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2026 · Photo: Boaz Liebes
Geometric goniobranchus
Philippines · Indo Pacific - South China Sea
A common Indo-West Pacific chromodorid named for the geometric, tile-like pattern on its back, which resembles the colouring of Phyllidiella pustulosa and is considered a mimic of that distasteful phyllidiid. It has a broad anterior mantle skirt, purple underneath, which it waves up and down as it crawls.
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Greyish to violet-tinged mantle covered with raised white tubercles set in a dark, net-like (roughly hexagonal) pattern; the mantle edge has a thin purple line. Rhinophores and gills translucent with greenish to yellow-brown tips, the rhinophore stalks peppered with white. A brownish form is also known.
Goniobranchus hintuanensis has a pale plum network, a few white nodules ringed in magenta and red-purple rhinophores and gills. G. conchyliatus (western Indian Ocean) has a deep purple network. Phyllidiella pustulosa has no gill plume on the back and a much firmer body.
Coral and rocky reefs, often in shallow water.
Sponges (feeding has been observed in the field).
