Author: Undescribed

Order: Nudibranchia  Family: Arminidae

Maximum Size: 7 mm

Sightings: Sunshine Coast

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Dermatobranchus sp. 12 Undescribed

The body is broad and flattened with parallel sides until the posterior-most fifth of its length at which point it acutely tapers to a point. The foot extends past the posterior end of the mantle and also acutely tapers to a point, being white dorso-medially but translucent with white speckling towards the edges. The notum is developed into a series of longitudinal ridges that are granular white with very fine diffuse dark speckling. The edges of each ridge, either along the top or bottom corner, or both, carry a denser speckling of dark brown creating lines that serve to delineate them from the grooves in-between. Grooves are wider than the ridges being the same depth as the width of the ridges. Grooves are similarly coloured to ridges. Whilst the central-most ridges follow the medial line the lateral ridges run at a slight angle to the midline thus finding the mantle edge. There are no distinct spots, ocelli, bands or other markings on the mantle surface. There is no coloured band to the mantle edge.

The rhinophore stalks are white with some diffuse black speckling and are slightly separated at the base of the stalks. There is no narrowing between stalk and clavus. The clavus is brown with some areas of concentrated darker speckling. It bears deeply grooved vertical lamellae approx. eight in number. The apices are similarly coloured.

The oral veil is as wide as the body and well developed anteriorly and laterally with expansive rounded corners. The colour of the oral veil is evenly granular white. The oral veil edge has a narrow translucent band.

The foot is translucent white with some sparse dark speckling medially to the sole. The anterior of the foot is well-developed into obvious corners and slightly tentacular, with white speckling dorsally.

This species is very slow moving. The rhinophores are normally carried extended upright in a vee configuration but will straighten erect, coming together, and then contract if the animal is disturbed.

David A. Mullins – March 2023