Tanaidacea (Crustacea) from sublittoral waters off West Scotland, including the description of two new genera

Abstract

Twelve species of tanaid are recorded from samples taken in a study of shallow waters near Oban and Millport on the west coast of Scotland in 1984. Two new species, Leptognathiopsis attenuata and Subulella scotti, belong to new leptognathiid genera, and Haplocope angusta and Anarthrura simplex are reported for the first time from British and western Scottish waters, respectively. The number of tanaid species recorded from the latter area has risen to 17 (57% of British species from <200 m). A revised key to the Leptognathiidae is given, as the number of both genera and species has changed since publication of the previous version (Holdich and Jones 1983 a). In addition, a revised key to British tanaid families is provided to accommodate changes in the status of the Paratanaidae.

Tanaids were collected at depths down to 153 m and at a maximum abundance of 700 m^-2. Three species, Tanaopsis graciloides, Araphura brevimana and Leptognathia gracilis, are the most common and abundant tanaids, especially in the muddy sand of sheltered loch localities. More species (12 versus 6) were recorded from the Oban than the Clyde Sea sites, but within-area differences in tanaid species richness are great. The maximum number of species recorded for a single grab sample was six. The Lynn of Lorn samples yielded eight species in the 1984 survey, even though three of the eight species recorded there in 1981 were not found. Sediments in the more open sea sites have a different tanaid composition from that in sediments from semi-enclosed lochs. There appears to be no clear correlation between the type of tanaid fauna and depth and sediment type.