Psolidium Ludwig, 1886

Diagnosis (O’Loughlin & Maric 2008). Small species of Psolidae, arched dorsally and flattened ventrally with a distinct ventral sole. Ten dendritic tentacles present, eight large and two small ventrally. Imbricating dorsal and lateral scales, decreasing in size ventro-laterally, orally and anally. Oral and anal openings lacking large discrete valves. Tube feet present dorso-laterally though not always macroscopically evident. Ventral tube feet in two sizes with outer peripheral series smaller when present. Mid-ventral series of tube feet variably present. Dorso-lateral and ventral ossicles can include combinations of multi-layered plates, perforated plates, cups, rosettes, crosses, cupped crosses, thorns (branched rods), and buttons. Always some tube foot canals present in dorso-lateral multilayered ossicles. Tentacle ossicles commonly include irregular rods and perforated end plates, with rosettes sometimes also present.