Phacodinium Prowazek, 1900 (ref. ID; 2014)
Class Polyhymenophora Jankowski, 1967: Subclass Spirotricha Butschli, 1889: Order Heterotrichida Stein, 1859 (ref. ID; 7529)
Class Polyhymenophora: Subclass Spirotricha: Order Heterotrichida: Suborder Heterotrichina (ref. ID; 2014)

Synonym; Conchophthirius Certes, 1891 (ref. ID; 2014)

[ref. ID; 1618]
Oval; marked grooves on body surface; cilia in cirrus-like fused groups; peristome long on left margin; cytostome posterior; contractile vacuole terminal; macronucleus horseshoe-shape; five to nine micronuclei; fresh water (one species). (ref. ID; 1618)

[ref. ID; 2014]
Body oval in outline, dorso-ventrally flattened with prominent longitudinal ribs on each side. Conspicuous AZM down left side of body stretching almost complete length so that cytostome is in the posterior body quarter. Cilia occur in tufts over entire surface. Dorsal surface with 'sensory' cilia. Contractile vacuole terminal. Macronucleus elongate to horseshoe-shape. First described by Certes as Conchophthirius and later redescribed and named by Prowasek.
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)

Phacodinium metchnicoffi Certes, 1891 (ref. ID; 1621) reported year? (ref. ID; 1618, 4842) reported author and year? (ref. ID; 7529), Phacodinuium metchnikoffi misspelling? (Ceres, 1891) (ref. ID; 3593, 4386)
Syn; Phacodinium muscorum Prowazek, 1900 (ref. ID; 1621)
Description; Phacodinium metchnikoffi is an oval-shaped ciliate, dorso-ventrally flattened. The profile where the adoral zone of membranelles is corresponds to the ventral zone and is opposite to the dorsal one. P. metchnikoffi is widest at its anterior end since the ventral side extends forward beyond the dorsal side which it covers at this anterior part. In most of the individuals observed, the posterior end terminates in an acute tip with the single, prominent contractile vacuole located near this tip. The surface is decorated with series of longitudinal crests situated on both the dorsal and ventral sides. The average number of crests is five on the dorsal side and four on the ventral side. (ref. ID; 4386)
[Somatic infraciliature]: Groups of somatic kineties alternate with the longitudinal crest. Each kinety consists of a varying number of structures which Dragesco (1979) calls "palettes". They are lineal groups of a few kinetosomes with a stem under them. Each kinety has 12-15 pallets in its central rows and 10-20 in the marginal ones. The length of the pallets varies with location, measuring 1-3 um on the dorsal side and 4-7 um on the ventral side. The dorsal pallets range from one kinetosome to 2-3 kinetosomes, all with one cilium. Most commonly, there are 9-11 ciliated kinetosomes per pallet on the ventral side. Furthermore, there are some double pallets with 16 kinetosomes in certain areas on the ventral side. (ref. ID; 4386)
[Buccal infraciliature]: Adoral zone of membranelles. The adoral zone of membranelles (AZM) is formed by a group of about 40-59 paramembranelles (Puytorac & Grain, 1976) which run along the left edge of the organism and enter the cytostome where the formation of the paroral structures begins. Two areas have been identified through structural analysis: the posterior and the anterior. In the posterior, paramembranelles have four rows of kinetosomes, two long ones (20-30 kinetosomes), a shorter one (8-10) and a very short one with only three kinetosomes. In the anterior area, paramembranelles are formed by the same elements as appear in the posterior area, but the long posterior row is separated from the others by a 45 degrees angle. (ref. ID; 4386)
[Paroral formation]: This formation, which has been minimally studied by Roque (1970) and Dragesco (1970), has a structure as yet unseen in other ciliates. We have called it a "polybrachystichomonad" because it consists of a range of short rows, each formed by 6-7 kinetosomes, which lie on a rigid stem, which does not exist in other paroral formations (Fernandez-Leborans, 1985). The kinetosomes of the paroral formation are continued by those of the AZM. (ref. ID; 4386)
[Nuclear apparatus]: Both Roque (1970) and Dragesco (1970) have noted that P. metchnikoffi has a horseshoe-shaped macronucleus. We have observed that during the greater part of the life cycle, the macronucleus does indeed have the form of a horse-shoe, with the posterior arm slightly bigger than the anterior one. The form varies throughout the life cycle, rounding off when the ciliate is about to divide and when the process of encystment begins. There are several micronuclei, varying in number with the stages of the individuals cellular cycle (according to Roque, 4-5; according to Dragesco, 4-7). Furthermore, we observed that there are three micronuclei in recently divided individuals and that the ciliate vegetative adult generally has seven micronuclei although we have been able to count up to 12 in several specimens. In the cyst there is only one micronucleus which multiplies during encystment until there are eight micronuclei. When the ciliate excysts, one of these eight micronuclei is reabsorbed during the first process of division. The remaining seven are those of the youngest individuals, that have three or four micronuclei (depending on whether they are proter or opisthe). Each cell will continue multiplying its number of micronuclei to as many as 12. (ref. ID; 4386)
The cortical ultrastructure. (ref. ID; 7529)
Comments; We observed that the structure of the paroral formation is not as Roque (1970) and Dragesco (1970) describe it, i.e. one kinety formed by +/- 20 kinetosomes supported by a semicircular ectoplasmic crest located inside a peristomial cavity. On the contrary, the structure that we observed and named a polybrachystichomonad is very different; it is a new type of paroral formation which as not been previously described in spirotrichs, hypotrichs (Fernandez-Leborans, 1985) or hetrotrichs (Albaret 1975, Fernandez-Leborans 1981, Santos et al. 1986). It is formed of a range of short rows, each with 6-7 kinetosomes. Nevertheless, this polybranchystichomonad looks somewhat like the paroral formation found in Euplotes. Further, we have made some new observation on the somatic infraciliature. In our opinion, the discovery of pallets with two kinetosomal strands is very important. Thus, a pallet could be considered the phylogenetic antecedent of the cirrus. Neither Roque (1970) nor Dragesco (1970) noticed this sort of pallet. (ref. ID; 4386)
Measurements; About 100 um long. (ref. ID; 1618)
After fixing with vapors from formaldehyde are: 135.88 x 82.77 um wide. (ref. ID; 4386)
Phacodinium muscorum Prowazek (ref. ID; 4111)
See; Phacodinium metchnicoffi (ref. ID; 1621)
Description; [Resting cyst]: Granular surface ornamentation on one pole, crescent-shaped nucleus enclosing a yellow mass of reserve products. (ref. ID; 4111)