Cobitis minamorii tokaiensis Nakajima, 2012

Nakajima, Jun, 2012, Taxonomic study of the Cobitis striata complex (Cypriniformes, Cobitidae) in Japan, Zootaxa 3586, pp. 103-130 : 123-124

Cobitis minamorii tokaiensis Nakajima , subsp. nov.

( Figs. 3H, 5H, 6H, 8E, F)

Cobitis taenia: Aizawa 1981: 188 , fig. 2A, B, C; Cobitis taenia striata Tokai small race: Saitoh and Aizawa 1987: 336, fig. 3E; Cobitis sp. S (Tokai-gata): Saitoh 1989: 389; Cobitis sp. 2 subsp. 2: Hosoya 2002: 275; Cobitis striata complex small race, Tokai form: Kitagawa et al. 2005: 112, table 1; Cobitis striata complex Tokai small race: Saitoh et al. 2010: 1003, table 1; Cobitis sp. 2 subsp. 2: Nakajima et al. 2012: 90, fig. 2c.

Holotype. MPM-FI1507, 1 male, 47.9 mm SL, Japan: creek of Kumozu River system, Tsu, Mie Pref., Honshu , 24. IV. 2011, J. Kitamura.

Paratypes. KPM-NI29509 , 1 male, 43.2 mm SL, creek of Ibi R. s., Tado, Mie Pref., Honshu , 21. X. 2007 , J. Nakajima; MPM-FI1508, 1 male, 39.3 mm SL, creek of Kushida R. s., Matsusaka, Mie Pref., Honshu , 11. IV. 2011 , J. Kitamura; TKPM-P17347 , 1 male, 39.0 mm SL, creek of Iride-ota R. s., Kosai, Shizuoka Pref., Honshu , 9. VI. 2008, J. Nakajima; FRLM24921 , 1 male, 52.4 mm SL, Ohtani R., Nagara R. s., Gifu, Gifu Pref., Honshu , 19. VII. 1997 , T. Okazaki .

Non-type specimens. 3 males and 4 females, 42.5–55.5 mm SL, creek of Ibi R. s., Tado, Mie Pref., Honshu , 21. X. 2007, J. Nakajima ; 2 males, 41.2, 42.3 mm SL, Harai R., Kushida R. s., Matsusaka , Mie Pref., Honshu , 7. III. 2008, K. Tominaga ; 1 male and 1 female, 37.5, 50.3 mm SL, creek of Iride-ota R. s., Kosai, Shizuoka Pref., Honshu , 9. VI. 2008, J. Nakajima ; 2 males and 1 female, 34.1–41.6 mm SL, Shonai R., Kasugai, Aichi Pref., Honshu , 2. VI. 2006, T. Oonaka .

Diagnosis. This subspecies is distinguishable from other Japanese striated spined loaches by the following characteristics: body size small, the mature size about 35–45 mm SL in males, 40–50 mm SL in females; lamina circularis at the base of the pectoral fin of adult male roundish plate, somewhat narrowing toward the outer part; upper segments of the first branched soft ray of pectoral fin narrow and weak ( Fig. 6H); PMN commonly 12; snout short; line L1 consisting of a series of 15–25 blotches; line L2 formed by sparse angular blotches, reaching to pre- or middorsal region, often fused with L1; line L3 formed by a longitudinal line, reaching to caudal base, fused with L1 and L4 on postdorsal body; line L5 organized in 10–16 blotches in non-spawning season; caudal and dorsal fin with thin 3–4 arcuate bars; upper spot at the caudal base black, smaller than eye diameter; lower spot at caudal base faint; spots not connected; egg yolk diameter approximately 0.8 mm; karyotype diploid (2n = 50).

Description. Lateral view in Figure 3H illustrate body shape, form and position of fins. Morphometric and meristic data for 12 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, 5–6; caudal-fin rays 8+8. Body somewhat waistless, laterally compressed. Snout short comparatively. Interorbital space broad, convex. Eye diameter relatively large. 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 12 (range, 11–13). Very small cycloid scales on the trunk. Lamina circularis at the base of pectoral fin of adult male roundish plate, somewhat narrowing toward the outer part ( Fig. 6H). 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 narrow and weak. 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: 47.9 mm SL in male, 55.5 mm SL in female.

Coloration. Male in the non-spawning season ( Figs. 3H, 8E). Body pearl white with dark brown pigmentation in fresh specimens. Clear streak running from the tip of snout to the occiput, crossing to the eye. Upper part of head covered with some roundish blotches or by longitudinal line. Opercle and snout covered with oval and amorphous shaped spots. Body pigmentation organized in one middorsal and four lateral zones. Line L1 consisting of a series of 15–25 blotches; blotches saddle or oval-shaped. Line L2 formed by sparse angular blotches, reaching to pre- or middorsal region, often fused with L1. Line L3 formed by longitudinal line, reaching to caudal base, fused with L1 and L4 on postdorsal body. Line L4 formed by tiny blotches or narrow incomplete longitudinal line. Line L5 organized in 10–16 blotches from upper part of the pectoral fin to caudal-fin base; blotches roundish or ovoid. Caudal fin and dorsal fin with thin 3–4 arcuate bars. Anal fin pigmented along the fin rays. Upper spot at the caudal base black, smaller than eye diameter; lower spot at caudal base faint; spots not connected.

Male in the spawning season ( Fig. 8F). Lines L2 and L4 not visible. Line L3 well developed with broad stripe from upper part of the pectoral-fin base to posterior part of body, fused with L1 on postdorsal body. Line L5 well developed with broad stripe from upper part of the pectoral-fin base to the caudal-fin base.

Female ( Fig. 5H). Appearance similar to males in the non-spawning season, but zone L4 tends to be better developed than in males.

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

Egg diameter. 0.84 ± 0.04 mm (female, N = 1; collected from the Iride-ota River system, Shizuoka Prefecture).

Karyotype. Diploid (2n = 50) ( Ueno et al. 1980; Kimizuka 1987; Saitoh et al. 2000).

Distribution. Rivers flowing into Ise Bay, Mikawa Bay, and western part of Enshu-nada coast, Tokai District, central Honshu: Shizuoka, Gifu, Aichi, and Mie Prefectures ( Saitoh & Aizawa 1987).

Habitat and biology. This subspecies inhabits sandy-mud bottoms of the lower reaches of rivers and small streams. Life histories are unknown.

Etymology. The subspecific name is derived from the Tokai District of Central Honshu, which is the main distribution area of this subspecies.

Remarks. The genetic features have been reported by Kitagawa et al. (2005) and Saitoh et al. (2010).

Japanese name. Tokai-kogata-suji-shima-dojyô.