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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Rhabdonellopsis

Rhabdonellopsis Kofoid & Campbell, 1929

[ref. ID; 3597]
Lorica elongated chalice-shaped, consisting of a conical bowl and a long pedicel with a knob and an apical lance; oral border with a gutter between the inner and outer rims; wall almost like the elongated species of Rhabdonella in structure. This genus is only different from the forms of Rhabdonella in having a slender pedicel and a distinct knob on the pedicel. A unique species mentioned above as the type species was examined in collections form the South Sea Islands and the East Indies. (ref. ID; 3597)
Type species; Rhabdonellopsis apophysata (Cleve) Kofoid & Campbell (ref. ID; 3597)
  1. Rhabdonellopsis apophysata Cleve, 1900 (ref. ID; 4600) reported year? (ref. ID; 4046) or (Cleve) Kofoid & Campbell (ref. ID; 3597)
  2. Rhabdonellopsis composita (Brandt) (ref. ID; 3597)
  3. Rhabdonellopsis intermedia Kofoid & Campbell (ref. ID; 4046)
    See; Comments of Rhabdonellopsis apophysata
  4. Rhabdonellopsis longicaulis Kofoid & Campbell (ref. ID; 4046)
    See; Comments of Rhabdonellopsis apophysata
  5. Rhabdonellopsis triton Zacharias (ref. ID; 4046)
    See; Comments of Rhabdonellopsis apophysata

Rhabdonellopsis apophysata Cleve, 1900 (ref. ID; 4600) reported year? (ref. ID; 4046) or (Cleve) Kofoid & Campbell (ref. ID; 3597)

Descriptions

Lorica elongated, consisting of a slightly conical bowl and a slender pedicel with a knob and a apical lance, its length 5.7-8.0 inner oral diameters; outer oral rim as high as an inner, widely flaring one (50-67 degrees), its diameter 1.2-1.3 inner oral diameters; bowl more or less narrowing (7-10 degrees) in its upper main part to a convex conical aboral region of 17-26 degrees; pedicel elongate, as long as the bowl, gradually tapering (1.5-3.5 degrees) and abruptly expanding to form a conical knob of 25-40 degrees with a blunt skirt at its distal end; lance short, conical (4-10 degrees), with a perforated terminal; wall finely prismatic, with 10-14 somewhat spiral longitudinal ribs extending from the outer oral margin to the skirt of the knob on the surface. (ref. ID; 3597)
The lorica is characterized by the presence of a posterior knob from which extends an "apical lance". The lance measures 21-19 in length in the Enewetak specimens. An irregular reticular pattern is visible under the light microscope at 1,000x. Pores are visible with SEM. A "gutter" is present at the anterior rim. (ref. ID; 4046)

Comments

The species differs from R. composita (Brandt) in finer structure and having more conspicuous ribs. The species is an euplegic plankter occurring in tropical regions. Kofoid & Campbell (1929) included six species in Rhabdonellopsis. Of those six species the following four, apophysata, triton, intermedia, and logicaulis, in all probability should be merged into a single species which is considerably variable in size, because the length of the lorica is not generally an important specific character in most species of the Tintinnoinea bearing an elongate lorica, and the fenestration of the bowl seems to be changeable in individuals as in species of Rhabdonella: Marshall (1934), in fact, sometimes observed fenestrae in specimens taken from the outer barrier of the Great Barrier Reef. The specimens examined in this research had few comparatively straight ribs and lacked fenestration in all cases. (ref. ID; 3597)
Hada merged Rhabdonellopsis triton Zacharias, Rhabdonellopsis intermedia Kofoid & Campbell, and Rhabdonellopsis longicaulis Kofoid & Campbell into this taxon. (ref. ID; 4046)

Measurements

Length 266-384; inner oral diameter 42-48; outer oral diameter 55-58; length of the apical lance 16-25 um. (ref. ID; 3597)
The dimensions of the lorica are: length 273-298, width 60+/-1.5 um (n=9). (ref. ID; 4046)