Nassula Ehrenberg, 1833 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Hypostomata: Order Nassulida: Suborder Nassulina (ref. ID; 2013)

[ref. ID; 2013]
Body shape ovoid, some species elongate. Body ciliature complete, sometimes with paired cilia, in many longitudinal kineties. There is always a frange of membranelles beneath, but extending only to the left of, the oral aperture. The number of membranelles in the frange varies but there are at least 3 and usually more. The anterior part of the kinety immediately to the right of the oral aperture may be modified to become a highly vibratile double row of cilia forming the paroral ciliature. The frange of membranelles always interrupts the left kineties so that they continue forwards past the frange to the suture line. This feature distinguishes it from the genera Furgasonia and Enigmostoma where the membranelles occur in the suture line area and thus do not interrupt the kineties. The cytopharynx is supported by a basket of trichites. There is a single contractile vacuole situated in the middle of the body. Macronucleus with adjacent micronucleus centrally positioned.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)


Nassula aurea Ehrenberg, 1833 (ref. ID; 1308, 1622, 2245, 4611, 4613, 7694) reported year? (ref. ID; 1618, 4678) reported author and year? (ref. ID; 7538)
See; Obertrumia aurea (ref. ID; 4611, 4613)
Description; Fresh and brackish water. (ref. ID; 1618)
The occurrence of alveolocysts in the somatic cortex. (ref. ID; 7694)
Measurements; 200-250 um long. (ref. ID; 1618)
Nassula citrea Kahl, 1930 (ref. ID; 7618, 7694) reported author and year? (ref. ID; 191, 1622)
Description; [Morphology of the trophic stage]: N. citrea is slightly flattened dorsoventrally and measures 80-120 um in length and 40-50 um in width. Starved animals reveal an asymmetrical outline with a cortex right side and a concave left side. In the anterior left part the cell there is a yellow spot which is not clearly seen in recently fed cells. Well fed cells are of ovoid shape. The holotrichous body ciliature consists of about 55 kineties with monokinetids as subunits. In N. citrea like in the undetermined Nassula studied by Tucker (1971) a field of irregularly arranged ciliated kinetosomes is seen between the cytostome and the contractile vacuole pore. During stomatogenesis this part of the cortex serves as the anlage for the paroral membrane of the future opisthe. The first somatic kinety on the right of the contractile vacuole pore is defined as kinety 1. It extends from the posterior end of the paroral membrane beyond the contractile vacuole pore to the cytoproct. In between the somatic kineties some spindle-shaped trichocysts are dispersed. The cytostome of N. citrea is located in the anterior quarter of the ventral cortex slightly on the right of the ventral mid-line. The club-shaped cytopharyngeal basket which consist of 34-38 rods (nematodesmata) is about 35 um long with a maximum width of 12 um. The right half of the cytostome with the anterior tip of a resting basket is covered by a lid-like fold of the pellicle. The buccal ciliature of N. citrea consists of a paroral membrane and 5-6 (rarely 4 or 7) adoral membranelles. The kinetosomes of the paroral membrane are arranged irregularly and can hardly be distinguished from the somatic kineties. The adoral membranelles form an adoral streak of membranelles ('adoraler Wimperstreifen" Stein 1859; 'frange hypostomienne' Faure-Fremiet 1967) which extends from the posterior edge of the oral opening the left along the ventral surface of the cell. In general the streak of membranelles is limited to the ventral cortex and ends near the yellow pigment-spot but sometimes it just reaches the dorsal side of the cell. The streak of membranelles cuts most of the kineties on the ventral left part of the cell into 2 segments, a shorter anterior one and a longer posterior one. Each membranelles has 3 rows of kinetosomes. The number of kinetosomes within a row varies from membranelle to membranelle and from cell to cell in a wide range. The paroral membrane of N. citrea forms the right border of the buccal cavity and runs along the lid-like fold of the pellicle which covers half of the basket's tip. The paroral membrane consists of about 20 kinetosomes which lie much closer together than in the somatic kineties. Partly the kinetosomes of the paroral membrane seem to be arranged in pairs with their axis parallel to the longitudinal axis of the paroral membrane. Sporadically such pairs are also found in the cortical region between the oral opening and the contractile vacuole pore which is located in the middle of the ventral surface of the cell between kinety 1 and n. About 15 um behind the contractile vacuole pore begins the cytoproct which nearly reaches the posterior pole of the cell. (ref. ID; 7618)
[Morphogenesis]: The cortical morphogenesis of N. citrea can be subdivided in 5 stages.
Stage 1. The oral opening is closed forming a narrow slit like in F. blochmanni. Close to the right edge of the adoral streak of membranelles a new contractile vacuole pore originates. The old cytopharyngeal basket is still connected to the buccal cortex. Within the cortical region between the old and the new contractile vacuole pore the anlage of the paroral membrane of the future opisthe is formed from the irregularly arranged kinetosomes in this area. At first shortrows of narrowly spaced kinetosomes arise at the right border of this region. Later on they unite to form a single slightly curved row. On a level somewhat anterior to the old contractile vacuole pore the anlage of the adoral streak of membranelles emerges within the somatic kineties left of ventral mid-line (kn to kn-5 in this early stage). The kineties involved in this process are curved to the right and show kinetosomal proliferation. There is a gradient of proliferation decreasing from the ventral mid-line to the left. At the left margin of the anlage kinetosomal proliferation spreads over more and more kineties. In the old buccal apparatus the kinetosomes of the paroral membrane which are rather dispersed during the trophic stage of the cell join again and form a curved row of narrowly spaced kinetosomes.
Stage 2. The old cytopharyngeal basket has shifted deeply into cytoplasm and is resorbed. New the anlage of the paroral membrane in the future opisthe mainly is composed of paired kinetosomes. The anlage of the paroral membrane in the future proter seems to remain a single row of kinetosomes. The anlage of the adoral streak of membranelles in the future opisthe now lies in front of about 15 somatic kineties and is composed of the same number of kinetosomal clusters. At the right edge of the anlage these clusters begin to fuse. The parental adoral steak of membranelles seems to be transfered to the proter without alterations.
Stage 3. The cleavage furrow becomes apparent on a level with the anterior end of the anlage of the paroral membrane in the opisthe. The nematodesmata, which later on form the rods of the baskets, separate from the kinetosomes of the paroral membrane in both the proter and the opisthe and arrange themselves to form a tube. The anlage of the paroral membrane in the opisthe now appears to be a single row of kinetosomes again. Meanwhile the kinetosomal clusters of the anlage of the adoral streak of membranelles are completely developed and fuse to form a homogeneous ribbon. The contractile vacuole pore of both daughter cells begins to migrate posteriorly. In the middle region of the somatic cortex of the dividing cell kinetosome proliferation begins.
Stage 4. The cell already possess a deeply constricted cleavage furrow. The tips of the new developing baskets are clearly visible. At the posterior end of the paroral membrane of both the proter and the opisthe kinetosomal proliferation occurs. These new kinetosomes fill the increasing space between the oral opening and the contractile vacuole pore. In the proter a new cytoproct is formed. The anlage of the adoral streak of membranelles in the opisthe is now a homogeneous ribbon composed of 3 rows of kinetosomes which extends from the posterior left edge of the oral opening to the left of the ventral surface of the cell. About 15 somatic kineties on the left of the ventral mid-line of the opisthe are separated by this ribbon into short anterior and longer posterior segments. Well-stained cell reveal that in this stage kinetosomal pairs and triads have originated from monokinetids in the somatic cortex.
Stage 5. Shortly before cytokinesis takes place, the kinetosomal proliferation between the cytostome and the contractile vacuole pore has ceased. In these regions fields of irregular arrangend kinetosomes have originated which will serve as the anlagen for new paroral membranes in the next division cycle. Proceeding from the right to the left in the opisthe the membranelles of the adoral streak of membranelles are cut off from the homogenous kinetosomal ribbon. Finally 5 to 6 (rarely 4 or 7) adoral membranelles of different length are formed. Within the somatic cortex the kinetosomes of the kinetosomal pairs and triads separate and form monokinetids again. (ref. ID; 7618)
The occurrence of alveolocysts in the somatic cortex. (ref. ID; 7694)
Nassula graciis Claparede & Lachmann (ref. ID; 3342)
Measurements; 135-218 x 55-110 um. (ref. ID; 3342)
Nassula ornata Ehrenberg, 1833 (ref. ID; 1622, 1629, 3115, 4488, 4611, 7694) reported year? (ref. ID; 3690, 3698) reported author and year? (ref. ID; 3292, 7538)
Description; The occurrence of alveolocysts in the somatic cortex. (ref. ID; 7694)
Nassula tumida Maskell, 1887 (ref. ID; 1622, 7563)
Syn; Nassula ambigua var. tumida Maskell (ref. ID; 1622)
Description; The ultrastructural study. (ref. ID; 7563)