Characters: Colonies are mostly encrusting, rarely more than 30 mm diameter. Corallites average 1.7 mm diameter, are crowded, angular. Septa are in two very unequal and irregularly fuse, in a Porites-like pair or trident. Columellae are absent. Polyps are extended during the day, and have 15-22 tentacles.
Colour: light green.
Similar Species: Polyps have a mixture of Porites-like and Goniopora-like characters. They do not closely resemble any other species.
Habitat: Reef habitats.
Abundance: Mostly uncommon.
Taxonomic Note: The type species of Calathiscus Claereboudt and Al-Amri, 2004. Placed in Goniopora by Kitano, Benzoni, Arrigoni et al. (2014), but the septal configuration clearly distinguishes this species from any Goniopora.
