Trinchesia sibogae is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusc in the family Trinchesiidae.Korshunova T.; Fletcher K.; Martynov A. (2025). The endless forms are the most differentiated—how taxonomic pseudo-optimization masked natural diversity and evolution: the nudibranch case Zoological Journal of the Linnean Society. Volume 204, Issue 4, August 2025.
Taxon Confusion It is very important to note that the sea slug known as 'Trinchesia' sibogae is not, and never has been the sea slug known as Phestilla sibogae . The two have been falsely synonymized frequently in literature and references despite being unique organisms that bear no physical resemblance.
The two slugs were both originally described in the same publication by the same author on adjacent pages as Phestilla sibogaeBergh, L. S. R. (1905). Die Opisthobranchiata der Siboga-expedition. In: Weber M. (ed.) Uitkomsten op Zoologisch, Botanisch, Oceanographisch en Geologisch Gebied verzameld in Nederlandsch Oost-Indië 1899-1900 aan boord H.M. Siboga onder commando van Luitenant ter zee 1e. kl. G.F. Tydeman. Siboga-Expeditie Monographie 50 (Livraison 25): pg. 232-233, pl. 20 fig. 4-12. and as Hervia sibogaeBergh, L. S. R. (1905). Die Opisthobranchiata der Siboga-expedition. In: Weber M. (ed.) Uitkomsten op Zoologisch, Botanisch, Oceanographisch en Geologisch Gebied verzameld in Nederlandsch Oost-Indië 1899-1900 aan boord H.M. Siboga onder commando van Luitenant ter zee 1e. kl. G.F. Tydeman. Siboga-Expeditie Monographie 50 (Livraison 25): pg. 231-232, pl. 2 fig. 17, pl. 20 fig. 1-3., the latter being the original combination for T. sibogae.
Unfortunately, as Trinchesiidae is a family rife with classification controversy, both the genera Phestilla and Trinchesia have at some point in their histories been merged into Tenellia, which is likely when the worst of the confusion began.
Thankfully, there are recent studies that acknowledge the validity of the two taxa as unique organisms Korshunova, T.; Lundin, K.; Malmberg, K.; Martynov, A.; (2022). Narrowly defined taxa on a global scale: The phylogeny and taxonomy of the genera Catriona and Tenellia (Nudibranchia, Trinchesiidae) favours fine- scale taxonomic differentiation and dissolution of the “lumpers & splitters” dilemma, Evolutionary Applications, vol. 16, no. 2, pp. 428–460., even explicitly stating the difference in radular structure, with T. sibogae bearing "ark-shaped teeth" characteristic to its genus.
Distribution This species was described from Kangean Island, Indonesia. Trinchesia sibogae is widespread throughout the tropical waters of the Indo-West Pacific region.Rudman, W.B., 2003 (October 20) Cuthona sibogae (Bergh, 1905). [In] Sea Slug Forum. Australian Museum, Sydney. This species is large for this family, with a maximum size of 35 mm length.Cuthona sibogae Bergh, 1905.
References
Marshall, J. G. and R. C. Willan. 1999. Nudibranchs of Heron Island, Great Barrier Reef : a survey of the Opisthobranchia (sea slugs) of Heron and Wistari Reefs. Backhuys: Leiden. x, 257 pp Miller, M. C.; Willan, R. C. (2005). A redescription and taxonomic reappraisal of the Indo-Pacific aeolid nudibranch Trinchesia sibogae (Bergh, 1905)(Gastropoda, Opisthobranchia). Vita Malacologica. 3: 69-75
External links McDonald, G. R. (2009). Nudibranch Systematic Index, second edition. University of California Santa Cruz: Institute of Marine Sciences