Elysia nigropunctata (Pease, 1871)

Description

A small sacoglossan reaching about 25 mm in body length. The ground colour in life is olive green, clouded with darker, paler beneath, and finely reticulately veined with darker green. The whole surface bears small irregular whitish spots and is densely punctured with jet black, the latter spots small beneath, larger and crowded along the margins of the parapodia and on the tentacles. The inner surface of the parapodia differs but slightly from the outer surface, being only much paler centrally and unclouded. The parapodia are rounded behind, the tentacles stout, the upper lip bilobed, and the locomotive disk small. Pease's type was about 1 inch (≈ 2.5 cm) long.

Distribution

Central and western Pacific. Type locality: Tahiti, Society Islands, based on a specimen collected by Andrew Garrett and described by Pease. Subsequently recorded from the Hawaiian Islands, Guam, Micronesia, southern Japan, the Philippines and Indonesia.

Etymology

The specific epithet nigropunctatus combines Latin niger ("black") and punctatus ("dotted"), meaning "black-spotted", in reference to the dense jet-black puncturing covering the body surface.

Remarks

Originally placed by Pease in his genus Pterogasteron. In the Remarks following this species Pease suggested that, as in Placobranchus, the branchiae of Pterogasteron are immersed in the surface of the parapodia and appear as lines radiating from the body. Pease also noted that Kelaart's Elysia grandifolia, E. punctata and E. coerulea from Ceylon belong to this genus, and that, because Kelaart's provisional name Hydropsyche was preoccupied, Pterogasteron takes precedence. Pterogasteron was later synonymised with Elysia Risso, 1818; the parentheses in the author citation reflect this generic transfer. The Japanese name "テンテンコノハミドリガイ" ("dotted leaf-green slug") refers to the many black spots on the body.

---

References

• Pterogasteron nigropunctatus Pease n. sp., Pease W.H. (1871). Descriptions of nudibranchiate Mollusca inhabiting Polynesia. American Journal of Conchology, 6(4): 299-305, pls. XIX-XXII.
• テンテンコノハミドリガイ（仮称）, 小野篤司. (1999). ウミウシガイドブック. TBSブリタニカ.
• エリシア属の1種, 殿塚孝昌. (2003). ウミウシガイドブック〈3〉. TBSブリタニカ.
• テンテンコノハミドリガイ, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• Yonow N. (2012). Opisthobranchs from the western Indian Ocean, with descriptions of two new species and ten new records (Mollusca, Gastropoda). ZooKeys. 197: 1-129. https://doi.org/10.3897/zookeys.197.1728
• Elysia nigropunctata, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• テンテンコノハミドリガイ, 中野理枝. (2018). 日本のウミウシ. 文一総合出版.
• Elysia nigropunctata, Terrence Gosliner, Ángel Valdés and David Behrens. (2018). Nudibranch and Sea Slug Identification Indo-Pacific 2nd Edition. New World Pubns Inc.