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Myxosporeans of the genus Ortholinea have a worldwide distribution and infect organs and tissues of exclusively marine fishes. Here we describe the morphological and molecular characteristics of Ortholinea mullusi sp. nov. parasitizing the urinary bladder and kidney tubules of red mullet Mullus barbatus collected from the coastal zone of Sinop in the Black Sea, Turkey. Polysporic plasmodia with immature spores were either elongate, 37.0 ± 4.5 SD (30-50) µm long and 45.0 ± 3.8 (40-55) µm wide, or were round, up to 100.0 µm in diameter. Mature, free spores were spherical in the frontal view and measured 9.3 ± 0.2 (9.0-9.7) µm in length, 8.7 ± 0.3 (8.2-9.3) µm in width and 7.7 ± 0.1 (7.5-7.9) µm in thickness. We observed 2 polar capsules of equal size, which measured 3.1 ± 0.1 (3.0-3.2) µm long by 2.5 ± 0.1 (2.4-2.6) µm wide, and the tips of the polar capsules were open towards the sutural line. The prevalence of infection by O. mullusi sp. nov. was 24.5%. Phylogenetic analysis based on nuclear small subunit ribosomal DNA (SSU rDNA) clearly suggested O. mullusi to be a new species, clustered within a lineage comprising O. labracis and O auratae. Pairwise nucleotide similarities and DNA distance values between O. mullusi sp. nov. and sister Ortholinea species also supported this suggestion.

IntroductionMany coccoid algae are very difficult to identify because of their extremely small size and simple morphology, and they have been referred to as "little green balls" (Callieri and Stockner, 2002). These little green balls have often been reported as Chlorella Beijerinck or Chlorella vulgaris Beijerinck (Fawley et al., 2004). Since C. vulgaris "Beijerinck strain" (SAG 211-11b) was first described and isolated in axenic culture about 120 years ago, Chlorella strains have been used as model organisms in plant physiology and biochemical research (Burja et al., 2001). Furthermore, mass cultures of Chlorella have been used in agriculture as a single cell protein both for humans and animals, in biotechnology as recovery agents for waste treatment, and in biofuel technology as microbial energy producers (Golueke and Oswald, 1964;Fogg, 1971;Soeder, 1976;Abbott and Cheney, 1982).Among the over 100 traditionally defined Chlorella species, a lack of morphological characters led to the adoption of various approaches, including several combinations of physiological, biochemical, and serological studies, for identifying Chlorella species (John et al., 2003). The morphologically-defined species are considered very artificial and house many cryptic taxa. Using molecular data, Huss et al. (1999) demonstrated that only 5 "true" species could be regarded as part of the genus Chlorella. Materials and methods Chlorella isolationsEnvironmental water samples were taken from the

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A total of 101 fungal samples were isolated from tobacco (Nicotiana tabacum L.) plants in Samsun, Turkey and identified as Rhizoctonia solani. Of these samples, three were identified as belonging to Anastomosis Group (AG) -1-IB, 6 to AG-2-1, 25 to AG-4-HG-I and 67 to AG-4-HG-II, using ITS1-5.8S-ITS2 rDNA RFLP analysis, base sequence phylogenies and conventional characters, such as anastomosis reactions, morphology and thiamine requirement. For five isolates from both the AG-4-HG-I and AG-4-HG-II groups and for all isolates of the AG-1-IB and AG-2-1 groups, molecular analysis and pathogenicity tests were performed. All selected Rhizoctonia solani isolates were highly virulent to tobacco plants, causing symptoms resembling damping-off, except for isolate 55TkTB63, which was only moderately virulent.