title: New phagotrophic euglenoid species (new genus Decastava; Scytomonas saepesedens; Entosiphon oblongum), Hsp90 introns, and putative euglenoid Hsp90 pre-mRNA insertional editing.
abstract: We describe three new phagotrophic euglenoid species by light microscopy and 18S rDNA and Hsp90 sequencing: Scytomonas saepesedens; Decastava edaphica; Entosiphon oblongum. We studied Scytomonas and Decastava ultrastructure. Scytomonas saepesedens feeds when sessile with actively beating cilium, and has five pellicular strips with flush joints and Calycimonas-like microtubule-supported cytopharynx. Decastava, sister to Keelungia forming new clade Decastavida on 18S rDNA trees, has 10 broad strips with cusp-like joints, not bifurcate ridges like Ploeotia and Serpenomonas (phylogenetically and cytologically distinct genera), and Serpenomonas-like feeding apparatus (8-9 unreinforced microtubule pairs loop from dorsal jaw support to cytostome). Hsp90 and 18S rDNA trees group Scytomonas with Petalomonas and show Entosiphon as the earliest euglenoid branch. Basal euglenoids have rigid longitudinal strips; derived clade Spirocuta has spiral often slideable strips. Decastava Hsp90 genes have introns. Decastava/Entosiphon Hsp90 frameshifts imply insertional RNA editing. Petalomonas is too heterogeneous in pellicle structure for one genus; we retain Scytomonas (sometimes lumped with it) and segregate four former Petalomonas as new genus Biundula with pellicle cross section showing 2-8 smooth undulations and typified by Biundula (=Petalomonas) sphagnophila comb. n. Our taxon-rich site-heterogeneous rDNA trees confirm that Heteronema is excessively heterogeneous; therefore we establish new genus Teloprocta for Heteronema scaphurum.
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK. Electronic address: tom.cavalier-smith@zoo.ox.ac.uk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Cavalier-Smith
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
authors.forename: Ema E
authors.initials: EE
authors.lastname: Chao
authors.affiliation: Division of Environmental and Evolutionary Biology, University of Glasgow, Glasgow C12 8QQ, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Vickerman
mesh_terms: D004275:DNA, Ribosomal / Q000235:genetics; D016822:Euglenida / Q000145:classification / Q000166:cytology* / Q000235:genetics*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics*; D007438:Introns / Q000235:genetics; D010802:Phylogeny; D017393:RNA Editing / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal; D018841:HSP90 Heat-Shock Proteins; D012322:RNA Precursors
keywords: 18S rRNA phylogeny; Biundula; Decastavida; Hsp90 phylogeny; Spirocuta; Teloprocta