Available online at www.sciencedirect.com ScienceDirect European Journal of Protistology 59 (2017) 1–13 Structures related to attachment and motility in the marine eugregarine Cephaloidophora cf. communis (Apicomplexa) Magdaléna Kovᡠciková a,∗ , Timur G. Simdyanov b , Andrei Diakin a , Andrea Valigurová a a Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlᡠrská 2, 611 37 Brno, Czech Republic b Department of Invertebrate Zoology, Faculty of Biology, Lomonosov Moscow State University, Leninskiye Gory 1-12, Moscow 119234, Russian Federation Received 2 December 2016; received in revised form 7 February 2017; accepted 28 February 2017 Available online 7 March 2017 Abstract Gregarines represent a highly diversified group of ancestral apicomplexans, with various modes of locomotion and host- parasite interactions. The eugregarine parasite of the barnacle Balanus balanus, Cephaloidophora cf. communis, exhibits interesting organisation of its attachment apparatus along with unique motility modes. The pellicle covered gregarine is arranged into longitudinal epicytic folds. The epimerite is separated from the protomerite by a septum consisting of tubulin-rich filamen- tous structures and both are packed with microneme-like structures suggestive of their function in the production of adhesives important for attachment and secreted through the abundant epimerite pores. Detached trophozoites and gamonts are capable of gliding motility, enriched by jumping and rotational movements with rapid changes in gliding direction and cell flexions. Actin in its polymerised form (F-actin) is distributed throughout the entire gregarine, while myosin, detected in the cortical region of the cell, follows the pattern of the epicytic folds. Various motility modes exhibited by individuals of C. cf. communis, together with significant changes in their cell shape during locomotion, are not concordant with the gliding mechanisms generally described in apicomplexan zoites and indicate that additional structures must be involved (e.g. two 12-nm filaments; the specific dentate appearance of internal lamina inside the epicytic folds). © 2017 Elsevier GmbH. All rights reserved. Keywords: Actin; -Tubulin; Apicomplexa; Cell motility; Eugregarine; Myosin Abbreviations: AB, alcian blue; CLSM, confocal laser scanning microscopy; FITC, fluorescein isothiocyanate; IFA, indirect immunoflu- orescent assay; IMC, inner membrane complex; LM, light microscopy; PBS, phosphate buffered saline; PFA, paraformaldehyde; RR, ruthenium red; SEM, scanning electron microscopy; TEM, transmission electron microscopy; TRITC, tetramethylrhodamine isothiocyanate. ∗ Corresponding author. Fax: +420 549 49 8331. E-mail address: kovacikova@sci.muni.cz (M. Kovᡠciková). Introduction Apicomplexans (Apicomplexa Levine 1980, emend. Adl et al. 2012) are one of the most investigated group of pro- tists, comprising exclusively parasites of vertebrates as well as invertebrates. Besides important pathogens of human and agricultural animals (Toxoplasma gondii, Plasmodium spp., Cryptosporidium spp., and Eimeria spp.), this group com- prises highly diversified basal lineages, including gregarines. Gregarines are obligate parasites that inhabit a wide range of http://dx.doi.org/10.1016/j.ejop.2017.02.006 0932-4739/© 2017 Elsevier GmbH. All rights reserved.