Cochliopodium megatetrastylus n. sp. is described based on light microscopy, fine structure and molecular genetic evidence. Amoebae are broadly oval to somewhat triangular during locomotion with average length of 37 μm and breadth of 50 μm, and surrounded by a hyaloplasm margin, somewhat narrow when at rest but more expanded during locomotion (~ 5–10 μm at the anterior). Sparsely occurring subpseudopodia, barely emergent from the hyaloplasm, are blunt and finger-like, occasionally becoming adhesive laterally or at the posterior. Cysts develop after 2–3 weeks in culture and are round with a distinct margin, decreasing in size from 20 to 5 μm during maturation. The granuloplasm contains refractile crystals. A vesicular nucleus (~ 6 μm), containing a nucleolus (2–3 μm), is variable in shape from somewhat lenticular in section to irregularly rounded with undulating or lobed margins. Surface scales (~ 0.3 μm in height) have an apical deeply concave funnel-like collar (~ 0.15 μm deep), without a spine, composed of radial fine rays and concentric filaments forming a finemesh, supported on four non-cross-linked styles (~ 0.2 μm apart) attached to a round to broadly angular base plate (0.6–1 μm) with a fine gridtexture. Cysts are rounded and enclosed by an organic wall bearing remnants of the scales on its outer surface. Both concatenated analysis of SSU-rDNA and COI genes and comparative morphologies support the designation of Cochliopodium megatetrastylus n. sp. as a new species.

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.
 

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.

This study used light and electron microscopy to describe a myxosporean, polysporic, histozoic plasmodium infecting the gill filaments of the freshwater teleost, Semaprochilodus insignis, specimens of which were collected from the Trombetas River (Central Amazonian Region, Brazil). Ultrastructural analyses of the fish-infecting spores identified the parasite as Myxobolus insignis, an organism that occurs within whitish unequal-sized plasmodia located in the intralamellar epithelium of the gill. Based on the observed morphological and ultrastructural features of the plasmodia in this study three stages in the plasmodial evolution were distinguished, related to the sporogonic stages of Myxobolus insignis. The plasmodium walls were also found to constitute a number of layers of fibroblasts, surrounded by collagen fibres, which displayed different morphological arrangements according to the different phases of evolution. This represents the first time such ultrastructural features have been described in detail for Myxobolus insignis plasmodia and offers potentially significant points of comparison with plasmodia from other species of myxosporea.
 

A new species of Isospora Schneider (Apicomplexa: Eimeriidae) is described from captive Blue-crowned Laughingthrush Dryonastes courtoisi (Ménégaux, 1923) (Passeriformes: Timaliidae). Sporulated oocysts of Isospora courtoisii n. sp. are ellipsoidal 24.5 × 14.5 μm. Micropyle and oocyst residuum are absent. Sporocysts are broadly ellipsoidal, 15.9 × 8.5 μm, with Stieda and substieda bodies. Sporocyst residuum is scattered composed of hundreds of small granules. Sporozoites are elongate and slightly curved, each with two refractile bodies. The nuclei of the sporozoites were not well discernible. Considering the critically endangered status of Dryonastes courtoisi and assumed high host specificity of described coccidium, also I. courtoisi can be classified as critically endangered organism.