Amphisiella antarctica, Wilbert & Song, 2005

Wilbert, Norbert & Song, Weibo, 2005, New contributions to the marine benthic ciliates from the Antarctic area, including description of seven new species (Protozoa, Ciliophora), Journal of Natural History 39 (13), pp. 935-973 : 969-970

publication ID 10.1080/00222930400001509

persistent identifier

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scientific name

Amphisiella antarctica

sp. nov.

Amphisiella antarctica nov. spec.

( Figures 11E–K View Figure 11 , 16A–F View Figure 16 ; Table VIII)


Slender marine Amphisiella 120–200630–50 M m in vivo with narrowed caudal portion. Eight to twelve frontal and five transverse cirri; single ventral row extending to posterior third of cell length with about 29 cirri on average; two small ventral cirri close to transverse cirri; 25–32 adoral membranelles; 39–56 left and 42–55 right marginal cirri; four dorsal kineties and four caudal cirri; two macro- and two micronuclei. Cortical granules large and sparsely distributed on dorsal side.


In vivo mostly about 160640 M m in size. Cells flexible, slightly contractile and often more or less distorted in middle portion (even twisted while gliding on debris, Figure 11H View Figure 11 ); dorsoventrally flattened by about two-thirds. Body shape distinctly slender with posterior portion distinctly narrowed; ratio of cell length to width about four to one ( Figure 11E View Figure 11 ), buccal field narrow and inconspicuous, about one-quarter of body length; cell margins generally parallel but often curved outward in middle portion. Dorsal side slightly uneven, irregularly bulging ( Figure 11G View Figure 11 ).

Pellicle soft and thin; ‘‘cortical granules’’ colourless and large (about 1 M m), not grouped and sparsely distributed on dorsal side ( Figure 11F View Figure 11 ). Cytoplasm greyish or colourless, often containing numerous light-reflecting globules (2–5 M m across), which render the cell dark under low magnification. Contractile vacuole not observed. Food vacuoles several to many, always containing small diatoms or flagellates ( Figure 11E View Figure 11 ). Two elongate macronuclei, ca 20615 M m in size in vivo, slightly separated from one another near left side of body; constantly two large (4–5 M m across), globular micronuclei, adjacent to macronuclei ( Figures 11K View Figure 11 , 16B View Figure 16 ).

Movement relatively slow, crawling without pause on debris. When swimming, spirally rotating about the longitudinal axis.

Buccal apparatus as shown in Figure 11I View Figure 11 . Adoral zone of membranelles (AZM) extending to about 25% of cell length, longest base of membranelles about 7 M m long; distal end of AZM bending only slightly posteriad at right. Paroral membrane two-rowed, parallel to zig-zagging endoral membranes. Along undulating membranes always some densely packed argentophilic granules (extrusomes?) recognizable ( Figure 11J View Figure 11 , arrowheads). Pharyngeal fibres conspicuous after protargol impregnation, about 30 M m long ( Figure 11I View Figure 11 ).

Four enlarged frontal cirri followed by usually five smaller ones posteriorly; single ventral row consisting of 21–36 cirri extends to about posterior third of cell length. Always two small cirri anterior to five enlarged transverse cirri, which are positioned almost completely at posterior end of cell ( Figure 11J View Figure 11 ) and are connected by five fibres about 40 M m long. The two marginal rows are widely separated posteriorly and terminate near transverse cirri ( Figure 11J View Figure 11 ).

Four dorsal kineties loosely ciliated, cilia about 5 M m long, comprising ca 10 pairs of basal bodies each. Four caudal cirri at margin of cell ( Figure 11K View Figure 11 ).


Considering the body shape, size, habitat and general appearance, at least two marine morphotypes should be compared with the new species described here: Amphisiella thiophaga (Kahl, 1928) Kahl, 1932 and A. annulata (Kahl, 1928) Kahl, 1932 . The new species differs from the former in having a narrowed caudal portion (versus broadly rounded in A. thiophaga ) and a relatively shorter ventral row of cirri that terminates far away from the transverse cirri (versus extends completely to the transverse cirri) ( Kahl 1932).

Compared with A. annulata , the new species can be distinguished by body shape (with narrowed posterior end versus broadly rounded), lack of ring-like granules (‘‘Ringkugeln’’) in cytoplasm (versus present in the former species) and probably the presence of conspicuous cortical granules (versus absence?; none were mentioned in original description).

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