Superorder ACROTHORACICA Gruvel, 1905

Cryptosomata Hancock, 1849: 313.

Abdominalia Darwin, 1854: 583.

Acrothoracica Gruvel, 1905: 310 .

Diagnosis. Small, soft-bodied barnacles. Females burrowing into calcareous substrates (molluscs, corals, limestone, thoracicans, etc.). Minute dwarf males attached either to the female, or to her burrow. Lacking calcareous shell plates, but possessing a single pair of chitinous plates, also known as opercular bars, guarding the aperture. 3–5 pairs of terminal cirri, a single pair of mouth cirri developed or reduced, adults with reduced abdomen. Caudal appendages present (some lithoglyptids) or absent (all cryptophialids).

Remarks. Currently the Acrothoracica consists of two orders, the Cryptophialida and the Lithoglyptida (Kolbasov, 2009) .