Light microscopical observation of infraciliary bands of Eodinium posterovesiculatum in comparison with Entodinium bursa and Diplodinium dentatum

Morphological features of the four morphotypes of the rumen ciliate, Eodinium posterovesiculatum, are described from pyridinated silver carbonate-impregnated specimens. Infraciliary bands are compared with those of Entodinium bursa and Diplodinium dentatum. In Entodinium bursa, the adoral polybrachykinety is "C" shaped and the vestibular polybrachykinety extends from the dorsal extremity of the adoral polybrachykinety as in other Entodinium species. In Diplodinium dentatum, the adoral polybrachykinety encircles most of the circumference of the vestibular opening and the vestibular polybrachykinety extends from the inner side of the adoral polybrachykinety as in other Diplodinium species. Infraciliary bands in Eodinium posterovesiculatum encircle the whole circumference of the vestibular opening and are, therefore, distinct from Entodinium, Diplodinium and other ciliates in the family Ophryoscolecidae. In Eodinium posterovesiculatum, the adoral polybrachykinety and the anterior part of the vestibular polybrachykinety encircle the vestibular opening. The wide and long vestibular polybrachykinety extends along the right wall of the tubular vestibulum and is bordered by a kinety. Kinetids in the central part of the vestibular polybrachykinety are randomly disposed. The genus Eodinium is valid because of this characteristic polybrachykinety arrangement in Eodinium posterovesiculatum.     

Infraciliary Bands in the Rumen Ophryoscolecid Ciliate Ostracodinium gracile (Dogiel, 1925), Observed by Light Microscopy

ABSTRACT Morphological features of the rumen ciliate Ostracodinium gracile (Dogiel, 1925) are described from pyridinated silver carbonate-impregnated specimens. Ostracodinium gracile has a characteristic arrangement of infraciliary bands not present in other ophryoscolecid ciliates. Buccal infraciliature is composed of three polybrachykineties. The adoral polybrachykinety does not completely encircle the circumference of the vestibular opening, but arches ventrally from its right to left side. The dorsoadoral polybrachykinety extends laterally along the dorsal side of the vestibular opening. The vestibular polybrachykinety extends along the dorsal wall of the long tubular vestibulum. Dorsal infraciliature consists of the dorsal polybrachykinety that extends laterally along the dorsal side of the body. During binary fission, four primordia, that is ventral, right, left, and dorsal primordia, form in the stomatogenic field and develop into the adoral, dorsoadoral, vestibular, and dorsal polybrachykineties of the opisthe. respectively.     

Two new entodiniomorphid Triplumaria ciliates from the intestine of the wild African white rhinoceros

Two new species of Triplumaria in the order Entodiniomorphida, T. alluvia n. sp. and T. grypoclunis n. sp., are described from the large intestine of the wild African white rhinoceros. T. alluvia has three bud-shaped caudalia, one broad skeletal plate with a wavy left dorsal edge, and an axe-shaped tail flap. T. grypoclunis has three short arched caudalia, two broad skeletal plates, and a pointed and ventrally curved tail flap. These two new species have a C-shaped adoral polybrachykinety, a slender perivestibular polybrachykinety, and paralabial kineties in their retractable adoral ciliary zone. In T. alluvia, the perivestibular polybrachykinety is joined to both ends of the adoral polybrachykinety and paralabial kineties along the ventral side of the adoral polybrachykinety, showing the same arrangement as in Cycloposthium species. In T. grypoclunis, the perivestibular polybrachykinety is joined only to the right end of the adoral polybrachykinety and paralabial kineties along the left ventral side of the adoral polybrachykinety, showing an arrangement analogous to the Tripalmaria species.     

Infraciliature and morphogenesis in three rumen Diplodinium ciliates, Diplodinium polygonale, Diplodinium leche, and Diplodinium nanum, observed by light microscopy

Infraciliature and morphogenesis of three rumen ophryoscolecid ciliates, Diplodinium polygonale Dogiel, 1925, Diplodinium leche Imai et al., 1992, and Diplodinium nanum Imai, 1988, are described from pyridinated silver carbonate-impregnated specimens. These three species have two polybrachykineties in the buccal area and a polybrachykinety in the dorsal ciliary zone. The vestibular polybrachykinety (VP) of D. polygonale and D. leche arises from the dorsal extremity of the adoral polybrachykinety (AP) as in Entodinium species, extending toward the left in D. polygonale and toward the left posterior in D. leche. The VP of D. nanum arises from the inner side of the AP, separate from its dorsal extremity, as in other Diplodinium species and extends toward the left posterior. These series of the polybrachykinety arrangements in D. polygonale, D. leche, and D. nanum can be regarded as transitional forms in the evolution of an Entodinium-like ancestor to Diplodinium. Morphogenesis of these three Diplodinium species is not different from that of other Diplodinium species.     

New entodiniomorphid ciliates from the intestine of the wild African white rhinoceros belong to a new family, the Gilchristidae

Gilchristia artemis n.g., n.sp. and Digilchristia draconis n.g., n.sp. in the order Entodiniomorphida are described from the large intestine of the African white rhinoceros, and a new family Gilchristidae is proposed to contain them. These new species have a C-shaped adoral polybrachykinety, a slender vestibular polybrachykinety, and paralabial kineties along the ventral side of the adoral polybrachykinety in their retractable adoral ciliary zone, showing the same arrangement as in the rumen ciliates in the family Ophryoscolecidae. G. artemis has two skeletal plates and D. draconis one plate. In both species the dorsal skeletal plate is bow-shaped, folded in half longitudinally, twisting in the anterior part, and lying along the dorsal left side of the macronucleus. The second plate of G. artemis is slender and lies along the ventral side of the macronucleus. G. artemis has three ciliary arches and D. draconis has four arches along the dorsal and ventral sides of the body. Their arches are long and non-retractable, closely resembling those of ciliates in the families, Spirodiniidae and Cycloposthiidae, and are not analogous to the single retractable ciliary arch of the rumen ciliates in the family Ophryoscolecidae.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Entodinium Stein (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of the rumen ciliates, Entodinium spp., was observed topographically in the SEM. The upper side of the anterior end of the body was indented by the vestibulum, which had cilia arranged on its right wall and ribs along the left wall. The adoral ciliary zone could be divided into at least two arrangements. The outer ciliary zone had many membranelle-like structures, which consisted of cilia arranged radially from the body axis. Each membranelle-like structure consisted of two rows of about eight cilia each lining up in a single file. It was, however, different from a typical membranelle, because its cilia were connected with the vestibular cilia and were arranged not spirally but on a plane. These cilia extended toward the outside because of the projecting cytoplasm from which they originated. In contrast, the cilia of the inner ciliary zone were aggregated to form relatively unsystematic bundles. Since the vestibular opening was slanted on the upper side of the body, the ciliary bundles were thick on the lower side and sparse on the upper side of the body. Neither outer nor inner ciliary zones completely surrounded the vestibular opening. The ciliature started from the left side of the vestibular opening, encircled the lower side of the body, and entered the vestibulum from its right side. The functions of these two types of ciliary arrangements are discussed.     

Infraciliature of eight Triplumaria species (Ciliophora, Entodiniomorphida) from Asian elephants with the description of six new species

Intestinal ciliates excreted in the feces of Asian elephants were surveyed. Fourteen species in the order Entodiniomorphida were detected. Nine Triplumaria species in the family Cycloposthiidae were found. Using the silver impregnation, two known species, T. antis and T. dvoinosi, were redescribed and six new species, T. sukuna n. sp., T. zuze n. sp., T. solea n. sp., T. suwako n. sp., T. fulgora n. sp., and T. harpagonis n. sp., were described. T. sukuna, T. zuze, T. solea, and T. suwako have the perivestibular polybrachykinety along the vestibular opening. The buccal infraciliary bands of T. suwako are similar to those of T. selenica found from elephants and the buccal infraciliary bands of T. sukuna, T. zuze, and T. solea are similar to those of T. grypoclunis described from rhinoceroses. T. antis, T. dvoinosi, T. fulgora, and T. harpagonis have the vestibular polybrachykinety extending down inside the vestibulum as found in rumen ciliates in the family Ophryoscolecidae. The caudalial ciliary zones of T. dvoinosi and T. fulgora were retractable as found in rumen ophryoscolecids. Raabena bella and Pseudoentodinium elephantis showed high composition values over 30%. Ciliate densities in the three fecal samples were 0.15, 1.09, and 2.07×10(4)/ml.     

A New Entodiniomorphid Ciliate,Troglocorys cava n. g., n. sp., from the Wild Eastern Chimpanzee (Pan troglodytes schweinfurthii) from Uganda

ABSTRACT. Troglocorys cava n. g., n. sp. is described from the feces of wild eastern chimpanzee, Pan troglodytes schweinfurthii, in Uganda. This new species has a spherical body with a frontal lobe, a long vestibulum, a cytoproct located at the posterior dorsal side of the body, an ovoid macronucleus, a contractile vacuole near the cytoproct, and a large concavity on the left surface of the body. Buccal ciliature is non‐retractable and consists of three ciliary zones: an adoral zone surrounding the vestibular opening, a dorso‐adoral zone extending transversely at the basis of the frontal lobe, and a vestibular zone longitudinally extending in a gently spiral curve to line the surface of the vestibulum. Two non‐retractable somatic ciliary zones comprise arches over the body surface: a short dorsal ciliary arch extending transversely at the basis of the frontal lobe and a wide C‐shaped left ciliary arch in the left concavity. Because of the presence of three ciliary zones in the non‐retractable buccal ciliature, the present genus might be a member of the family Blepharocorythidae, but the large left concavity and the C‐shaped left ciliary arch are unique, such structures have never been described from other blepharocorythids.     

Rumen ciliates from Tanzanian short horn zebu cattle,Bos taurus indicus,and the infraciliature of Entodinium palmare n.sp. and Enoploplastron stokyi ()

Rumen ciliates of ten Tanzanian short horn zebu cattle were examined. A total of 15 genera and 46 species were identified, including a new Entodinium species. The ciliate density was 22.2×10⁴ ml^?1. The number of species per host and the diversity index showed high values, 33.8 and 2.80, respectively. Rumen ciliates had a low percentage composition of the genus Entodinium (7.0–25.0%) and a slightly higher percentage composition of the genera, Eudiplodinium (19.3%), Diplodinium (14.1%), and Ostracodinium (13.1%). Entodinium palmare n.sp., Eudiplodinium kenyensis, and Enoploplastron stokyi were found in all cattle examined. The former two species have been found only in African zebu cattle. Entodinium palmare n. sp. has a characteristic right surface of the body like the “palm of a hand” because of the concave part on the postero-dorsal part of the body, and has the same pattern of infraciliary bands as in other Entodinium species. Enoploplastron stokyi has a characteristic pattern of infraciliary bands analogous to those of Epidinium ecaudatum and Ostracodinium mammosum; with the right side of the adoral polybrachykinety gradually tapering and a slender short vestibular polybrachykinety.     

Light Microscopic Observations of Infraciliature and Morphogenesis in Six Species of Rumen Ostracodinium Ciliates

Infraciliature and morphogenesis of six rumen ciliates, Ostracodinium mammosum, O. munham, O. dilobum, O. rugoloricatum, O. iwawoi, and O. tiete are described from pyridinated silver carbonate-impregnated specimens. These six Ostracodinium have a similar polybrachykinety arrangement, distinct from that of other ophryoscolecid ciliates and intermediate between those of O. gracile and 0. damaliscus. Buccal infraciliature is composed of three polybrachykineties, a kinety loop, and paralabial kineties. Small dorso-adoral polybrachykinety, slender vestibular polybrachykinety, and kinety loop are characteristic. Dorsal infraciliature consists of the dorsal polybrachykinety that extends laterally along the dorsal side of the body. Morphogenesis is different from that of O. gracile, because the right end of ventral primordium extends dorsally to grow into a right primordium without separation.     

Scanning Electron Microscopy of the Adoral Ciliary Zone of Cycloposthium Bundle (Ciliophora,Entodiniomorphida)1

The adoral ciliary zone of Cycloposthium spp., inhabiting the large intestine of the horse, was studied by scanning electron microscopy. It could be divided into four parts: outer, inner, left, and right zones. The outer zone, extending on the anterior periphery of the apical cone of the body, had 20 tuft-like syncilia arranged radially around the longitudinal axis. Each ciliary tuft consisted of about 170 cilia, and in cross section it had a rectangular shape. The cilia of the inner zone, situated at the top of the apical cone, were aggregated irregularly to form shorter bundles than the tufts of the outer zone. The innermost cilia of this zone were shorter than the outermost. There was a distinct non-ciliated border between the outer and inner zones. A horseshoe-like operculum having no cilia was present at the center of the adoral ciliary zone, and the opening of the vestibulum was situated as a cleft crossing from the center to the right periphery of this zone. No cilia extended onto the vestibular wall. The left ciliary zone was situated beneath the outer zone and consisted of five short rows of barren kinetosomes of which only the central row possessed very short cilia. The right ciliary zone, consisting of a few rows of cilia situated at the bottom of the inner adoral lip, was also easily distinguished from the other ciliary zones. This zone was interpreted as an extension of the outer adoral zone passing along the right side of the apical cone. These ciliary zones were considered to be highly differentiated and useful for both movement of and ingestion of food.     

Intestinal ciliated protozoa of the Asian elephant Elephas maximus Linnaeus, 1758 with the description of Triplumaria izmirae n. sp.

Species composition and distribution of intestinal ciliates excreted in the feces of three Asian elephants living in Sasalı National Park, Izmir, Turkey, were investigated. Seven ciliate genera consisting of 36 species were identified. This is the first report on intestinal ciliates in elephants living in Turkey; one new species, T. izmirae n. sp., was described. This new species has a special macronucleus shape, skeletal rod plates with two wings and posterior contractile vacuole lying beneath the dorsal left base of the tail flap. The buccal infraciliary bands of T. izmirae are similar to those of T. selenica and T. suwako known from elephants. Triplumaria ovina and Raabena bella occurred in highest percentages in two elephants, whereas Latteuria polyfaria was highest in the third one. Ciliate densities in the three fecal samples were 3.5, 1.5 and 5.0 × 10⁴/mL.     

Morphological and phylogenetical studies on a new soil hypotrich ciliate: Kahliella matisi spec. nov. (Hypotrichia,Kahliellidae)

The morphology, ontogenesis, encystment, and 18S rRNA gene sequence of a new soil hypotrich ciliate, Kahliella matisi, were studied. Main characteristics of K. matisi are: (1) two short and six longitudinal cirral rows right of the adoral zone of membranelles and four longitudinal rows left of it; (2) three dorsal kineties, of which kinety 1 extends along the left cell margin, kinety 2 runs in a slightly sigmoidal line, and kinety 3 is distinctly shortened posteriorly. Ontogenesis is similar to that in congeners, especially in the development of the marginal rows and long dorsal kineties, the preservation of some old cirral rows after division, and the direction of the neokinetal wave. However, there are some peculiarities: (1) reorganization of the proximal parental adoral membranelles; (2) splitting of opisthe's anlage II into the cirral streak II and III; and (3) formation of the parental cirral row R3 from anlagen IV and V. During encystment, the body diminishes and becomes globular, the nuclear apparatus is reorganized, and the ciliature is resorbed. In our molecular phylogenies, the family Kahliellidae is polyphyletic and the position of K. matisi is rather poorly resolved, indicating a relationship with oxytrichids.     

Ultrastructure of the nephrostome in Enchytraeus albidus (Annelida, Clitellata)

 The nephrostome of Enchytraeus albidus exhibits a longitudinal slit-like opening on the dorsal side of a bulbous organ which is mainly composed of three cells, one flame cell situated centrally and endowed with a ciliary flame, and two cells lying superficially, called the mantle cell and the accessory mantle cell. The mantle cell occupies the ventral side of the organ extending on both sides up to the opening to constitute its immediate border on the frontal and lateral sides. Here it forms a kind of crest which is heavily subdivided into many protrusions and infoldings endowed with long cilia which exclusively spread into the coelomic cavity. The accessory mantle cell borders the narrow posterior slit of the opening, forming the roof of the initial canal which is devoid of cilia. From its anterior region a projection arises extending above the opening. The flame cell forms a groove from which the ciliary flame arises which extends into the canal. At its posterior region it replaces the accessory mantle cell displacing it onto the dorsal surface of the organ. It is argued that the mantle cell and the accessory mantle cell have presumbly originated from coelothelial cells. Thus the metanephridium may be a composite organ developing from a nephridioblastic and a coeloblastic source. A discussion of results in other annelid species indicates that metanephridia in the Annelida may have evolved more than once. Accepted: 13 October 1997     

Scanning electron microscopy of the adoral ciliary zone of Cycloposthium bundle (Ciliophora, Entodiniomorphida)

The adoral ciliary zone of Cycloposthium spp., inhabiting the large intestine of the horse, was studied by scanning electron microscopy. It could be divided into four parts: outer, inner, left, and right zones. The outer zone, extending on the anterior periphery of the apical cone of the body, had 20 tuft-like syncilia arranged radially around the longitudinal axis. Each ciliary tuft consisted of about 170 cilia, and in cross section it had a rectangular shape. The cilia of the inner zone, situated at the top of the apical cone, were aggregated irregularly to form shorter bundles than the tufts of the outer zone. The innermost ciliar of this zone were shorter than the outermost. There was a distinct non-ciliated border between the outer and inner zones. A horseshoe-like operculum having no cilia was present at the center of the adoral ciliary zone, and the opening of the vestibulum was situated as a cleft crossing from the center to the right periphery of this zone. No cilia extended onto the vestibular wall. The left ciliary zone was situated beneath the outer zone and consisted of five short rows of barren kinetosomes of which only the central row possessed very short cilia. The right ciliary zone, consisting of a few rows of cilia situated at the bottom of the inner adoral lip, was also easily distinguished from the other ciliary zones. This zone was interpreted as an extension of the outer adoral zone passing along the right side of the apical cone.(ABSTRACT TRUNCATED AT 250 WORDS)     

CELL FORM AND SURFACE PATTERNS IN CHROOMONAS and CRYPTOMONAS CELLS (CRYPTOPHYTA) AS REVEALED BY SCANNING ELECTRON MICROSCOPY1

Fifteen freshwater cryptomonad species were freeze-dried and examined with the scanning electron microscope. Surveys of cell surfaces revealed four general cell types. Chroomonas type cells lack a furrow but possess a shallow vestibular depression where the flagella are inserted. The presence of a gullet could not be detected. Cryptomonas spp. displayed three morphological types, all lacking gullets. The first type of Cryptomonas has a simple, shallow furrow with ridges that apparently can close to form a raphe but an oval opening or stoma remains at the posterior end and an opening from the vestibulum is formed at the anterior end. The second Cryptomonas type consists of a complex furrow with furrow ridges and folds that extend almost two-thirds of the cell length. A sloma is present in the central region of the closed furrow. The folds apparently can separate thereby exposing the underlying furrow. The third type of Cryptomonas possesses a simple, non-closing furrow. At the anterior end there is a vestibular ligule which extends from the dorsalleft side of the cell and covers the region of the vestibulum where the contractile vacuole discharges.     

A new species of Asthenocotyle Robinson, 1961 (Monogenea: Microbothriidae), a skin parasite of the great lanternshark Etmopterus princeps Collett from the Azores, with a redescription of A. kaikourensis Robinson, 1961 and observations on A. taranakiensis Beverley-Burton, Klassen & Lester, 1987

Asthenocotyle azorensis n. sp. (Monogenea: Microbothriidae) is described from the dermal denticles of the great lanternshark Etmopterus princeps Collett off the Azores. The type-species of the genus, A. kaikourensis Robinson, 1961, is redescribed and additional observations are made on A. taranakiensis Beverley-Burton, Klassen & Lester, 1987. The generic diagnosis is revised. The new species is distinguished from its two congeners by the large size of the pharynx and fewer testes. The ejaculatory bulb of A. kaikourensis is much larger than those of A. taranakiensis and A. azorensis and is supplied with many ducts from an extensive field of male accessory gland-cells located outside the genital pouch and extending posteriorly to the region of the germarium and external seminal vesicle. Asthenocotyle taranakiensis is distinguished from the other two species by its copulatory sclerite, which forms a double loop, although this may not be the case when the copulatory organ is extended. The bodies of A. azorensis and A. kaikourensis are similar in shape, with the maximum width approximately 37% and 25%, respectively, of the total length from the anterior end. In addition to the relatively small size of the genital pouch and ejaculatory bulb in A. azorensis and A. taranakiensis, the vaginal opening is adjacent to the common genital opening. In A. kaikourensis, the vaginal opening is distant from and posterior to the common genital opening. The functional morphology of the copulatory organ of A. azorensis is considered. The relative importance, for the taxonomy of microbothriids, of the number of testes versus the anatomy of the copulatory complex is discussed.     

Morphological Comparison of Diophrys scutum (Dujardin, 1841) and Diophrys peloetes n. sp. (Hypotrichida, Ciliophora)

SYNOPSIS. Diophrys scutum , collected from four locations on the New Hampshire coast, ranged from 89–195 7mu; in length, 50–105 μ in width, and 68–88 μ in buccal cavity length. The end of the adoral zone of membranelles (AZM) extends 37–59 μ (average = 45.6 μ) posteriorly in a groove on the right side of the body. Dorsally are five rows of stiff cilia. The silverline system (Chatton-Llvoff technique) appears as a fine meshwork, entirely different from that found in Euplotes or Uronychia . There are two elongate macronuclei (Feulgen reaction) and several micronuclei. Diophrys peloetes n. sp., collected from one location in Alligator Harbor. Florida, ranged from 95–134 μ in length, 62–84 μ in width. and 60–80 μ in buccal cavity length. The terminal portion of the AZM extends posteriorly in a groove 30–44 7mu; (average = 36.8 μ) on the right side of the body. Dorsally are eight rows of stiff cilia. The details of the silverline system are similar to those of D. scutum .
There is insufficient difference in ranges of body length, width. and buccal cavity length to use these characters in separating the two species. However, a statistical analysis shows that the length of the portion of the AZM on the right side of the body in D. scutum is significantly different (longer) from that of D. peloetes. Furthermore, these two species differ not only in number of dorsal ciliary rows, but also in the number of cilia per row. The degree of difference in these two species is similar to that between closely related species in other hypotrich genera, and also to that between some varieties of Paramecium aurelia.     

Morphology and ontogenesis of two new Hemiholosticha species (Ciliophora,Hypotrichia, Hemiholostichidae nov. fam.)

The morphology and ontogenesis of two new hypotrich ciliates, Hemiholosticha solitaria and Hemiholosticha germanica, were studied using live observation, protargol impregnation, and scanning electron microscopy. Both species share a medium-sized, almost globular body with a short anterior projection; two macronuclear nodules with a single micronucleus in between; a central contractile vacuole; three or four ventral, one postoral, one right and one left marginal cirral row; and three dorsal kineties extending along ribs. However, H. germanica is distinguished from congeners by a higher number of cirri in ventral rows R1 and R2 (3–6 vs. 2 cirri in each row). Hemiholosticha solitaria differs from congeners by having four (vs. three) ventral cirral rows and by the lack (vs. presence) of intracellular green algae. The ontogenesis of H. solitaria follows the H. pantanalensis mode in that (i) the oral primordium develops in a deep pouch and generates the first two cirral streaks in addition to adoral membranelles and undulating membranes, (ii) the undulating membrane anlage does not produce any cirri, and (iii) the longitudinal ventral cirral row R3 originates from two anlagen. The ontogenetic peculiarities along with the 18S rRNA gene phylogenies suggest classification of Hemiholosticha, Psilotrichides, and Urospinula into a new family, Hemiholostichidae.     

Agolohymena aspidocauda nov. gen., nov. spec., a histophagous freshwater tetrahymenid ciliate in the family Deltopylidae (Ciliophora,Hymenostomatia), from Idaho (northwest U.S.A.): Morphology,ontogenesis and molecular phylogeny

Morphology, ontogeny and the molecular phylogeny of Agolohymena aspidocauda nov. gen., nov. spec., a new freshwater tetrahymenid ciliate from Idaho, U.S.A, are described. The ontogeny and histophagous mode of nutrition are similar to those of Deltopylum rhabdoides Fauré-Fremiet and Mugard, 1946. The new genus is placed with Deltopylum in the resurrected family Deltopylidae Song and Wilbert, 1989. We emend the diagnostic features of the family to include division by polytomy, right and left somatic kineties extending into the preoral suture, crook-shaped or sigmoid adoral membranelles 1 and 2, markedly reduced adoral membranelle 3 and a tetrahymenid silverline pattern. The main diagnostic features of the new genus are a disc-shaped caudal ciliary array and formation of two types of resting cysts, one smooth and the other bearing tangled tubular or cylindrical lepidosomes. Nuclear small subunit ribosomal RNA gene and mitochondrial cytochrome oxidase subunit 1 gene sequences place the new genus basal within the order Tetrahymenida, well separated from members of the family Tetrahymenidae (Lambornella and Tetrahymena) and also from other tetrahymenids (Colpidium, Dexiostoma, Glaucoma). The genetic divergences between this species and other genera in Tetrahymenida are large enough to suggest placement of the new genus in a separate family. This corroborates the morphological data, since the elaborate caudal ciliary array and the lepidosome-covered resting cyst of this species are not found in other Tetrahymenidae.