Cobitis magnostriata Nakajima, 2012

Nakajima, Jun, 2012, Taxonomic study of the Cobitis striata complex (Cypriniformes, Cobitidae) in Japan, Zootaxa 3586, pp. 103-130 : 118-119

Cobitis magnostriata Nakajima , sp. nov.

( Figs. 3E, 5E, 6E, 7C, D)

Cobitis taenia striata: Okada and Nakamura 1948:185 , fig. 113; Cobitis taenia striata large race: Minamori 1956: 91, fig. 1;? Cobitis taenia striata: Aoyagi 1957: 169 , fig. 142; Cobitis taenia striata: Okada 1960: 562 , figs. 93a, 93b; Cobitis taenia striata: Nakamura 1963: 161 , figs. 97a, b; Cobitis taenia f. striata: Miyadi et al. 1976: 247 , pl. 31; Cobitis taenia striata large race: Saitoh and Aizawa 1987: 336, fig. 3A; Cobitis sp. L: Saitoh 1989: 386; Cobitis sp. L: Saitoh and Matsuda 1990: 19, fig. 1; Cobitis sp. 1 : Hosoya 2002: 276; Cobitis striata complex large race: Kitagawa et al. 2005: 112, table 1; Cobitis striata complex large race: Saitoh et al. 2010: 1003, table 1; Cobitis sp. 1 : Nakajima et al. 2012: 90, fig. 2a.

Holotype. TKPM-P17344 , male, 62.4 mm SL, Japan: small stream flowing into Biwa Lake, Adogawa, Shiga Pref., Honshu , 6. V. 2007, K. Tominaga.

Paratypes. FRLM24920 , 1 male, 63.3 mm SL, Chinai R., Takashima, Shiga Pref., Honshu , 16. VIII. 1997, Y. Fujioka ; KPM-NI29506 , 1 male, 64.3 mm SL, same data as holotype; MPM-FI1504, 1 male, 63.8 mm SL, same data as holotype; JNC049, 1 female, 93.3 mm SL, same data as holotype; JNC040, 1 male, 72.5 mm SL, small stream flowing into Biwa Lake, Takashima, Shiga Pref., Honshu , 3. VII. 2007, J. Nakajima .

Non-type specimens. 5 males and 3 females, 60.4–84.0 mm SL, same data as holotype ; 1 male and 2 females, 55.4–60.4 mm SL, small river of Yodo R.s., Otsu, Shiga Pref., Honshu , 22. VII. 2008, K. Tominaga .

Diagnosis. This species is distinguishable from other Japanese striated spined loaches by the following characteristics: body size large, mature size about 60–70 mm SL in males, 70–90 mm SL in females; lamina circularis at the base of the pectoral fin of adult male simple roundish plate, the upper segments of the first branched soft ray broad and strong ( Fig. 6E); PMN commonly 14; caudal peduncle relatively deep; line L1 organized in longitudinal line from snout tip to dorsal-fin base, and formed by some oval- or saddle-shaped blotches on postdorsal body; line L2 lacking commonly; line L3 formed by sharp longitudinal line, reaching beyond dorsal fin; line L4 lacking or formed by weak dotted line; line L5 well developed with broad stripe; caudal and dorsal fins margined by a broad black band; upper and lower spot at caudal base connected into dumbell-shape; egg yolk diameter approximately 1.1 mm; karyotype tetraploid (2n = 98).

Description. Lateral view in Figure 3E illustrate body shape, form and position of fins. Morphometric and meristic data for 10 males and 6 females are summarized in Table 2. 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 diameter slightly small. Caudal peduncle relatively deep. Mouth small, inferior, arched with fleshy lips; lower lip divided with two well- developed lobes; upper lip with transverse wrinkles on surface. Barbels, 3 pairs, first on rostora, second on maxillae, third on maxillomandibula; each barbel well developed, length of maxillary barbel same as eye diameter; length of rostral and mandibular barbels shorter than that of maxillary barbel. Lateral line short, reaching the central region between the pectoral-fin base and the tip of the fin. PMN commonly 14 (range, 13–14). Very small cycloid scales on the trunk. Lamina circularis at the base of the pectoral fin of adult male simple roundish plate ( Fig. 6E). The first branched soft ray of pectoral fin longer than the other rays; pectoral fin of the male relatively longer than that of the female. The upper segments of the first branched soft ray of pectoral fin broad and strong. Dorsal-fin base equidistant from the base of the caudal fin and the tip of the snout. Pelvic-fin origin below first or second branched dorsal-fin ray. Anal fin not reaching caudal-fin base. Margin of anal and dorsal fins slightly roundish. Caudal fin slightly roundish. Largest recorded specimens: 72.5 mm SL male, 93.3 mm SL female.

Coloration. Male in the non-spawning season ( Figs. 3E, 7C). Body yellowish white with black pigmentation in fresh specimens. Clear streak running from the tip of snout to the occiput, crossing to the eye. Opercle and snout covered with some large amorphous patterns. Line L1 organized in longitudinal line from the snout tip to the dorsal-fin base, and formed by some oval- or saddle-shaped blotches on postdorsal body; uncommonly formed by 4–6 predorsal and 4–6 postdorsal blotches. Line L2 lacking; uncommonly formed by tiny oval blotches, reaching to subdorsal body. Line L3 formed by sharp longitudinal line, reaching beyond dorsal fin. Line L4 lacking or formed by weak dotted line, present only in anterior half of body. Line L5 well developed with broad stripe from upper part of the pectoral fin to the caudal-fin base. Caudal fin and dorsal fin margined by a broad black band; various cloudy blotches or broken marks on other regions. Anal fin pigmented along the fin rays. Upper and lower spot at caudal base connected into dumbell-shape; upper spot jet-black, larger than eye diameter.

Male in the spawning season ( Fig. 7D). Line L3 well developed with broad stripe from upper part of the pectoralfin base to the posterior part of the dorsal fin. Line L5 well developed with broad stripe from upper part of the pectoral-fin base to the caudal-fin base. Lines L2 and L4 lacking.

Female ( Fig. 5E). Appearance similar to males in the non-spawning season.

Sexual dimorphism. Males have roundish lamina circularis at the base of the pectoral fins, but females do not. Generally, the body size of females is larger than that of males.

Egg diameter. 1.16 ± 0.05 mm (female, N = 1; collected from the Biwa Lake, Shiga Prefecture).

Karyotype. Tetraploid (2n = 98) ( Ueno & Ojima 1976; Ueno et al. 1980; Ueno 1981; Saitoh et al. 1984, 2000; Kimizuka 1987).

Distribution. Biwa Lake and tributary rivers, central Honshu: Shiga Prefecture ( Saitoh & Aizawa 1987).

Habitat and biology. This species inhabits sandy-mud bottoms 1–3 meters below the surface of the lake, and migrates to small streams in the spawning season ( Saitoh & Matsuda 1990).

Etymology. This species has the largest body and the most awesome appearance in the Japanese Cobitis striata complex; this is reflected by the specific epithet magno-, which in Latin means ‘large’ or ‘great’.

Remarks. Although this is an endemic species of Biwa Lake and tributary rivers, it has been introduced in some rivers in Honshu Island ( Kitahara 2007; Matsuzawa & Senou 2008). The genetic features have been reported by Kitagawa et al. (2005) and Saitoh et al. (2010).

Japanese name. Ôgata-suji-shima-dojyô.