In this paper we report the diversity of metchnikovellids discovered in two surveys at the silt littoral/sublittoral zone in vicinity of Marine Biological Station of St. Petersburg State University, Island Sredniy, Chupa Inlet, Kandalaksha Gulf of the White Sea performed in 1986-1987 and in 2009-2011. The list of metchnikovellid species that had been recorded for the locality includes: Metchnikovella hovassei, a parasite of the gregarine Lecudina sp. from the polychaete Allita (Nereis) virens; M. selenidii, a parasite of Selenidium sp. from Ophelia limacina; M. spiralis and M. incurvata from Polyrhabdina sp. from Pygospio elegans; and Amphiamblys capitellae from Ancora sagittata from Capitella capitata. Noteworthy, M. incurvata was never observed in the 1986-1987 survey. In 2009-2011 though, it became even more abundant than M. spiralis. Given the patchy distribution of metchnikovellids among gregarine and polychaete populations, M.incurvata might have been overlooked in 1986-1987 survey. Alternatively, the emergence of M. incurvata in the White Sea polychaetes can be the result of spreading of North Atlantic populations of Pygospio elegans species complex infected with M. incurvata, to the North and mixing them with local M. incurvata-free but M. spiralis-infected populations. Such tendency of expanding ranges for certain species presumably due to global warming and/or anthropogenic factors has been recently shown for several free living and parasitic organisms including microsporidia.