All species discovered from Manimala river in Idukki, Pathanamthitta

Four new species of freshwater catfish have been reported from Idukki and Pathanamthitta districts, highlighting the rich biodiversity of the riverine ecosystem in the State.

All the four species, namely Horabagrus melanosoma, Mystus heoki, Mystus indicus and Mystus menoni, were discovered from the Manimala river by Mathews Plamoottil, Assistant Professor in Zoology, Government College, Chavara, and Nelson P. Abraham, Associate Professor, St. Thomas College, Kozhenchery.

The researchers have published their findings in the latest issue of two prominent scientific journals, Biosystematica and the International Journal of Pure and Applied Zoology. The International Commission of Zoological Nomenclature (ICZN) has also approved the names given by the researchers to the new species.

Discovered from Venpala near Thiruvalla, H.melanosoma is deep black in colour with short fins and spine. It grows up to 23.5 cm. M.indicus was collected from Kuttoor in Pathanamthitta district. It is characterised by yellowish green colour on the upper lateral side and clear white on the lower lateral and grows up to 10 cm.

Featuring a bluish black mid lateral line and a long dorsal fin, M.menoni grows up to 12 cm. It is named after A.G.K. Menon, eminent freshwater fish taxonomist. An unusually long catfish, M. heoki was named after Singaporean taxonomist Heok Hee Ng. Both M.menoni and M.heoki were discovered from Elankadu in Idukki district. All the four species are edible.

According to Mr. Mathews Plamoottil, no new fish of the Mystus genus had been reported from Kerala since 1865 when Francis Day discovered Mystus armatus from Thrissur. In the course of his research work spanning several years, Mr. Mathews Plamoottil had collected almost all Mystus fish species in Kerala from various places in Kerala, including Wayanad, Thrissur and Kottayam.

This, he said, had enabled him to identify the new species.

Specimens (holotypes) of the new fish have been deposited at the Indian Museum, Kolkata, and the freshwater fish museum of the Zoological Survey of India, Kozhikode. All the new fish have also been registered in the World Zoobank of ICZN. A few months ago, Mr. Mathews had discovered another new catfish, Glyptothorax elankadensis from Idukki.