Korotnevella hemistylolepis n. sp. and Korotnevella monacantholepis n. sp. (Paramoebidae), two new scale-covered mesohaline amoebae.

Two new species of Korotnevella Goodkov, 1988, Korotnevella hemistylolepis n. sp. and Korotnevella monacantholepis n. sp., are described from mesohaline ecosystems. The amoebae are characterized on the basis of light and electron microscopy with special emphasis on the structure of the basket scales, which have species-specific architecture. The two new species are the second and third ones recovered from environments other than freshwater. In terms of scale morphology they most closely resemble a freshwater species, Korotnevella bulla (Schaeffer, 1926) Goodkov, 1988. Two genus names, Dactylamoeba Korotnev, 1880 and Korotnevella Goodkov, 1988, are in current use. The latter name is preferred, pending rediscovery and characterization of Dactylamoeba elongata Korotnev, 1880, the type species of the genus. Korotnevella species can be divided into three groups on the basis of scale morphology, suggesting that the genus may not be monophyletic. A key to species is provided.

A molecular reassessment of the Leptomyxid amoebae.

Leptomyxid amoebae encompass a diverse assemblage of amoeboid protists that have been implicated as encephalitis-causing agents. This characteristic is attributed to recent studies identifying new members of the Leptomyxidae, in particular, Balamuthia mandrillaris, that cause the disease. Their morphologies range from limax to plasmodial, as well as reticulated and polyaxial. Although systematic studies have identified B. mandrillaris as a new member of the Leptomyxidae, its precise placement within the leptomyxids is uncertain. To further assess the taxonomic placement of Balamuthia among the leptomyxid amoebae and to determine whether the members of the Leptomyxida form a monophyletic assemblage, we have sequenced 16S-like rRNA genes from representatives of three leptomyxid families. Our phylogenetic analyses revealed that current members of the order Leptomyxida do not constitute a monophyletic assemblage. Our analyses clearly show that Gephyramoeba, as well as Balamuthia do not belong in the order Leptomyxida. We highlight where molecular data give differing insights than taxonomic schemes based on traditional characters.