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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Lentomonas

Lentomonas Farmer & Triemer, 1994 (ref. ID; 7304 original paper)

Euglenid

[ref. ID; 7304]
Diagnosis; Colorless euglenid found moving slowly among substrate and/or detritus with a creeping motion. Cells are heterodynamically biflagellate with both flagella possessing paraxial rods and merging from a subapical opening. The transition region of each flagellum is constricted slightly and is occluded by a dense matrix. The thinner flagellum is directed anteriorly and beats with a fiarly regular movement. The somewhat thicker and longer posterior flagellum contrasts irregularly, is directed posteriorly, and lies adjacent to the cell's ventral surface. Cells possess a feeding apparatus composed of two supporting rods an four vans that extend for nearly the entire length of the cell. The supporting rods are reinforced by a few central microtubules and a partially encircling in of microtubules. The four vanes are of approximately equal length, are centrally positioned between the supporting rods, and form a folded, loricate arrangement at their posterior end. Cells are rigid with a pellicle composed of longitudinally arranged ridges, each of which is slightly bifurcate ont is outermost edge, each of which is slightly bifurcate on the outermost edge. (ref. ID; 7304)
  1. Lentomonas applanatum (Preisig, 1979) Farmer & Triemer, 1994 (ref. ID; 7304 redescribed paper) reported author and year? (ref. ID; 4872)
    See; Ploeotia applanatum (ref. ID; 4872)
    Syn; Entosiphon applanatum Preisig, 1979 (ref. ID; 7304)

Lentomonas applanatum (Preisig, 1979) Farmer & Triemer, 1994 (ref. ID; 7304 redescribed paper) reported author and year? (ref. ID; 4872)

See

Ploeotia applanatum (ref. ID; 4872)

Synonym

Entosiphon applanatum Preisig, 1979 (ref. ID; 7304)

Diagnosis

Cells rigid, and obviously ventrally flattened, body shape oval, 13.5-19.5 um long, 10-14 um wide, and 6-8 um thick, posterior frequently being slightly rimmed. Also in the anterior with slight rim at the spot where the vestibulum opens. Pellicle with 10 longitudinal ridges separated by many wide and rounded furrows. Seven to eight ribs are located on the obviously convex dorsal side, with 2-3 small ribs on the flat to slightly convex of concave ventral side. The anterior flagellum is usually somewhat shorter than the body, while the posterior flagellum is 1.5-2.0 times the body length. Cytoplasm colorless, never rich in grains. The nucleus is indistint and lies slightly left of the cell's center. (ref. ID; 7304)

Descriptions

Cells of L. applanatum are rigid, ventrally flattened, and oval when viewed from the dorsal side. The pellicle is composed of 10 longitudinally arranged ridges (seven on the dorsal side, three on the ventral surface), two of which form a channel on the ventral surface in which the posterior flagellum lies. The anterior flagellum is slightly less than body length and beats with an undulating motion while the thicker posterior flagellum trails underneath the cell's ventral side and is one and a half to two times body length. A large nucleus with permanently condensed chromosomes and a single nucleolus lies to the cell's left (when viewed dorsally) in a median to anterior position. Numerous mitochondria with plate-like cristae are present throughout the cytoplasm as are several Golgi apparatuses, including one that apparently produces the feeding apparatus vesicles. Trichocysts were seen near the periphery of the cell and are docked beneath the crests of pellicular ridges. Food vacuoles were primarily found in the posterior portion of the cell. Paramylon grains were not observed. (ref. ID; 7304)

Remarks

The organism described in this paper was identified synonymously with E. applanatum Preisig (1979). Lentomonas applanatum has many of the characteristics found in Entosiphon species (e.g. prominent pellicular ridges, heterodynamic flagellation, well-developed feeding apparatus) and based solely on light microscopic observations the original assignment of L. applanatum to the genus Entosiphon was appropriate (Preisig 1979). What Preisig (1979) could not determine with light microscopy was that L. applanatum did not share many ultrastructure features with E. sulcatum and that a more appropriate taxon was required. Of the many described species of Entosiphon (Huber-Pestalozzi 1955; Preisig 1979; Skvortzov 1957; Skvortzov et al. 1969), only the type species E. sulcatum has been examined with electron microscopy (Mignot 1966; Mignot & Hovasse 1973; Solomon et al. 1987; Triemer 1988; Triemer & Fritz 1987). While light microscopic observations show that L. applanatum bears a resemblance to E. sulcatum, a careful examination of the ultrastructural characters reveals that the two species differ significantly in terms of their flagellar apparatus, feeding apparatus, and pellicular structure. Based on these features it is clear that the two organisms do not belong to the same genus and that L. applanatum cannot be assigned to any existing euglenid genus. For this reason we have chosen to erect the new genus Lentomonas to describe the "leisurely manner" in which the cell moves. (ref. ID; 7304)