Alkaidia is an extinct genus of sea stars which lived in the western Tethys Ocean from the Barremian to Cenomanian stages of the Cretaceous period.

The authors determined that over 50 specimens (some complete and other fragmentary) originating from the Washita Group represented a new genus and species which they named Alkaidia sumralli.

A complete specimen (1786TXI) found in deposits of the Del Rio Formation at Waco Dam Quarry was designated as the holotype, and was placed in the Texas Memorial Museum.

[1] A second species of Alkaidia was described in 2020 by paleontologists Timothy A. M. Ewin and Andrew S. Gale based on material originating from the Taba Starfish Bed of the Barremian-aged Taboulouart Formation in Morocco and purchased from commercial fossil collectors.

The studied specimens are well-preserved and represent numerous individuals of various growth stages, allowing an ontogenetic series to be shown.