Cytological Studies ofTrichophrya rotunda(Hentschel)1

Abstract

Morphological, ultrastructural, and reproductive studies of a suctorian suggest its designation as Trichophrya rotunda (Hentschel) as distinct from Heliophrya collini, Heliophrya rotunda, and Craspedophrya rotunda of previous descriptions. Trichophrya rotunda has a round or slightly irregular, dorsoventrally flattened body (37–73 μm) with peripheral tentacles arranged randomly within 4–13 fascicles, a central polymorphic macronucleus, and 7–21 peripheral contractile vacuoles with ventrally terminating discharge pores. The tentacles are contractile and highly flexible. The axoneme consists of microtubules forming seven curved lamellae and 35 outer microtubules, which are separated into seven groups. Deviations from this prevailing pattern include helically arranged lamellae at the points of apical and basal termination, outer ring microtubules joined in an apical connective sheath, and the presence of a basal connective sheath near the point of axoneme termination. In common with other suctorians the cortex is multilayered and the cytoplasm contains characteristic organelles such as crescentic bodies and elongate dense bodies, but the haptocysts have unusual radial projections. Trichophrya rotunda feeds readily on motile vorticellids, attachment of the tentacular knobs occurring at their trochal band. Reproduction is endogenous, producing a single, slightly flattened, oval-shaped swarmer with five equatorial kineties. The swarmer cytoplasm shows no evidence of primordia of tentacle axonemes nor any stages in development of the tentacle.