Newly identified diversity of Dinomycetaceae (Rhizophydiales, Chytridiomycota), a family of fungal parasites of marine dinoflagellates

12 pages, 5 figures, 2 tables, supplementary data https://doi.org/10.1016/j.ejop.2024.126053.-- Data availability statement: Molecular sequences generated in this study are publicly available in GenBank. Phylogenetic alignments analysed in the present study are available from the corresponding author upon request

We identified two new parasite species of Chytridiomycota isolated during blooms of the dinoflagellate Alexandrium minutum in the coastal Mediterranean Sea. Light and electron microscopy together with molecular characterization of the nuclear 18S, ITS, and 28S rDNA regions led to their identification as two new species, Dinomyces gilberthii and Paradinomyces evelyniae, both belonging to the family Dinomycetaceae, order Rhizophydiales. Dinomyces gilberthii differs from the previously described D. arenysensis by the presence of discharge papillae and the development of a drop-shaped sporangium. Paradinomyces evelyniae differs from the previously described P. triforaminorum by the prominent lipid globule present in early sporangia and by the pointed end producing a rhizoid. The two chytrids differed in their geographical distribution. Dinomyces gilberthii was detected in several Mediterranean habitats, including harbours and beaches, and was particularly prevalent during summer dinoflagellate blooms. Its widespread occurrence in coastal ecosystems suggested a high level of adaptability to this environment. Paradinomyces evelyniae had a more restricted distribution in the coastal-marine environment, occurring in harbour sediments and only occasionally in the water column during winter and early spring. Paradinomyces evelyniae has previously been detected in the Baltic Sea, suggesting that its distribution encompasses contrasting coastal environments, although its presence is rare

This study was funded by the Spanish MICINN Project SMART PID2020-112978GB-I00, with institutional support from the “Severo Ochoa Centre of Excellence” (CEX2019-000928-S). A. D. Fernández-Valero was funded by the MICIU grant “Ayudas para contratos predoctorales para la formación de doctores 2018” (PRE2018-084893). This work was partly supported by the Russian Science Foundation, grant no. 21–74–20089 (light and electron microscopy analysis, manuscript writing). SAK thanks Saint-Petersburg State University for a research grant (project ID Pure 115624290) and ZIN RAS program 122031100260-0

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