OKINAWAN
OPISTHOBRANCH OF THE WEEK

Aegires hapsis Fahey & Gosliner, 2004 (6mm)

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 hapsis is considered to be very rare in the waters of Okinawa's main island as I have seen and collected only two individuals over a period of many years of diving here. The above image is of the holotype* deposited at the California Academy of Sciences (CASIZ 115721). The above featured animal was collected while at the end of a SCUBA decompression from ten feet of water at the Horseshoe Cliffs dive site from a stony coral reef near a reef edge drop-off into deeper waters. The animal was noted to totally retract the rhinophores completely into the mantle when touched. The animal which was initially collected from Tengan Pier is shown on a second page.

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

        EXTERNAL MORPHOLOGY.-- The body shape is elongate. The dorsum has small raised tubercles, arranged in a somewhat regular fashion on the sides of the dorsum and along the midline behind the gill. Spicules protrude from the tops of all tubercles. The rhinophore pocket is raised and the outer edge is formed by three large tubercles. The rhinophores are smooth. The gill pocket lies in the posterior third of the dorsum and is protected by a tri-lobed appendage. Each appendage is further divided into 4-5 smaller lobes. The small gill leaves are tri-pinnate.
        The background color is pale tan and white. There is a fine network of white webbing covering the dorsum, especially noticeable on the posterior third, behind the gill pocket. There are small brown dots on either side of the dorsum midline. The tubercles that lie on the edge of the rhinophore pocket have a dark brown top. The rhinophores are dark brown. The gill branches are white.
        REMARKS.-- Externally, Aegires hapsis does not closely resemble any other Aegires species. Only A. malinus has a similarly smooth dorsum with a fine network pattern overall and tiny dorsal tubercles. But that species has a very different background color (red-brown) and apple green rhinophoral and gill appendages.
        The radular teeth of A. hapsis are different from other species as well. In A. hapsis the teeth are much more elongate and numerous than found in other species. For example, the inner lateral teeth have a longer hook than the outer lateral teeth and most teeth have a downward bend at the tip. This feature is not found in any other Aegires species.
        The reproductive morphology has some similarities to other Aegires. The long thin deferent duct and the wider, tubular prostate are features shared with A. exeches, A. incusus and A. malinus. Aegires ninguis and A. incusus also have a large, balloon-shaped ampulla like A. hapsis. However, the combination of a large ampulla, a long thin deferent duct with a wider prostate combined with a receptaculum that leads from a separate duct into the vaginal duct is not shared by any of the other Aegires species.
        The particular combination of morphological characters separates Aegires hapsis as a distinct species.

        The following Aegires species are known from the waters of Okinawa:

Etymology:

Literature Cited:

*Holotype: See "Type" Dictionary for explanation.

Page Date: 31 Jan '05
Page Modification Date: 01 April '16
Digitally manipulated photo
Copyright © 2016 Robert F. Bolland