Petz, Song & Wilbert (1995: 130, fig. 39)
Trunk in vivo 55–80 × 50–75 µm, barrel-shaped; tail (caudal appendix) long, contractile, ciliferous, detaches easily. Equatorial kinety long, extending equatorially and across antapical pole to mid-body again, composed of dikinetids; 1 kinety on tail (homologous to ventral kinety?). Adoral membranelles 15 or 16 anterior, separate from 22–25 ventral membranelles. Paroral membrane 1. Subpellicular platelet layer in posterior two-thirds of body. Extrusomes c. 13 µm long, probably posterior to adoral zone and around buccal overture. Macronuclear nodules 13–28; micronuclei several. Movement: very slow, swimming with tail extended or rolled up and laid against body.
Ross Sea, in the region 66.00°–76.60°S and 162.43°–164.97°W, in the plankton and sometimes slush ice (Petz, unpublished data); Weddell Sea (Petz et al., 1995).