title: Morphological and molecular characterization of the name-bearing type species Rimaleptus binucleatus (Kahl, 1931), with a phylogenetic re-analysis of dileptid evolutionary history (Ciliophora: Litostomatea: Rhynchostomatia).
abstract: We collected Rimaleptus binucleatus from soil in the surroundings of the town of Ulsan, South Korea. Its morphology and 18S rRNA gene were studied using standard methods. This possibly widely distributed species is characterized by: (i) a size of about 170-400×20-65μm; (ii) a narrowly to cylindrically dileptid body with proboscis occupying about 30-65% of body length; (iii) two dorsal contractile vacuoles; (iv) two size groups of rod-shaped extrusomes; and (v) about 18-29 ciliary rows, 4-6 of them anteriorly differentiated into a staggered dorsal brush. Phylogenetic analyses of five new rhynchostomatian 18S rRNA gene sequences supported monophylies of the orders Tracheliida and Dileptida, but revealed that the genera Rimaleptus and Pseudomonilicaryon are polyphyletic. Monophyly of genera with two macronuclear nodules was consistently rejected, but monophylies of dileptids with many scattered macronuclear nodules and of dileptids with moniliform macronucleus and multi-rowed dorsal brush could not be excluded by statistical topology tests. Nevertheless, phylogenetic network analyses indicated considerable conflict in the phylogenetic signal provided by the 18S rRNA gene to resolve unambiguously relationships among dileptid genera.
authors.affiliation: Department of Biological Science, College of Natural Sciences, University of Ulsan, Ulsan 680-749, South Korea.
authors.forename: Seok Won
authors.initials: SW
authors.lastname: Jang
authors.affiliation: Department of Zoology, Faculty of Natural Sciences, Comenius University, Mlynská dolina B-1, 842 15 Bratislava, Slovak Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Vďačný
authors.affiliation: Department of Biological Science, College of Natural Sciences, University of Ulsan, Ulsan 680-749, South Korea.
authors.forename: Shahed Uddin Ahmed
authors.initials: SU
authors.lastname: Shazib
authors.affiliation: Department of Biological Science, College of Natural Sciences, University of Ulsan, Ulsan 680-749, South Korea. Electronic address: mkshin@ulsan.ac.kr.
authors.forename: Mann Kyoon
authors.initials: MK
authors.lastname: Shin
mesh_terms: D016798:Ciliophora / Q000145:classification / Q000166:cytology / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D056910:Republic of Korea; D012987:Soil / Q000469:parasitology*; D013045:Species Specificity
chemical_list: D012337:RNA, Ribosomal, 18S; D012987:Soil
keywords: 18S rRNA gene; Dimacrocaryonidae; Korea; Morphometry; Nomenclature; Pseudomonilicaryon