Urostyla Ehrenberg, 1830 (ref. ID; 2014)
Class Polyhymenophora: Subclass Spirotricha: Order Hypotrichida: Suborder Stichotrichina: Family Urostylidae (ref. ID; 2014)

[ref. ID; 2014]
Flexible, elongate, dorso-ventrally flattened oval body. Many (4-12) longitudinal rows of ventral cirri from which the marginal are not clearly distinct. Frontal cirri are numerous, small and not always easily distinguishable from the anterior parts of the ventral cirri rows. Transverse cirri present. All ventral cirri arise from one primordial field during division. Many species have been described.
Several species were removed from this genus by Borror (1972) and placed in either Paraurostyla or Pseudourostyla on the basis of their morphogenetic patterns. Furthermore, he did not recognize either Hemicycliostyla or Eschaneustyla. Jankowski (1979) discusses this genus in detail and creates Metaurostyla polonica for U. grandis of Jerka-Dziadosz (1972). Borror (1979) reviews the genus and its relative, and declares that in fact 2 mid-ventral rows are present, in addition to several rows of marginal cirri on the right.
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)

[ref. ID; 3925]
Several row of right marginal cirri; midventral cirri in typical zigzag series, 2 cirri per original oblique ciliary streak, except for the first several streaks that differentiate several isolated frontal cirri each.
Type species (by monotypy); Urostyla grandis Ehrenberg, 1830 (ref. ID; 3925)

Urostyla caudata Stokes, 1886 (ref. ID; 1621) reported year? (ref. ID; 1618)
Description; Elongate ellipsoid; flexible; narrowed anterior part bent to left; peristome one-third the body length; macronucleus in many parts; contractile vacuoles near left margin; fresh water with sphagnum. (ref. ID; 1618)
Measurements; About 600 um long. (ref. ID; 1618)
Urostyla coei Turner, 1939 (ref. ID; 1618)
Description; Elliptical, with a more pointed posterior end; 4 rows of ventral cirri, the right row being the longest; 5 frontals; macronucleus in 2 masses; 4 micronuclei. (ref. ID; 1618)
Measurements; 200 by 50 um. (ref. ID; 1618)
Urostyla grandis Ehrenberg, 1830 (ref. ID; 4488, 4609) or 1838 (ref. ID; 1621, 1629, 2099) reported year? (ref. ID; 1618, 5462) reported author and year? (ref. ID; 191, 3292, 3925, 4471, 7758)
Syn; Urostyla trichogaster Stokes, 1885 (ref. ID; 4609)
Description; Macronucleus in 100 or more parts; 6-8 micronuclei; fresh water. (ref. ID; 1618)
Light microscopy. The Urostyla grandis cysts are spherical and average 22-24 um in diameter. The volume of the cyst is smaller than that of the vegetative cell. The cytoplasm exhibits an homogeneous aspect and in older cysts is possible to observe a dark granule, in the center, that stands out clearly from the rest of the cytoplasm. Cysts possess the normal vegetative nuclear complement consisting of a lot of macronuclei and a few micronuclei. (ref. ID; 7758)
Electron microscopy. The cysts surface appears irregular with wrinkles that give a rough aspect. Ostioles or pores have never been observed on the wrinkled mature cyst surface; although, it is possible to see some bacteria adhering to the folds. Observations of ultrathin sections reveal that the cyst wall of Urostyla grandis consists of three morphologically distinct layers. The outer most layer (ectocyst), the thickest one, is composed of fibrillar material which has also electron density. For this reason, the structure of this layer is very difficult to observe, but in cysts stained with ruthenium red, two zones can be clearly recognized: the outer zone formed by fibrous material randomly oriented and less packed and the inner zone, also fibrillar and more packed. The endocyst is very homogeneous and regular both in shape and thickness. It is made up of an electro-dense, highly compact, amorphous substance. The granular layer, the most internal one, appears fibrillar in some sections and granular in others. The thickness of this layer is not uniform since it is uniting the spherical cyst wall to the grooved cell surface. As a consequence of the loss of the external membrane-unit, the cyst pellicle, beneath the cyst wall, presents one membrane-unit less than that of the vegetative cell. Likewise, the network of subpellicular microtubules, although visible in young cysts, disappears almost completely. In the mature cysts, it is posible to observe some remains at only a few points underneath the pellcile. The function of these remainders of subpellicular microtubules in the cyst is unknown, but we thick they might ensure the maintenance of the shape during the encystment. The only ciilature we could observe consists of a few isolated pairs of kinetosomes. Mitochondria can be seen to be formed in tight clusters or scattered throughout the cytoplasm. When they appear isolated a closely association with rough endoplasmic reticulum and Golgi apparatus has been noted and, in every case, the transition vesicles are clearly observed. Both the vegetative cell and resting cyst present numerous mucocyts, but in the vegetative cell those organelles exhibit several different aspects, apparently representing different stages of development, while in the resting cyst all of them show the same appearance. They appear as highly osmiopilic-granules surrounded by a double membrane. Unlike the vegitative cell, no fusion of mucocysts with the pellicle was noted in the resting cyst. (ref. ID; 7758)
Measurements; 300-400 um long. (ref. ID; 1618)
Urostyla marina Kahl, 1932 (ref. ID; 3925) reported year? (ref. ID; 3771) reported author and year? (ref. ID; 191, 1621)
Description; [Ciliature]:
Buccal - This ciliature consists of 16-24 membranelles. Mediad, several cilia of each membranelle in posterior half of AZM arise slightly anterior to remaining cilia of that membranelle and beat independently as a ciliary brush along mediad edge of AZM, as is typical of most hypotrichs. Undulating membrane consists of 2 longitudinal series of apparently single cilia, an endoral membrane close to mediad wall of buccal cavity, and a paroral membrane arising just mediad to right buccal overture. (ref. ID; 3925)
Somatic - This ciliature usually comprises 3 dorsal rows of stiff cilia ~ 4 um long, ~ 7 um apart. Two to four rows each of right and left marginal cirri, the rightmost 2 rows of right marginal cirri extending onto the dorso-lateral surface anteriorly. About 20 cirri are present per marginal row, each cirrus being ~ 8 um long. (ref. ID; 3925)
Frontal - Three slightly hypertrophied anterior frontal cirri constitute this ciliature. An additional isolated frontal cirrus posterior of the rightmost cirrus and a cirrus adjacent to the paroral membrane are also present. A series of midventral cirri extends from about the level of the midpoint of the paroral membrane posteriorly just beyond the level of the cytostome, terminating in a longitudinal group of 3-4 individual cirri. Transverse cirri, ~ 15 um long, are frayed at the tips. Usually 4-5 of these inconspicuous organelles are in a group. Transverse cirri are viable in number, often being missing in small individuals of older cultures. (ref. ID; 3925)
[Cytoplasmic Structure]: Cortex contains oval granules ~ 1 um long, each with a longitudinal crease giving them the appearance of a grain of oats. Such granules occur in scattered groups along row of cirri, dorsal rows of cilia, and along the dorsal margin of the AZM, but not adjacent to the rightmost midventral cirri. Contractile vacuole is oval, slightly to the left of the long axis. Food vacuoles contain remains of algae and diatoms. Macronucleus is in ~ 32 fragments, each oval, ~ 2-4 um long. Two spherical micronuclei are present. (ref. ID; 3925)
[Behavior]: When feeding undisturbed on the bottom of the culture vessel, individuals proceed clockwise in circular patterns, due to anterior-posterior locomotory reversals about every second, alternating with slight bending of the anterior half of the body to the right. During such a process, the posterior end of the body is oriented toward the center of the circle of progress. Urostyla marina also can crawl over irregular masses of detritus with considerable flexibility. During fast crawling, the body is stiffer, and the ciliate moves several body length/second with a slight veer to the left. The ciliate swims in a counterclockwise helix, ventral surface inward, slightly concave, the membranelles flaring, and the posterior end in a straighter line. (ref. ID; 3925)
Comments; Urostyla marina closely resembles the larger fresh-water species, U. grandis, not only in cortical structure but in developmental pattern. (ref. ID; 3925)
Measurements; Length of typical interphase individual ranges 68-100 um; its width ranges 24-32 um (n = 20). Individuals as small as 50 um are common in older cultures. (ref. ID; 3925)
Urostyla polymicronucleata Merriman, 1937 (ref. ID; 1618)
Description; Elliptical with broadly rounded ends; flexible; opaque, green or brown because of the ingested diatoms; 3 large and 10 small frontals; 4 ventral rows of cirri; marginals; macronucleus in 2 parts; 3-11 micronuclei. (ref. ID; 1618)
Measurements; 225 by 65 um. (ref. ID; 1618)
Urostyla trichogaster Stokes, 1885 (ref. ID; 1618)
See; Urostyla grandis (ref. ID; 4609)
Measurements; 250-330 um long. (ref. ID; 1618)
Urostyla weissei Stein, 1859 (ref. ID; 1621, 2245, 4609) reported year? (ref. ID; 1219)
See; Paraurostyla weissei (ref. ID; 4609, 5462)
Syn; Urostyla paragrandis Wang, 1930 (ref. ID; 1621)
Description; Ellipsoid; sensory bristles on the dorsal side only; ventral side furnished with cirri as follows; right and left marginal cirri meet as a continuous row posteriorly; 3 long rows of ventral cirri and 1 (or 2) short rows of about 5-8 ventral cirri just behind the buccal area; 4 strong frontal cirri near the anterior pole and 4 smaller ones close to the ventral rows; the number of ventral rows and of frontal cirri may vary with the individual; 8 transverse cirri; macronucleus in two parts; 1 contractile vacuole. Since there are about 15 species of Urostyla, taxonomic difficulties may occur. (ref. ID; 1219)
Measurements; Length 220-300 um. (ref. ID; 1219)