Marionia rubra (Ruppell & Leuckart, 1828)

Description

A large tritoniid reaching about 18 cm in body length. The body bears numerous bushy gill plumes (secondary branchiae) along each side and is overall reddish-brown to red, with some variation among individuals; the colouration provides effective camouflage against the host soft corals.

The rhinophores are multi-lobed and branched, and the leading edge of the oral veil bears several finger-like papillae.

Distribution

Long regarded as a Red Sea endemic, but subsequently recorded from Indonesia, Israel, Papua New Guinea and Tanzania. The species inhabits shallow waters down to about 20 m depth.

Etymology

The specific epithet rubra is the feminine of Latin ruber ("red"), in reference to the reddish body colour.

Remarks

Feeds exclusively on soft corals of the genus Lemnalia. Originally described by Rüppell & Leuckart 1828 from Red Sea Egyptian material as Tritonia rubra; the parentheses in the current author citation reflect the transfer to Marionia. Marioniopsis rubra is a junior synonym. The genus Marionia was erected by Vayssière 1877 with Marionia berghii as type, all members being soft-coral feeders.

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References

• Marionia rubra (genus Marionia), Vayssière A. (1877). Sur un nouveau genre de la famille des Tritoniadés. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. 85: 299-301.
• マリオニア・ルブラ, 小野篤司 & 加藤昌一. (2020). 新版 ウミウシ. 誠文堂新光社.