FUNCTIONAL-MORPHOLOGY OF THE FOREGUT OF LOPHOGASTER TYPICUS AND L-SPINOSUS (CRUSTACEA, MYSIDACEA, LOPHOGASTRIDA)

The foreguts of two Lophogaster species (Crustacea, Mysidacea, Lophoga strida), one benthic and another pelagic, are described. Their morphol ogy is characteristic of the genus and does not seem related with the ecology of the species, as it would be expected. The foregut is very d ifferent from that observed in other Lophogastrida (Eucopia and Gnatho phausia). Indeed, the cardiac chamber is followed by a large alimentar y pouch occupying half the length of the cephalothorax, and which prob ably corresponds to the dorsal pyloric chamber. Such storage system is original among crustaceans exhibiting the caridoid facies (Mysidacea, Euphausiacea and Decapoda). As the dorsal pyloric chamber is posterio rly closed by this pouch, the junction between the stomach and the int estine takes place at the level of the ventral pyloric chamber, instea d of the dorsal one as in other Mysidacea. The gastric mill also is or iginal, since the lateral teeth look like mandibles owing to their mor phology and internal musculature. Lastly, at the junction with the sto mach, the very small size of the lumen of the intestine probably do no t allow the passage of coarse particles, contrary to what occurs in ot her Mysidacea, Euphausiacea and Decapoda.