Ascetoaxinus gen. nov.

Type species. Ascetoaxinus quatsinoensis sp. nov., this paper.

Type locality. Quatsino Sound, off of Vancouver Island, British Columbia, Canada; 50°15.482’N, 128°26.400’W to 50°14.519’N, 128°26.567’W; 1086–1318m.

Species included. Ascetoaxinus quatsinoensis sp. nov.; Ascetoaxinus ovoidea (Dall, 1890).

Diagnosis. Medium sized shells. Equivalve. Inequilateral, prosogyrous beaks close to the anterior, outline obliquely oval. Anterior margin sloping steeply, almost straight; anterior area defined by a distinct keel, with a deeply impressed lunule encompassing the entire anterior area. Lunule edge scalloped by rounded projections. Posterior margin broadly rounded, indented by a single sinus; posterior sulcus large, deep, distinctly angulated; submarginal sulcus smaller, sharply defining escutcheon but no distinct marginal sinus. Weak angulation between umbo and posterior ventral margin resulting in flattened area adjacent to the posterior sulcus. Anterior adductor muscle scar greatly elongate. Hinge teeth lacking. Ligament partially sunken.

Gill anatomy of Dufour type 3 (Dufour 2005), filaments laminar, frontal surface broad, flat with marginal arrays of cilia. Lateral body pouches large, dense arborescent, dorsal extension of digestive gland prominent with external outgrowths.

Etymology. From the Greek asketos meaning curiously fashioned and pertaining to the unusual scalloped lunule and the Greek axinus meaning like an axe, but also pertaining to the thyasirid genus Axinus; gender feminine (Brown 1956).