Aegires incusus
Fahey and Gosliner, 2004

Suborder: DORIDINA
Family: Aegiretidae


Reported from Madagascar, the Philippine Islands and from Japan.


Upper right: Aegires incusus. CASIZ 156668, photo by T. Gosliner, Cemetery Beach, Luzon, Philippines, 5 mm. Lower photos: SEM of radula Scale bar = 10µm. Photos from Fahey & Gosliner (2004).

This species differs from other Aegires in that there is no obvious oral veil. The background color is creamy white and there are a few rounded blotches of tan or light brown spots between some of the tubercles. The tubercle stalks are white and the flattened tops are either all white or all tan. The rhinophores are creamy white on the specimens with white tubercle tops, or are yellowish on specimens with tan tubercle tops. The gill leaves are white. The specimens examined range from 4–5 mm in length.

This species is externally most similar to Aegires pruvotfolae Fahey and Gosliner, nom. nov. (Formerly known as Aegires citrinus Pruvot-Fol, 1930). Although both Aegires incusus and A. pruvotfolae can have a pale yellow background and light brown to tan dorsal spots, the tubercle color of A. pruvotfolae is also yellow with tan apices. But in A. incusus, the tubercles are brown to tan with a darker top. The rhinophores of A. pruvotfolae have a tan top, but those of A. incusus do not. The spicules that project from the tops of the tubercles are lower and more inconspicuous in A. pruvotfolae than in A. incusus. There are multiple tubercles on the head of A. incusus, but in A. pruvotfolae there are only two prominent flat-topped tubercles on the head.

  • Fahey, S. J. & Gosliner, T. M. (2004) A Phylogenetic Analysis of the Aegiridae Fischer, 1883 (Mollusca, Nudibranchia, Phanerobranchia) with Descriptions of Eight New Species and a Reassessment of Phanerobranch Relationships. Proceedings of the CaliforniaAcademy of Sciences, 55, (34): 613–689, 82 figs., 4 tables (Appendix).

Note: This species was previously Aegires sp. 1 on Forum

Authorship details
Fahey, S. J. & Gosliner, T. M. , 2005 (July 8) Aegires incusus Fahey and Gosliner, 2004. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Aegires from Kerama Island.

April 29, 1999
From: Rie Nakano

Note added 8 July 2005: This species has been named Aegires incusus.

Dear Bill,
Here is another of Mr Atsushi Ono 's images from Kerama Island, near Okinawa which you offered to identify for us.

It is from the inner reef, Depth: 7 m, Length:  5mm.

Rie Nakano

Nakano, R., 1999 (Apr 29) Aegires from Kerama Island.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Rie,
This is a species of Aegires. Species of Aegires are generally small, about 10mm or less, and feed on calcareous sponges. This white colour form is not uncommon in the western Pacific and is possibly a colour form of Aegires citrinus Pruvot-Fol, 1930 which, as its name suggests, is yellow.
Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Apr 29). Comment on Aegires from Kerama Island. by Rie Nakano. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from