Julia exquisita A. A. Gould, 1862

Description

A small juliid sacoglossan, 4-6 mm in length, characterised by a strikingly bivalve-like shell consisting of two convex valves covering the soft body. The shell is greenish with thin concentric bands of reddish-brown or white. The body is dark green with scattered small white patches outlined by brown rings. Julia exquisita closely resembles Julia japonica but is distinguished by a posterior end that is not pointed.

Distribution

Type locality: Hawaiian Islands. Broadly distributed in the tropical Indo-Pacific, with records from Madagascar, New Zealand and Reunion. Occurs in intertidal sand-mud flats and has been observed down to about 10 m depth.

Etymology

The specific epithet exquisita is Latin for "exquisite" or "elaborate", in reference to the finely sculpted bivalve-like shell. The Japanese vernacular "ハワイユリヤガイ" ("Hawaiian Julia") reflects the Hawaiian type locality.

Remarks

The family Juliidae is unique among sacoglossans in bearing a bivalved external shell. Julia exquisita feeds on green algae and is known to retain the algal chloroplasts in its digestive gland for continued photosynthesis (kleptoplasty).

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References

• ハワイユリヤガイ, 川口四郎. (1983). 二殻腹足類ユリヤガイ. 川崎医療短期大学紀要. 2: 93-100. https://doi.org/10.18928/00000643
• Julia exquisita, McCarthy-Taylor J.B., Krug P.J., Muro S., Vendetti J., Maestrati P., Wong N.L.W.S., Gosliner T.M. & Valdés Á. (2025). The slug within the bivalve: molecular and morphological systematics of the family Juliidae (Gastropoda: Panpulmonata: Sacoglossa). Zoological Journal of the Linnean Society. 204(2): zlaf056. https://doi.org/10.1093/zoolinnean/zlaf056