Chen Shao

The urostylid family Pseudokeronopsidae Borror and Wicklow, 1983 was considered to be a well-outlined taxon. Nevertheless, recent evidence, including morphological, ontogenetic, and molecular information, has consistently revealed the polyphyly of this family. In the present work, a new population of Thigmokeronopsis stoecki Shao et al., 2008 was found and its binary divisional process was described for the first time. In addition, the morphogenetic features of Thigmokeronopsis species and all the other pseudokeronopsids, for which detailed ontogenetic data are available, were rechecked and compared. This reveals that: (1) the ontogenetic process of T. stoecki corresponds well with its congeners T. jahodai and T. rubra except for the macronuclear behavior; (2) Apokeronopsis and Thigmokeronopsis share a similar ontogenetic mode despite of the differences in the number and origin of their buccal cirri; (3) most pseudokeronopsids share the same pattern in the origins of their oral primordia and fronto-ventral-transverse cirral anlagen, except for Pseudokeronopsis similis, which may not be a valid member of the family Pseudokeronopsidae.
 

In 1988, we found a large (250–400 × 80–150 μm in protargol preparations) Uroleptus-like hypotrich in a freshwater pond in Harbin, China. We studied the morphology of non-dividers and the cell division using protargol impregnation. Since we disregarded live observations and due to the lack of a modern revision of the uroleptids, a final identification was not possible. A detailed comparison with the most similar limnetic Uroleptus-like hypotrichs and with Rigidothrix goiseri revealed that the Chinese population is very likely identical with Uroleptus magnificus [basionym Holosticha (Paruroleptus) magnificus Kahl, 1932], a very rare species possibly confined to limnetic, stagnant water bodies of the holarctic region. Besides the large size, main features of U. cf. magnificus are: (i) about 80 adoral membranelles; (ii) three or four inconspicuous transverse cirri; (iii) 5–8 dorsomarginal kineties; (iv) the oral primordium originates de novo left of the postoral midventral cirri; (v) the frontal-ventral-transverse cirri anlagen of the proter and the opisthe originate via primary primordia; (vi) the left frontal cirrus of the proter originates from the middle portion of the disorganizing parental paroral; (vii) the parental endoral becomes the undulating membrane anlage for the proter; and (viii) the frontoterminal cirri originate in the plesiomorphic manner, that is, from the rearmost anlage. A compilation reveals that 59 species, subspecies, etc. have been described in or assigned to Uroleptus and Paruroleptus, but only about 50% of them seem to be true uroleptids. Many species of this predominantly limnetic group are little known.

The morphology and morphogenesis of the hypotrich ciliate Urosoma macrostyla (Wrześniowski, 1866) Berger, 1999, collected from a puddle in Harbin, China, were investigated using live observation and protargol impregnation. Based on previous and present studies, an improved diagnosis of U. macrostyla is supplied. It differs from its congeners mainly by the body shape, no cortical granules and number of macronuclear nodules. The ontogenesis of U. macrostyla is typical for species with such a somatic ciliary pattern: the oral primordium develops hypoapokinetally and FVT-anlagen develop in 5-streaks and primary mode. However, a unique characteristic in morphogenetic process is reported: anlagen for both the left and right marginal cirri occur de novo to the right of the parental structure which has never been seen in other oxytrichids. This characteristic was considered an apomorphy (Berger 1999). This indicates that U. macrostyla possibly has a high phylogenetic position within the genus Urosoma, or perhaps it represents a distinct subgenus.

Euplotes balteatus (Dujardin, 1841) Kahl 1932, collected from coastal waters near Qingdao, northern China, was investigated using live observation and silver staining methods. An improved diagnosis and morphometric data are provided. Euplotes balteatus can be identified by the following combination of characters: 10 frontoventral cirri, 2 widely separated marginal cirri, 2 fine caudal cirri, 8 dorsal kineties and a double-eurystomus type silverline system. Its morphogenesis, which is similar to that of several congeners, can be summarized as follows: (1) the opisthe’s oral primordium appears de novo under the pellicle whereas the old oral apparatus is retained by the proter; (2) two groups of frontoventral transverse cirral anlagen, each with five streaks, occur de novo and then develop into the frontoventral and transverse cirri separately according to the formula of “3:3:3:3:2” from left to right; (3) the anlagen for the marginal cirri occur de novo near the parental oral apparatus; (4) migratory cirri of both dividers derive from the anlagen near the paroral membrane; (5) the dorsal kinety anlagen come from dedifferentiation of the parental structures in the mid-body region; (6) caudal cirri are formed at the posterior ends of the two rightmost dorsal kineties. In the light of the present findings, it was concluded that the Antarctic population of E. balteatus reported by Song and Wilbert (2002) was misidentified. A new species, Euplotes wilberti nov. spec., is established for this population.

The morphology, the infraciliature, and two stages of physiological reorganization of Hemigastrostyla elongata spec. nov.,isolated from the Yellow Sea near Qingdao (China), are described. The new species differs from the type H. stenocephala, inter alia, by the length of the dorsal bristles and the position of the pretransverse ventral cirri; from H. enigmatica by the number of caudal cirri; and from H. para-enigmatica spec. nov. – established for the H. enigmatica populations from the Yellow Sea – by the arrangement of the postoral ventral cirri and the cortical granulation. A key to the Hemigastrostyla species and some other 18-cirri hypotrichs is provided. Hemigastrostyla szaboi is fixed as type species of Heterooxytricha gen. nov. because the type population lacks the extra cirri which are characteristic for Hemigastrostyla. In addition, Oxytricha geleii is assigned to this new genus, whose species have, like many oxytrichids, 18 frontal-ventraltransverse cirri, but a Gonostomum dorsal kinety pattern. The old, large, and difficult genus Oxytricha is briefly reviewed, mainly on the basis of the dorsal kinety pattern. Very likely, only species with the Oxytricha pattern belong to this genus. Oxytricha marcili and O. pseudofurcata, which have the Urosomoida kinety pattern (i.e. kinety 3 fragmentation lacking), are transferred to Urosomoida which is, inter alia, defined by a more or less distinctly reduced number of ventral and transverse cirri. Some other Oxytricha species with this kinety pattern (O. islandica, O. lanceolata, O. pseudosimilis, O. setigera) are not transferred to Urosomoida, but preliminarily classified as incertae sedis in Oxytricha, because they have the full set of 18 cirri. The available molecular data on O. lanceolata indicate that this type of 18-cirri hypotrichs likely needs a genus of its own because O. lanceolata does not cluster with O. granulifera, type of this genus. The marine Actinotricha saltans, classified for a very long time in Oxytricha, seems to be a non-dorsomarginalian hypotrich according to molecular data, justifying the reactivation of the old genus Actinotricha. Oxytricha shii has a multiple dorsal kinety 3 fragmentation, three dorsomarginal rows, and the undulating membranes arranged in the Cyrtohymena pattern, strongly indicating that it is a member of the subgenus Cyrtohymena (Cyrtohymenides). This brief review is a further step to unravel the complicated systematics of the old, but still little-known genus Oxytricha. The following new combinations are made in this paper: Cyrtohymena (Cyrtohymenides) shii (Shi et al., 1997) comb. nov.; Heterooxytricha szaboi (Wilbert and Song, 2005) comb. nov.; Heterooxytricha geleii (Wilbert, 1986) comb. nov.; Urosomoida marcili (Paiva and Silva-Neto, 2004) comb. nov.; Urosomoida pseudofurcata (Berger, 1999) comb. nov.

The morphology and infraciliature of two marine scuticociliates, Pleuronema puytoraci Grolière and Detcheva, 1974, and Parauronema longum Song, 1995, collected from China, were investigated using live observation and protargol impregnation methods. Based on the data obtained for the China population, new information of the living morphology of Pleuronema puytoraci is documented and details of the complete infraciliature is available for the first time. The stomatogenesis of Parauronema longum is basically similar to that of its congeners and can be summarized as follows: membranelle 1, membranelle 2 and the scutica of the opisthe originate from the parental paroral membrane, whereas membranelle 3 of the opisthe develops from the parental scutica; the paroral membrane originates from the parental paroral membrane.

The morphology, morphogenesis and infraciliature of two marine euplotid ciliates, Euplotes dammamensis n. sp. and Euplotes balteatus (Dujardin, 1841) Kahl, 1932, isolated from a sandy beach of the Arabian Gulf, Saudi Arabia, were investigated using observations in vivo and protargol-impregnation methods. Euplotes dammamensis n. sp. is characterized by a combination of features including its huge body size (100–170 × 80–120 μm), 10 conspicuous dorsal ridges, 10 normal-sized frontoventral and two marginal cirri, and 11 dorsal kineties. Euplotes balteatus is mainly characterized by 10 frontoventral, two caudal, and two left marginal cirri, 7–10 dorsal kineties and 5–7 prominent dorsal ridges as well as double-eurystomus silverline system. The small subunit rRNA (SSU-rRNA) gene sequences were determined for both species and phylogenetic analyses based on these data indicated that E. dammamensis is most closely related to E. parabalteatus Jiang et al., 2010, and E. balteatus clusters with E. plicatum Valbonesi et al., 1997, E. orientalis Jiang et al., 2010, and E. bisulcatus Kahl, 1932.