Family EPIMENIIDAE

Epimeniidae

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Family EPIMENIIDAE

Compiler and date details

A.H. Scheltema, Woodshole Oceanographic Institute, Massachusetts, USA

Introduction

The Epimeniidae is a tropical and subtropical Indo-Pacific family of Neomeniomorpha. Members have been found off Hong Kong, Korea, southern Japan, New Caledonia, Papua New Guinea, Indonesia, the Maldive Islands, and the Red Sea, as well as off the north-west coast of Australia—the type locality and only record for Australia and its territories. The family has a single well-defined genus, Epimenia Nierstrasz, with an ill-defined second genus Epiherpia Salvini-Plawen based on a single immature specimen. There are six named species of Epimenia and at least two more awaiting description (Baba 1940a; Salvini-Plawen & Benayahu 1991; Salvini-Plawen 1997; Scheltema & Jebb 1994). Scheltema & Jebb (1994) considered that the nominate species, E. australis (Thiele), is found throughout the waters off Indonesia and New Guinea, where it was known by the name E. verrucosa (Nierstrasz).

Epimenia species are unusual because of their large size, up to 30 cm long, and bright colours, with iridescent spots or stripes of blue, lavendar, green, or yellow. The body is narrow relative to length, up to 1 cm. Both skeletal and upright spicules are present and are morphologically similar to each other, hollow with a single curve. Copulatory spicules are absent. The radula consists of 20 or so rows of paired, hook-like teeth, each borne on a pedestal. The anterior pedal gland is unusually small. There are six or more paired seminal receptacles. Eggs are either retained, with embryos brooded in the mantle cavity, or they are laid in paired mucous ribbons; there is a short-lived lecithotrophic larva (Baba 1940a; Scheltema & Jebb 1994).

Species are found close to shore at diving depths of 24 m or less, although individuals have been dredged from depths up to 112 m (Nierstrasz 1902). In the Red Sea and off Madang, Papua New Guinea, divers collected specimens of Epimenia from steeply sloping coral rocks with swift currents and abundant alcyonarian soft corals belonging to the family Nephthyidae. In Papua New Guinea, easiest collecting was by turning over coral rock slabs that had fallen from the rock face, beneath which the Epimenia species hid during daylight. The type locality of E. australis lies at the edge of the continental shelf bordering the northwest coast of Australia somewhere along the 108 m isobath before the steep drop into deeper waters.

More is known about the behaviour, physiology and embryology of Epimenia species than about any other Aplacophora (Baba 1938, 1940b, 1940c; Scheltema & Jebb 1994). Large size and proximity to shore make members of this genus available for such studies.