title: Cthulhu Macrofasciculumque n. g., n. sp. and Cthylla Microfasciculumque n. g., n. sp., a newly identified lineage of parabasalian termite symbionts.
abstract: The parabasalian symbionts of lower termite hindgut communities are well-known for their large size and structural complexity. The most complex forms evolved multiple times independently from smaller and simpler flagellates, but we know little of the diversity of these small flagellates or their phylogenetic relationships to more complex lineages. To understand the true diversity of Parabasalia and how their unique cellular complexity arose, more data from smaller and simpler flagellates are needed. Here, we describe two new genera of small-to-intermediate size and complexity, represented by the type species Cthulhu macrofasciculumque and Cthylla microfasciculumque from Prorhinotermes simplex and Reticulitermes virginicus, respectively (both hosts confirmed by DNA barcoding). Both genera have a single anterior nucleus embeded in a robust protruding axostyle, and an anterior bundle flagella (and likely a single posterior flagellum) that emerge slightly subanteriorly and have a distinctive beat pattern. Cthulhu is relatively large and has a distinctive bundle of over 20 flagella whereas Cthylla is smaller, has only 5 anterior flagella and closely resembles several other parababsalian genera. Molecular phylogenies based on small subunit ribosomal RNA (SSU rRNA) show both genera are related to previously unidentified environmental sequences from other termites (possibly from members of the Tricercomitidae), which all branch as sisters to the Hexamastigitae. Altogether, Cthulhu likely represents another independent origin of relatively high cellular complexity within parabasalia, and points to the need for molecular characterization of other key taxa, such as Tricercomitus.
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Erick R
authors.initials: ER
authors.lastname: James
authors.forename: Noriko
authors.initials: N
authors.lastname: Okamoto
authors.forename: Fabien
authors.initials: F
authors.lastname: Burki
authors.forename: Rudolf H
authors.initials: RH
authors.lastname: Scheffrahn
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000818:Animals; D001483:Base Sequence; D058893:DNA Barcoding, Taxonomic; D016054:DNA, Protozoan / Q000235:genetics; D020049:Isoptera / Q000235:genetics / Q000469:parasitology*; D008969:Molecular Sequence Data; D056900:Parabasalidea / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D013559:Symbiosis
chemical_list: D016054:DNA, Protozoan; D012335:RNA, Ribosomal