Lagynus
Lagynus Quennersted, 1867 (ref. ID; 4347, 4612)
[ref. ID; 4347]
The genus Lagynus was erected by Quennersted (1867) in order to accommodate some Lacrymaria that were very slightly, if at all, contractile. Some of them had a neck, and their somatic kineties followed a somewhat spiral course. This author transferred into this new genus the species Lacrymaria elegans described Engelmann (1862). Later, Gruber (1884), Stokes (1888), Penard (1922) and Kahl (1926, 1927) described additional species of the genus Lagynus. However, Kahl (1935) later considered the separation of these two genera unjustified and transferred the species described up to then as Lagynus to the genera Lacrymaria, Enchelys, Enchelyodon and Trachelocerca. With this change, the species Lacrymaria elegans was once again assigned to the genus Lagynus (Lacrymaria elegans Engelmann, 1862 = Lagynus elegans Quennersted, 1867). Corliss (1979) considered the genus Lagynus as "nomina oblita". However, Foissner (1983) reconsidered the differences between the genera Lagynus and Lacrymaria. He is the 1st and only author that described, through the application of silver impregnations, the infraciliature of the genus Lagynus for the species L. verrucosa (Foissner, 1983), Foissner (1988) recommended the urgent need of study of more species of the genus Lagynus, pointing out that such research should bring new and interesting data on the taxonomic position of the genus, which, according to this author should not, probably, be included in the family Lacrymariidae but in the family Metacystidae. (ref. ID; 4347)
- Lagynus crassicollis Maupas, 1883
See; Trachelocerca laevis Quennerstedt, 1867 (ref. ID; 3540)
- Lagynus cucumis (Penard, 1922) (ref. ID; 4730) reported author and year? (ref. ID; 4612)
Syn; Lacrymaria cucumis Penard, 1922 (ref. ID; 4730)
- Lagynus elegans Maupas, 1883
See; Chaenea vorax Quennerstedt, 1867 (ref. ID; 3540)
- Lagynus elegans (Engelmann, 1862) Quennerstedt, 1867 (ref. ID; 4347, 4612) or Quennerstedt, 1867 (ref. ID; 3540) reported author and year? (ref. ID; 191, 1629)
See; Lacrymaria elegans Engelmann, 1862 (ref. ID; 1619, 3540, 4347)
Syn; Lacrymaria elegans Engelmann, 1862 (ref. ID; 4612)
- Lagynus faurei Kahl, 1927
See; Enchelys pellucida Eberhard, 1862 (ref. ID; 3540)
- Lagynus ornatus Stokes, 1893
See; Trachelocerca laevis Quennerstedt, 1867 (ref. ID; 3540)
- Lagynus sulcatus Gruber, 1884
See; Trachelocerca laevis Quennerstedt, 1867 (ref. ID; 3540)
- Lagynus sulcatus Gruber, 1888 (ref. ID; 2130)
- Lagynus verrucosa Foissner, 1983 (ref. ID; 4347) reported year? (ref. ID; 3698)
Lagynus elegans (Engelmann, 1862) Quennerstedt, 1867 (ref. ID; 4347, 4612) or Quennerstedt, 1867 (ref. ID; 3540) reported author and year? (ref. ID; 191, 1629)
See
Lacrymaria elegans Engelmann, 1862 (ref. ID; 1619, 3540, 4347)
Synonym
Lacrymaria elegans Engelmann, 1862 (ref. ID; 4612)
Descriptions
Lagynus elegans observed "in vivo" is an elongate ciliate dark in color, with an amphora-like shape. The cytoplasm, of blackish color, appears full of refringent granules. The main part of the cell is cylindrical and wider than the rest of the body. In the anterior region, four or five step-like formations end in a retractable neck at the tip of which a tuft of cilia originates. The posterior part of the ciliate is narrower and flattened, and has in the interior a large contractile vacuole. The macronucleus is usually reniform, even though it sometimes appears oval. It is located in the middle region of the ciliate. Beside it is a small elongated micronucleus which is, sometimes, placed in the central concavity of the macronucleus. The dimensions of the species (after fixation with osmium) are 75.7-116.2 um in length and 40.5-54.6 um in width. During impregnation the ciliate's shape changes drastically. The body is more oval-like, the macronucleus is located in the posterior half of the cell, and numerous minute argyrophilic granules and extrusomes are observed in the cytoplasm. (ref. ID; 4347)
- Somatic infraciliature: The somatic infraciliature of L. elegans is made up of 37-46 meridional kineties composed of isolated kinetosomes (monokinetids) that have thick and long kinetodesmal fibers. Beside each kinetosome a parasomal sac can be observed. The silver impregnation technique reveals numerous argentophilic structures distributed in ample longitudinal ribbons separated by clear spaces that seem to correspond to the peak of the interkinetal ridges. These structures might correspond to mitochondria. Somatic kinetosomes are also observed on these longitudinal ribbons, slightly shifted to the right. All the somatic kineties converge at the antapical pole of the cell without forming any suture. (ref. ID; 4347)
- Circumoral infraciliature: The circumoral infraciliature of this species surrounds the oral opening and is composed of short, slightly oblique kinetal segments. Each segment is formed of three kinetosomes, more argyrophilic and closer to each other than the remaining somatic kinetosomes, so that their kinetodesmal fibers overlap each other. Moreover, the kinetodesmal fibers of the somatic kinetosomes placed posterior to these segments, reach the last kinetosome of each segment, forming a wide crown that surrounds the buccal zone. (ref. ID; 4347)
- Brosse: The brosse of Lagynus elegans is very difficult to impregnate. It is located between the circumoral infraciliature and the crown of nematodesmata that surrounds the cytostome. The infraciliature of this structure is composed of 3 or 4 groups (depending on the specimen) of 4 to 6 ciliated kinetosomes. These groups are disposed obliquely with respect to the longitudinal axis of the cell, and no kinetodesmal fibers are observed on their kinetosomes. (ref. ID; 4347)
- Nematodesmal crown: Finally, on the most apical zone of the cell, and surrounding the cytostome, there is a crown of strongly argentophilic nematodesmata. These nematodesmata, as they appear in our preparations, seem to be united to each other by an argentophilic fibrillar structure. In addition, numerous extrusomes are found between the circumoral infraciliature and the nematodesmata. In this species, division begins with the proliferation of all somatic kineties at the equatorial level of the cell. This process proceeds slowly towards the two poles of the cell which remain two invariant zones, anterior and posterior. When the fission furrow is apparent, fragmentation of all the kineties occurs. During basal body duplication the kinetodesmal fibers disappear in the proliferation zone. The macronucleus is condensed during the 1st stages of the division process, separated into the two daughter cells after the appearance of the fission furrow. The micronucleus divides simultaneously with the elongation of the macronucleus. With respect to the conjugation process of L. elegans we have observed that the conjugants come into contact through their oral cilia. This union then becomes more intimate and the conjugants make contact at their respective oral zones. After synkarion formation, two or three postzygotic divisions occur in each postconjugant cell. (ref. ID; 4347)