(Düben & Koren, 1844)
Body with a central disc of up to 5 mm in diameter and 5 fine arms of 12-15 times that length. Disc coloured olive-green or brownish green, with white radial shields; the arms are coloured dark brownish, in the proximal part somewhat lighter.
Disc completely naked, not covered by scales except for parts of the radial shields which are narrow, parallel and contiguous in their whole length (A. securigera disc).
Dorsal arm plates are fan-shaped, the ventral arm plates are pentagonal. In the proximal parts of the arms 4, elsewhere 3, arm spines per segment. The tube foot pores are not covered by tentacle scales (A. securigera arm).
The mouth shields are rounded triangular. Paired infradental papillae on top of the jaws, and one small, pointed outer mouth papilla on each side of the jaws, not contiguous with the infradental papillae. Two pairs of tube-feet within the mouth (A. securigera mouth).
This species prefers hard substrata where it conceals itself among shells or stones; found in depths of about 40-600 metres. Rarely recorded.