Halgerda sp.

Image courtesy of Gary Cobb
Wall at Old Woman Island, Queensland, Australia
Canon G10 in Ikelite housing with one Inon Z220 strobe

Halgerda sp. Gills

Halgerda sp. Undescribed To compliment the recent BOW of Halgerda aurantiomaculata here is a pic of an undescribed species of Halgerda. This too was a very large specimen (120 mm) found ten days later and not more than 10 metres from where the former was sighted on The Wall at Old Woman Island. The size of both these specimens has been cause for remark. There are a number of similar looking species based around the appearance of Halgerda willeyi. The species pictured above though differs in a number of respects. The rhinophores and gills (seen at left) are much darker with the usual brown line up the inner axes of the gills presenting instead as a series of distinct spots. The mantle edge has a well-defined and continuous thin yellow margin with an almost plain translucent submarginal band except that it carries brown spots and small yellow pustules but the yellow and brown lines of the mantle stop short of, or just extend into, this band never extending to the mantle edge itself. Interestingly the close-set pattern of those narrow alternating brown and yellow lines does not carry through to the tips of the most lateral of the large tubercles making them stand out with translucent white apices. The rhinophoral pockets also have a distinct yellow lip. Given their size and healthy appearance one must draw the conclusion that the sponges they eat out there must be most agreeable. References: Marshall & Willan 1999. Nudibranchs of Heron Island, Great Barrier Reef, Backhuys Publishers. Cobb & Willan 2006. Undersea Jewels, ABRS, Canberra Debelius & Kuiter 2007. Nudibranchs of The World, Helmut Debelius, Publisher.

For more information go to Nudibranch ID iPhone Apps for more information (pricing, etc)
or contact Gary Cobb directly at gary@nudibranch.com.au

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