Fauré-Fremiet, 1970
Free-swimming (rarely loricate), pelagic species; pellicle especially in posterior half of body made rigid by subpellicular platelet layer; perilemma present in some species. With girdle of extrusomes ("trichites"). Predominantly in marine habitats, also ectosymbiotic on echinoids, several very common planktonic freshwater forms.
Planctonic species recorded:
Strombidium antarcticum
Strombidium compressum
Strombidium conicoides
Strombidium conicum
Strombidium crassulum
Strombidium diversum
Strombidium sulcatum
Laboea strobila
Note
A phylogenetic approach using morphologic and morphogenetic characters resulted in a considerably different system for aloricate oligotrichs (Petz and Foissner, 1992). As this group dominates the ciliate fraction in the marine plankton, this improved scheme is given below. Apomorphies showed that strombidiids are more closely related to tintinnids and strobilidiids than to halteriids, which makes the recently proposed order Choreotrichida Small and Lynn, 1985 superfluous. It also followed from that study that the hypotrichs should be elevated to class rank as later proposed by Tuffrau and Fleury (1994).
Outline classification
Class Oligotrichea Bütschli, 1887
Subclass Halteriia Petz and Foissner, 1992
Order Halteriida Petz and Foissner, 1992
Family Halteriidae Claparède and Lachmann, 1858
Subclass Oligotrichia Bütschli, 1887
Order Strombidiida Jankowski, 1980
Family Strombidiidae Fauré-Fremiet, 1970
Order Oligotrichida Bütschli, 1887
Suborder Strobilidiina Jankowski, 1980
Family Strobilidiidae Kahl in Doflein and Reichenow, 1929
Suborder Strombidinopsina Small and Lynn, 1985
Family Strombidinopsidae Small and Lynn, 1985
Suborder Tintinnoinea Kofoid and Campbell, 1929 (see separate chapter)