Family EURYALIDAE

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Family EURYALIDAE

Compiler and date details

2012 - Tim O'Hara, Museum Victoria, Carlton, Victoria, Australia

2001 - Tim O'Hara, Museum Victoria, Carlton, Victoria, Australia

1995 - F.W.E. Rowe & J. Gates, Australian Museum, Sydney, New South Wales, Australia

Introduction

The Euryalidae are widespread in the Indo-west Pacific. Of the eleven known genera, eight are recorded in Australian waters, represented by 17 species.

This family is distinguished from other euryalid families by the following combination of character states: teeth large and stout, forming a single ventral row on the dental plate; pavement-like oral papillae covering the side of jaws; basal portion of the arms widened in mature specimens due to extension of gonads from the disc; the first tentacle pore with two, rarely three arm spines.

The family has recently been revised and is now considered to contain three subfamilies, Euryalinae, Astrocharinae and the Asteroschematinae (Okanishi et al. 2011). The latter was formerly considered a family in its own right (Baker 1980). The Euryalinae differs from the other subfamilies in having lateral arm plates that are separated ventrally throughout the arm, either by ventral arm plates (Astrobrachion) or a specialised ‘bridge’ on the arm vertebrae that spans the two ventrolateral spurs and encloses the radial canal and nerve (Asteromorpha, Asterostegus, Astroceras, Euryale, Sthenocephalus and Trichaster). The radial shields are made out of a single layer of calcite in the Astrocharinae (Astrocharis and Squamophis) and multiple overlapping layers of calcite in the Asteroschematinae (Asteroschema and Ophiocreas).