Accepted Article This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/jeu.12376-4829 This article is protected by copyright. All rights reserved. Received Date : 20-Apr-2016 Revised Date : 30-Sep-2016 Accepted Date : 12-Oct-2016 Article type : Original Article Yubuki wt al.--- Iotanema spirale, a New Endobiotic Fornicata Ultrastructure and Molecular Phylogeny of Iotanema spirale gen. nov. et sp. nov., a New Lineage of Endobiotic Fornicata with Strikingly Simplified Ultrastructure Naoji Yubuki a , Eliška Zadrobílková a, b and Ivan Čepička a a Department of Zoology, Faculty of Science, Charles University, Vinicna 7, 128 44 Prague, Czech Republic b Centre for Epidemiology and Microbiology, National Institute of Public Health, Srobarova 48, 100 42 Prague, Czech Republic Correspondence I. Čepička, Department of Zoology, Faculty of Science, Charles University in Prague, Vinicna 7, Prague, 128 44, Czech Republic Telephone number: +420 221951072; FAX number: +420 221951841; e-mail: ivan.cepicka@centrum.cz ABSTRACT Fornicata (Metamonada) is a group of Excavata living in low oxygen environments and lacking conventional mitochondria. It includes free-living Carpediemonas-like organisms from marine habitats and predominantly parasitic/commensal retortamonads and diplomonads. Current modest knowledge of biodiversity of Fornicata limits our ability to draw a complete picture of the evolutionary history in this group. Here, we report the discovery of a novel fornicate, Iotanema spirale gen. nov. et sp. nov., obtained from fresh feces of the gecko Phelsuma madagascariensis. Our phylogenetic analyses of the small subunit ribosomal RNA gene demonstrate that I. spirale is closely related to the free-living, marine strain PCS and the Carpediemonas-like organism Hicanonectes teleskopos within Fornicata. Iotanema spirale exhibits several features uncommon to fornicates, such as a single flagellum, a highly reduced cytoskeletal system, and the lack of the excavate ventral groove, but shares these characters with the poorly known genus Caviomonas. Therefore, Iotanema spirale is accommodated within the family Caviomonadidae, which represents the third known endobiotic lineage of Fornicata. This study improves our understanding of character evolution within Fornicata when placed within the molecular phylogenetic context. Keywords Caviomonadidae; evolution; Fornicata; Metamonada; morphology; new taxa; parasite; taxonomy. EXCAVATA is one of the three major assemblages of eukaryotes along with Amorphea (e.g., Opisthokonta, Amoebozoa, Apusomonadida, Breviatea) and Diaphoretickes (e.g.,