The zoeal stages and megalopa of Portunus rubromarginatus (Lanchester) (Decapoda: Portnnidae), reared in the laboratory

Abstract

The present state of knowledge concerning Portunus larvae is reviewed, and the three zoeal and the megalopa stages of P. rubromarginatus are described and figured. Details of appendage setation are tabulated. This species is unusual amongst known Portunus spp. in having only three zoeal stages and, like other Portunus spp. but in contrast with other Portuninae, it has 4 + 4, or 4 + 1 + 4, setae on the posterior telson border.When compared with larvae of the five other Indo-West Pacific Portunus species whose larvae are known P. rubromarginatus zoeae are readily distinguished from all, except P. hastatoides, using the key features given by Kurata (1975). Comparison was made between first zoeae of these two species, and also of P. pelagicus and P. sanguinolentus, using larvae reared by the authors. It was found telson characters alone allow distinction between larvae of these four species. These characters are tabulated.P. rubromarginatus megalopae differ from those known for congenitors in having a large spine on the uchium of the first pereiopod, but not on the carpus, and in having relatively very small sternal cornuae.Several of these features disagree with those previously thought to characterise larval Portuninae or Portunus species.