Avern's Glossodoris

Ardeadoris averni is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusc in the family Chromodorididae.

Description

Ardeadoris averni is a large elongate-oval shaped dorid nudibranch recorded up to 70 mm in length.

There is a broad mantle overlap and the mantle edge presents with many folds, usually with a large distinctive infold each side at the midway mark of the mantle. The edge of the mantle is thick giving a “puffy” look when combined with all the folds. The tail of the foot is visible where it extends past the posterior edge of the mantle.

The rhinophores can retract into protective pockets. The gills too can retract into a protective pocket. The gill is large and arranged in an arc around the anus, open posteriorly, with each end of the arc forming an inward spiral. The gills move continuously with a regular rhythmical motion when expanded.

The mantle colour is a semi-translucent white with a thick red-orange margin both dorsally and ventrally. There is also a sub-marginal band of vivid opaque white that contain underlying mantle glands. The margin of the foot/tail carries a narrower band often of a lighter colour to that of the mantle margin. The coloured band to the foot/tail margin is considered diagnostic in separating this species from otherwise similarly-coloured species. (In other words, should be present to confirm this species – sometimes there is just a hint of the orange.)

The rhinophore clubs are orange/brown and bear white lines up both the anterior and posterior faces. The colour of the clubs tapers off to translucent white stalks. The gills have a white core but with brown edging and light brown to both inner and outer faces.

Distribution

Western Pacific Ocean from Papua New Guinea and the Philippines, also Japan and Eastern Australia

Habitat

Ardeadoris averni is a spongivore but the type of sponge preyed upon has not been identified/recorded. It lives at small shallow with green algae, sand bottom with coral and rock boulders.

The spawn of Ardeadoris averni is laid as an upright yellow coil apparently without extra-capsular yolk.