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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Notohymena

Notohymena Blatterer & Foissner, 1988 (ref. ID; 4894)

Family Oxytrichidae Ehrenberg, 1838: Subfamily Oxytrichinae Jankowski, 1979 (ref. ID; 4894)

[ref. ID; 4894]
Improved characterization; Adoral zone of membranelles formed like a question mark. Undulating membranes in Notohymena pattern. Frontoventral cirri in V-shaped pattern. Postoral ventral cirri in dense cluster underneath buccal vertex. Two pretransverse ventral and five transverse cirri. One right and one left row of marginal cirri. Six dorsal kineties. Caudal cirri present. Primordia V and VI of proter originate de nove. Dorsal morphogenesis in Oxytricha pattern. (ref. ID; 4894)
Remarks; The cladistically significant character, viz. the hook-shaped distal end of the paroral, is recognizable only after protargol impregnation. Sterkiella and Steinia have a broader and more rigid body. In addition, Notohymena species possess distinct cortical granules, organelles lacking in all genera of the subfamily Stylonychinae. (ref. ID; 4894)
Type species (original designation); Notohymena rubescens Blatterer & Foissner, 1988 (ref. ID; 4894)
  1. Notohymena antarctica Foissner, 1996 (ref. ID; 2128 original paper)
  2. Notohymena australis Foissner & O'Donoghue, 1996 (ref. ID; 2128)
  3. Notohymena rubescens Blatterer & Foissner, 1988 (ref. ID; 4801, 7423) reported author and year? (ref. ID; 191)

Notohymena antarctica Foissner, 1996 (ref. ID; 2128 original paper)

Descriptions

Cortical granules yellow, mainly around cirral bases and dorsal bristles. On average 31 adoral membranells, 17 right marginal cirri, 18 left marginal cirri, 5 transverse cirri, 3 caudal cirri, and 6 dorsal kineties. Shape prolate ellipsoidal, right side straight or slightly concave, left rather distinctly convex, both ends broadly rounded, flattened laterally up to 3:1. Flexible like, e.g., Oxytricha granulifera. Macronuclear nodules distinctly ellipsoidal (2:1), rather close together in middle third of body to left of midline. Usually one globular micronucleus attached to each macronuclear nodule. Contractile vacuole in mid-body at left margin, with two inconspicuous collecting canals. Cytopyge in posterior end between transverse cirri and left marginal cirral row; fecal balls contain yellowish globular like those found in cytoplasm. Pellicle colourless, flexible; cortical granules arranged in groups around cirral bases and dorsal bristles, yellow to yellow-green, give cell yellowish colour at low magnification (< /_ x100), do not stain with protargol. Cytoplasm colourless, contains some 1-4 um sized, yellowish fat globules and rather many 1-3 um long crystals, mainly in posterior half. Feeds on ciliates, heterotrophic flagellates and, possibly, on bacteria. Scrabbles rather fast amongst soil particles. Magical cirri about 15 um long, frontal, transverse and caudal cirri about 20 um long. Gap between posterior end of marginal rows indistinct because left row extends to midline of cell and indistinctly separate from caudal cirri. Arrangement of ventral cirri oxytrichid, cirral number very constant. Dorsal cilia about 3 um long in vivo, arranged in 6 rows: rows 1 and 4 slightly shortened anteriorly, rows 2 and 3 as long as body, row 5 terminates sub-equatorially, row 6 consists of about 5 dikinetids only and ends pre-equatorially. Oral apparatus and adoral zone of membranelles conspicuous, occupy about 37% of body length. Buccal field rather large and deep, anterior portion semicircularly curved, similar as in Cyrtohymena. Paroral and endoral membrane conspicuously curved, intersect optically in mid-portion, paroral distinctly longer than endoral, its distal end hooked (main genus character), both very likely composed of dikinetids. (ref. ID; 2128)

Notes

Notohymena antractica is very similar to N. australis as concerns size, shape, and cortical granules. However, it has fewer adoral membranelles and marginal cirri and, more importantly, only 3 caudal cirri. The unusual high number, viz. 6-8, of caudal cirri in N. australis has been confirmed and in thus a constant character. N. australis is also easily confused with Cyrtohymena citrina, which is very similar in all characters, except for the undulating membrane, which lacks the anteriorly directed hook. This character, which is rather difficult to recognize, has been confirmed by ontogenetic studies. (ref. ID; 2128)

Etymology

Named after the continent found. (ref. ID; 2128)

Measurements

In vivo 80-110x30-40 um. (ref. ID; 2128)