Climacostomum Stein, 1859 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Heterotrichida: Suborder Heterotrichina (ref. ID; 2014)
Family Climcostomidae Repak (ref. ID; 4813)

[ref. ID; 2014]
Oval in outline with anterior slightly pointed in some species. Body flattened and uniformly ciliated. The peristomial area entirely ciliated and a conspicuous AZM on the left edge spirals down to the cytostome. The right edge without a membranelle. The contractile vacuole is terminal and served by 2 longitudinal canals. Macronucleus may be spherical or ribbon-like.
Quote; Colin R. Curds, Michael A. Gates and David McL. Roberts "British and other freshwater ciliated protozoa Part II Ciliophora: Oligohymenophora and Polyhymenophora" Cambridge University Press, 1983 (ref. ID; 2014)

Climacostomum gigas Meunier, 1907 (ref. ID; 3540)
Description; Marine form. (ref. ID; 3540)
Climacostomum virens (Ehrenberg, 1833) (ref. ID; 1308, 1335, 1621, 1629) reported year? (ref. ID; 1219, 1618, 3777, 3901) or (Ehrenberg, 1838) Stein, 1859 (ref. ID; 4168, 4488, 4610, 4813), (Ehrenberg) Stein, 1859 (ref. ID; 3116) reported author and year? (ref. ID; 191, 7725)
Syn; Bursaria virens Ehrenberg, 1833 (ref. ID; 3116); Leucophrys curvilata Stokes, 1886 (ref. ID; 3116); Spirostomum virens Ehrenberg, 1838 (ref. ID; 4610, 4813)
Description; With or without zoochlorellae; fresh and brackish water. (ref. ID; 1618)
Climacostomum virens is a dorsoventrally flattened, noncontractile heterotrich ciliate whose prominent buccal apparatus occupies the anterior 1/3-1/4 of the ventral surface. Kineties on the left side of the ventral surface are postoral, and kineties of the right side extend to the anterior tip of the cell. Torsion of the ventral kineties is evident and is more pronounced in some preparation than in others. A zone without kinetosomes cleaves the postoral kineties into 2 groups. Generally 4 or 5 short kineties approach this zone at a slight angle from the right, whereas the kineties bordering the left side of the zone are approximately parallel to the longitudinal cell axis. The angle of approach and the number of short kineties on the right are variable among cells. A secant zone of kineties occurs on the posterior left lateral or dorsal surface; the exact position depends upon the degree of kinety and cell torpsion. All dorsal kineties do not terminate anteriorly at the same level nor do they extend as far as the adoral zone of membranelles. Kineties of the somatic cortex are uniformly composed of rows of paired kinetosomes with a fine fiber extending posteriorly and to the right from each kinetosomal pair, uniting kinetosomes of the kinety. Incomplete or overlapping kineties are frequently observed. The buccal apparatus consists of an AZM on the left, the apical membranelles on the right, and an intervening peristomal field. Kineties of the peristomal field extend deep into the cell forming a buccal tube at the end of which are located the haplokinety and the cytostome. Membranelles of the anterior part of the AZM consist of 2 kinetosomal rows, those of the middle region consist of 2 kinetosomal rows and a short 3rd kinetosomal row, and those of the posterior region consist of 3 complete kinetosomal rows. A curtain of nemadesmata lies under the entire length of the AZM. Every apical membranelle is composed of 2 short rows of kinetosomes. Nemadesmata were not observed under the apical membranelles in our protargol preparations, nor were fibrous connections observed between the apical membranelles and other buccal structures. The fan of 14 or 15 peristomal field kineties spirals to the left and centripetally, and then the kineties descent into the cytoplasm as the buccal tube. Each kinety is composed of a series of ciliated kinetosomal pairs. Phase-contrast observations of the buccal tube of nonfeeding cells reveal that the orientation of the cilia frequently reverses, sometimes being directed toward the cytostome and sometimes away form it. The haplokinety is a collar of paired ciliated kinetosomes which completely surrounds the cytostome. Climacostomum virens possess numerous algal endosymbiotes which generally strain with protargol as translucent spheres 1.5-3.0 um in diameter, each containing an eccentric, opaque spot. Ciliates maintained in strong illumination and without food became green due to the large number of symbiotes. The coiled macronucleus is without nodes and has numerous nucleoli. The macronuclear configuration and position within the cell are variable. Micronuclei, ~ 2 um in diameter, stain pycnotically like the nucleoli of the macronucleus. (ref. ID; 3777)
[Cyst]: Cysts, varying in shape from round to slightly oval, are rare, except when the culture medium becomes depleted. The external cyst wall is covered with small protuberances and frequently has a "beak". The separation between cyst wall and cytoplasm evident in protargol preparations is an artifact, since live cysts observed with phase contrast have no such separation. (ref. ID; 3777)
The anterior 1/4-1/3 of the ventral surface of C. virens is occupied by its buccal apparatus, which consists of an adoral zone of membranelles on the left, and on the right, the apical membranelles and a peristomial field, whose kineties extend into the cell, forming a buccal tube. In the somatic cortex, immediately to the right of the buccal apparatus, 1-6 preoral kineties are observed. Posterior to the buccal apparatus, a zone of discontinuity separates kineties oriented obliquely to the long axis of the cell, from kineties oriented obliquely to the long axis. The oblique kineties are observed along the right border of the zone of discontinuity. In all cells, the zone of discontinuity and the oblique kineties are readily identified, despite considerable variability in the number and disposition of the latter. (ref. ID; 3901)
Comments; C. virens is the only confirmed species, having been redescribed by numerous workers. The following characteristics distinguish C. virens from other species of this genus: a dorsoventrally flattened body with a truncate anterior end; a prominent AZM and peristomal field which occupy the anterior 1/4-1/3 of the ventral surface; the long, coiled macronucleus; the ciliated buccal tube; and a contractile vacuole at the posterior end. (ref. ID; 3777)
Measurements; 100-300 um long. (ref. ID; 1618)
Length 162-235 (average 190.0); width 62-112 (average 86.2) um (n = 50). (ref. ID; 3777)