Genus ACANTHASTER Gervais, 1841

Gervais 1841: 461–481. Madsen 1955.

Diagnosis. Medium to large body discoidal, multi-radiate; skeleton surrounded by numerous bi-articulated spines on mammiform tubercles; madreporic tubercles numerous, conical, ten to 25 in number, arranged in a circle; ambulacral spines small, placed in a group beside them, a continuous small row of thin, enlarged spines. The spines are either long (up to ~ 3 cm) and venomous [ A. planci -complex] or very short (up to 10 mm) [ A. brevispinus]; they usually have a second joint about one third of the way down. They occur in tropical regions of the Indo-Pacific Ocean, including the Red Sea, and extend to the Eastern Pacific.