Lamtopyxis callistoma Bonnet, 1974

Diagnosis: In lateral view, the test is semi-spherical. In oral view, the ventral sole invaginates into a tubular tapering, reinforced cylinder at the base of a chitinoid squared frame. At the top of the cylinder, the elliptical pseudostome is bordered by a ridge. At the base of the cylinder, the aperture is cruciform with four strong siliceous teeth, thick, rounded, limited by a narrow refractive edging. The lower part of the teeth is slightly down compared to the ventral plan of the sole. Sometimes, specimen are found with five teeth.

Dimensions: Diameter mean 175 µm (n=18); height about 2/3 of the diameter. Length of the pseudostomal cylinder 1/3 – 1/2 of the height.