Chloromyxum schurovi

Remarks: The spore measurements of C. schurovi largely vary in their size from 5.5 to 8.9 μm (Table 2; Fig. 2). Spore size parameters in the original species description (Shulman and Ieshko 2003) are the smallest ones from all parasite reports (Lom and Dyková 1993, Holzer et al. 2004, 2006 a; present study). However, according to species redescription of Holzer et al. (2006 a), spores in data were measured from the fixed material and spore shrinkage most likely affected these values. Approximately 15 – 18 % shrinkage of the myxozoan spore valves can be due to fixation (Holzer et al. 2006 a). After the normalisation, spore sizes of all C. schurovi records correspond to each other. The reports of C. cf. majori of Lom and Dyková (1993), Chloromyxum sp. of Sedlaczek (1991), Feist et al. (2002), and Wootten and Smith (1980) are most likely C. schurovi detections, sharing the same host preference (Salmo spp.), tissue localisation (kidney tubules) and European distribution of the fish host. However, no sequence data exist for these records and spore measurements are available only in the first publication. Overall, two Chloromyxum species have been described from the kidneys of salmonids (Yasutake and Wood 1957, Shulman and Ieshko 2003, Table 2). While the spore length and width of C. schurovi and C. majori overlap (Table 2), these two myxozoans differ in host species preference, tissue affinity and geographic distribution. Chloromyxum schurovi predominantly infects the renal tubules of S. salar and S. trutta in Europe, while C. majori primarily targets the glomeruli of Oncorhynchus mykiss and O. tshawytscha in North America.

Type host: Salmo trutta Linnaeus, brown trout (Holzer et al. 2006 a, Shulman and Ieshko 2003, Lom and Dyková 1993; present study). O t h e r h o s t: Salmo salar Linnaeus, Atlantic salmon (Holzer et al. 2006 a, Shulman and Ieshko 2003). Ty p e l o c a l i t y: Not specified. Samples of Shulman and Ieshko (2003) were collected in Russia (Lake Onega, Pulonga River, Vonga River, White Sea area), Norway (Vefsna River, Namsen River) and Finland (Teno River). O t h e r l o c a l i t i e s: Clyde River, Scotland, UK; Allan Water, Scotland, UK; Amhainnan Stratha Bhig. Scotland, UK (Holzer et al. 2006 a, b); Blanice River, Czech Republic (Lom and Dyková 1993); Lužnice River, Czech Republic (present study). S i t e o f t i s s u e d e v e l o p m e n t: Coelozoic in renal tubules. P r e v a l e n c e o f i n f e c t i o n: 8.6 % (14 / 163) (Lom and Dyková 1993); 61 % (161 / 264) (Holzer et al. 2006 a); 5 % (1 / 19) (present study). M a t e r i a l s d e p o s i t e d: DNA material stored at the Protistological Collection of the Institute of Parasitology, Biology Centre of the Czech Academy of Sciences (BC CAS), České Budějovice, Czech Republic (code: IPCAS Pro 82); 18 S rDNA sequence (2,000 bp, GenBank Acc. Number PP 749024). P l a s m o d i a: Oval polysporic plasmodia ranging 16.0 – 26.2 (n = 2) (present study, not shown) or up to 13.2 (Shulman and Ieshko 2003). S p o r e: Mature spores almost spherical, 7.2 ± 0.4 (6.6 – 8.1) in length and 6.7 ± 0.4 (5.7 – 7.5) in width; many fine ridges on the shell valve surface; four anteriorly pointed, pyriform polar capsules, 2.8 ± 0.3 (2.1 – 3.4) in length and 2.0 ± 0.4 (1.5 – 3.2) in width (n = 20) (Table 2, Fig. 1).