Zoological Studies

Vol. 40 No. 2, 2001

Clarias microstomus, a New Species of Clariid Catfish from Eastern Borneo (Teleostei: Siluriformes)

Heok-Hee Ng

Fish Division, Museum of Zoology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, Michigan 48109-1079, USA Department of Biological Sciences, National University of Singapore, Kent Ridge Crescent, Singapore 119260, Republic of Singapore

Heok-Hee Ng (2001) Clarias microstomus, a new species of clariid catfish is de- scribed from the Kayan and Mahakam River drainages in eastern Borneo. It differs from its congeners in having a narrow snout (with an egg-shaped head), a gently-sloping anterior margin of the dorsal fin, and a unique combination of the following characters: a gray body with white spots, a smooth anterior edge of the pectoral spine, a head length of 21.4%-22.5% SL, a head depth of 67.1%-70.6% HW, and an interorbital distance of 46. 7%-50.2 % HL.

Key words: Clariidae, Kalimantan Tengah, Kayan River, Mahakam River.

*Correspondence: Fax: 1-734-7634080. E-mail: heokheen@umich.edu