14 Goniodoris castanea

14 Goniodoris castanea

Fully expanded, basally thickset gills with tripinnate structure discernible distally (1).
This pair are in the head to tail mating position with their genital openings in close proximity so the penes, if extended, are hidden from view.
Sublittoral, Oosterschelde, Nederland. © S. Verheyen.