Furgasonia Jankowski, 1964 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Hypostomata: Order Nassulida: Suborder Nassulina (ref. ID; 2013)
Class Nassophorea: Order Nassulida (ref. ID; 7340)
Synonym Cyclogramma Perty, 1852 (ref. ID; 2013)
[ref. ID; 2013]
Outline shape oval to elongate. Completely ciliated (sometimes with paired cilia) in about 35 longitudinal meridians. Without frange of membranelles as in Nassula but is reduced to 3 membranelles lying on left of the oral aperture. Membranelles do not interrupt the left ventral kineties as in Nassula but occur in the region of the suture line. There is a double row of cilia to the right of the oral aperture forming the paroral ciliature. Cytopharynx supported by a basket of trichites. Fusiform trichocysts always present in large numbers beneath the pellicle. Single contractile vacuole always situated ventrally in middle of body. Macronucleus large with adjacent micronucleus centrally positioned. Body often colored blue-green to red due to color of ingested algae.
Genus erected by Jankowski (1964) for Cyclogramma Perty, 1852.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)
- Furgasonia blochmanni Faure-Fremiet, 1967 (ref. ID; 3355, 7618, 7694) reported author and year? (ref. ID; 191, 7340)
Syn; Cyclogramma blochmanni (ref. ID; 3355, 7340, 7694)
- Furgasonia lateritia Claparede & Lachmann, 1858 (ref. ID; 1622)
- Furgasonia protectissima (ref. ID; 191)
- Furgasonia rubens Perty, 1852 (ref. ID; 1622) reported year? (ref. ID; 3698)
- Furgasonia sorex (Penard, 1922) (ref. ID; 1622)
- Furgasonia trichocystis (Stokes, 1894) (ref. ID; 1622) reported year? (ref. ID; 3698)
Furgasonia blochmanni Faure-Fremiet, 1967 (ref. ID; 3355, 7618, 7694) reported author and year? (ref. ID; 191, 7340)
Syn; Cyclogramma blochmanni (ref. ID; 3355, 7340, 7694)
Description; 16S-like rRNA gene sequences. (ref. ID; 7362)
[Morphology of the trophic stage]: F. blochmanni has a cylindrical shape, it measures 110-130 um in length and 55-70 um in width. The somatic cilia are arranged in about 55 kineties which are orientated longitudinally. The first kinety which lines the buccal apparatus on its right side and passes the paroral membrane is defined as kinety 1. It ends just behind the contractile vacuole pore. Apart from kinety 1 and kinety 2, which ends beside the cytoproct, all other somatic kineties run towards the posterior pole of the cell where the arrangement of kinetosomes becomes irregular. The somatic kineties are composed of monokinetids mainly, dikinetids are found only in the anterior parts of kinety 1 and 2 (on a level with the paroral membrane) and at the anterior ends of the postoral kineties near to the adoral membranelles. Many trichocysts are clearly visible between the somatic kineties with Nomarski differential interference-contrast. The cytostome of F. blochmanni is located in the anterior quarter of the ventral surface slightly on the left of the ventral mid-line (The 'ventral mid-line' is according to Tucker (1970) a meridian passing over the cell's ventral surface joining its anterior and posterior poles. It divides the ventral surface into 2 halves, in F. blochmanni and N. citrea the contractile vacuole pore and the cytoproct are on this line). The oral opening is surrounded by a complex buccal ciliature which consists of a paroral membrane on the right and 3 adoral membranelles on the left side. The paroral membrane is made of about 25 kinetosomal pairs, the axis of the pairs being orientated perpendicular to the axis of the entire organelle. Each adoral membranelle shows 3 rows of kinetosomes. Membranelle 1 is located anterior of the cytostome in the projection of the paroral membrane and has about 9 kinetosomes in each rows. Membranelle 2 has about 11 kinetosomes in each row and lies perpendicular to the ventral mid-line. Membranelle 3 is located parallel to the ventral mid-line between the oral opening and the tips of kineties n-1 and n-2 and has about 8 kinetosomes in each row. The cytopharynx of F. blochmanni is a club-shaped cytopharyngeal basket composed of 16-18 rods (nematodesmata). This rigid feeding apparatus measures about 40 um in length with a maximum width of 13 um. It enables the cell to ingest filamentous blue-green algae at a very high rate. The contractile vacuole of F. blochmanni has a single pore which penetrates the pellicle in the middle of the ventral side of the cell. Just behind the contractile vacuole pore there is the cytoproct which extends towards the posterior pole of the cell seen as a twisted argentophilic line. (ref. ID; 7618)
[Morphogenesis]: The morphogenetic events which take place in the cortex of F. blochmanni before cytokinesis can be subdivided into 5 stages.
Stage 1. The cytostome becomes a narrow slit and is finally closed. At the same time the paroral membrane is divided into 2 segments of different length. The anterior segment or about two thirds of the parental paroral membrane remains in situ. The posterior segment representing one third of the parental paroral membrane migrates towards the contractile vacuole pore and becomes the anlage of the paroral membrane of the opisthe. Following the partition of the parental paroral membrane a new contractile vacuole pore appears near the posterior end of the anterior segment of the paroral membrane. Simultaneously this segment of the paroral membrane splits longitudinally into the anlage of a new paroral membrane and a new kinety 1' of the future proter. As compensation for the appearance of this new kinety 1' the kinety n disappears in the proter. Slightly anterior of the parental contractile vacuole pore the somatic kineties n to n-5 are cut into anterior and posterior segments. At the anterior tips of the posterior segments of these kineties kinetosomal proliferation occurs. Here the anlagen for the adoral membranelles of the future opisthe originate in a telokinetal mode. Kinetosomal proliferation in the somatic cortex begins in the posterior part of the kinety 1.
Stage 2. The parental cytostome has vanished completely. The old dedifferentiating cytopharyngeal basket has detached from the buccal cortex and has migrated deeply into the cytoplasm. The anlage of the paroral membrane in the proter forms a curved row of about 18 narrowly spaced kinetosomes accompanied by a broad dark streak which probably represents the growing nematodesmata of the anlage. The new kinety 1' reaches just behind the new contractile vacuole pore. The parental adoral membranelles which persist during stomatogenesis, appear slightly dispersed and partly curved in this stage. M1 and M3 change their orientation in such a manner that they are finally parallel to M2, thus all membranelles now lying almost perpendicular to the ventral mid-line. In the future opisthe the anlage of the paroral membrane reaches its final position just in front of the old contractile vacuole pore and grows to the same length as the anlage of the paroral membrane in the proter. The intensive argentophilic staining of the prospective oral regions may be due to the rigid nematodesmata of these anlagen. The anlagen of the adoral membranelles of the opisthe grow by kinetosomal proliferation. Seven kineties (kn to kn-6) are involved in this process. Within the somatic cortex kinetosomal proliferation spreads to the kineties on the right of kinety 1. At the same time the parental kinety 1 is subdivided into anterior segment, the new kinety 2 of the proter and a posterior segment which persists as kinety 1 in the opisthe.
Stage 3. Stage 3 is characterized by a distinct anlage of the paroral membrane in both the proter and in the opisthe. These anlagen are still connected with the now fully developed nematodesmata of the future cytopharyngeal baskets. In the meantine 4-5 adoral membranelles have originated in the telokinetal mode in the opisthe from somatic kineties left of the ventral mid-line. Within a wide belt-shaped zone surrounding the middle of the dividing cell kinetosomal pairs and triads have grown from somatic monokinetids. More and more somatic kineties are cut on the level of the presumtive cleavage furrow.
Stage 4. The nematodesmata separate simultaneously from the kinetosomes of the anlage of the paroral membrane both in the proter and in the opisthe. Afterwards the nematodesmata become arranged to form tube-like structures, the anlagen of the new baskets. In the opisthe the number of the adoral membranelles is reduced to 3, this is achieved by resorption of the posterior membranelle(s) lying near the ventral mid-line. The adoral membranelles of the proter move back to their original position. The distance between the cytostome and the contractile vacuole pore increases in both halves of the dividing cell. At the same time kinety 1' in the proter and kinety 1 in the opisthe gradually increase in length so that their posterior ends always stay behind the contractile vacuole pores. Some supernumerary kinetosomes are detectable in the gap between the posterior end of the paroral membrane and the contractile vacuole pore. In the proter a new cytoproct is formed. Within the somatic cortex of the dividing cell except for the pole regions the kineties consist of kinetosomal triads. Meanwhile most of the somatic kineties are cut and the cleavage furrow becomes apparent.
Stage 5. The last stage of before cytokinesis, is characterized by a distinct increased length of the dividing cell and a more distinct cleavage furrow. The circularly arranged nematodesmata increase in length and tie up to form the rigid cytopharyngeal baskets. The distance between the cytostome and the contractile vacuole pore continues to grow. Within the somatic cortex the kinetosome triads separate and form monokinetids. Only in some parts of the cortex mentioned above somatic dikinetids persist. After cytokinesis the daughter cells stretch until they have reached the cylindrical shape typical for the trophic stage of F. blochmanni. (ref. ID; 7618)
The occurrence of alveolocysts in the somatic cortex. (ref. ID; 7694)