Goniobranchus sp. e048

This is an apparently undescribed species of Goniobranchus that we have seen at Kwajalein and Enewetak Atolls. It lives under dead coral rocks by day and has been observed several times exposed on lagoon pinnacles at night. At least a dozen specimens have been found at depths of 1 to 13 meters and ranging in size up to about 25mm.

At first glance, this animal kind of looks like it should be some kind of dendrodorid rather than a chromodorid. However, its reproductive system anatomy and radular tooth morphology place it firmly in the Chromodorididae.

The species varies somewhat in color. The specimen below was nearly devoid of the magenta coloration that appeared in variable patches on most other specimens. This one, the 25mm specimen found at Kwajalein, had only a few small patches that were more reddish brown than magenta.

The next three shots show a small 8mm-long specimen found on 2 November 2009 on a shallow Kwajalein lagoon reef. The internal orange blob of yolk visible through the dorsum a short ways behind the right rhinophore indicates it is sexually mature, however. This yolk will be deposited in orange extra-capsular yolk bodies in their egg masses.

The specimen below was found on 21 June 2010 under a sheet of corrugated aluminum blown into Kwajalein Harbor long enough before to develop a good crop of sponges and other encrusting organisms on its underside.

This was the shallowest one we've seen. It was under a concrete slab along the Kwajalein Island lagoon shore in less than a meter of water at mid tide.

Created 16 December 2005
Updated 1 July 2012

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