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Acanthocorbis apoda (Leadbeater, 1972) Hara and Takahashi, 1984. Cells are 4-6 microns in length, with a truncated anterior, and the posterior end may be pointed. Lorica 13-18 microns long with a constricted posterior chamber, and 12-16 projections protruding from the wider anterior chamber. A single transverse costa in the anterior chamber, formed of overlapping strips, and two or three transverse costae in the posterior chamber. Cells are located in the posterior chamber of the lorica, with the flagellum extending to the top of the lorica or just beyond it.
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Acanthocorbis campanula (Espeland, 1986) Thomsen in Thomsen et al., 1991. Cells are located at the posterior of a cone-shaped lorica. Lorica 12-16 microns long, pointed posteriorly and widest anteriorly, with two transverse costae and 7-9 longitudinal costae which project above the lorica as projections.
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Acanthocorbis haurakiana Thomsen in Thomsen et al., 1991. Conical lorica 20-27 microns long, including a posterior spine. One transverse costa at the anterior of the lorica, with the most anterior costal strip of each of 6 longitudinal costae projecting as a spine. The costal strips forming the anterior spines and the posterior spine are tapered distally. There is a band of rather obliquely arranged costae around the protoplast in the middle of the main lorica chamber.
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Acanthocorbis asymmetrica (Thomsen, 1979) Hara and Takahashi, 1984. Cell solitary, planktonic. Protoplast 4 x3 microns, flagellum 6-9 microns long, surrounded by a ring of tentacles. Protoplast lodged in a lorica 15 -20 microns long, diameter at level of anterior transverse costa approximately 8 microns Lorica composed of 15-17 longi tudinal costae, which converge at the posterior end to form a stalk (4-11 microns long). The location of the stalk deviates markedly from the long axis of the cell, giving it an asymmetrical appearance (hence the specific epithet). Each longitudinal costa consists of four costal strips. The longitudinal costae project anteriorly as free spines (one and a half costal strips long). Two transverse costae (separated by one-third of a longitudinal costal strip) encircle the lorica at the anterior end, the lower-most is connected to the junctions between the second and third longitudinal costal strips (counted from the anterior lorica end). A single transverse ring is attached to the junctions between the third and fourth longitudinal costal strips (counted from the anterior lorica end). The complexity of the strip arrangement in the posterior part of the lorica is somewhat variable, depending on the number of strips entering the upper part of the stalk.
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Acanthocorbis prolongata Thomsen et al., 1997. Cells are solitary, attached to the substratum by means of a cluster of costal strips terminating a simple pedicel, about 30 microns long and consisting of up to 8 linearly arranged costal strips. Lorica funnel shaped, about 13 microns long, and with anterior projections (8-10) that continue downwards as longitudinal costae. The length of an anterior projection equals one costal strip. The anterior transverse costa (diameter about 5 microns) consists of 8-10 strips with considerable overlaps between neighbouring strips and a small vertical displacement (about 0.4 microns) between strips where they attach to or cross a longitudinal costa. Costal strip arrangement at the posterior lorica end is somewhat more irregular, although 2 transverse costae are discernible. Costal strips are rod-shaped, and 3-4 microns long. The protoplast, about. 4x3 microns, is posteriorly located within the lorica. The single flagellum is about 7 microns long, surrounded by a ring of tentacles (each about 2 microns long), and with a conspicuous hairpoint.
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Acanthocorbis weddellensis Thomsen, Garrison and Kosman, 1997. Cells are solitary. Lorica funnel shaped, about 15 microns long, and with anterior projections (12-14). The length of an anterior projection almost equals two longitudinal costal strips in length. Each longitudinal costa consists of 4 costal strips. Two anterior transverse costae (diameter about 7 microns) encircle the lorica at the level of the front end of the protoplast. A single transverse costa encircles the posterior part of the lorica. The lorica has no pedicel. Costal strips are rod-shaped, and about 5 microns long. The single flagellum is about 20 microns long, surounded by a ring of tentacles (each about 3 microns long), and with a conspicuous hairpoint.
