Larval development of the Chinese mitten crab Eriocheir sinensis H. Milne-Edwards (Decapoda: Grapsidae) reared in the laboratory

Abstract

Larvae of the Chinese mitten crab Enocheir sinensis were reared in the laboratory from the time of hatching and through metamorphosis. Development normally consists of a Prezoea, 5 Zoea stages, and a Megalopa. Occasionally, an additional (stage VI) Zoea and, in one case, an additional Megalopa (transitional to the first crab stage) were observed. Detailed morphological descriptions of all larval and the first two juvenile instars are given, and larval morphology is compared with that of two closely related species, Eriocheir japonicus and Eriocheir rectus, descriptions of which have recently become available. The zoeal stages of these species can be distinguished by their different number of aesthetascs and setae on the antennules, and different setation of maxillipeds 1 and 2. The Megalopa shows differences in the shape of the rostrum and again in the morphology of the antennule. These and other morphological differences (mainly in setation and spinulation of the zoeal carapace) between E. sinensis and E. japonicus larvae suggest that they may be very closely related but separate species; this contradicts a recent study of adult morphometrics and molecular genetics (Li et al., 1993), suggesting that they are only varieties of a single species. © Biologische Anstalt Helgoland, Hamburg.