Arcuospathidium
- Arcuospathidium cooperi Foissner (ref. ID; 2308 original paper)
- Arcuospathidium vermiforme Foissner, 1984 (ref. ID; 2308)
Descriptions
Shape slightly fusiform to slenderly cylindroid, flattened only in oral region, widest usually close below proximal end of oral bulge. Macronucleus slenderly reniform to boomerang-shaped, near centre of body, with many roundish nucleoli, Micronucleus globular, attached to macronucleus. Single contractile vacuole in posterior end. No extrusomes recognizable in oral bulge and cytoplasm. Cortex flexible, colourless, contains loose rows of 0.5-1 um sized granules. Cytoplasm conspicuously dark at x100 due to innumerable, highly refractile crystalline inclusions; macronucleus and contractile vacuole thus stand out as bright blisters; crystals 3-5 um long, of variable shape, do not dissolve in water when cell is disrupted. Movement serpentine and slow. Somatic cilia 8-10 um long, widely spaced, arranged as in other members of genus, i.e., in longitudinal rows distinctly separate from circumoral kinety. Dorsal brush short, usually consisting of 3 (rarely 4) rows of paired cilia with slightly inflated distal end; cilia of row 1 about 2 um long, those of rows 2 and 3 up to 5 um long, row 3 continues with single, about 2 um long bristles to mid-body. Oral bulge distinctly oblique and slenderly cuneate, hyaline, inconspicuous, base surrounded by cuneate circumoral kinety composed of rather widely spaced dikinetids having only one basal body ciliated. (ref. ID; 2308)
Notes
Size, shape, ciliary pattern, and terrestrial habitat of A. cooperi highly resemble A. vermiforme Foissner, 1984 which, however, has two ellipsoid macronuclear nodules. These species also share another, however negative, character, viz., the absence of extrusomes, at least in the light microscope. Foisnner checked this very carefully in many specimens and with optimum technical equipment. No Spathidium species was found in the older literature which might be identical with A. cooperi. (ref. ID; 2308)
Etymology
Named after Mr. John Cooper (University of Cape Town, South Africa), who provided the samples investigated in this study. (ref. ID; 2308)
Measurements
Size in vivo about 90-160x20-25 um. Macronucleus slenderly reniform, 30x6 um on average. Oral bulge short, i.e., about 1/4 of body length. 11 somatic kineties on average. (ref. ID; 2308)