Biddulphiophycidae or Biddulphiineae is a grouping of Centrales.

[1] In some taxonomic schemes Centrales or Centric diatoms are named Coscinodiscophyceae and may have different naming of suborders and families.

Valves primarily bipolar.

They do not have a marginal ring of processes.

[1] This diatom article is a stub.