Abstract Detailed morphology of the first three postembryonic developmental stages (Stages I-III juvenile) in representatives from all four crayfish families, Austropotamobius torrentium (von Paula Schrank, 1803) (Astacidae), Procambarus virginalis Lyko, 2017 (Cambaridae), Cambaroides japonicus (De Haan, 1841 [in De Haan, 1833-1850]) (Cambaroididae) and Cherax destructor Clark, 1936 (Parastacidae) are described and the diagnostic characters for each family are indicated. A phylogenetic tree of freshwater Astacidea, based on these new diagnostic juvenile characters is constructed to suborder, superfamily and family levels, and compared with a molecular phylogenetic tree. The evolutionary history of maternal care in freshwater crayfish is discussed based on particular features of the postembryonic stages of each family. Using comparisons between the phylogenetic tree and global geo-history, the location and timing of the early evolution of maternal care in postembryonic development and the extension of this care are estimated.

Abstract Until recently, three subspecies had traditionally been recognized in the astacid species Pacifastacus leniusculus (Dana, 1852): Pacifastacus leniusculus leniusculus, Pacifastacus leniusculus klamathensis (Stimpson, 1857), and Pacifastacus leniusculus trowbridgii (Stimpson, 1857). The type specimens attributed to these taxa were re-described with detailed illustrations of taxonomic characteristics for further taxonomic works.