Hippoporidra edax, the type species of
Hippoporidra Canu & Bassler 1927, has been revised following a study of type and other specimens from the Pliocene Coralline Crag of Suffolk. Recent British bryozoans previously referred to
H. edax are considered to be a distinct species,
H. lusitania sp. nov. This and four established species of
Hippoporidra are distinguished by a key which uses the form of the interzooidal avicularium and the shape of the autozooidal orifice. Miocene and Pliocene fossil populations of
H. edax from Europe compare closely with some living populations from the western Atlantic but differ from the four recognizable living species of
Hippoporidra from the eastern Atlantic.
