The diphyletic nature of the infraorder Thalassinidea (Decapoda, Pleocyemata) as derived from the morphology of the gastric mill.

A comparison of the gastric mill in some representative species of the Thalassinidea, indicates that the Thalassinidea are possibly diphyletic, consisting of the superfamily Callianassoidea Dana, 1852, including the families Callianassidae Dana, 1852, Axiidae Huxley, 1879, Callianideidae Kossmann, 1880, Ctenochelidae Manning & Felder, 1991, and Gourretiidae Sakai, 1999, in which the propyloric ossicle is simple and has a smooth posterior surface; and the superfamily Thalassinoidea Latreille, 1831, including the Thalassinidae Latreille, 1831, Upogebiidae Borradaile, 1903, and Laomediidae De Haan, 1849, in which the propyloric ossicle is triangularly protruded downwards and has a series of fine, transverse septa on its posterior face. [ABSTRACT FROM AUTHOR]