New Species of Saprobic Labyrinthulea (=Labyrinthulomycota) and the Erection of a gen. nov. to Resolve Molecular Polyphyly within the Aplanochytrids

• Published in: Journal of Eukaryotic Microbiology
• Main Authors: Hassett, Brandon Thomas, Gradinger, Rolf
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2017
• Subjects: VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497; VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497; 18S rRNA; homoplasia; Norwegian Sea; pollen baiting; thraustochytrid; Norway; Tromsø
• Online Access: https://hdl.handle.net/10037/13570; https://doi.org/10.1111/jeu.12494

This is the peer reviewed version of the following article: Hassett, B.T. & Gradinger, R. (2017). New Species of Saprobic Labyrinthulea (=Labyrinthulomycota) and the Erection of a gen. nov. to Resolve Molecular Polyphyly within the Aplanochytrids. Journal of Eukaryotic Microbiology, 65(4), 475-483. https://doi.org/10.1111/jeu.12494, which has been published in final form at https://doi.org/10.1111/jeu.12494 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. A culture of a unicellular heterotrophic eukaryote was established from pollen‐baited seawater acquired from the nearshore environment in Tromsø, Norway. Light microscopy revealed the production of ectoplasmic nets and reproduction by biflagellated zoospores, as well as binary division. After culturing and subsequent nucleotide extraction, database queries of the isolate's 18S small ribosomal subunit coding region identified closest molecular affinity to Aplanochytrium haliotidis , a pathogen of abalone. Testing of phylogenetic hypotheses consistently grouped our unknown isolate and A. haliotidis among the homoplasious thraustochytrids. Transmission electron microscopy revealed complex cell walls comprised of electron‐dense lamella that formed protuberances, some associated with bothrosomes. Co‐culturing experiments with the marine fungus Penicillium brevicompactum revealed prolonged interactions with hyphal strands. Based on the combined information acquired from electron microscopy, life history information, and phylogenetic testing, we describe our unknown isolate as a novel species. To resolve molecular polyphyly within the aplanochytrids, we erect a gen. nov. that circumscribes our novel isolate and the former A. haliotidis within the thraustochytrids.