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Authority
(H.A.Thomsen) Manton, in Manton & Bremer (1981: 290, figs 1–5)
Class
Craspedophyceae/Choanoflagellida
Order
Choanoflagellida
Family
Acanthoecidae
Additional References
Thomsen et al. (1990: 382, figs 68, 69)
Basionym
Pleurasiga sphyrelata H.A.Thomsen (1973: 24, figs 22–26)
Synonyms
Campanoeca dilatata Throndsen (1974: 109, figs 2, 8, 29)
Description
Cells solitary. Lorica barrel-shaped, 15–20 µm long, c. 10 µm diameter; longit-udinal costae 7 or 8; transverse costae 3. Longitudinal costae extend for about 10% of their length beyond the anterior transverse costa, each comprising 4 costal strips. Transverse costae comprising 7 or 8 costal strips; costal strips of anterior and middle costae, but only one of the posterior costa, bearing a small square facet in the middle of the costal strip. Protoplast ellipsoidal, 4 µm long, located posteriorly in the lorica; collar of tentacles c. 3 µm long.
Distribution
Inshore areas of Prydz Bay, East Antarctica; New Zealand (Moestrup, 1979); South Africa (Manton et al., 1975); type locality, Denmark (Thomsen, 1973).
Comments
Posteriorly, this organism resembles Polyfibula elatensis (H.A.Thomsen) Manton and P. caudata (B.Leadb.) Manton. However, the arrangement of the remainder of the lorica, especially insofar as the anterior ends of the longitudinal costae neither make T-junctions (as in P. caudata), nor that these costal strips extend well beyond the anterior transverse costal strips as spines (as in P. elatensis), indicates that this organism should be regarded as P. sphyrelata. In the Prydz Bay material, the square costal strip facets were not well developed on the middle and posterior transverse costae.