Comparison of gut morphology and gut microflora of seven species of mud shrimp (Crustacea : Decapoda : Thalassinidea)

The gut morphology is described for seven species of Thalassinidea; Callian assa subterranea (Montagu), Jaxea nocturna Nardo, Axius stirhynchus Leach, Calocaris macandreae Bell, Upogebia pusilla (Petagna), U. deltaura (Leach) and U. stellata (Montagu). Differences were observed in the structure of th e dorsal and lateral teeth of the gastric mill. Callianassa subterranea and A. stirhynchus had simple robust dorsal teeth and proportionally larger la teral teeth with flexible spines. The three upogebiids had complex dorsal t eeth that were highly ridged and proportionally smaller lateral teeth with inflexible spines. The dorsal and lateral teeth of J. nocturna were interme diate in form. The dorsal tooth of Calocaris macandreae, although relativel y simple in design, possessed accessory projections, or "wings", on either side of the main structure. The lateral teeth were proportionally quite lar ge, but lacked ridges and spines. The epithelia surfaces of the digestive g land, midgut and posterior diverticulum were similar for all seven species. Differences were observed in the morphology of the hindgut. The hindgut li ning was completely smooth for the three upogebiid species. The other thala ssinidean species had four distinct rows of cuticular projections situated on top of the ridges formed by the longitudinal convolutions of the hindgut . The arrangement of these projections varied between species. A gut flora was observed for six of the seven species, the exception being C. macandrea e. The differences observed in the structure of the gut are discussed in re lation to feeding and thalassinidean phylogeny.