Cephalodiscida

Cephalodiscida is one of two orders in the class Pterobranchia, which are small, worm-shaped animals. Members belong to the hemichordates.^[1][2] Species in this order are sessile, living in clear water and secrete tubes on the ocean floor.^[3]

Cephalodiscida
Cephalodiscus dodecalophus
Scientific classification
Kingdom:	Animalia
Phylum:	Hemichordata
Class:	Pterobranchia
Order:	Cephalodiscida Fowler, 1892
Families
Cephalodiscidae †Rotaciurcidae
Synonyms
Atubaridae Sato 1936 Eocephalodiscidae Kozlowski 1949 Melanostrophidae Zessin & von Puttkamer 1994

Taxonomy

The order is a small one, with only two known families, each containing a single extant genus. The validity of the family Atubaridae, who has only a sole member, is regarded as questionable.^[4]

• Order Cephalodiscida Fowler 1892^[5]
  • Family Cephalodiscidae Harmer 1905
    • Genus †Aellograptus Obut 1964
    • Genus †Eocephalodiscus Kozlowski 1938 ex Kozlowski 1949
    • Genus †Melanostrophus Öpik 1930 ex Öpik 1933
    • Genus †Pterobranchites Kozlowski 1967
    • Genus Atubaria Sato 1936
    • Genus Cephalodiscus M'Intosh 1882
  • Family †Rotaciurcidae Briggs and Koch 2023
    • Genus †Rotaciurca Briggs and Koch 2023