Kuehneltiella
Kuehneltiella Foissner, 1990 (ref. ID; 6945 original paper)
Family Colpodidae (ref. ID; 6945)
[ref. ID; 6945]
Diagnosis; Medium-sized to large rapacious Colpodidae with huge, cave-like vestibulum occupying anterior half of cell. Right wall of vestibulum overhangs semicircularly grooved left, forming large, bright, circular patch anteriorly. Right oral polykinetid consisting of short, single row of dikinetids.
Etymology; The new genus is named in honour of the late (1905-1988) Professor Dr. Wilhelm Kuhnelt, famous Austrian soil biologist. Feminine.
Type species; Kuehneltiella terricola
- Kuehneltiella terricola (ref. ID; 6945 original paper)
Diagnosis
In vivo about 110-170x80-120 um, bean-shaped, macronucleus elliptical, about 70 somatic kineties. Left oral polykinetids composed of 16 kineties on average. Outer layer of resting cyst hexagonally sculptured. (ref. ID; 6945)
Descriptions
Size moderatel variable, usually about 140x100 um, large trophonts occasionally up to 250 um in length; starved and precystic cells usually smaller, about 80-120 um long. Shape fairly constant, bean-like, dorsal side markedly convex, ventral side concave at level of bottom of vestibulum, anterior and posterior ends broadly rounded. Right wall of vestibulum semicircular to slightly sigmoid, extends to posterior third of cell. Left wall of vestibulum commences at level of the bottom of vestibulum, extends semicircularly dorsad, to meet cowl-like anterior end. Thus, right wall of vestibulum distinctly longer than left. Right side markedly convex, left side flat to slightly covex, no diagonal groove; flattening usually lost during preparation. Similarly, left wall of vestibulum often becomes more sigmoid in prepared specimens because vestibulum collapses more or less during preparation. Such individuals resemble Krassniggia auxiliaris (cp. Foissner 1987). Macronucleus elliptical (about 2:1), usually located in posterior half of body. Nucleolus net-like. Single, elliptical micronucleus attached to macronucleus. Contractile vacuole in posterior third of left side of cell; during diastole surrounded by many smaller collecting vesicles, single excretory pore. Pellicle soft, flexible. Many subpellicular mucocysts, about 1.5x1 um, arranged in small clusters between somatic kineties, give cells brownish colour at low magnification. Mucocysts become extruded after addition of methylgreen-pyronin, form spongy envelope around cell consisting of 5-10 um long threads. Cytoplasm colourless, in well-nourished cells densely filled with about 1 um roughly spherical, yellowish crystals and 1-10 um greasily shining globules. Many small and large food vacuoles containing few to hundreds of small, colourless flagellates or one to few individuals of various species of ciliates (Tetrahymena pyriformis, Colpoda spp., Drepanomonas sp., Sathrophilus muscorum, swarmers of Vorticella sp.). In starved cultures, cannibalism may even occur. Movement slowly gliding on right side or rotating about main body axis, remains nearly motionless during feeding. Kuehneltiella terricola waits for prey, which is captured in huge vestibulum and then apparently sucked in by strong cytoplasmic cyclosis.
Cilia. Cilia about 10 um long, paired. Somatic infraciliature as in genus Bresslaua (cp. Lynn 1979; Foissner 1985), highly complicated due to large vestibulum. About 15 kineties of ventral side project onto inner side of right vestibular wall, forming vestibular kineties. Other ventral and left lateral somatic kineties cover bottom and inner side of left wall of vestibulum. Vestibular, ventral and left lateral kineties adjoin at dorsal wall of vestibulum, forming long suture (homologous to "keel" of genus Colpoda), which extends anteriorly on ventral side of cell. No diagonal groove, but ciliature is slightly condensed on left of left oral polykinetid where shortenend kineties not projecting onto left side frequently occur.
Vestibulum. Vestibulum occupying anterior half of cell, cone-shaped, very large. Oral polykinetids near centre of cell, do not project out of vestibulum; very small compared with size of cell. Left polykinetid horizontally orientated, banana-shaped, consists of 16 rather distally spaced rows, length of which gradually decreases to ends of kinetid. Right polykinetid consists of single row of densely spaced dikinetids. In about 30% of individuals investigated, even this row lacking or at least hardly distinguishable from neighbouring vestibular kineties.
Silver line system. Silver line system colpodid, without peculiarities. Y-shaped silverlines rather frequent. Extrusomes usually do not impregnate with applied silver methods.
Reproduction. Reproduction within cysts, usually four tomites. Membrane of reproductive cysts thin (about 1 um), surrounded by mucous envelope about 8 um thick. Before establishing a resting cyst, cells become smaller and Colpoda maupasi-shaped, because their vestibulum flattens out and the vestibular walls become nearly straight. Such cells hardly comparable with trophonts, easily mistaken for separate species! After cells have rounded up, approximately 2-um thick, honey-coloured membrane, probably later mesocyst, and voluminous mucous sheath is secreted. Material (cytoplasmic? macronuclear?) extruded, remains outside cyst membrane. Old (completed) resting cysts still possess mucous sheath and three membranes about 6 um thick. Colourless endcyst about 2 um thick and smooth. Meso- and ectocyst distinctly honey-coloured (yellowish to brownish), about 4 um thick and hexagonally sculptured. Mucous sheath surrounding cyst always densely populated with bacteria and colourless flagellates. Colourless content of resting cyst contains many greasily shining globules 2-4 um in diameter. Unlike some species of Colpoda (Foissner, unpublished data), no brownish spheres attached to ectocyst.
Kuehneltiella terricola has been found only at the type location and at a site nearby. There is a high probability that Kuehneltiella terricola is endemic to the Australian continent or at least to Gondwanaland, because it has not been found in any of more than 1000 soil samples from many other regions of the world. (ref. ID; 6945)
Comparison of Kuehneltiella terricola with related genera and species
The family Colpodidae comprises the genera Colpoda Muller, 1773, Bresslaua Kahl, 1931, and Krassniggia Foissner, 1987. I now consider four other genera (Tillina Gruber, Pseudocolpoda Ilowaisky, Repoma Novotny, Paracolpoda Lynn; for dating of these genera see Foissner 1985) as junior synonyms of Colpoda. Kuehneltiella is obviously closely related to Bresslaua. In both, the right wall of the vestibulum overhangs the semicircularly grooved left vestibular wall forming a large, bright, circular patch anteriorly. The important difference between Bresslaua and Kuehneltiella concerns the structure of the right oral polykinetid. It is a rather large field of disordered, short kineties in Bresslaua and a single row of dikinetids in Kuehneltiella. I checked this special structure of the right polykinetid of Kuehneltiella very carefully because it is highly uncommon in colpodids s. str. However, within the Marynidae, a family closely related to the Colpodidae, there is also one genus, Ilsiella Foissner, 1987, whose right oral polykinetid consists of a single row of dikinetids only. Both Kuehneltiella and Ilsiella look rather specialized, suggesting that their simple right oral polykinetid is apomorphic. A right oral polykinetid composed of an ordered row of dikinetids is, however, common in the colpodid order Cyrtolophosidida (Foissner 1985). This indicates that simple, single-rowed, right oral polykinetids have evolved independently several times in the Colpodea and even within the colpodids s. str. Lynn (1979) claimed that Bresslaua insidiatrix lacks a right oral polykinetid. He suggested that this is an adaptation to carnivory. However, this observation was doubted by Foissner (1985, 1987), who found a well-developed right oral polykinetid in B. vorax and B. terricola. Thus, I restudied the Chatton-Lwoff silvered specimens of Lynn. A few well orientated specimens show very clearly, in my opinion, that B. insidiatrix has a right oral polykinetid similar in size and structure to that of B. vorax. Thus, B. insidiatrix does not belong to the new genus Kuehneltiella.
No other species have been found in the literature which might be identical with Kuehneltiella terricola. Superficially. Krassniggia auxiliaris Foissner, 1987, and Bresslauides australis Blatterer and Foissner, 1988, resemble Kuehneltiella terricola. However, both have a typic colpodid or hausmanniellid right oral polykinetid and the ectocyst of their resting cysts smooth (Blatterer and Foissner 1988; Foissner unpublished data). Likewise, the resting cysts of Bresslaua spp. are smooth. (ref. ID; 6945)
Etymology
"Terricola", because of living in soil. (ref. ID; 6945)
Type location
Upper soil layer of an arid hummock grassland near Alice Springs, Northern Territory, Australia, 133 degrees E, 24 degrees S. (ref. ID; 6945)
Type specimens
One slide of holotype specimens and two slides of paratype specimens (cultured material impregnated by the Chatton-Lwoff silver nitrate method) have been deposited in the collection of microscope slides of the "Oberosterreichisches Landesmuseum" in Linz (Austria). (ref. ID; 6945)