Cobitis minamorii saninensis Nakajima, 2012

Nakajima, Jun, 2012, Taxonomic study of the Cobitis striata complex (Cypriniformes, Cobitidae) in Japan, Zootaxa 3586, pp. 103-130 : 124-125

Cobitis minamorii saninensis Nakajima , subsp. nov.

( Figs. 3I, 5I, 6I, 8G, H)

Cobitis taenia striata spotted-small race: Minamori 1956: 91, fig. 1; Cobitis taenia striata spotted small race: Saitoh and Aizawa 1987: 336, fig. 3F; Cobitis sp. S (San-in-gata): Saitoh 1989: 389; Cobitis sp. 2 subsp. 3: Hosoya 2002: 275; Cobitis striata complex small race, San-in form: Kitagawa et al. 2005: 112, table 1; Cobitis striata complex spotted small race: Saitoh et al. 2010: 1003, table 1; Cobitis sp. 2 subsp. 3: Nakajima et al. 2012: 90, fig. 2d.

Holotype. TKPM-P17348 , 1 male, 62.1 mm SL, Japan: creek of Hii River system, Izumo, Shimane Pref., Honshu , 10. IV. 2011, J. Nakajima.

Paratypes. KPM-NI29510 , 1 male, 53.8 mm SL, Hiwa R., Hokuei, Tottori Pref., Honshu , 9. IV. 2011 , J. Nakajima; MPM-FI1509, 1 male, 43.9 mm SL, same data; JNC034, 1 male, 47.6 mm SL, same data; JNC036, 1 male, 48.4 mm SL, Terauchi R., Hino R. s., Nanbu, Tottori Pref., Honshu , 10. IV. 2011 , J. Nakajima; KPM-NI9218 , 1 male, 59.3 mm SL, Tai R., Kishida R. s., Shin-onsen, Hyogo Pref., Honshu , 17. VIII. 1998 , T. Kitagawa .

Non-type specimens. FAKU55788 , 3 males, 44.1–52.1 mm SL, Shimizu R., Sendai R. s., Tottori, Tottori Pref., Honshu , 31. V. 1981, K. Saitoh; FAKU055797 , 2 females, 50.9, 73.0 mm SL, Kouchi R., Kedaka, Tottori Pref., Honshu , 16. X. 1983 , K. Saitoh; 3 males and 2 females, 49.0– 52.1 mm SL, Tai R., Kishida R. s., Shin-onsen, Hyogo Pref., Honshu , 23. V. 2008, K. Tominaga; 3 males, 50.4–54.0 mm SL, creek of Hii R. s., Izumo, Shimane Pref., Honshu , 31. V. 2008, J. Nakajima; 2 females, 50.9, 73.0 mm SL, Hiwa R., Hokuei, Tottori Pref., Honshu , 9. IV. 2011 , J. Nakajima.

Diagnosis. This subspecies is distinguishable from other Japanese striated spined loaches by the following characteristics: body size relatively small, the mature size about 40–60 mm SL in males, 50–70 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. 6I); PMN commonly 12; snout elongated; line L1 consisting of a series of 15–20 blotches; line L2 formed by longitudinal jagged line, reaching to postdorsal region, fused with L1; line L3 formed by incomplete longitudinal line, reaching to caudal base, fused with L1 and L4 on postdorsal body in non-spawning season; line L5 organized in 11–13 blotches in non-spawning season; caudal and dorsal fins with thin 4–6 arcuate bars; upper spot at the caudal base black, approximately 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 3I illustrates body shape, form and position of fins. Morphometric and meristic data for 14 males and 6 females are summarized in Table 2. Dorsal-fin rays iii, 7; anal-fin rays iii, 5; pectoral-fin rays i, 7–9; pelvic-fin rays ii, 6; caudal-fin rays 8+8. Body elongate, laterally compressed. Head and snout elongated. Interorbital space broad, convex. Snout elongated. Caudal peduncle relatively compressed. 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, 11–14). 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. 6I). 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: 62.1 mm SL male, 73.0 mm SL female.

Coloration. Male in the non-spawning season ( Figs. 3I, 8G). Body yellowish white with brown pigmentation in fresh specimens. Clear streak running from the tip of snout to the occiput, crossing to the eye. Upper part of head, opercle and snout covered with oval or amorphous shaped spots. Body pigmentation organized in one middorsal and four lateral zones. Line L1 consisting of a series of 15–20 blotches; blotches saddle or oval-shaped, often chained. Line L2 formed by longitudinal jagged line, reaching to postdorsal region, fused with L1. Line L3 formed by incomplete longitudinal line, reaching to caudal base, fused with L1 and L4 on postanal body. Line L4 formed by longitudinal jagged weblike line, reaching to postanal body. Line L5 organized in 11–13 blotches; blotches roundish or ovoid. Caudal fin and dorsal fin with 4–6 arcuate bars. Anal fin pigmented along the fin rays. Upper spot at the caudal base jet-black comparable in size to eye diameter, lower spot at caudal base faint or missing.

Male in the spawning season ( Fig. 8H). Line L4 not visible or formed by narrow longitudinal line, present only in anterior half of body. Lines L3 and L5 well developed with broad stripes from upper part of the pectoral-fin base to the caudal-fin base.

Female ( Fig. 5I). Appearance similar to males in the non-spawning season. But line L4 often formed by longitudinal jagged line, broader or as wide as L3.

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. 0.86 ± 0.08 mm (females, N = 4; collected from the Hii River system, Shimane Prefecture).

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

Distribution. Rivers flowing into Japan sea, San-in District, western Honshu: Hyogo, Tottori, and Shimane Prefectures ( Saitoh & Aizawa 1987).

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

Etymology. The subspecific name is derived from the San-in District of eastern 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. San-in-kogata-suji-shima-dojyô.