Postembryonic Stages of Procambarus clarkii (Girard, 1852) (Decapoda: Cambaridae) and Evolution of the Freshwater Astacidea

Abstract Freshwater Astacidea evolved from marine Astacidea, giving rise to four families with remarkable diversity. The Red Swamp Crayfish, Procambarus clarkii (Astacoidea: Cambaridae), is the most economically utilized and invasive species. The morphology of the postembryonic development of this species is described and illustrated for comparison with other Astacidea members. The evolutionary history of the rudimentary vestigial line and filaments on the epipodal plate was examined. Abbreviation of postembryonic stages and the development of telson segmentation of members of the freshwater Astacidea were compared with marine Astacidea. The abbreviation of the larval stage may be related to the phylogenetic relationships among Astacidea members in marine and freshwater environments. The body size of each postembryonic stage was compared among species from each of the four families. Largersized Astacidae and Cambaroididae become independent at Stage II, while smaller-sized Cambaridae and Parastacidae leave maternal care at Stage III. The smallest juveniles belong to Cambaridae in North and Middle America, contributing to the highest species diversity among the four families. Smaller size led to a larger number of juveniles and an extended maternal care period that was related to the higher survival of juveniles. It is proposed that the higher fertility contributed to the evolutionary success of the Cambaridae.