Phestilla lugubris (Bergh, 1870)

Description

The spirit-preserved specimen was 14 mm long; the foot sole 5 mm wide near its middle; the body height 6.5 mm to the tips of the cerata. The colour was uniformly pale yellowish clay-grey. The oral tentacles were about half the length of the cerata, the rhinophores slightly shorter than the tentacles. The dorsum bears twelve ceratal cushions on each side, increasing in size from the first to the fifth (where eleven to thirteen cerata stand in a single row, the longest 4.5 mm) and decreasing thereafter; the hindmost cushion bears only two cerata. The cerata are slightly compressed and usually slightly curved. Notably, no cnidosacs are present, and the masticatory edge of the jaws is almost completely smooth.

Distribution

Type locality: Zamboanga, Mindanao, Philippines. The species is widely distributed across the Indo-West Pacific in coral reef habitats.

Etymology

The Latin adjective lugubris means "mournful, gloomy". The original description records the colour of the preserved specimen as "uniformly pale yellowish clay-grey"; the descriptive epithet evidently refers to the dull uniform colour of the preserved animal.

Remarks

The species was originally placed in Cratena with a question mark, the original describer doubting that placement because of the absence of cnidosacs and the smooth masticatory edge of the jaws. It was later transferred to Phestilla; the parentheses in the author citation reflect this generic transfer. Phestilla is now recognised as a highly specialised group of aeolids that feed on stony corals (mainly Porites and related genera).

---

References

• Cratena? lugubris Bgh. n. sp., Bergh R. (1870). Malacologische Untersuchungen. In: Semper C. (ed.), Reisen im Archipel der Philippinen. II. Wissenschaftliche Resultate. Bd. II, Heft I: 1-44, Taf. I-VIII. Wiesbaden: C.W. Kreidel's Verlag.
• ルグブリス, 小野篤司. (1999). ウミウシガイドブック. TBSブリタニカ.
• ジライヤウミウシ（新称）, 小野篤司. (2000). ウミウシガイドブック. 第2版. TBSブリタニカ.
• ジボガミノウミウシ, 小野篤司. (2004). 沖縄のウミウシ. ラトルズ.
• ジボガミノウミウシ, 中野理枝. (2004). 本州のウミウシ. ラトルズ.
• ジボガミノウミウシ, 小野篤司 & 加藤昌一. (2009). ウミウシ. 誠文堂新光社.
• Phestilla lugubris, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.
• Mehrotra R., Arnold S., Wang A., Chavanich S., Hoeksema B.W. & Caballer M. (2020). A new species of coral-feeding nudibranch (Mollusca: Gastropoda) from the Gulf of Thailand. Marine Biodiversity. 50(3): 36. https://doi.org/10.1007/s12526-020-01050-2
• Tenellia lugubris, Fritts-Penniman A.L., Gosliner T.M., Mahardika G.N. & Barber P.H. (2020). Cryptic ecological and geographic diversification in coral-associated nudibranchs. Molecular Phylogenetics and Evolution. 144: 106698. https://doi.org/10.1016/j.ympev.2019.106698