Author: Rudman, 2007

Order: Nudibranchia  Family: Goniodorididae

Maximum Size: 15 mm

Sightings: Sunshine Coast

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Okenia atkinsonorum Rudman, 2007

This species is very similar in external appearance to Okenia hallucigenia and both also feed upon the bryozoan Pleurotoichus clathratus.

Some differentiating features of O. atkinsonorum include:
– Body flatter, lacking the higher profile of O. hallucigenia.
– Body shape more oval than elongate.
– Possesses 5 to 7 lateral pairs of mantle papillae not always arranged in matching pairs (In O. hallucigenia the number is constant as four matching lateral pairs.)
– Papillae tips may be tapered or rounded.
– Head is indistinguishable from foot in dorsal aspect and lacks the distinct oral veil of O. hallucigenia.
– Possesses a V-shaped groove on sole of foot that differentiates foot from head ventrally.

David A. Mullins – March 2023

References:
– Rudman, W. B. (2007) Two new species of Okenia (Gastropoda: Nudibranchia: Goniodorididae) from eastern Australia and Tanzania. Zootaxa, 1657: 57–67.