Table 1.

Description of the chytrid strains used in this study and maintained in parasite-host tandem cultures, including strain labels of susceptible and resistant diatom species ¹. For identification of chytrids the studies of Sparrow [16], Johnson & Sparrow [46], and Letcher & Powell [47] were used.

Host Species (Author)	Parasite	Description of the Parasites
Navicula Bory NavHrú1542S NavHrú1523R	Chytridium type I	Sporangium on a stalk (extrametrical, up to 15.8 μm long), ovate or ellipsoid (also spherical was observed), around 16 μm long by 10–16 μm wide. Similarities with Chytridium sp.
Nitzschia Hassall NitzIsa15101S NitzIsa15106R	Rhizophydium type I	Sporangium: sessile, ovoid or spherical (globose), 17–35 μm high, 17–40 μm diameter; wall thin and smooth, colorless, double-contoured, 1–1.5 μm thick, with a broad apical or sub apical papilla. Similarities with Rhizophydium Schenk
Rhizosolenia Brightwell RhizSka1503S RhizSka1512R Chaetoceros Ehrenberg ChaeSka1517S ChaeSka1511R	Rhizophydium type II	Sporangium: sessile, ovoid, 5–11 μm high by 5–9 μm in diameter, wall smooth, colorless. Similarities with Rhizophydium Schenk

¹ Strains are maintained at the indoor culture collection at BioPol ehf.