Leptomyxa echinata n. sp. - a remarkable species of the genus Leptomyxa (Amoebozoa: Tubulinea) from the sediment of an artificial freshwater pond.

The genus Leptomyxa unifies two morphologically distinct groups of species: reticulate and non-reticulate. Previously, it was believed that only large reticulate species were capable of adopting a fan-shaped form. In recent years, fan-shaped cells have been discovered in four small non-reticulate species. In this study, we describe Leptomyxa echinata n. sp., isolated from a bottom sediment sample from Sobachiy Pond, Izmailovsky Park, Moscow, Russia. Amoebae of this species are non-reticulate, flattened, and branched, and can adopt a monopodial form. Interestingly, the morphology of monopodial cells differs on the surface of glass slides and in culture dishes. Leptomyxa echinata n. sp. is capable of adopting a remarkable fan-shaped form with numerous pointed outgrowths along the anterior margin. In addition, the karyoplasm of these amoebae, besides rounded nucleoli, contains tiny rounded granules. These features have not previously been described for other species of the genus Leptomyxa. The 18S rRNA gene sequence differentiates L. echinata n. sp. from all other species of this genus.