Embryonic and postembryonic development in the Tasman freshwater crayfishes Astacopsis gouldi, Asatcopisis franklinni and Parastacoides tasmanicus tasmanicus (Decapoda : Parastacidae)

Abstract

The embryonic and postembryonic development of the endemic Tasmanian freshwater crayfishes of the genera Astacopsis and Parastacoides was studied and described in detail. The embryonic development was similar in the two genera and corresponded to that described for other Parastacidae and Astacidae, but a prominent change in the colour of the yolk that parallels embryonic development was also noted. The general development sequence of young from Stage 1 to Stage 3 in Astacopsis and Parastacoides is similar to that described for other parastacid, astacid and cambarid crayfishes, but major differences in development between Astacopsis and other crayfishes are an extra developmental stage as well as the timing of the development of the uropods. The postembryonic development in Astacopsis is different from that in other parastacids as well as astaciddcambarids in having retained some of the ancestral marine larval characters, and it is considered to be primitive. Given this new information, it is proposed that early development in freshwater crayfishes recapitulates the entire primitive decapod sequence of larval stages.