Description of a new species of marine amoeba Korotnevella mutabilis n. sp. (Amoebozoa, Dactylopodida).

Korotnevella (Amoebozoa, Dactylopodida) is a genus of naked lobose amoebae with a dactylopodial morphotype. The cell membrane of these amoebae is covered with a monolayer of scales. The structure and size of scales are considered as species-specific features. Here, we describe a new marine species, Korotnevella mutabilis n. sp., isolated from the bottom sediment sample of Nivå Bay (Baltic Sea, The Sound) and studied with light and electron microscopy as well as with molecular phylogenetic analysis. This species has a number of morphological similarities with Korotnevella monacantholepis, such as size of the cell, L/B ratio, the nucleus structure and the type of a biotope from which both species were isolated. At the same time, Korotnevella mutabilis n. sp. differs from K. monacantholepis in the structure of basket-shaped scales: Korotnevella mutabilis n. sp. has an enclosed hammock-shaped latticework basket and up to two spines while K. monacantholepis has an opened two-row latticework basket and never has two spines. According to molecular phylogenetic analyses based on the sequences of the mitochondrial COI gene, Korotnevella mutabilis n. sp. is a distinct species, highly divergent from other Korotnevella species.