Cobitis striata striata Ikeda, 1936

Nakajima, Jun, 2012, Taxonomic study of the Cobitis striata complex (Cypriniformes, Cobitidae) in Japan, Zootaxa 3586, pp. 103-130 : 107-113

Cobitis striata striata Ikeda, 1936

( Figs. 3A, 4A, B, 5A, 6A)

Cobitis taenia striata Ikeda, 1936: 984 , figs. 10, 11, 12, 13 (original description; type locality: near Takamatsu, Kagawa Pref., Shikoku, Japan); Cobitis taenia striata middle race: Minamori 1952: 201, fig. 2A; Cobitis taenia striata: Aoyagi 1957: 170 , fig. 143; Cobitis taenia striata middle race: Saitoh and Aizawa 1987: 336, fig. 3G; Cobitis sp. M: Saitoh 1989: 390; middle form: Saitoh 1990: 240, figs. 3f, g, h, i, j: 241, fig. 4 (lower four); Cobitis taenia striata: Sezaki et al. 1994: 684 , fig. 1B; Cobitis cf. striata: Kim et al. 1999: 388 , fig. 9; Cobitis sp. 3 : Hosoya 2002: 275; Cobitis striata complex middle race: Kitagawa et al. 2005: 112, table 1; Cobitis striata (middle race): Nakajima et al. 2008: 13, fig. 2E; normal type (Setouchi form) of middle race in Cobitis striata complex: Kitagawa et al. 2009: 12, fig. 2C; Cobitis striata complex middle race: Saitoh et al. 2010: 1003, table 1; Cobitis sp. 3 subsp. 1: Nakajima et al. 2012: 92, fig. 3a.

Specimens examined. 1 male, 53.3 mm SL, Kizu River, Yodo River system, Yawata, Kyoto Pref., Honshu, 16. V . 2009, J. Nakajima; 1 male, 59.1 mm SL, Kino R ., Wakayama, Wakayama Pref., Honshu , 29. XII. 2007, M. Nakatani; MPM-FI1500 , 1 male, 58.6 mm SL, Muko R ., Sanda , Hyogo Pref., Honshu, 7. VI . 2009, K. Tominaga; 3 males, 50.8–55.9 mm SL, Kagato R ., Yoshii R . s., Setouchi , Okayama Pref., Honshu, 6. VI . 2007, J. Nakajima ; FRLM24922 , 1 male, 68.4 mm SL, Ota R ., Hiroshima, Hiroshima Pref., Honshu , 29. IX. 1996, M. Watanabe; FAKU55767 , 2 males, 58.9, 66.6 mm SL, Shimata R ., Shuto , Yamaguchi Pref., Honshu, 4. V . 1982, K. Saitoh ; TKPM-P17340 , 1 male, 55.6 mm SL, Koto R ., Takamatsu, Kagawa Pref., Shikoku , 3. XI. 2007, K. Tominaga ; 1 male and 1 female, 49.6, 47.7 mm SL, Kasuga R ., Takamatsu, Kagawa Pref., Shikoku , 28. IX. 2008, Y. Hashimoto ; 2 males and 2 females, 55.3–73.7 mm SL, Doki R ., Man-nou, Kagawa Pref., Shikoku , 3. XI. 2007, K. Tominaga; TKPM-P2283 , 1 male and 2 females, 58.2–69.2 mm SL, Miyagouchitani R ., Yoshino R . s., Kamiita, Tokushima Pref., Shikoku , 18. VII. 1995, Y. Sato; KPM-NI29502 , 1 male and 1 female, 56.8, 61.5 mm SL, Kitara R ., Ima R . s., Miyako, Fukuoka Pref., Kyushu , 12. XII. 2010, J. Nakajima ; 1 male, 66.8 mm SL, Harai R ., Yukuhashi, Fukuoka Pref., Kyushu , 25. X. 2007, J. Nakajima .

Diagnosis. This species is distinguishable from other Japanese striated spined loaches by the following characteristics: body size moderate, the mature size about 50–60 mm SL in males, 60–80 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 narrow and weak; PMN commonly 13; lines L3 and L5 well developed with broad stripes in all season; line L4 faint; caudal fin and dorsal fin with 3–4 arcuate bars; upper spot at the caudal base jet-black, approximately eye diameter; lower spot at caudal base faint or missing; egg yolk diameter approximately 1.0 mm; karyotype diploid (2n = 50).

Description. Lateral view in Figure 3A illustrate body shape, form and position of fins. Morphometric and meristic data for 15 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. 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, three 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 13 (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. 6A). The first branched soft ray of pectoral fin longer than the others; 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: 93.0 mm SL male, 98.0 mm SL female ( Minamori 1952).

Coloration. Male in the non-spawning season ( Figs. 3A, 4A). Body yellowish white with light 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 amorphous spots, these spots often stringed. Opercle and snout covered with large amorphous patterns. Body pigmentation organized in one middorsal and four lateral zones. Line L1 consisting of a series of 10–20 saddles or oval-shaped blotches. Line L2 formed by few small angular spots, only present on the predorsal region, reaching dorsally to interspaces of L1, barely distinct from L1 occasionally. Line L3 formed by sharp longitudinal line, reaching to caudal base. The posterior part of L3 often intermissive. Line L4 formed by weak dots or a narrow line, reaching beyond dorsal fin, sometimes nonexistent. Line L5 formed by broad longitudinal line from upper part of pectoral fin to the caudal-fin base. Caudal fin and dorsal fin with 3–4 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. 4B). Lines L2 and L4 not visible, L3 and L5 well developed with broad stripes from the upper part of the pectoral-fin base to the caudal-fin base.

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

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

Egg diameter. 0.98 ± 0.05 mm (females, N = 2; collected from the Yoshii River and the Asahi River, Okayama Prefecture)

Karyotype. Diploid (2n = 50) ( Ueno & Ojima 1976; Ueno et al. 1980; Ueno 1981; Saitoh et al. 1984, 2000; Kimizuka 1987)

Distribution. Rivers flowing into the Seto Inland Sea in Honshu, Shikoku, and Kyushu, and rivers flowing into the Japan Sea in Honshu: Kyoto, Osaka, Wakayama, Hyogo, Okayama, Hiroshima, Yamaguchi, Kagawa, Tokushima, Ehime, and Fukuoka Prefectures ( Saitoh & Aizawa 1987; Nakajima et al. 2008).

Habitat and biology. This species inhabits sandy-mud bottoms of the middle and lower reaches of rivers. Saitoh (1990) described the spawning ecology of this species as the middle form of Cobitis striata .

Remarks. Although this loach had been previously described as a subspecies of C. taenia Linnaeus, 1758 , some recent genetic analysis refuted this designation ( Šlechtová et al. 2008; Nakajima et al. 2011a). It has been confused what is the true C. striata described by Ikeda (1936) because the original description of this loach has ambiguous information on the type locality, and the type series is missing and feared lost ( Saitoh & Aizawa 1987). However, the author, Dr. Hyoji Ikeda, had stated that the type locality of C. striata is ‘near Takamatsu, Kagawa’ in his other literature ( Okada & Ikeda 1939; Aoyagi 1957) (Ikeda and Aoyagi are names of the same person). The results obtained in my field and literature surveys confirm that there is only one species, Cobitis sp. 3 subsp. 1 (sensu Nakajima et al. 2012), near this type locality. In addition, the description of C. striata is consistent with the morphological characters of Cobitis sp. 3 subsp. 1. Therefore, I conclude that C. striata Ikeda, 1936 is identical to Cobitis sp. 3 subsp. 1. The genetic features have been already reported by Kitagawa et al. (2005) and Saitoh et al. (2010).

Japanese name. Chûgata-suji-shima-dojyô.