Distomatopyxis praecursor Bonnet, 1979

Diagnosis: Shell with propylostome in 2/3 to 3/4 spherical cap externally similar to that of Cyclopyxis. Ventral side (sole) almost flat. Vestibule double-domed, formed of two symmetrical “spoons”, welded in the median plane and with a constriction between the two “spoons”. The pseudostome is distally bi-lobed and partly closed by an incomplete diaphragm formed of two spatulate teeth with a narrow base (flange) and a wide, rectilinear end. The axis of the teeth are in the plane of symmetry. The pseudostome is a spherical rectangle elongated along the plane of symmetry, located in a deep groove separating the two vertices of the dome, and descending along it until close to the sole and the base of the teeth. At the junction between the walls of the vestibule and the test, there is a brown fibroid frame extending around the pseudostome. The test is covered with remodeled siliceous elements partly lacking in populations of humus very rich in organic matter.

Measurements. (out of 13 individuals), diameter of the test, average 117 µm; dorso-ventral distance (height): 2/3 to 3/4 of the diameter; depth of the vestibule: 1/5 to 1/4 of the dorso-ventral distance; distal opening of the vestibule on the sole, major axis 49 µm; small axis (width of a lobe, measured parallel to the plane of symmetry) 36 µm; width of the pseudostome at the top of the vestibule, perpendicular to the plane of symmetry 13 µm; width of the diaphragm (spatula of the tooth): 26 µm.

Habitat: Forest soils of eastern New Guinea (Papua).