Catriona columbiana (O'Donoghue, 1922)

Description

A small aeolid reaching about 4.5 mm in length × 1.5 mm wide, with cerata projecting up to 3 mm above the dorsum so that the animal appears bright pink when viewed from above. Body slender and elongate, dorsum fairly high and smooth, sides moderately marked off from the foot by a wide undulating flange. Foot elongate and narrow, slightly bilobed and rounded anteriorly, tapering posteriorly into a short slender tail. Head rounded and broad with a transverse slit-like mouth and two cylindrical oral tentacles of moderate length at the antero-lateral corners. Rhinophores cylindro-conical, of moderate length, not perfoliate but the distal two-thirds slightly wrinkled. 17–20 cerata per side, very long and cylindrical with blunt tips, slightly constricted where they join the dorsum, arranged in transverse rows of 2–3 in two ill-defined groups. Body and foot opaque white; ceratal cores light vermilion overlain by a translucent pale grey sheath, giving the bright pink overall appearance. Penis blunt and cylindrical, bearing a small flattened spine. Radula uniseriate, 65–69 rows of pale yellow teeth, narrow and tapering.

Distribution

North Pacific. The type locality is Gabriola Pass, British Columbia, Canada, dredged at 7–12 fathoms (end of June).

Etymology

The specific epithet columbiana refers to British Columbia, the type-locality region. (O'Donoghue first proposed the name "Galvina columbiana" in the discussion before settling on Amphorina for the genus.)

Remarks

Originally described as Amphorina columbiana by O'Donoghue in "Notes on the Nudibranchiate Mollusca from the Vancouver Island Region. III. Records of species and distribution" (Transactions of the Royal Canadian Institute 14: 160-161, 1922). Subsequently transferred to Catriona Winckworth, 1941 (Trinchesiidae / Cuthonidae). Some Japanese authors have provisionally treated this species as コヅチミノウミウシ, but the latter is now treated as Trinchesia alpha (Baba & Hamatani, 1963), with white-flecked dorsum/cerata/tentacles distinguishing it from C. columbiana.

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References

• Amphorina columbiana, O'Donoghue C.H. (1922). Notes on the Nudibranchiate Mollusca from the Vancouver Island Region. III. Records of species and distribution. Transactions of the Royal Canadian Institute, 14: 145-167.