Disk circular (dd = 4.45 mm). Covered by imbricating scales of irregular shape (Fig. 7a). Margin of interradial field with 12-13 small, enlarged, blunt spines that decrease in size in the direction of the radial shields (Fig. 7a). Radial shields slightly longer than wide, united, except at proximal end, where a small triangular scale occurs between the pair of radial shields. Ventral interradius covered by scales similar to dorsal scales (Fig. 7b). Oral shields arrow-shaped (Fig. 7c). Adoral shields enlarged laterally, contiguous in proximal region. Two papillae on each side of jaw angle, the distal one longer and wider (Fig. 7c). Infradental papillae robust, and rectangular. Dorsal arm plate wider than long, rectangular, with rounded borders (Fig. 7d). Ventral arm plate pentagonal, with small notch on distal margin (Fig. 7e). Two small, perpendicular, tentacle scales, inner scale slightly longer than outer scale. Three small, compressed, blunt, arm spines, the ventral one largest (Fig. 7e).

Florida and Dry Tortugas, the Antilles, Gulf of Mexico, and Brazil (Thomas 1962, Hendler et al. 1995). In Brazil from Paraíba (Gondim et al. 2008), Espírito Santo, and Rio de Janeiro (Manso 1988, 1993). Depth 22 to 87 m. Recorded from 30 m in this study.

Species known from bottoms with sand, in which bryozoans predominate (Manso 1988). We consider Amphiodia riisei distinct from Ophiophragmus brachyactis and use the name Amphiodia riisei for the former taxon (see discussion under this species).