Atagema spongiosa

Atagema spongiosa
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Nudibranchia
Family:	Discodorididae
Genus:	Atagema
Species:	A. spongiosa
Binomial name
Atagema spongiosa (Kelaart, 1858) [1] synonyms = Atagema paagoumenei(Risbec, 1928) junior subjective synonym Dendrodoris areolata(Alder & Hancock, 1864) junior homonym Doris areolataAlder & Hancock, 1864 · Doris spongiosaKelaart, 1858 Phlegmodoris mephiticaBergh, 1878 Phlegmodoris paagoumeneiRisbec, 1928 Trippa (Phlegmodoris) paagoumeneiRisbec, 1928 junior subjective synonym

Atagema spongiosa is a species of sea slug or dorid nudibranch, a marine gastropod mollusk in the family Discodorididae. ^{[2] [3]}

Description

The body is oval and flattened, characterized by a dorsal surface covered in prominent, rounded tubercles that gradually decrease in size toward the mantle margin. A distinct longitudinal ridge runs centrally along the midline, spanning the area between the rhinophores and the gill. This ridge is flanked on either side by a series of depressions that also diminish in size as they approach the mantle edge. Apart from these recessed depressions, the entire dorsal surface is densely carpeted with caryophyllidia (specialized, microscopic sensory organs located on the dorsal surface of the mantle).

The branchial sheath is divided into three large, well-defined lobes. The gill itself consists of five tripinnate branchial leaves, which are held in a horizontal orientation in living specimens. The rhinophoral sheaths are elevated, housing elongated rhinophores that feature 24 individual lamellae. Notably, juvenile specimens exhibit less pronounced dorsal tubercles compared to adults.

In adult specimens, the body color is an opaque grayish-brown, with the exception of the depressions, which range from dark brown to black. In contrast, juveniles are a translucent gray. Both the rhinophores and the branchial leaves have the same color with the rest of the dorsum. ^[4]

Distribution

This species was described from Sri Lanka. It is reported to be widespread in the tropical Indo-West Pacific Ocean and off Australia.

References

1. Kelaart, E.F. (1858). Description of new and little known species of Ceylon nudibranchiate molluscs and zoophytes. Journal of the Ceylon Branch of the Royal Asiatic Society, Columbo, 3(1): 84–139. page 108.
2. Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O, eds. (2022). "Atagema spongiosa (Kelaart, 1858)". MolluscaBase. World Register of Marine Species . Retrieved 19 February 2022.
3. Rudman, W.B., 2002 (May 15) Atagema spongiosa (Kelaart, 1858). [In] Sea Slug Forum. Australian Museum, Sydney.
4. Innabi, J., Stout, C. C. & Valdés, Á. (2023). "Seven new "cryptic" species of Discodorididae (Mollusca, Gastropoda, Nudibranchia) from New Caledonia". ZooKeys. 1152. Retrieved 20 December 2025. This article incorporates text from this source, which is under a CC BY 4.0 license.