Amphisiellides

Amphisiellides Foissner, 1988 (ref. ID; 2129, 7307)

Family Amphisiellidae Jankowski, 1979 (ref. ID; 7307)
Family Parakahliellidae Eigner, 1997 (ref. ID; 7423)

[ref. ID; 2129]
The oral primordium originates in close contact with the ACR. The ACR commences anlagen formation at its posterior end and originates from two rightmost anlagen. One dorsal kinety develops from the right marginal row. More than one cirrus left of ACR. Usually two cirri right of ACR. Transverse cirri longitudinally arranged, usually originate from single anlage. Caudal cirri present. (ref. ID; 2129)

[ref. ID; 7307]
The ACR originates from two rightmost anlagen. One dorsal kinety develops from right marginal row. More than one cirrus left of ACR. Usually two cirri right of ACR. Transverse cirri longitudinally arranged, usually originating from single anlage. Caudal cirri present.
Species assignable: A. illuvialis n. sp. and A. atypicus (Hemberger, 1985) Foissner, 1988. A complete description of the morphogenesis in A. atypicus is not available, thus family assignment is uncertain. (ref. ID; 7307)

Amphisiellides atypicus (Hemberger, 1985) Foissner, 1988 (ref. ID; 7307)
Amphisiellides illuvialis Eigner & Foissner, 1994 (ref. ID; 7307 original paper, 7423) reported author and year? (ref. ID; 191)

Amphisiellides illuvialis Eigner & Foissner, 1994 (ref. ID; 7307 original paper, 7423) reported author and year? (ref. ID; 191)

Diagnosis

Lanceolate, in vivo 50-140x20-50 um. 2 macronuclear segments, 25 adoral membranelles, 1 buccal cirrus at anterior end of paroral membrane, 2 cirri right and 3 cirri left of amphisiellid cirral row, 2 transverse cirri, and 3 caudal cirri on average. (ref. ID; 7307)

Descriptions

Size and shape highly variable, typical cells in vivo about 120x30 um and lanceolate, i.e. distinctly tapering anteriorly and posteriorly. Dorso-ventrally flattened about 2:1; highly flexible. Two ellipsoid macronuclear segments in left body half, shape and size highly variable; nucleoli in vivo 1.5-2.5 um in diameter. Several micronuclei (2-3.5 um) adjacent to macronuclear segments, only faintly stained by protargol. Contractile vacuole slightly above mid-body at left body margin. Cytoplasm colorless, yellowish crystals about 4 um long maily in posterior portion. Food vacuoles 10-20 um in diameter, contain small ciliates and bacteria. No conspicuous cortical granules. Adoral zone of membranelles about 30% of body length. Bases of membranelles in vivo 8 um, cilia of membranelles 13 um, all cirri about 10 um long. Buccal cavity inconspicuous, i.e. flat and narrow; oral lip slightly curved, parallels undulating membranes. Three slightly enlarged frontal cirri, right frontal cirrus to distal end of adoral zone of membranelles. Three slightly enlarged frontal cirri rignt frontal cirrus at distal end of adoral zoen of membranelles. Amphisiellid cirral row (ACR) commences at right frontal cirrus and terminates near center of ventral surface. In about 45% of cells 1-2 cirri occur right to the ACR; and they also lack in about 45%; many cirri right of the ACR forming a row occur in about 10%; occasionally, a sixth anlage develops 2-4 cirri. Usually 2-3 cirri left of ACR; numerous cirri left of the ACR forming a row occur in about 3% of cells. One buccal cirrus (rarely two) at anterior end of paroral membrane. Transverse cirri arranged longitudinally in single row containing usually two, rarely up to five cirri; rarely they arrange in two rows. Right marginal row commences on dorsal surface distinctly below anterior end of body; both marginal rows extend to posterior end of cell, leaving small gap. Dorsal cilia 3-4 um long, arranged in three rows almost as long as cell; one short kinety on right anterior surface, occasionally accompanied by faintly stained second kinety from previous generation. Caudal cirri usually at posterior end of kineties 1 and 2. (ref. ID; 7307)

Comparison with related species

Amphisiellides illuvialis differs from the sole congener, Amphisiellides atypicus (Hemberger, 1985) Foissner, 1988, mainly in the number of macronuclear segments (2 versus 23). Further differences relate to the arrangement of the transverse cirri (transverse in type species, longitudinal in A. illuvialis), the smaller body size (100 um versus 200 um) and the fewer cirri in the ventral and marginal rows of A. illuvialis as well as in the morphogenesis. Live specimens of A. illuvialis are difficult to distinguish from other binucleate amphisiellid hypotrichs, viz. Amphisiella binucleata (Hemberger, 1985) Foissner, 1988 (buccal cirrus in posterior half of paroral membrane, no caudal cirri), Amphisiella australis Blatterer & Foissner, 1988 (no caudal cirri), Amphisiella teriicola Gellert, 1955 (redescription (Foissner 1984); transverse cirri obliquely arranged, no caudal cirri), Amphisiella magnigranulosa Foissner, 1988 (conspicuous cortical granules, buccal cirrus in posterior half of paroral membrane, transverse cirri obliquely arranged, no caudal cirri) and Amphisiella polycirrata Bergre & Foissner, 1989 (conspicuous row of buccal cirri). Likewise, distinction from binucleate species of the genus Gastrostyla (Kahl, 1932) may be difficult. They differ from A. illuvialis mainly by their obliquely arranged transverse cirri (longitudinally in A. illuvialis) and the postperistomial cirrus. Protargol impregnation should thus be used for determining binucleate hypotrichs with a more or less distinct median cirral row. (ref. ID; 7307)

Divisional morphogenesis

The nuclear apparatus and the marginal rows divide in the usual way and thus demand no further comment.

Stage 1: Stomatogensis commences with the proliferation of basal bodies near the posterior cirri of the ACR which, however, appears unchanged.
Stage 2: A large, wedge-shaped field of basal bodies develops in them middle portion of the ventral surface left of the ACR; most probably cirri from the posterior segment of the ACR disaggregate and contribute to this field. Membranelles differentiate at the left anterior end of the oral primordium. One long and one very short streak originate from the right anterior end of the oral primordium and extend left and right of the ACR, respectively. A third streak develops right of the ACR from a disaggregated cirrus of the ACR or, possibly, de novo.
Stage 3: The formation of membranelles in the oral primordium proceeds posteriorly. Five cirral anlagen for the opisthe are recognizable. The cirral primordium right of the ACR appears nearly unchanged. The parental buccal cirrus disorganizes to a short streak of basal bodies.
Stage 4: Five anlagen each are recognizable in the proter and opisthe. The anlagen of the proter develop slightly later than those of the opisthe. All anlagen of the opisthe derive from the oral primordium, whereas those of the proter evolve from parental frontoventral cirri, with the possible exception of anlage 5. Anlage 1 of the proter is generated by the parental undulating membranes; anlage 2 by buccal cirrus; anlage 3 by cirri left of the ACR; anlagen 4 and 5 by the posterior (left) segment of the ACR, or (anlage 5), possibly, de novo. Some cirri may develop between the posterior portions of anlagen 4 and 5, possibly forming the second row of transverse cirri found in about 3% of cells. Dorsal kineties 1 to 3 and the caudal cirri develop within the parental kineties. Dorsal kinety 4 is produced by an anlage which develops within the right marginal row.
Stage 5: The new adoral zone of membranelles is almost complete. The anlagen of the proter and opisthe organize in the same manner. Some posterior cirri of anlagen 2-5 are usually resorbed during cytokinesis; thus, their number is smaller in interphase than in dividing specimens. Anlage 1 splits longitudinally to form the paroral and endoral membrane as well as the first frontal cirrus. Anlage 2 develops one or two buccal cirri and the second frontal cirrus. Anlage 3 develops the third frontal cirrus and two or more cirri in the frontal field which may form a row. Anlage 4 does not migrate and forms the posterior (lef) segment of the ACR. Anlage 5 develops three kinds of cirri: the anterior portion migrates anteriorly and to the left forming the anterior segment of the ACR; the posterior portion migrates posteriorly to form longitudinally arranged transverse cirri; the middle portion forms the cirri right of the ACR. The cadual cirri develop at the posterior end of kineties 1 and 2, rarely also in kinety 3. The short dorsal kineties which originate near the right marginal row migrate on the dorsal surface.
Stage 6: The new ACR in nearly complete, i.e. the anterior portion of anlage 5 aligns with anlage 4. The posterior portion of anlage 5 migrates posteriorly forming the transverse cirri. (ref. ID; 7307)

Remarks

Most likely cirri from row five contribute to the forming of the N1 development for proter. Row four shows a great variability in number of cirri, thus the N1 anlagen-part for proter may also develop de novo. (ref. ID; 7423)

Etymology

"illuvies" (Lat.), dirty water. (ref. ID; 7307)

Type location

Village of Schrotten, Ceutsch Goritz, Austria, 46 degrees 47'N, 15 degrees 49'E, 320 m alt. (ref. ID; 7307)

Occurrence and ecology

The species was discovered 7 December 1991 in a litter sample from a disused pigpen in village of Schrotten, Deutsch Goritz, Austria. A second population was found near Eching (Bavaria) in a tiny track puddle, which was heavily polluted by sewage from an activated sludge plant. (ref. ID; 7307)

Type specimens

A holotype and a paratype of A. illuvialis mounted as two slides of protargol-impregnated cells have been deposited in the collection of microscope slides of the Oberosterreichische Landesmuseum in Linz. Accession numbers: 10, 11/1994. (ref. ID; 7307)