Opisthobranch of the Week Data
Aegires incususis considered to be rare in Okinawan waters; I've not personally seen nor collected any specimens of this attractive little aegirid and it is currently unknown from Okinawa's main Island, but it has been photographed by Atsushi Ono in the Kerama Islands. * The close proximity of the main island of Okinawa to the Kerama Islands, as well as the similar opisthofauna to that of the Kerama Islands, suggests the possibility that it is also present here on Okinawa's main island. The above featured animal is one which was photographed in the waters of Zamami Island by Atsushi Ono during January of 1999, in 7m of water on a buoy chain. Atsushi's photograph is used here with his kind permission and he considers the species to be rare in the Kerama Islands, having seen around 4-6 individuals there (pers. comm.).
The following description of external morphology and remarks concerning Aegires incusus is taken from Fahey & Gosliner (2004):
EXTERNAL MORPHOLOGY.-- The body shape is elongate and slightly rounded. There is no obvious oral veil as is found in other Aegires species. The posterior third of the body is much narrower than the rest of the body. The dorsum has tall, anvil or mushroom-shaped tubercles with flat tops. There are smaller tubercles along the edge of the posterior end of the foot and one prominent tubercle on the tip. Spicules protrude from the tops of all tubercles. The rhinophore pocket is slightly elevated and is usually surrounded by three tubercles that vary in size. The rhinophores are smooth. The gill pocket lies in the posterior third of the dorsum and three tubercles protect the anterior side of the gill pocket. The small gill leaves are bipinnate.
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.
REMARKS.— Aegires incusus is externally most similar to Aegires pruvotfolae. . . . The particular combination of external, reproductive and radular characters distinguish A. incusus as a distinct Aegires species.
I've previously featured on these pages the following species of Aegires from Okinawan waters:
* Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.