Amphileptus Ehrenberg, 1830 (ref. ID; 2013)
Class Kinetofragminophora: Subclass Gymnostomata: Order Pleurostomatida: Family Amphileptidae (ref. ID; 2013)

Synonym Hemiophrys Wrzesniowski, 1870 (ref. ID; 2013)

[ref. ID; 2013]
Body laterally compressed, highly elongate with anterior neck-like region which bends towards the dorsal edge. Oral aperture a slit on convex edge of neck region, extends less than halfway down the body. Ciliation present on both lateral surface although there is a tendency to some reduction on the left surface resulting in it being difficult to distinguish. Ciliation on right surface is extensive and forms longitudinal rows which converge on each other in the anterior region. There is a distinctive area of cilia along the oral slit forming a mane-like brush. Trichocysts commonly present particularly in neck. Macronucleus in 2 to 4 spherical parts with single micronucleus placed between macronuclei. Many contractile vacuoles present, usually lying along dorsal and ventral edges. The recommendations and finding of Canella (1960) and Frys-Vesavel et al. (1976) have been adopted here so that the genus Hemiophrys has been submerged into the above genus. This is because cilia do appear to be present on the left surface even though difficult to resolve without the use of silver impregnation techniques.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)

Amphileptus branchiarum Wenrich (ref. ID; 1618)
Description; On the integument and gills of frog tadpoles; swimming individuals killed with iodine. (ref. ID; 1618)
Measurements; 100-135 by 40-60 um. (ref. ID; 1618)
Amphileptus claparedei Stein, 1867 (ref. ID; 1219, 1335, 1622, 1629, 1629, 2245, 2570, 2574, 3115) reported year? (ref. ID; 1618), claparedii Stein, 1867 (ref. ID; 4612)
Syn; Amphileptus meleagris Claparede & Lachmann, 1858 (ref. ID; 1219, 1622, 2245, 3115) or 1861 (ref. ID; 4612) reported year? (ref. ID; 1618) reported author and year? (ref. ID; 3292)
Description; Mouth is on the convex (ventral) side, slit-like, clearly visible only when the ciliature is feeding; ciliation uniform and nearly complete but ciliary rows of the left side of the body are nor distinct and somewhat reduced by comparison with those on the right side; numerous contractile vacuoles irregularly distributed along the ventral and dorsal margins; 2 macronuclei; fission takes place with in cysts. (ref. ID; 1219)
Slightly flattened; broadly flask-shaped; with bluntly pointed posterior and neck-like anterior end; cytostome about two-fifths from ventral margin; trichocysts indistinct; dorsal ciliary rows also not distinct; contractile vacuoles irregularly distributed; fresh and salt water, on stalks of Zoothamnium, Carchesium, Epistylis, etc. (ref. ID; 1618)
Measurements; Length 120-150 um. (ref. ID; 1219, 1618)
Amphileptus marinus (Kahl, 1931) Song, Wilbert & Hu, 2004 (ref. ID; 4942 redescribed paper)
Basonym; Lionotus (Hemiophrys) marina Kahl, 1931 (ref. ID; 4942)
This organism was originally described as a new species under the subgenus Hemiophrys by Kahl (1931), Lionotus (Hemiophrys) marina Kahl, 1931. Our current work has confirmed that it is a valid and distinct species with the characteristic pattern of the genus Amphileptus, hence a new combination is made because the genus/subgenus Hemiophrys is a junior synonym of Amphileptus. Since no ciliary information was previously available for this organism, here we supply an improved diagnosis and detailed data on the infraciliature as well as on the morphology of living cells, based on a Chinese population. (ref. ID; 4942)
Revised diagnosis; Large marine Amphileptus 200-450 um long in vivo with a slender lanceolate body, two macronuclear nodules and several micronuclei; 10-12 left and 20-27 right somatic kineties; two perioral kineties extending posteriorly to the extreme end of the cell; several contractile vacuoles positioned ventrally in the posterior half of the cell; extrusomes bar-shaped, c. 12 um long in vivo, densely arranged along the ventral edge. (ref. ID; 4942)
Description; Size highly variable, in vivo from 200 to 450 x 50 to 90 um, but mostly around 300-350 um in length. Cells basically slender lanceolate and changeable in shape, i.e. conspicuously flexible and contractile as commonly seen in most other large pleurostomatids. Nevertheless, specimens mostly with a rounded posterior end, sometimes narrowed in the caudal portion (most frequently in small cells) but never tail-like. Margins of main cell portion from parallel (generally when stretched) to considerable convex. Neck about 1/4-1/3 of cell length, often curving highly backwards. Bilaterally about 1:2-3 flattened in body part, hence strongly compressed considering the large size; when crawling on debris, often slightly twisted even folded. Pellicle thin and flexible, which renders body outline sometimes uneven; no conspicuous grooves or ridges on left side ("dorsal side" when viewed in vivo); beneath cell surface, many tiny (< 0.8 um across) cortical granules, sparsely distributed between ciliary rows; cilia sparsely distributed on "dorsal" side and c. 2 um long (very difficult to detect in life). Right side densely ciliated, with more or less distinct grooves, in which kineties originate; cilia on this side about 8-10 um long. Cytoplasm colorless to slightly brown-grayish, often with numerous differently sized greasily shining globules, which render the main part of the body more or less opaque (especially at low magnification). Extrusomes bar-shaped, straight and c. 12 um long, nevertheless, inconspicuous in vivo (detectable only under high magnifications), densely arranged along whole oral region as well as the ventral side, scattered in other body portions. Food vacuoles small (< 5 um) and low in number (even unrecognizable), containing likely flagellates and diatoms. Several (3-7) contractile vacuoles about 5-20 um across, pulsating infrequently, positioned near the ventral margin along posterior 2/5 to 1/2 of cell length; the largest vacuoles usually at the posterior of the cell, others smaller and unevenly distributed. Two macronuclear nodules, separated in mid-body, basically ellipsoid in shape, in vivo often as two large transparent areas. After protargol impregnation (and after days of culture), however, macronuclei often different in shape and size, sometimes in 3 or 4 semi-detached or linked parts. Nucleoli small, high in number and evenly distributed. Micronuclei several in number (maximum 5 observed), about 4-5 um across, near or adjacent to macronuclear nodules. Generally not sensitive to disturbance. Movement typical of genus, usually gliding on substrate. When swimming, slowly turning around its longitudinal axis for only a short while. (ref. ID; 4942)
[Oral structure]: Genus specifically, two densely ciliated perioral kineties (PK1, PK2), one each on the right and left of cytostome extending to the posterior end of the cell, 80% of kinety lengths consist of dikinetids. No typical PK3 present as commonly seen in Litonotus or Loxophyllum (Foissner 1984; Song & Wilbert 1989) though always some basal body pairs are observed near PK2. Nematodesmata long and strongly developed, originating from perioral kinetids and extending to about middle of the cell length. (ref. ID; 4942)
[Somatic ciliature]: Somatic ciliature genus-specific. All somatic kineties (20-27 excluding the perioral kinety) on right side being relatively densely ciliated, among which the central ones are anteriorly shortened and thus make an anterior suture. On the left side, all kineties of full body length and cilia much more loosely arranged. Dorsal brosse (DK) composed of close-set basal body pairs, terminating about 1/2 of cell length and continuous posteriorly with a row of monokinetids. (ref. ID; 4942)
Comments; A. marinus was originally found in the North Sea, Germany by Kahl (1931) and reported under the name of Hemiophrys marina. It was transferred into the present genus because Hemiophrys is a junior synonym of Amphileptus (Foissner, 1984; Aescht, 2001). Since then, it was only once redescribed, by Borror (1963), but the infraciliature remained unknown. We identify our population (Chinese population) mainly from the following characters, as described originally: (1) several contractile vacuoles on ventral side in the posterior half of cell, which is a reliable and critical feature for species identification as known as present: (2) general body shape and living appearance (e.g no grooves or ridges on the left side): (3) the large size, though Kahl's population was slightly smaller, i.e. 150-300 um; (4) presence of two macronuclei and (5) marine habitat. The only difference, compared with the original descriptions, is the distribution of extrusomes: in the German form, as depicted by Kahl (1931) the extrusomes are arranged only along the cytostome area (no written details were included), i.e. extending to about mid-length of the cell (vs. continuously all along the ventral side in the Chinese population). Nevertheless, we suppose that Kahl possibly did not correctly illustrate this feature, because the extrusomes are rather inconspicuous in vivo as we noticed in the Chinese population (recognizable only under high magnification) and might have been overlooked by Kahl (1931). Thus, it is permissible to consider both forms conspecific. Borror (1963) found the present species [called Litonotus marina (Kahl, 1931)] in sand from Alligator Harbor, Florida, USA. As to his description, the US-population is "...300 x 70-100 um, right side flat, left side flat anteriorly, humped posteriorly, semicircular in cross section. Cilia arising from 27-38 longitudinal shallow furrows 3-4 um apart on flat surface. All but the outer 5-6 meridians anastomosing along midline of flat surface, both anteriorly and posterior ... Trichocysts 10 um long, free in anterior endoplasm, fixed near cytostome. Contractile vacuoles about 10 um in diameter scattered through endoplasm...". The main dissimilarities are the distribution of (1) extrusomes ("trichocysts") in his form, which are, like those in the original report, located only in the portion of the cytostome rather than along the whole ventral side, (2) the contractile vacuoles: as Borror depicted, the CV in the US population are scattered in the posterior half of the body (vs. on the ventral side in both the original and the Chinese population) and (3) the appearance of the suture of the right side: in the former, it seems to have both anterior and posterior sutures, while in our population, the suture is present only in the anterior cell part. We basically agree with Borror's identification. Considering the fact the only the Chatton-Lwoff method was applied for the fixed materials, we suppose that the presence of the posterior suture and the "sparse" distribution of the contractile vacuoles in the US population are possibly misinterpreted (? from life this structure is hard to detected when the cell is highly granulated). Similarly, the distribution of extrusomes is also an artifact interpretation: for the anterior part is flat and easy to observe. (ref. ID; 4942)
Comparison with its congeners; Up to now, about 10 Amphileptus-like morphotypes with 2-Ma and 150 um or more in non-extended length have been described from various habitats, but only a few of them were found in marine biotopes (Borror, 1963; Fryd-Versavel et al., 1975; Wilbert & Kahan, 1981; Dragesco & Dragesco-Kerneis, 1986; Song, 1991). Compared with the morphologically similar Amphileptus litonotiformis Song, 1991, which was found from the same biotope (Song, 1991), A. marinus is identified by having several contractile vacuoles (vs. one at the posterior end in A. litonotiformis), relatively larger size (200-450 vs. 150-250 um), bar-like extrusomes (vs. thick nail-like) and lower number of somatic kineties on both sides (12 left and 25 right kineties on average vs. 8-10 left and c. 20 right ones respectively). It is also different from congeners found in fresh water, A. pleurosigma (Stokes, 1884), A. procerus (Penard, 1922), Hemiophrys meleagris (Ehrenberg, 1835), Lionotus (Hemiophrys) pectinata Kahl, 1926 and Lionotus (Hemiophrys) rotunda Kahl, 1931. The present organism can be recognized from the following combined characters: shape and arrangement of extrusomes, number and location of contractile vacuoles, habitat and body shape (Kahl, 1926, 1931; Fryd-Versavel et al., 1975; Foissner 1984; Song & Wilbert, 1989). Morphologically, A. marinus is possibly also similar to the freshwater form, L. (H.) rotunda Kahl, 1931, of which the infraciliature remains unknown. They can be separated, nevertheless, because the former is a marine form, much larger (200-450 vs. 160-200 um) and has long needle-like extrusomes arranged along the whole ventral side (vs. short and within cytoplasm only). In addition, the presence of a connecting collecting channel between contractile vacuoles also seems characteristic in L. (H.) rotunda Kahl, 1931. (ref. ID; 4942)
Type specimens; Since no silver impregnated specimens have been preserved before, one permanent slide of protargol prepared material as a neotype is deposited in the Natural History Museum, London, UK (Registration No. 2003:4:24:1). (ref. ID; 4942)
Amphileptus parafusidens Song & Wilbert, 1989 (ref. ID; 4942)
Description; This species is diagnosed by small size (40-90 um in length in vivo), being non-flexible and planktonic, possessing a long and column-like neck; cells conspicuously stable (form-constant) in shape and only slightly flattened bilaterally; about 10 somatic kineties on the right side and 4-5 on the left; 2 macro- and 1 micro-nuclei; few thick spindle-shaped extrusomes, which do not form a so-called apical group but distributed sparsely within the cytoplasm; single contractile vacuole positioned subcaudally near the ventral side. In their monograph, Foissner et al. (1995, pp 303-308) considered this species and A. meiianus Song & Wilbert, 1989 supposed junior synonyms of L. punctatus Kahl, 1926, which is, as originally described, characterized by: "... 80 um, aussergewohnlich kontracktil und metabolish wuhlend. Acht tiefe Furchen mit dichten, langen Wimpern, am Munde noch langer bewimpert, dorsal deutlich Borsten. Kern-teile kugelig, Plasma dicht gekornt. Eine etwas dorsal nahe dem hinteren Pol liegende Vakuole..." (Kahl, 1926). Although no details of infraciliature are available, L. punctatus can be separated from A. parafusidens by the following points: (1) body highly contractile and flexible (vs. form-constant and non-contractile even in the long neck part, i.e. very shape-consistent in a given individual in A. parafusidens, although the latter could be relatively more slender or plump in bigger and smaller cells, namely, body differences can be seen only among individuals); (2) presence of eight conspicuous longitudinal furrows on right side in L. punctatus as emphasized by Kahl (1926) (vs. no conspicuous furrows detected in the latter); (3) considerably broader body shape with no definite neck portion (vs. remarkably slender, always with a long, column-like and non-contractile neck in A. parafusidens); (4) cytoplasm highly granulated (vs. always highly transparent and colorless in A. parafusidens). As the drawings originally depicted, L. punctatus should be similar to a Litonotus, i.e. it has a compressed thin cytostome margin, which is definitely not seen in A. parafusidens. In addition, A. parafusidens is evidently a true "pelagic" form, always wandering in the water and has never been observed attached to the bottom or crawling on the debris (even when pressed by the coverglass during observation). It was isolated repeatedly (not in abundance) in spring and early summer and it is easily recognized by its motile behavior: medium fast, swimming continuously straight ahead, swinging slightly and spiraling along its longitudinal axis. This species is not very sensitive to the coverglass and contractility was never observed. In 1984, Foissner described a morphotype under the name of Amphileptus punctatus (Kahl, 1926) [basonym: Lionotus (Hemiophrys) punctata Kahl, 1926] with 18-25 somatic kineties on the right and 4-6 on the left side. Considering the extremely higher number of ciliary rows (vs. 8 in original), the conspicuous suture on right side (vs. inconspicuous in original) and some other different features in vivo, e.g. the long neck and ventrally positioned contractile vacuole (Foissner, 1984), we agree that it could not be conspecific with L. (H.) punctata as also noticed by Foissner et al. in their subsequent work (Foissner et al., 1995) because, as known today, the number of somatic kineties is rather stable in small pleurostomatids (Foissner, 1984: Song & Wilbert, 1989, 2002; Song, 1991). In addition, A. punctatus sensu Foissner, 1984 shows a very distinct suture, which is clearly different from that in L. (H.) punctata (Kahl, 1926, 1931). Thus, as a conclusion derived from the above facts, the species A. parafusidens Song & Wilbert, 1989 should be considered a valid and well-outlined taxon. The highly contractile form, L. punctatus Kahl, 1926 remains unclearly defined and needs new descriptions using modern methods, while the "population" of A. punctatus sensu Foissner, 1984 represents very possibly a distinct but unknown species. (ref. ID; 4942)
Type locality; Isolated from a eutrophic pond in Bonn, Germany (Song & Wilbert, 1989). (ref. ID; 4942)
Amphileptus punctatus (Kahl, 1926) Foissner, 1984 (ref. ID; 4612, 4942) reported author and year? (ref. ID; 1629)
Syn; Lionotus punctatus Kahl, 1926 (ref. ID; 4612)
Description; See the description of Amphileptus parafusidens. (ref. ID; 4942)