Paraclevelandia brevis in ‘brevis’ form

(Figs 23A–G, 24A, B, D, E;

Supporting Information, Tables S25–S29)

When present, the ‘brevis’ form was highly abundant.

Description based on ASS, PAA, PAC, PRG, STH in vivo, and PRG and STH in protargol preparation: Small Clevelandellidae (on average 44 × 28 µm in vivo, range 34–58 × 21–48 µm; on average 34 × 21 in protargol preparations, range 26–47 × 15–28 µm). Broadly ovate, slightly dorsoventrally flattened, anterior end tapers to rounded point, posterior end transversely truncate. Posterior peristomial projection absent. Peristomial overture on left posterior margin of cell. Macronucleus elongated ellipsoidal, chromatin coarsely granular. Micronucleus ellipsoidal, relatively large (4–6 µm across), dorsal to macronucleus (Fig. 23D). Karyophore not detected. A sack-like structure formed between anterior margin of macronucleus and anterior end of cell as reported by Kidder (1937, 1938), not evident in protargol preparations (Fig. 23A). Cortex with refractile interkinetal granules, probably mucocysts (Fig. 23B). Somatic kineties strongly spiralled leftward (Fig. 24B). Somatic cilia absent on right, ventral, left parts of posterior cortex (Fig. 24A, B, E), extend to posterior cell margin dorsally. Kinetal furrows prominent. Two ciliated circumperistomial kineties. About 10 ciliated kinetofragments in midportion of right suture, increase in length from posterior to anterior (Figs 23E, F, 24B, D). Organization of oral ciliature as for the family except, in absence of peristomial projection, oral structures are situated in body proper (Fig. 23A, B, D, H, J). Adoral zone narrows from posterior to anterior, extends about 50% of cell length on average, composed of an average of 15 membranelles (range 14–17).