Ultrastructural and Other Observations Which Suggest Suctorian Affinities for the Taxonomically Enigmatic Ciliate Cyathodinium*

Abstract

SYNOPSIS. Two species of the taxonomically enigmatic genus Cyathodinium, C. piriforme and C. cunhai, were studied in some detail at both light and electron microscopic levels. Data obtained strongly suggest suctorian affinities for the genus, since a number of structures or features are strikingly reminiscent of similar (if not homologous) structures recently discovered in ciliates belonging to the order Suctorida. Endosprits (suctorial tentacles?) of Cyathodinium show an arrangement of microtubules not unlike that known for several suctorians, especially Acineta and Tokophrya. Haptocysts or missile‐like bodies, ca. 600 mμ long, have been observed within endosprits and free in the cytoplasm; again this is reminiscent of the complex organelles recently described from several suctorian groups. Mouthlessness, coupled with the presence of a ventral depression (functioning in gathering prey at distal ends of endosprits?) and the presence of food vacuoles in the cytoplasm, further support a suctorian mode of feeding. Finally, stages in the curious life cycle of Cyathodinium suggest neoteny and a basic similarity to endogenous budding processes in certain suctorians.

Anaerobic ciliates as a model group for studying symbioses in oxygen‐depleted environments

“…and Enchelyomorpha sp. (Foissner & Foissner, 1995; Paulin & Corliss, 1969), nassophorean Zosterodasys sp. (Finlay, Tellez, et al, 1993), prostomatid Metacystis sp.…”

Ultrastructural Features of Allantosoma intestinalis, a Suctorian Ciliate Isolated from the Large Intestine of the Horse1

“…Cyathodinium spp. were reported from the caeca of domestic and wild guinea pigs by da Cunha (8) and later redescribed by Lucas (21), Nie (27), Paulin (28), and Paulin & Corliss (30). These organisms do not have a recognizable adult stage but possess cilia, haptocysts, and modified tentacles and undergo a type of evaginative budding (29).…”

PATTERN VARIABILITY IN MICROTUBULAR ARRAYS ASSOCIATED WITH THE TENTACLES OF ACTINOBOLINA (CILIATEA: GYMNOSTOMATIDA)

“…A "static" supportive function could be assigned to the microtubular arrays in the axonemes of Heliozoa (Actinophrys, 7 ; Echinosphaerium, 18) and Radiolaria (Nassellaria, 5), in the tentacles of Suctoria (Acineta, 3 ; Tokophrya, 12), and in the endosprits of the ciliate Cyathodinium (9) . Models for "dynamic" functions of microtubular arrays have been proposed for the ciliary axoneme (4,13,15), the coccid sperm flagellum (11), the extension of heliozoan axonemes (16), and the transport of cellular substances (2,19) .…”