Gnathia pilosus sp. nov. (Crustacea, Isopoda, Gnathiidae) from the East Coast of South Africa

The larvae of gnathiid isopods are known to parasitise a large variety of intertidal fish worldwide. In South Africa, the larvae of Gnathia africana Barnard, 1914, have been recorded from various intertidal fish hosts along the cold West and South Coasts. The warmer East Coast, however, has not previously been sampled for gnathiids. From March 2006 to February 2007, intertidal fishes were collected on the East Coast using hand held nets and kept in aerated tanks until the gnathiids completed their feeding. Once fed, the gnathiids were kept alive in 50 ml bottles with fresh sea water till moulting occurred. Results indicated that all the East Coast intertidal gnathiids were from the same species and new to science, and subsequently described as Gnathia pilosus sp. nov. The G. pilosus male and female can be clearly distinguished from other South African species in having numerous tubercles and setae covering the cephalosome and pereon which are not as pronounced in the other species. The G. pilosus larva can also be distinguished from the other South African species by the triangular-shaped cephalosome and numerous sensory pits covering the body.