Comparison of the mouthpart setal fringes of seven species of mud-shrimp (Crustacea: Decapoda: Thalassinidea)

Abstract

A detailed description of the mouthpart morphology is provided for Axius stirhynchus Leach, Calocaris macandreae Bell, Upogebia deltaura (Leach) and U. pusilla Petagna. The distribution of setae on the mouthparts of three additional species of thalassinidean mud-shrimp, Callianassa subterranea (Montagu), Jaxea nocturna Nardo and U. stellata (Montagu), is also given. Particular attention was paid to the mouthpart setal fringes, where major differences were observed in setal type, inter-setal distances and inter-setule distances. The mouthparts of the three upogebiid species examined were characterized by plumed setae with very small intersetal distances. The mouthparts of the other four species of thalassinidean were dominated by more robust serrate setal types. The setal screens of the upogebiids were often made up of a single setal type, whereas those of Calocaris macandreae and Axius stirhynchus were often comprised of a number of different setal types. The observations made for Callianassa subterranea and J. nocturna fall between these two extremes. These differences are discussed and related to particle size selectivity during feeding and the number of different feeding modes employed by a particular species.