Morphologic and genetic variability in the marine planktonic ciliate Laboea strobila Lohmann, 1908 (Ciliophora, Oligotrichia), with notes on its ontogenesis

Laboea strobila Lohmann, 1908 is a conspicuous oligotrich ciliate in the marine plankton. In order to compare different populations, the morphology of specimens from the Mediterranean Sea, North Sea, and Irish Sea was investigated using live observation, protargol impregnation, and scanning electron microscopy. Furthermore, the PCR-amplified products of the SSrRNA gene from a monoclonal culture of L. strobila from the Mediterranean Sea were sequenced and aligned with sequences of other oligotrichs, including a population of L. strobila from the Atlantic coast of the USA. Finally, the data from the ecological literature were summarized and the cultivation methods were described. The SSrRNA gene sequences of the two distantly located L. strobila populations from the North Atlantic are identical. Likewise, the morphometrics of most populations so far investigated after protargol impregnation (i.e. from the North Atlantic) do not show obvious differences. In all computed phylogenetic trees, L. strobila groups with Strombidium species, forming a monophyletic taxon corresponding to the subclass Oligotrichia. These results are corroborated by the ontogenetic comparison. Since no type species was fixed for Laboea Lohmann, 1908, L. strobila was designated in the present paper.     

Revision of the Genus Askenasia Blochmann, 1895, with Proposal of Two New Species, and Description of Rhabdoaskenasia minima N. G., N. Sp. (Ciliophora, Cyclotrichida)

ABSTRACT. The planktonic ciliate genus Askenasia Blochmann, 1895 is reviewed and the new genus Rhabdoaskenasia n. gen. is established. Askenasia is characterized by three circumferential kinety belts and a circumoral wreath of paired argyrophilic granules without recognizable cilia and nematodesmata. A "brush" is absent. Askenasia apparently lacks the key characters of the Haptorida and is thus transferred to the Cyclotrichida, family Mesodiniidae. Rhabdoaskenasia differs from Askenasia in having single files of basal bodies in all kinety belts and club-shaped extrusomes. It possesses a circumoral kinety composed of dikinetids from which nematodesmata originate, forming a distinct rhabdos. Although very similar to Askenasia in its general appearance, R. minima n. sp. could belong to another order. Based on an extensive review of the literature and on silver impregnated specimens the following Askenasia species are recognized and described in detail: A. volvox (Eichwald, 1852) Kahl, 1930, A. stellaris (Leegaard, 1920) Kahl, 1930, A. acrostomia n. sp., and A. chlorelligera n. sp. Askenasia faurei Kahl, 1930 and A. humilis Gajewskaja, 1928 are transferred to the genus Cyclotrichium: C. faurei (Kahl, 1930) n. comb., C. humilis (Gajewskaja, 1928) n. comb. The systematic position of the genus Askenasia is discussed and keys to the genera of the Mesodiniidae and to the species of Askenasia are provided.     

Description and Phylogeny of Urostyla grandis wiackowskii subsp. nov. (Ciliophora,Hypotricha) from an Estuarine Mangrove in Brazil

Interphase specimens, aspects of physiological reorganization and divisional morphogenesis were investigated in a strain of a hypotrichous ciliate highly similar to Urostyla grandis Ehrenberg, 1830 (type species of Urostyla), collected from a mangrove area in the estuary of the Paraíba do Sul river (Rio de Janeiro, Brazil). The results revealed that albeit interphase specimens match with the known morphologic variability in U. grandis, morphogenetic processes have conspicuous differences. Parental adoral zone is entirely renewed during morphogenesis, and marginal cirri exhibit a unique combination of developmental modes, in which left marginal rows originate from multiple anlagen arising from innermost left marginal cirral row, whereas right marginal ciliature originates from individual within‐row anlagen. Based on such characteristics, a new subspecies, namely U. grandis wiackowskii subsp. nov. is proposed, and consequently, U. grandis grandis Ehrenberg, 1830 stat. nov. is established. Bayesian and maximum‐likelihood analyses of the 18S rDNA unambiguously placed U. grandis wiackowskii as adelphotaxon of a cluster formed by other U. grandis sequences. The implications of such findings to the systematics of Urostyla are discussed.     

Morphology of two marine euplotids (Ciliophora: Euplotida), Aspidisca fusca and A. hexeris,with notes on their small subunit rRNA gene sequences

We investigate the living morphology, infraciliature, and small subunit rRNA gene sequences of two poorly known marine euplotids, Aspidisca fusca Kahl, 1928 and A. hexeris Quennerstedt, 1869, isolated from intertidal sewage outfall, northern China and sandy sediments, southern China, respectively. Improved diagnoses and morphometric data are provided for both species. Aspidisca fusca is characterized by having a peristomial spur, seven frontoventral cirri in a “polystyla-arrangement”, and two oval macronuclear nodules. Aspidisca hexeris can be recognized by having an elliptical body shape, a peristomial spur, seven membranelles in the anterior portion of adoral zone and 11–13 in the posterior part, as well as seven frontoventral cirri arranged in two oblique rows. In addition, the presence and degree of projections along the left margin of A. hexeris are highly variable among populations. Phylogenetic analyses based on small subunit rRNA gene sequence data support the validity of both A. hexeris and A. fusca as distinct species, and indicate that A. fusca is most closely related to A. aculeata and A. steini, whereas A. hexeris shows a close relationship with A. magna.     

Description of Four New Soil Dileptids (Ciliophora, Haptoria), with Notes on Adaptations to the Soil Environment

We studied the morphology of four new dileptid ciliates, using standard methods. Dileptus microstoma, which was discovered in Benin (Africa), is outstanding in having a very small oral opening (~4 μm), an interrupted dorsal row of contractile vacuoles, and ampulliform extrusomes. Dileptus semiarmatus, which was discovered in Austria, possesses extrusomes only in the right posterior half of the proboscis and has very widely spaced circumoral and perioral kinetids. Dileptus longitrichus, which was discovered in Japan, is almost unique in having up to 15 μm long brush bristles and a row of contractile vacuoles each in ventral and dorsal side of body. Pseudomonilicaryon brachyproboscis, which was discovered in Greece, differs from the congeners by the narrowly ellipsoidal micronuclei, the dimorphic dorsal brush, the extrusomes, and the contractile vacuole pattern. Four new features are introduced for distinguishing species in dileptids: shape of micronucleus, monomorphic/dimorphic dorsal brush, shape of oral opening, and spacing of circumoral dikinetids. The terrestrial dileptids share several distinct morphological features that are probably adaptations to the soil environment: (1) the body is comparatively slender and small, what is likely related to the narrowness of the habitat; (2) the proboscis is short, which increases the relative volume of the trunk, what might be related to its fragility and/or to the space available for prey digestion; (3) the long dorsal bristles might foster prey recognition; and (4) the pronounced body flexibility in all dileptids likely fosters their high diversity in the narrow and wrinkled soil habitat.     

Establishment of a new amphileptid genus, Apoamphileptus nov. gen. (Ciliophora, Litostomatea, Pleurostomatida), with description of a new marine species, Apoamphileptus robertsi nov. spec. from Qingdao, China

A new pleurostomatid genus Apoamphileptus is described, which is diagnosed as: Belonging to the Amphileptidae with spica on right side; on each side of the cell, a single perioral kinety, which encircles the cytostome and does not extend to the posterior end of the cell; somatic kineties of both sides near ventral margin shortened and forming a postoral suture; two to several extra fragments with densely arranged dikinetids located in anterior portion of left side. As the type species, the morphology and infraciliature of Apoamphileptus robertsi nov. spec., isolated from a shrimp-farming pond near Qingdao (Tsingtao), China, have been investigated using living observations and the protargol silver impregnation method. The diagnosis for this new species is: Apoamphileptus 90-180 x 30-60 microm in vivo, body elongate pyriform-shaped and slightly flattened; with one cross-striated band along the cytostome; 2-6 (generally 4) large macronuclear nodules, one micronucleus; 33-43 right somatic kineties; left side 6-8 kineties; two extra anterior fragments on left side; about 13 contractile vacuoles dispersed throughout whole body; extrusomes absent or not recognizable; marine habitat. Some morphologically related morphotypes are discussed and tabulated. Regarding the pattern of infraciliature and other morphological features, the well-described fresh-water species, Amphileptus claparedii Stein, 1867 is believed to be a member of this new genus, hence a new combination is suggested: Apoamphileptus claparedii (Stein, 1867) nov. comb.     

Descriptions of Protospathidium serpens (Kahl, 1930) and P. fraterculum n. sp. (Ciliophora, Haptoria), two species based on different resting cyst morphology

Protospathidium serpens (Kahl, 1930) is frequent in semiterrestrial and terrestrial habitats worldwide. Conventionally, all populations are considered as conspecific because they have very similar overall morphologies and morphometrics. We studied in detail not only the morphology of the vegetative cells but also the resting cysts using live observation, protargol impregnation, and scanning electron microscopy. These revealed a cryptic diversity and biogeographic pattern in details of the dorsal brush and cyst wall morphology. The cyst wall is spiny in the Austrian specimens, while smooth in the South African and Antarctic populations. Accordingly, P. serpens consists of at least two species: P. serpens (with spiny cyst wall) and P. fraterculum n. sp. (with smooth cyst wall); the latter is probably composed of two distinct taxa differing by the absence (South African)/presence (Antarctic) of a monokinetidal bristle tail in brush row 3, the number of dikinetids comprising brush row 1 (seven versus three), and the total number of brush dikinetids (29 versus 17). Protospathidium serpens is neotypified with the new population from Austria. The significance of resting cyst morphology is discussed with respect to alpha-taxonomy and overall ciliate diversity.     

Morphology,Morphogenesis, and Phylogeny of Urosoma caudata (Ehrenberg, 1833) Berger, 1999 (Ciliophora,Hypotrichia) based on a Chinese Population

We report the morphology and morphogenesis of Urosoma caudata (Ehrenberg, 1833) Berger, 1999 based on in vivo observation and protargol impregnation and provide an improved diagnosis of U. caudata based on previous and current work. Urosoma caudata differs from its congeners mainly by the combination of the following features: tail‐like posterior end, colorless cortical granules, and two macronuclear nodules. Urosoma caudata shares most of the ontogenetic features with its congeners: the oral primordium of the opisthe develops apokinetally, and the frontal‐ventral‐transverse cirral anlagen develop in five streaks. However, a unique morphogenetic characteristic is recognizable: the anlagen of three dorsal kineties occur de novo to the left of the parental structures differing from their intrakinetal origin in other Urosoma species. The first record of the 18S rRNA gene sequence for the species is also provided. Phylogenetic analyses based on 18S rRNA gene sequence data suggest that the genus Urosoma is a nonmonophyletic group.     

Morphological description of three marine ciliates (Ciliophora, Scuticociliatia), with establishment of a new genus and two new species

Three marine scuticociliates, Falcicyclidium fangi nov. gen., nov. spec., Falcicyclidium atractodes nov. spec., and Cristigera media Kahl, 1928 were investigated using live observation and silver impregnation methods. The genus Falcicyclidium is distinguished by the combination of: (i) dorsoventrally flattened body, (ii) hook-like (falciform) paroral membrane, (iii) anterior end of paroral membrane posterior to anterior end of membranelle 1, and (iv) multiple caudal cilia. Falcicyclidium fangi nov. spec., the type of the new genus, can be recognized by the combination of its large size, extremely dorsoventrally flattened (3:1) body, consistently 10 somatic kineties, and the broad, elongate buccal area occupying 60% of the body length. Falcicyclidium atractodes nov. spec. is mainly characterized by a unique spine projecting from both the anterior and posterior end. The uncommon form, Cristigera media is redescribed based on the population from Qingdao, the statistic data and additional features, especially the morphology of the living cells, are documented.     

Morphology and molecular phylogeny of two new brackish-water species of Amphisiella (Ciliophora,Hypotrichia), with notes on morphogenesis

Two new species of the taxonomically confused genus Amphisiella were isolated from brackish-water habitats in southern China, and their morphology and morphogenesis were investigated. The genes coding for small subunit (SSU) rRNA were sequenced in each species and included in a phylogenetic analysis with all data available from nominal species of Amphisiella and related hypotrichs. Both new species are diagnosed by an elongate body shape, yellow-brown/grey-brown cell color, one kind of cortical granule, and two macronuclear nodules. The cortical granules in A. pulchra sp. n. are grouped in small clusters which are irregularly distributed both ventrally and dorsally; in A. candida sp. n., they are irregularly and sparsely distributed ventrally and form longitudinal stripes dorsally. The ontogenetic processes of both species show similarities to those of other congeners. Phylogenetic trees based on SSU rRNA gene sequences suggest that the family Amphisiellidae is a paraphyletic assemblage. The results further demonstrate that two isolates identified as Amphisiella annulata (DQ832260 and GU170843) are very likely cryptic species, and a sequence identified as A. milnei (DQ845293) may belong to a genus other than Amphisiella.     

Two new species of Epistylis (Ciliophora: Peritrichida) on the blue crab (Callinectes sapidus) in the Gulf of Mexico

Two epibiotic peritrichs infested the blue crab, Callinectes sapidus, from the Gulf of Mexico, Mississippi, USA. Epistylis callinectes n. sp. was isolated from the epipods of maxillipeds, bases of gill-cleaning setae, and gills, and Epistylis clampi n. sp. was isolated from the exterior surfaces of the exoskeleton. Epistylis callinectes has short, symmetrically and dichotomously branched stalks; its zooid is elongate ovoid and conspicuously longer than the individual stalk branches, measuring 40-57 (49) x 18-33 (26) microm in vivo and containing a thick, undivided peristomial lip (PL). It has a single contractile vacuole and a transverse horseshoe-shaped macronucleus. Its haplokinety (H) and polykinety (Po) complete one and one-half circuits on the peristome before entering the infundibulum. There is a distal kinetal fragment present at the distal end of both the H and Po. Epistylis callinectes has 48-70 transverse silverlines from the oral area to the trochal band (TB) and 19-26 from the TB to the scopula. Epistylis clampi has long, asymmetrically, and dichotomously branched stalks. Its zooid is elongate vase-shaped, measuring 35-64 (48) x 21-30 (27) microm in vivo and with a thick, transversely folded PL. The stalks supporting zooids are unequal in length. Its zooid has a single contractile vacuole and a transverse horseshoe-shaped macronucleus occurs in the upper half of the body. Its H and Po complete approximately one circuit around the peristome before entering the infundibulum. There is a distal kinetal fragment present at the distal end of both the H and Po. This species has 71-112 transverse silverlines from the peristome to the scopula.     

Morphology and morphogenesis of a new marine hypotrichous ciliate (Protozoa,Ciliophora, Pseudoamphisiellidae), including a report on the small subunit rRNA gene sequence

The morphology and morphogenesis of a new marine hypotrichous ciliate Pseudoamphisiella elongata sp. nov. isolated from mussel‐farming waters near Qingdao, China, are described based on living and protargol‐impregnated specimens. Morphologically, the new species can be distinguished from its known congeners by its elongate body shape, narrow oral field, having fewer dorsal kineties and caudal cirri, more marginal cirri, and differentiated pretransverse cirri. The identification as a new species is firmly supported by the sequences of the small subunit ribosomal rRNA (SSU rRNA) gene, compared with other known Pseudoamphisiella species, and the phylogenetic analysis. The morphogenetic characteristics can be summarized as follows: (1) the parental adoral zone of membranelles and undulating membranes are entirely rebuilt by the oral primordium, which develops de novo in the outermost region of the cortex; (2) the oral primordium in the opisthe and the frontoventral–transverse (FVT) anlagen in both dividers are formed independently on the cell surface; (3) an ‘extra’ marginal anlage originates to the right of the right marginal anlage, and develops into two or three ‘extra’ marginal cirri; (4) the FVT anlagen develop in the primary mode, and the last FVT streak contributes two migratory cirri (frontoterminal cirri), which are probably resorbed; (5) the right marginal anlagen in both dividers occur close together, independent of the old structure. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 231–243.     

Description of a new Homidia species (Collembola,Entomobryidae) from Korea

A new species, Homidia pseudoformosana from Korea is described in the present paper. The new species is characterized by labral papillae, ciliated labial seta L₁ and dorsal chaetotaxy of abdominal segment IV. The detailed differences between similar Homidia species are provided.