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Vampyrellids (Vampyrellida, Rhizaria) are a major group of predatory amoebae known primarily from freshwater and soil. Environmental sequence data indicate that there is also a considerable diversity of vampyrellids inhabiting marine ecosystems, but their phenotypic traits and ecology remain largely unexplored. We discovered algivorous vampyrellids of the filoflabellate morphotype in coastal habitats in Atlantic Canada, established cultures by single-cell isolation, and characterised three strains using light microscopy, SSU rRNA gene sequencing, feeding experiments and growth experiments at various salinities. These strains exhibit orange, discoid trophozoites with ventral filopodia, moving granules ("membranosomes"), and rolling locomotion, similar to freshwater species previously assigned to Hyalodiscus Hertwig & Lesser, but here moved to Placopus Schulze (due to homonymy with Hyalodiscus Ehrenberg). SSU rRNA gene phylogenies place our strains in two distinct positions within "lineage B3" (here referred to as Placopodidae). Based on these morphological, habitat and molecular data, we describe two new species, Placopus melkoniani sp. nov. and Placopus pusillus sp. nov., both of which feed on chlorophyte flagellates (Tetraselmis, Pyramimonas) and the cryptophyte Chroomonas. They perforate the theca of Tetraselmis to extract the protoplast, and thereby represent the first vampyrellids known to degrade the biochemically exotic cell wall of the Chlorodendrales (Chlorophyta, Viridiplantae)., (© 2018 International Society of Protistologists.)

A novel biflagellate protist that consumed chloroplasts inside material of the invasive marine green alga Codium fragile was reported from the U.S. east coast in 2003. We observed a similar association in C. fragile from five sites in Nova Scotia, Canada during 2013 and 2014. After incubating Codium fragments for 2-3 days, some utricles and filaments contained numerous chloroplast-consuming cells. Transmission electron microscopy (TEM) confirmed that these were kinetoplastids with a pankinetoplast, large electron-dense droplets in the cytoplasm and a connective between the paraxonemal rod bases, but no conspicuous para-cytopharyngeal rod, all consistent with U.S. material observed in 2003. The ITS1-5.8S rRNA-ITS2 sequences from 13 Nova Scotia isolates were identical. SSU rRNA gene phylogenies placed the Codium-associated kinetoplastid in neobodonid clade '1E'. Clade 1E likely contains no previously described species, and branches outside all other major neobodonid groups, either as their sister or as a separate lineage, depending on rooting. These results indicate that the kinetoplastid represents a single species that merits a new genus (and family), and we describe it as Allobodo chlorophagus n. gen., n. sp. The lack of evidence for food sources other than Codium is consistent with a parasitic association, but other possibilities exist (e.g. necrotrophy)., (Copyright © 2018 Elsevier GmbH. All rights reserved.)