THE SPATANGOID ECHINOID SCHIZASTER (SCHIZASTER) COMPACTUS (KOEHLER, 1914) IN WESTERN AUSTRALIA

WA Museum Records and Supplements | Updated 1 decade ago

Abstract - The spatangoid echinoid Schizaster (Schizaster) compactus (Koehler, 1914) is recorded from Australian waters for the first time. A sample consisting of a juvenile and adults collected from off the Dampier Archipelago, Western Australia is shown to undergo significant ontogenetic variation in a number of parameters, notably number of pore pairs in all aboral ambulacra; relative size and shape of the peristome and periproct; relative width of ambulacrum III aborally; and relative length of the posterior petals. A number of morphological characters also show appreciable intraspecific variation, in particular the number of gonopores; position of the peristome; the width of the plastron; test width; and position of the apical system. An understanding of the degree of phenotypic variation in this species aids in the delimitation of species of Schizaster and in the characterisation of the taxa Schizaster and Paraster.