Phanerophthalmus luteus (Quoy & Gaimard, 1833)

Description

Body cylindrical and elongate, reaching about 22 mm (fixed) in total length. Body colour ranges from pale to dark green. Cephalic shield triangular with the pair of posterior lobes slightly separated. Periocular area pigmented — a distinctive feature within the genus. Shell external, plate-like, thin and fragile; white to translucent, squarish oval, with a developed pointed shoulder enlarged at its tip.

Distribution

Centred on the Coral Triangle (the Philippines, Sulawesi, Indonesia, East Timor and northwestern New Guinea — the Manokwari area being the type locality), extending north to southern Taiwan, the Ryukyu Islands and mainland Japan, and east to Fiji and the Line Islands (Kiribati) in the Central Pacific. Occurs from the rocky intertidal to about 25 m, on rubble, back-reef areas, mangrove fringes and seagrass beds, where it feeds on diatoms.

Etymology

Latin luteus, "yellow". The original name Bulla lutea meant "yellow bubble" and was based on a single 3 mm specimen from West Papua that was almost certainly a juvenile; adults are in fact green.

Remarks

Indo-West Pacific material was long identified as Phanerophthalmus smaragdinus, a name now treated as a junior synonym of P. olivaceus (Ehrenberg, 1828), a species restricted to the Red Sea. Recent molecular and morphological revision confirmed that this material belongs instead to P. luteus, which differs from P. olivaceus by its pigmented periocular area, external shell, and the long, enlarged seminal duct.

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References

• Bulla lutea Quoy & Gaimard, 1833, Quoy J.R.C. & Gaimard J.P. (1832-1834). Mollusques. In: Dumont d'Urville J. (ed.) Voyage de la corvette l'Astrolabe exécuté par ordre du Roi pendant les années 1826-1827-1828-1829, Zoologie. Tome 2, parts 1 (1832) & 2 (1833). J. Tastu, Paris.
• Phanerophthalmus luteus (genus Phanerophthalmus), Adams A. (1850). Monograph of the family Bullidae. In: Sowerby G.B. (II) Thesaurus Conchyliorum, or Monographs of Genera of Shells. Vol. 2. London: Sowerby. pp. 553-608, pls. 119-125.
• チョウチョウミドリガイ, 小野篤司. (1999). ウミウシガイドブック. TBSブリタニカ.
• チョウチョウミドリガイ, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• チョウチョウミドリガイ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
• Phanerophthalmus smaragdinus, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• Austin J., Gosliner T. & Malaquias M.A.E. (2018). Systematic revision, diversity patterns and trophic ecology of the tropical Indo-West Pacific sea slug genus Phanerophthalmus A. Adams, 1850 (Cephalaspidea, Haminoeidae). Invertebrate Systematics. 32(6): 1336-1387. https://doi.org/10.1071/is17086
• Phanerophthalmus luteus, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.
• Oskars T.R., Too C.C., Rees D., Mikkelsen P.M., Willassen E. & Malaquias M.A.E. (2019). A molecular phylogeny of the gastropod family Haminoeidae sensu lato (Heterobranchia: Cephalaspidea): a generic revision. Invertebrate Systematics 33(3): 426-472.