Hermaea vancouverensis
O'Donoghue, 1924

Family: Hermaeidae


Upper: Hermaea vancouverensis found on Neorhodomela larix. Middle: red alga Neorhodomela larix. Lower: chain forming diatom Isthmia nervosa which lives attached to Neorhodomela - note mm scale in upper part of photo. Oregon, USA, NE Pacific Ocean, mid-1980s. Photographer: Cynthia Trowbridge.


Northeast Pacific - Alaska to California (Trowbridge, 2002)
Northwest Pacific - South Kuril Islands, Russia (Chernyshev - in Forum)

The elongate body is translucent clear with a pattern of green to brown lines and spots cause by the colour of the digestive gland ducts and tubules. The cerata are arranged in a  row down each side of the body, but as they are frequently detached, it is difficult to find a specimen with a full complement. The rhinophores are enrolled and auriform. The digestive gland as a duct running along each side of the body which gives off a single branch to each ceras. Anteriorly, in front of the pericardial swelling, there is a U or V shaped
green or dark coloured mark which is a branch of the digestive gland extending out inot each rhinophore. At the anterior base of each rhinophore there is a similar coloured patch and a line running up the anterior (or ventral) side of the rhinophore. Posteriorly, the digestive gland ducts extend down the foot beyond the last cerata. O'Donoghue records animals reaching about 5.5 mm in length.

It has been reported from the base of diatom covered Zostera leaves (O'Donoghue) and from the red algae Neorhodomela larix, where it eats the attached, chain-forming diatom Isthmia nervosa [see Trowbridge (2002) and Chernyshev (#14612)].

Note: Chernyshev [#14612 ] initially identified this species as  S. akkeshiensis Baba, 1935, but agrees with Trowbridge's suggestion that Russian animals are identical with Hermaea vancouverensis [message #15995] . What is not clear is whether true Stiliger akkeshiensis Baba, 1935 is the same species.

  • O'Donoghue, C.H. 1924. Notes on the nudibranchiate Mollusca from the Vancouver Island region. IV. Additional species and records. Transactions of the Royal Canadian Institute 15: 1-33.
  • Trowbridge, C.D. 2002. Northeastern Pacific sacoglossan opisthobranchs: natural history review, bibliography, and prospectus. The Veliger 45:1-24.

Authorship details
Rudman, W.B., 2006 (March 2) Hermaea vancouverensis O'Donoghue, 1924. [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/hermvanc

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