takeno, the discoverer of this spined loach.

Distribution.

Tango District, Kyoto prefecture, Honshu Island, Japan.

Habitat and biology.

This species inhabits sandy-mud bottoms of the middle and lower reaches of rivers (Fig. 2). Life histories are unknown.

mtDNA cytb sequence.

AB533231-AB533234 ( Takeno et al. 2010).

Japanese name.

Tango-suji-shima-dojyô ( Nakajima et al. 2012).

Comparison.

This new species is distinguished from nine species of Cobitis in the Japanese archipelago ( Cobitis biwae , Cobitis striata , Cobitis matsubarae , Cobitis takatsuensis , Cobitis shikokuensis , Cobitis magnostriata , Cobitis minamorii , Cobitis kaibarai and Cobitis sakahoko ) by a combination of the following character states: a short maxillary barbel equaling in length the eye diameter (vs. longer than the eye diameter in Cobitis matsubarae , Cobitis takatsuensis , Cobitis shikokuensis and Cobitis sakahoko ); a simple roundish lamina circularis (vs. beak-shaped or narrow in Cobitis biwae ; quite narrow in Cobitis takatsuensis and Cobitis shikokuensis ; rectangular with a neck in Cobitis sakahoko ); a narrow USP (vs. broad in Cobitis matsubarae , Cobitis takatsuensis , Cobitis shikokuensis , Cobitis magnostriata and Cobitis sakahoko ); PMN 14 (vs. commonly 12 in Cobitis minamorii ; commonly 13 in Cobitis striata and Cobitis kaibarai ); a L5 formed of blotches out of spawning season (vs. stripe-like in and out of spawning season in Cobitis takatsuensis and Cobitis magnostriata ); both spots at caudal base obvious (vs. lower spot inconspicuous in Cobitis striata and Cobitis kaibarai ); and ploidy tetraploid (vs. diploid in Cobitis striata , Cobitis takatsuensis , Cobitis shikokuensis , Cobitis minamorii and Cobitis kaibarai ). These comparative data were summarised from Nakajima and Suzawa (2016).

Remarks.

Till date, Cobitis takenoi has only been found in one small river system, and the habitat is under threat from river improvement. In addition, some threatened freshwater fishes are captured and sold illegally in Japan (e.g. Parabotia curtus , Watanabe et al. 2015), and this new species is similarly at the risk of being commercially overfished for the ornamental fish market ( Takeno et al. 2010). Therefore, the species is ranked as a critically endangered species (CR) - as Cobitis sp. - in the Japanese Red List ( Kitagawa 2015). The distribution pattern, suitable habitat and life history of this species are not well-known. Basic biological investigations are required for its effective conservation.