Trapania armilla Gosliner & Fahey, 2008

Description

Body 7 mm long, elongate and convex, lacking a notal margin. Widest at the branchial region. The dorsum is lumpy rather than smooth. Oral tentacles are relatively short, cylindrical with rounded apices. Rhinophores are relatively short with 13–14 lamellae; stalk is lumpy and the club is about the same thickness. Extra-rhinophoral appendages are relatively short, stout and curved. The two bifurcated extra-branchial appendages are large, curved and much thicker than the extra-rhinophoral appendages. Gill of three bipinnate branches.
The body is completely white, as are the anterior head tentacles. Oral tentacles are white but bear a dark ring on the outer third — the most diagnostic feature of this species. Extra-rhinophoral and extra-branchial appendages, rhinophores and gill leaves are also white.

Distribution

Known only from Bali, Indonesia (type locality: Liberty Wreck, Tulamben).

Etymology

Verbatim from the original description (Gosliner & Fahey, 2008, p.83):

The specific name armilla is from the Latin word for 'bracelet', to describe the only contrasting colour pigment on this species; the ring of dark pigment on the oral processes.

Remarks

Described as one of 16 new Indo-Pacific Trapania species in Gosliner, T.M. & Fahey, S.J. 2008 Zoological Journal of the Linnean Society 152: 53-111. Externally, this species is distinct from all other Trapania in being entirely white apart from the dark ring on the oral processes. T. palmula and T. tora also bear dorsal tubercles, "but in T. palmula the tubercles are small while in T. armilla and T. tora they are large and rounded" (p.82).

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References

• Trapania aureopunctata (M. Miller 1998, Sea Slug Forum), Rudman W.B. (1998-2010). Sea Slug Forum. Australian Museum, Sydney. http://www.seaslugforum.net/
• Trapania armilla sp. nov., Gosliner T.M. & Fahey S.J. (2008). Systematics of Trapania (Mollusca: Nudibranchia: Goniodorididae) with descriptions of 16 new species. Systematics and Biodiversity. 6(1): 53-98. https://doi.org/10.1017/s1477200007002587
• Trapania armilla, Trapania sp. 5, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• クチワツガルウミウシ（新称）, 中野理枝. (2018). 日本のウミウシ. 文一総合出版.