1	Distal oral papilla never opercular	4
–	Distal oral papilla opercular (Fig. 5i, 7j)	2
2	Disk covered by scales. Two perpendicular tentacle scales	3
–	Disk covered by small papillae (Fig. 7f, h). Two almost parallel tentacle scales	Ophiostigma isocanthum
3	Three or four arm spines, the second and third with two hyaline denticles at tip (Fig. 5f). Radial shields narrow and long (Fig. 5a)	Amphipholis januarii
–	Three arm spines with tip tapering (Fig. 5j). Radial shields slightly longer than broad (Fig. 5g)	Amphipholis squamata
4	Oral papillae continuous (Fig. 6g). Two tentacle scales	5
–	Oral papillae separated from infradentals by a gap (Fig. 6c). Single reduced tentacle scale (Fig. 6e)	Amphiura stimpsoni
5	Radial shields divergent (like a sheep hoof) (Fig. 6e). Three arm spines slightly flattened	Ophiocnida scabriuscula
–	Radial shields contiguous, separated only proximally	6
6	With a fence of broadened papillae on margin of disk (Fig. 7a). Radial shields small and rounded	Ophiophragmus brachyatis
–	Without spines on margin of disk	7
7	Primary scales not evident (Fig. 4a). Three arm spines compressed, flattened and blunt	Amphiodia planispina
–	Primary scales very evident (Fig. 4f). A well marked row of large scales in interbrachial region. Three short and blunt arm spines, compressed in median and distal region	Amphiodia riisei