OKINAWAN
OPISTHOBRANCH OF THE WEEK

Halgerda willeyi Eliot, 1904 (67mm)

Opisthobranch of the Week Data

Taxonomy:

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


Species Account:

        Halgerda willeyi is a relatively large discodorid, considered uncommon on Okinawa; thirteen individuals have been collected since the first Okinawan specimen was collected on the sixteenth of October, 1984. H. willeyi is one of thirty-five described species of Halgerda, all found within the Indo-Pacific (Fahey & Gosliner, 2001). As of mid-October, 2001, eleven of the thirty-five described species are found in Okinawan waters (H. diaphana and H. onna are unique to the Ryukyu Archipelago*). As of early May, 2013, thirteen described species of Halgerda have been featured on these pages, from Okinawa's main island and the Keramas. These thirteen species are:

  • H. albocristata
  • H. batangas
  • H. brunneomaculata
  • H. carlsoni
  • H. dalanghita
  • H. diaphana
  • H. elegans
  • H. malesso
  • H. okinawa
  • H. onna
  • H. tessellata
  • H. wasinensis
  • H. willeyi - The featured animal above
  •         The above featured animal was found crawling on the upper surface of coral rubble in an area of mixed sand and strewn coral rubble during a mid-morning SCUBA dive. I've not found H. willeyi in association with any prey species; Marshall & Willan (1999) suggest that it probably feeds on siliceous sponges. I've included three additional images, illustrating some of the variation seen in the Okinawan material.


    * Okinawa is the largest of approximately seventy-two islands making up the Ryukyu Archipelago which stretches for 600km.

    Literature Cited:


    Page Date: 06 Mar '00
    Page Modification Date: 01 Mar '14
    Digitally manipulated photo
    Copyright © 2014 Robert F. Bolland