Pseudocapillaria Freitas, 1959

Kirjusina, Muza, Paidere, Jana, Rubenina, Ilze, Kecko, Sanita, Bricis, Reinis, Mežaraupe, Ligita & Gavarane, Inese, 2023, Common Freshwater Fish Nematodes In Latvia, Acta Biologica Universitatis Daugavpiliensis (Sao Paulo, Brazil) 23 (2), pp. 189-206 : 192

Genus Pseudocapillaria Freitas, 1959

Pseudocapillaria (Pseudocapillaria) tomentosa (Dujardin, 1843) Moravec, 1987

For the first time in Latvia, this freshwater nematode has been reported by S. S. Shulman (1949) as syn. Capillaria tomentosa Dujardin, 1843 in intestine of four fish species from the mouth of the Daugava River. Prevalence of infection was 6.6% in ide ( Leuciscus idus ) and vimba ( Vimba vimba ). Single specimens of the parasite were found in common bream ( Abramis brama ) and common chub ( L. cephalus ) ( Shulman 1949). Infection of fish by this species can be both through an intermediate host and in a direct way. However, oligochaetes ( Tubifex tubifex , Limnodrilus hoffmeisteri , L. variegatus ) play a significant role in the development cycle of this nematode ( Moravec et al.1987). This nematode is widely distributed in Palearctic Eurasia. The frequently heavy infections of P. tomentosa in carp and other fishes in ponds of economic importance suggest that this species may be a pathogenic parasite for fish in intensive pond aquaculture, especially in the breeding of carp fry. The pathogenic effect is expressed in damage to the intestinal mucosa of the host (Moravec 1994, Moravec 2001).

Genus Schulmanela Ivashkin, 1964 Schulmanela petruschewskii (Shulman, 1948) Ivashkin, 1964

For the first time in Latvia, this freshwater nematode has been reported by S.S. Shulman (1949) as syn. Hepaticola petruschewskii Shulman, 1948 . Parasite was found in mesenteries of spined loach ( Cobitis taenia ) and

192 ruffe ( Gymnocephalus cernua ) from Kegums Water Reservoir. The prevalence of S. petruschewskii in fish ranged from 8.0% in carp ( Cyprinus carpio carpio ) from ponds to 100.0% in ruffe from themouth of the Daugava River. The highest infection intensity was 50.6 specimens in the ruffe intestine. According to the studies, 53.3% of vimba ( Vimba vimba ) form the mouth of the Daugava River were infected ( Shulman 1949, Kirjusina & Vismanis 2004, Kirjusina & Vismanis 2007). Intermediate hosts of parasitic nematode sare oligochaetes Eiseniella tetraedra and Criodrilus lacuum . Fish become infected by feeding infected oligochaetes. From the intestines of the fish, the larva migrates to the liver, where it develops to the adult stage within six months ( Bauer 1987, Moravec 1987). Criodrilus lacuum has a Palearctic distribution and is registered in Latvia ( Perel 1979, Perel 1997, Ventins 2011). Heavy infections by this nematode were reported to cause liver pathology in fish species such as grass carp and ruff, resulting in emaciation and sluggishness ( Moravec 2001).