FAMILY CATOPHRAGMIDAE UTINOMI, 1968

Diagnosis: Shell consisting of eight solid plates fully integrated into sheath (rostrum, rostromarginals, marginals and carinomarginals, and carina); wall encircled by a few to numerous whorls of monomorphic imbricating plates; radii absent; opercular plates thick; mandible tridentoid; first two pairs of cirri as maxillipeds; caudal appendages when present multi-articulate.

Comment: The phylogeny provided by Chan et al. (2017a), based on six molecular markers (both mitochondrial and nuclear), showed Catophragmidae as sister to Pachylasmatidae within the Chthamaloidea clade. Chan et al. (2018) sequenced the mitogenome of Catomerus and found that it is more closely related to Tetraclitodea rather than to Chthmaloidea. The molecular position of Catophragmidae might need further confirmation from additional molecular studies.

Catolasmus Ross & Newman, 2001 (one species)

Catomerus Pilsbry, 1916 (one species)

Catophragmus Sowerby, 1826 (one species)