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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Australothrix

Australothrix Blatterer & Foissner, 1988 (ref. ID; 4861)

[ref. ID; 4861]
Type species; Australothrix australis Blatterer & Foissner, 1988 (ref. ID; 4861)
  1. Australothrix australis Blatterer & Foissner, 1988 (ref. ID; 4861)
  2. Australothrix alwinae Blatterer & Foissner, 1988 (ref. ID; 4861)
  3. Australothrix gibba (Claparede & Lachmann, 1859) (ref. ID; 4861)
  4. Australothrix steineri Foissner, 1995 (ref. ID; 4861 original paper)
  5. Australothrix zignis (Entz, 1884) (ref. ID; 4861)

Australothrix steineri Foissner, 1995 (ref. ID; 4861 original paper)

Diagnosis

Size in vivo 160-320x20-30 um. Many macronuclear nodules. 25 adoral membranelles, 5 ventral cirral rows and 4 dorsal kineties on average. Midventral row slightly shorter than adoral zone of membranelles, consists of 2-3 cirral pairs, continues as ventral cirral row. (ref. ID; 4861)

Descriptions

Very slender and flexible, often slightly sigmoidal and contorted along major body axis; widest in oral area, posteriorly gradually narrowed with posterior end pointed or even elongated tail-like; slightly flattened dorsoventrally. About 70-150 macronuclear nodules, exact number difficult to ascertain because of similar sized and stained food vacuoles and irregular distribution in postoral body portion. Several compact micronuclei, 4x2.5 um in vivo, weakly stained by protargol. Contractile vacuole in mid-body at left margin, with two long collecting canals extending to anterior and posterior end of cell. Cortex and cytoplasm colourless, no cortical granules or cytoplasmic crystals; posterior end often containing shiny fat droplets 1-3 um in diameter. Food vacuoles 5-10 um in diameter, contain fungal spores and, possibly, bacteria and heterotrophic flagellates. All cirri 8-10 um long, frontal cirri distinctly, midventral cirri slightly enlarged. Both marginal rows extend to pointed posterior end of cell. Rightmost ventral cirral row as long as right marginal rows, other ventral rows commence underneath very short midventral row and posteriorly; leftmost row distinctly shortened, does not extend into posterior half of cell. About 4-8 caudal cirri, exact number difficult to recognize because located at pointed posterior end. No transverse cirri. Dorsal kineties slightly shortened anteriorly and posteriorly, cilia 3 um long. Adoral zone of membranelles only about 13% of body length, bases of largest membranelles about 5 um wide. Buccal area flat, narrow and short, oral lip inconspicuous. Undulating membranes one upon the other, paroral membrane distinctly bent anteriorly. Pharyngeal fibres distinct after protargol impregnation. (ref. ID; 4861)

Comparison with related species

So far, four species have been assinged to the genus Australothrix Blatterer & Foissner, 1988: A. australis Blatterer & Foissner, 1988 (type), A. alwinae Blatterer & Foissner, 1988, A. zignis (Entz, 1884), A. gibba (Claparede & Lachmann, 1859). The first two species, which are found in terrestrial biotopes of Australia, are distinctly wider, have conspicuous cortical granules, and possess a higher number of ventral cirral rows and midventral pairs. Australothrix zignis resembles A. steineri in size, shape and cirral pattern, but is highly contractile, reddishly pigmented and lives in marine environments. Australothrix gibba has, like A. steineri, 4 ventral cirral rows, but is much smaller (100-130 um), less slender and lives in freshwater. (ref. ID; 4861)

Etymology

This species is named in honour of my friend Prof. Erich Steiner (Vienna), president of the "Mikrographische Gesellschaft Wien", a great lover of microscopy. (ref. ID; 4861)

Type location

Upper soil layer of bank of Rio Corobici at the hacienda "La Pacifica" (Centre Ecologia La Pacifica) near town Canas in Costa Rica (Central America), W85 degrees 08', N10 degrees 27'. (ref. ID; 4861)