Haeckel, 1881, emend. Riedel, 1967
Skeletons restricted to a simple tri- or tetraxonic nassellarian spicule (Tetraplecta pinigera), or a well developed system of main spines enclosed within a fully formed cephalis (main spines/skeleton; main spines/skeleton 2; main spines/skeleton 3). The degree of development of the cephalis may vary from a few anastomosed bars (Neosemantis distephanus; Sethophormis rotula) to a well developed, latticed or latticed/spongy chamber. Usually without postcephalic segments. In addition to several fairly well-defined species, the Plagoniidae comprise many probably related forms of obscure taxonomic status usually cited under various generic names. The classification of these forms needs detailed ad hoc studies, for which reason many of them are provisionally lumped under the designation Plagoniidae group in the present chapter.
The following species (or higher taxa) of this family are treated in the present volume:
Antarctissa spp.
Arachnocorys circumtexta
Callimitra carolotae
Clathrocanium coarctatum
Clathrocorys teuscheri
Helotholus histricosa
Lampromitra coronata
Lampromitra danaes
Lampromitra quadricuspis
Lampromitra schultzei
Lophophaena butschlii
Lophophaena hispida
Neosemantis distephanus
Peromelissa phalacra
Phormacantha hystrix
Plagoniidae group
Pseudocubus obeliscus
Sethophormis aurelia
Sethophormis rotula
Tetraplecta pinigera
Trisulcus triacanthus