Quadrulella texcalense  Pérez-Juárez, Serrano-Vázquez & Lara, 2017.

Diagnosis: Shell pyriform, with a rounded posterior end (posterior 1/3 of the shell), sides converging towards the aperture either straight, slightly convex or slightly concave, laterally compressed and transparent. shell composed of square endogenous plates that range in size between 3.3 and 6.5 µm in a single cell, generally arranged in an orderly fashion although some may be irregularly arranged. The aperture is curved (convex), oval-shaped in frontal view, with the typical organic rim considered as a synapomorphy of the family Hyalospheniidae.

Dimensions: According to Pérez-Juárez et al. (2017): Shell length 97–126 µm; width 53–68 µm; aperture width 24–32 µm.

Habitat: Calcareous soils.

Geographical distribution: Mexico.

Remarks: Quadrulella texcalense exceeds most other species in size, with the exception of Q. scutellata and Q. quadrigera, from which it differs on the base of its more regular plates. The size of its plates and its general pyriform shape reminds of the much smaller Q. variabilis

References: Pérez-Juárez, H., Serrano-Vázquez, A., Kosakyan, A., Mitchell, E.A.D., Rivera Aguilar, V.M., Lahr, D.J.G., Hernández Moreno, M.M., Cuellar, H.M., Eguiarte, L.E., Lara, E., 2017. Quadrulella texcalense sp. nov. from a Mexican desert: An unexpected new environment for hyalospheniid testate amoebae. European Journal of Protistology 61, 253–264. https://doi.org/10.1016/j.ejop.2017.06.008