Glypheidea is an infraorder of lobster-like decapod crustaceans, comprising a number of fossil forms and the two extant (living) genera Neoglyphea and Laurentaeglyphea:[1] The infraorder was thought to be extinct until a living species, Neoglyphea inopinata, was discovered in 1975. They are now considered "living fossils", with over 256 fossil species discovered, and just two extant species.[2]
Glypheidea belongs to the clade Reptantia within the order Decapoda, although its exact placement within Reptantia is difficult to determine.[3] Some phylogenetic studies consider Glypheidea to be most closely related to the infraorder Astacidea, which consists of the lobsters and crayfish,[2] whereas other studies instead consider Glypheidea to be more closely related to the infraorder Polychelida, a group of deep-sea blind lobsters.[3]