Cornutheca equicalceus (Leidy, 1874) Kosakyan et al., 2016

Diagnosis: Shell elongated-piriform in broad view, compressed sides gradually taper towards the pseudostome. The fundus and lateral margins of the body of the test are surrounded by a thick, horseshoe-like keel, the ends of which project towards the pseudostome and inward into the cavity. The entirety of this peculiar appendage occupies ca. 2/3rds of the test length. Its horns divide off from the general cavity of the test, as a pair of elongated conical recesses extending towards the fundus of the test and outward along the lateral border. Shell pale yellowish, composed of circular or ovoid plates. Aperture linear or slightly curved in broad view.

Dimensions: Shell length 252—260 µm; width 140—160 µm; aperture 40—45 µm wide.

Ecology: in Sphagnum-dominated peat lands.

Geographical distribution: North America.

References: Kosakyan, A., Meisterfeld, R., Lara, E., Duckert, C., Mitchell, E., 2025. A taxonomic monograph of hyalospheniid testate amoebae. Amoebozoa: Arcellinida: Hyalospheniformes, Mémoire XIV. Éditions Alphil-Presses universitaires suisses, Neuchâtel.