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New Zealand Journal of Marine and Freshwater Research abstractsLIFE-HISTORY STUDIES ON NEW ZEALAND BRACHYURA 1. EMBRYONIC AND POST-EMBRYONIC DEVELOPMENT OF PILUMNUS NOVAEZEALANDIAE FILHOL, 1886, AND OF P. LUMP1NUS BENNETT, 1964 (XANTHIDAE, PILUMNINAE)Robert G. WearZoology Department, Victoria University of Wellington, New ZealandAbstract Abbreviated or direct development is described in Pilumnus novaezealandiae Filhol, 1886 and P. lumpinus Bennett, 1964 from New Zealand. Embryonic development is separated into Nauplius, Metanauplius and embryonic zoeal stages. The ontogenetic position of the pre-zoeal cuticle suggests that it represents the Metanauplius stage, and the absence of plumose pre-zoeal aesthaetes in P. novaezealandiae implies relationship with the more recently evolved brachyuran families. The significance of the pre-zoeal cuticle in brachyuran phylogeny is discussed. In P. noveazealandiae four embryonic zoeal phases are recognised as approximately equivalent to the four Zoea larval stages occurring in the majority of xanthid Brachyura. It was not possible to distinguish similar phases in embryonic zoeal development of P. lumpinus because of advanced anachronism which is normally associated with abbreviated development. The appearance of relatively advanced structures very early in ontogeny is attributed to the absence of the need for successive developmental stages to be adapted for free life. In the embryonic Zoea, carapace spines considered to assist with flotation and orientation, and natatory setae, are together reduced or absent in abbreviated development where such structures woulld be of no use within the egg.
N.Z. Jl mar. Freshwat. Res. 1: 482-535 PDF file of entire paper: medium quality (3402K); (scanned from paper original: notes about this process) This year's abstracts | Journal home page | All abstracts | Publishing home page |