Some features of the biology and composition of the diet of the rock lobster Acantharctus posteli (Decapoda, Crustacea, Scyllarinae) (West Africa)

Abstract

Acantharctus posteli (Crustacea, Decapoda, Achelata, Scyllarinae) belongs to the old relic circumtropical genus of mainly upper shelf rock lobsters. It is an endemic species of the West African tropical zoogeographic region with its distribution between the cape of Cap Blanc (21°40′ N) to the north and the mouth of the Congo River to the south (approximately 4° S). The length of the studied rock lobsters ranges from 10 to 80 mm. Males are slightly smaller than females. The smallest size of ovigerous females was 29 mm. The life cycle of A. posteli appears to be about 2 years. The stomach contents of 43 specimens ranging in size from 42 to 68 mm from the waters of the Republic of Sierra Leone were analyzed. Rock lobsters consume mainly detritus that includes benthic foraminifera. In addition, fish, echinoderms, mollusks, and decapods are secondary prey items. The mean Froerman coefficient of 3.96 allows suggesting that A. posteli can be characterized as a predator-collector, which is similar to rock lobsters of the genera Jasus and Projasus.