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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Centropyxiella

Centropyxiella Valkanov, 1970 (ref. ID; 3175 original paper)

ref. ID; 5852

Diagnosis

Test with Centropyxis-like foreign particles. Aperture ventral or subterminal. Diameter of pseudostome elongation/diameter of test <1. Width of pseudostome elongation/diameter of test=1/3-1/5. (ref. ID; 5852)
  1. Centropyxiella arenaria Valkanov, 1969 (ref. ID; 2038, 2115, 2116, 2123, 2216) or 1970 (ref. ID; 2292, 2425, 2432, 3175 original paper, 3519)
  2. Centropyxiella elegans Golemansky (ref. ID; 2115)
  3. Centropyxiella elegans Valkanov, 1970 (ref. ID; 3175 original paper, 3519)
  4. Centropyxiella gibbosa Valkanov (ref. ID; 2115)
  5. Centropyxiella gibbula Valkanov, 1970 (ref. ID; 3175 original paper, 3519) reported year? (ref. ID; 2123)
  6. Centropyxiella gibbulina Chardez & Thomas, 1980 (ref. ID; 2119 original paper, 3519)
  7. Centropyxiella lucida Golemansky, 1971 (ref. ID; 2038 original paper, 2115, 3519)
  8. Centropyxiella oopyxiformis Chardez, 1977 (ref. ID; 3519) reported year? (ref. ID; 2123)
  9. Centropyxiella platystoma Golemansky, 1981 (ref. ID; 3519) reported year? (ref. ID; 2123)

Centropyxiella arenaria Valkanov, 1969 (ref. ID; 2038, 2115, 2116, 2123, 2216) or 1970 (ref. ID; 2292, 2425, 2432, 3175 original paper, 3519)

Descriptions

This species appears to have a cosmopolitan distribution and is found in salinities varying from 26.1-37.8 0/00. The shell is colourless, ovoid in outline sometimes having almost parallel lateral margins which curve evenly in the aboral region but often curve irregularly around the aperture. In lateral view it is elliptical, tapering rapidly towards the aperture. The aperture is oval and invaginated. Most of the shell surface is smooth, and composed of overlapping, flattish particles of quartz held together by organic cement. It would appear that the apertural surface is made of small flat particles, whilst the curved surface of the remainder of the shell is made from a mixture of small and large, flattish particles. The aperture is surrounded by a thickened, often rough, irregular disc-like extension composed of an assortment of quartz particles. In original description Valkanov (1970) noted that the quartz particles bordering the aperture were larger than those of the shell, whilst Golemansky (1976) described some small specimens, 28-31 µm long, with transparent organic shells and particles principally around the aperture. Centropyxiella elegans also described by Valkanov (1970) appears to differ in size alone, varying between 70-80 µm in length, whereas C. arenaria reaches only 60 µm. (ref. ID; 2292)