OKINAWAN
OPISTHOBRANCH OF THE WEEK

Hallaxa cryptica Gosliner & Johnson, 1994 (15mm)
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:

        The above featured little dorid, Hallaxa cryptica, was photographed by Atsushi Ono from the waters of Zamami Island in the Kerama Islands, one of a series of islands in the Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa Capitol, Naha. This featured animal was found beneath the surface of a rock in twelve meters of water and was photographed and collected by Atsushi during August of 2002. Atsushi (pers. comm.) reports seeing several individuals but has collected only two specimens. I've added a second page showing an additional animal (12mm from 25m), also from the Keramas; this second animal is of a darker phase than that above.

        The following partial description of H. cryptica is taken from Gosliner & Johnson (1994):

Extenal morphology: The living animals are 7-25 mm in length with a rounded body shape. The general body color is variable and may be either creamy yellowish white or, less commonly, light purple brown. The purple form may have darker purple flecks. Both forms have scattered opaque white spots that appear as tubercles, but are not elevated from the notum. Whitish specimens may also have light tan streaks and spots perpendicular to the notal margin. The rhinophores and gills are the same color as, or slightly darken than, the general body color. Purple specimens have a white tip at the apex of the rhinophores. The branchial plumes consist of 8-15 unipinnate gills. The rhinophores are bulbous with five to nine lamellae. The foot is concavely curved anteriorly with broad, anteriorly directed foot corners. A small pit is present at the lateral margins of the mouth and head.

        H. cryptica is one of five described Hallaxa species known from Okinawan waters; the five species are:

  • H. cryptica - the above featured animal
  • H. hileenae
  • H. indecora
  • H. iju
  • H. paulinae
  • Etymology:

    Literature Cited:


    Page Date: 09 Aug '04
    Page Modification Date: 09 Aug '04
    Digitally manipulated photo
    Copyright © 2004 Robert F. Bolland