OKINAWAN
OPISTHOBRANCH OF THE WEEK

Aegires lemoncello Fahey & Gosliner, 2004 (10mm)
Photo by Atsushi Ono

Opisthobranch of the Week Data

Taxonomy:

Frequency on Okinawa: Collection Data:
[brackets indicate range for all Okinawa-collected specimens of the species]


Species Account:

        Aegires lemoncellois considered to be very 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 on Okinawa's main island. The above featured animal is one which was photographed in the waters of Zamami Island by Atsushi Ono during May of 2015, in 12m of water from a rock wall. Atsushi's photograph is used here with his kind permission and he considers the species to be very rare in the Kerama Islands, having seen only the above featured animal (pers. comm.).

        The following description of external morphology and remarks concerning Aegires lemoncello is taken from Fahey & Gosliner (2004):

        EXTERNAL MORPHOLOGY.-- The body shape is elongate, slightly raised and has a very narrow posterior. The dorsum has elongate papillae with flattened tops. Spicules protrude from the tops of the tubercles. The extended oral veil has 10-11 rounded tubercles on the dorsal surface. The rhinophore sheath is slightly elevated, smooth and protected by a single elongated papilla on the outer edge. The rhinophores are smooth. The gill pocket lies in the posterior third of the dorsum and is protected on the anterior side by five elongate papillae that project posteriorly. Posterior to the gill are two small papillae near the center-line. The three small gill branches are bipinnate.
        The background color is pale yellowish white to creamy yellow. The papillae are deeper yellow, with a single ring of orange approximately half way along the length. The rhinophores are the same deeper yellow as the papillae. The gill branches are pale yellow.
        REMARKS.- Externally, Aegires lemoncello does not resemble any other Aegires species. Although A. lemoncello has elongate tubercles like Aegires villosus, the tubercles in that species are more numerous and more complex especially around the rhinophores where there are 4-5 tubercles on a raised pocket. The tubercles of A. lemoncello look more like soft papillae, and there is only one tubercle that lies at the outer side of the rhinophores. The color of these two species is not similar at all. Aegires lemoncello has a yellow or whitish background color with orange rings around the rhinophores and tubercles. Aegires villosus has a white body color with purple and yellow irregular markings covering the notum.
        Internally, the morphological characters also set this species apart from other Aegires. Aegires lemoncello has three elongate curved inner lateral teeth, a feature found in other Aegires (A. ortizi and A. petalis). Aegires pruvotfolae has one elongate inner lateral tooth while both A. ortizi and A. petalis have two. Neither of these species even closely resembles A. lemoncello externally, either in color or tubercle morphology.
        The reproductive morphology also sets A. lemoncello apart from other Aegires. The combination of a long, thin deferent duct leading from a narrow prostate and into a slightly wider penis is not found in other Aegires. The species that most closely matches this anatomy, A. hapsis, does not share any other internal or external characters. The large ovoid receptaculum that enters the common oviduct at the base of the bursa copulatrix is different from other Aegires species also. The receptaculum of other Aegires species either enters a common oviduct with the bursa, or enters the vaginal duct or into the vagina directly (A. ninguis).
        The combination of characters exhibited by Aegires lemoncello sets it apart as a previously undescribed species of Aegires.

        There's a photo of A. lemoncello in the recent nudibranch book (Gosliner, et al. 2015, p. 148). In addition, there are currently images of Aegires lemoncello posted on several sites, notably at several of the following locations: Mike Miller's Slug Site, Bill Rudman's Sea Slug Forum, and Kwajalein Underwater.

        I've previously featured on these pages the following species of Aegires from Okinawan waters:

Etymology:

Literature Cited:


        * Keramas = the Kerama Islands Group, located 30 ~ 40 kilometers west of the Okinawa capitol, Naha.


Page Date: 01 April '16
Page Modification Date: 01 April '16
Digitally manipulated photo
Copyright © 2016 Robert F. Bolland