A new species of cobitid spinous loach has been described from Shikoku Island in Japan.
Yuzuru Suzawa of the Institute of River Biology in Yokohama Kanagawa named the new loach Cobitis shikokuensis in a paper in the latest issue of the journal Ichthyological Research.
Cobitis shikokuensis was described from a series of 297 specimens collected from Shikoku Island and was formerly known as the Shikoku group of Cobitis takatsuensis.
Cobitis takatsuensis, which is endemic to Japan, was described by Mizuno in 1970.
Previous genetic research by Suzawa and co-authors, which was published in Ichthyological Research in 2004, showed that the Chugoku-Kyushu and Shikoku groups of Cobitis takatsuensis were clearly diverged.
The current study now provides morphological evidence to back this up:
"It can be distinguished from other species of Cobitis and closely related genera by a combination of the following characters: dorsal fin with 6 branched soft rays; anal fin with 5 branched soft rays; one brownish streak across eye from the tip of nose, no streak on cheek; a black spot smaller than eye diameter near the dorsal corner of the caudal fin base; 3-5 small brownish speckles on ventral side of caudal peduncle; high caudal peduncle with well-developed fleshy keels on dorsal and ventral side; a lamina circularis at base of dorsal part of pectoral fin absent; first branched soft ray of pectoral fin broad in males; pectoral soft rays widely branched from the approximate midpoint; last anal fin ray with 2 elements; interorbital width 11.2-17.1% of head length."
Previous studies of C. takatsuensis on Shikoku Island by Shizumu have surveyed the Hijikawa and Iwamatsugawa river systems. The temperate species was found to live among pebbles and boulders under shallow banks around pools.
For more details see the paper: Suzawa Y (2006) - A new loach, Cobitis shikokuensis (Teleostei: Cobitidae), from Shikoku Island, Japan. Ichthyological Research, Vol. 53, No. 4, pp. 315-322.
Also see: Shimizu T; Suzawa Y and H Sakai (2004) - Allozyme divergence between two groups of the Japanese spinous loach, Cobitis takatsuensis. Ichthyological Research, Volume 51, Number 3, August 2004, pp. 241-247(7).
Shimizu, T (2002) - Life history of a Japanese spinous loach, Cobitis takatsuensis, in Shikoku Island. Japanese Journal of Ichthyology . Vol. 49, no. 1, pp. 33-40. 24 May 2002.