Hapalosoma Mortensen, 1903

Type species: Asthenosoma pellucidum A. Agassiz, 1879, by original designation.

Diagnosis —Like Araeosoma but smaller and lacking primary tubercles from admedian regions of aboral ambulacral and interambulacral plates. Blades of dactylous pedicellariae reduced to fine, gland-enveloped rods (emended from Fell 1966).

Remarks —There are three assigned species, all Recent (Table 2).