Cobitis minamorii yodoensis Nakajima, 2012

Nakajima, Jun, 2012, Taxonomic study of the Cobitis striata complex (Cypriniformes, Cobitidae) in Japan, Zootaxa 3586, pp. 103-130 : 126-127

Cobitis minamorii yodoensis Nakajima , subsp. nov.

( Figs. 3J, 5J, 6J)

Cobitis taenia striata Yodo small race: Saitoh and Aizawa 1987: 336, fig. 3C; Cobitis sp. S (Yodogawa-gata): Saitoh 1989: 388; Cobitis striata complex Yodo small race: Saitoh et al. 2010: 1003, table 1; Cobitis sp. 2 subsp. 5: Nakajima et al. 2012: 90, fig. 2f.

Holotype. FAKU55719 , 1 male, 45.1 mm SL, Japan: Yodo River, Asahi-ku, Osaka Pref., Honshu , 16. X. 1980, K. Saitoh.

Paratypes. FAKU134643 , 1 male, 43.0 mm SL, same data as holotype ; FAKU134643 , 1 male, 43.1 mm SL, same data as holotype ; FAKU134643 , 1 female, 70.6 mm SL, same data as holotype ; FAKU55701 , female, 64.9 mm SL, Uji R., Yodo R. s., Uji, Kyoto Pref., Honshu , 15. VII. 1976, K. Saitoh ; FAKU55702 , 1 male, 50.5 mm SL, Uji R., Yodo R. s., Uji , Kyoto Pref., Honshu, 12. V. 1978, K. Saitoh; KUN-P41321, 6 females, 59.9–73.9 mm SL, Yodo R., Asahi-ku , Osaka Pref., Honshu, 8. V. 1971, collector unknown.

Diagnosis. This subspecies is distinguishable from other Japanese striated spined loaches by the following characteristics: body size small, the mature size about 50 mm SL in males, 60 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. 6J); PMN commonly 12; snout elongated; eye diameter relatively small; line L1 consisting of a series of 14–17 blotches; line L2 formed by tiny angular blotches, reaching to pre- or middorsal region, often fused with L1; line L3 formed by incomplete longitudinal narrow line, reaching beyond dorsal fin, fused with L1 and L 4 in posterior part; line L5 formed by narrow longitudinal line; caudal and dorsal fins margined by a narrow black band, two or three speckles on other regions; upper spot at the caudal base black, smaller than eye diameter; lower spot at caudal base existing but faint; spots not connected; karyotype diploid (2n = 50).

Description. Lateral view in Figure 3J illustrate body shape, form and position of fins. Morphometric and meristic data for 4 males and 8 females are summarized in Table 2. Dorsal-fin rays iii, 7; anal-fin rays iii, 5; pectoral-fin rays i, 7; pelvic-fin rays ii, 5–6; caudal-fin rays 8+8. Body elongate, laterally compressed. Snout short. Interorbital space narrow, convex. Eye diameter relatively small. Caudal peduncle relatively compressed. Eye diameter small. 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 the pectoral fin of adult male roundish plate, somewhat narrowing toward the outer part ( Fig. 6J). 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: 50.5 mm SL male, 73.9 mm SL female.

Coloration. Male ( Fig. 3J). Body pearl white with black pigmentation in fresh specimens. Clear streak running from the tip of snout to the occiput, crossing to the eye. Head, opercle and snout covered with some large amorphous patterns. Body pigmentation organized in one dorsal and four lateral zones. Line L1 consisting of a series of 14–17 blotches; blotches saddle shape. Line L2 formed by tiny angular blotches, reaching to pre- or middorsal region, often fused with L1. Line L3 formed by incomplete longitudinal narrow line, reaching beyond dorsal fin, fused with L1 and L 4 in posterior part. Line L4 formed by narrow longitudinal line, reaching near caudal base, fused with L1 and L 3 in posterior part. Line L5 formed by narrow longitudinal line from upper part of the pectoral fin to the caudal-fin base. Caudal fin and dorsal fin with 3–4 bars of small speckles, exterior bar often margined. 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.

Female ( Fig. 5J). Appearance similar to males. But line L4 more developed than 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. Unknown.

Karyotype. Diploid (2n = 50) ( Ueno & Ojima 1976; Ueno et al. 1980; Saitoh et al. 2000).

Distribution. Middle and lower reaches of Yodo River system, central Honshu: Kyoto and Osaka Prefectures ( Saitoh & Aizawa 1987).

Habitat and biology. This subspecies inhabits sandy-mud bottoms of lower reaches of rivers and wando-pools ( Saitoh & Aizawa 1987; Saitoh 1989).

Etymology. The subspecific name is derived from the type locality.

Remarks. The subspecies is endemic to the middle and lower reaches of the Yodo River system; however, the last known individual of this subspecies was collected in August 1996. It points out that the decline of the subspecies has been attributed to river improvement and urbanization ( Saitoh 1989, 2005). The morphology of this subspecies has been well studied by Saitoh and Aizawa (1987). The genetic features have been reported by Saitoh et al. (2010).

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