Madrella sanguinea (Angas, 1864)

Description

A medium-sized arminoid reaching about 50 mm, with an oval, fairly thick body whose dorsum is densely covered with conical to wart-like tubercles. Ground colour is a bright to deep blood-red — the source of the specific epithet sanguinea ("blood-red") — with tubercle tips tinged yellow or orange.

The rhinophores are red and lamellate. The species lacks a typical dorid gill plume; instead the dorsum bears extensive secondary branchial structures (caryophyllidia-like papillae) closely resembling those of Madrella ferruginosa. The two are externally near-identical and are distinguished mainly by colour and size: M. sanguinea is decidedly darker red and larger.

Distribution

Type locality: Port Jackson (Sydney Harbour), New South Wales, Australia (Angas, 1864). Recorded from the eastern coast of Australia (New South Wales, Queensland), northern New Zealand and adjacent temperate-subtropical western Pacific waters. It inhabits the lower intertidal and shallow subtidal of rocky reefs.

Etymology

The specific epithet sanguinea is the feminine of Latin sanguineus ("of blood, blood-red"), in reference to the species' striking red ground colour.

Remarks

Originally described in 1864 by Angas from Port Jackson material. The genus Madrella was erected by Alder & Hancock in April 1864 with the Indian M. ferruginosa as type species; under the ICZN priority rule the genus name Madrella Alder & Hancock has nomenclatural precedence even though Angas's species was named in January of the same year. Apart from colour and adult size, M. sanguinea is morphologically near-identical to the type species, and species-level validity rests largely on geographic and pigmentation differences. Members of the genus are known sponge-feeders.

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References

• Madrella sanguinea, Alder J. & Hancock A. (1863). On a new genus and some new species of mollusks from the Pacific Ocean, in the collection of Hugh Cuming, Esq. Proceedings of the Zoological Society of London. 31: 105-109.
• Madrella sanguinea (Angas, 1864) — original description (Port Jackson), Angas G.F. (1864). Description d'espèces nouvelles appartenant à plusieurs genres de Mollusques Nudibranches des environs de Port-Jackson (Nouvelle-Galles du Sud), accompagnée de dessins faits d'après nature. Journal de Conchyliologie, 12(1): 43-70, pl. IV.