Paracondylostoma
- Paracondylostoma cavistoma oligostriatum Foissner & Kreutz, 1998 (ref. ID; 2856 original paper)
- Paracondylostoma setigerum Foissner (ref. ID; 3698)
- Paracondylostoma setigerum chlorelligerum Foissner & Kreutz, 1998 (ref. ID; 2856 original paper)
- Paracondylostoma setigerum setigerum Foissner, 1980 (ref. ID; 2856)
Diagnosis
In vivo about 35x20 um. 20 ciliary rows and 11 adoral organelles on average. (ref. ID; 2856)
Descriptions
Very fragile and thus difficult to observe in vivo, usually disintegrates when taken up with fine pipettes and/or observed under slight coverglass pressure. Size in vivo 25-40x18-25 um, usually about 35x 0 um. Broadly ellipsoidal (1.5:1), ellipsoidal (2:1) or slightly conical; anterior end slightly to distinctly broader than evenly rounded posterior, transverse truncate with dorsal side slightly longer than ventral, thus oblique when viewed laterally. Macronucleus usually in posterior body half, broadly ellipsoidal, contains many minute (about 0.3 um) nucleoli. Two to three globular micronuclei (1.2-2 um, average 1.7, n=13, protargol impregnation) attached to macronucleus, impregnate only faintly with protargol. Contractile vacuole subterminal on ventral side. Cortex flexible and very fragile, rather distinctly furrowed by ciliary rows, contains a stripe of minute (about 0.2 um), colourless granules (mucocysts?) between each two ciliary rows. Cytoplasm colourless, contains some bright fat globules and food vacuoles 4-8 um across with bacteria and granular material, very likely bacterial remnants. Swims rather fast by rotation about main body axis. Somatic cilia about 8 um long and rather evenly spaced, except for anterior end, where each row commences with three narrowly spaced cilia, forming rather distinct ribbon in live specimens. Ciliary rows distinctly separate from paroral membrane, equidistant and very slightly spiral, composed of dikinetids having only the posterior basal body ciliated. Oral (vestibular) opening on anterior end of cell, margin opaque and slightly indented in midline of ventral side by minute vestibular cleft. Vestibulum fragile, occupies circa 35% of body length, oblique conical, that is, straight ventrally and obliquely extending dorsally. Adoral zone of organelles (left polykinetid) on left wall of vestibulum, inconspicuous because short, narrow and oriented with the smaller side to the observer when the cell is viewed ventrally or dorsally. Individual organelles slightly cuneate, touch each other proximally, connected by fine line distally, forming reticulate patter. Paroral membrane encircles anterior body end, except for ventral cleft, where about 10 dikinetids are lacking; consists of dikinetids, whose cilia form, together with the ciliary ribbon produced by the narrowly spaced cilia at anterior end of the somatic kineties a conspicuous corona. (ref. ID; 2856)
Comments
Paracondylostoma cavistoma oligostriatum is very likely closely related to Cyrtolophosis cavistoma, discovered by Gelei (1954) in a temporary pool in Hungary. Gelei (1954) mentioned that he did no study the species, especially its oral structures, in detail. Our investigations confirm Foissner (1993), who transferred Gelei's species to Paracondylostoma. Gelei's species and the Venezuelan population differ mainly in some morphometric characteristics: size about 60x30 um vs. about 35x20 um, 30-34 distinctly spiral ciliary rows vs. 18-21 almost straight rows. Thus we separate the Venezuelan population only at subspecies level. A more distinct character would be the dwelling tube P. cavistoma cavistoma inhabitats. However, we cannot exclude that P. cavistoma oligostriatum also produces a dwelling tube, although we did not find any, because it was rare and fragile and thus could not be studied in great detail. Paracondylostoma setigerum setigerum and P. setigerum chlorelligerum have a length of 65-90 um, 45-50 ciliary rows, and 30-40 adoral organelles, whereas P. cavistoma oligostriatum is 25-40 um long and has 18-21 ciliary rows and 10-13 adoral organelles. These differences are large enough to classify both types as distinct species. (ref. ID; 2856)
Etymology
Composite of the Greek adjective oligos (few) and the Latin noun striatus (striae), meaning a Paracondylostoma with few ciliary rows. (ref. ID; 2856)
Type location
Soil and sediment from rock-pools on a Laja near the farm of Mr. Eisenberg, vicinity of Puerto Ayacucho (W68/N5), Venezuela. (ref. ID; 2856)
Diagnosis
As P. setigerum setigerum Foissner, 1980, but with symbiotic green algae. (ref. ID; 2856)
Descriptions
Size in vivo 65-88x28-43 um, on average 73x30 um. On slides usually elongate ellipsoidal to slightly conical, natural shape, however, that is, cylindrical with distinctly broadened anterior region, which can be contracted, providing cells with obconical appearance; anterior end obliquely truncate to right and ventral side, posterior rounded. Macronucleus slightly underneath mid-body on average, globular to slightly ellipsoidal, contains many minute (<1 um) nucleoli; 1-3, usually 3, micronuclei attached to macronucleus. Contractile vacuole in fourth fifth of body, with single excretory pore in midline of ventral side. Cortex flexible, rather distinctly furrowed by ciliary rows, contains many tightly spaced, minute (<0.5 um), colourless granules (mucocysts?). Cytoplasm colourless, cells, however, appear greenish due to 18-64, on average 29, symbiotic algae; symbionts irregularly distributed, about 5x4 um, with cup-shaped chloroplast and without eyespot. Feeds on bacteria and algae (globular green algae, Scenedesmus, diatoms). Paracondylostoma setigerum chlorelligerum lives in a mucous dwelling tube, which is very hyaline and thus difficult to recognize when not covered by organic particles. The dwelling tube is left when the cell is transferred from the natural sample to the slide, and rebuilt within 12 hr. When the cell is slightly disturbed and/or the elongated (tactile) cilia touch certain objects, it draws back into the tube, soon extending and assuming the obconical shape typical of the sessile, swirling organism. Normal somatic cilia in vivo ca 5 um long and rather evenly spaced, except of anterior end, where each row commences with 4-8 narrowly spaced cilia, forming distinct ribbon. About 20-30 distinctly elongated (20 um) tactile cilia around anterior end, very likely originate from first and/or second dikinetid under-neath circumoral ribbon. Ciliary rows distinctly separate from paroral membrane, equidisitant and rather distinctly spiralling, composed of dikinetids with, probably, only the posterior basal body ciliated. Oral apparatus more conspicuous, but of same fine structure, than in P. cavistoma oligostriatum because occupying almost 50% of body length. Adoral zone composed of about 30-35 organelles. Paroral widely open ventrally, that is, surrounds vestibular opening by about 300 degrees. (ref. ID; 2856)
Comments
P. setigerum chlorelligerum is very similar, if not identical, to P. setigerum setigerum Foissner, 1980, except for the symbiotic algae, whose taxonomical value is controversial. We find it appropriate to separate such populations at subspecies level, considering the distinctiveness of the character and the physiological and ecological differences they show. (ref. ID; 2856)
Etymology
chlorelligerum (bearing chlorellae) refers to the main subspecies character, that is, the symbiotic green algae. (ref. ID; 2856)
Type location
Pond mud near Hegne, a suburb of Constance, Germany (E9 degrees 10', N47 degrees 40'). (ref. ID; 2856)