Quadrulella (Cockerell 1909) sensu Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara

Anush Kosakyan, Daniel J. G. Lahr, Matthieu Mulot, Ralf Meisterfeld, Edward A. D. Mitchell & Enrique Lara, 2016, Phylogenetic reconstruction based on COI reshuffles the taxonomy of hyalosphenid shelled (testate) amoebae and reveals the convoluted evolution of shell plate shapes, Cladistics 32, pp. 606-623 : 619

Quadrulella (Cockerell 1909) sensu Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara

Updated description. Test pyriform, or elongatedpyriform, with the lateral sides tapering towards the pseudostome, with or without distinct neck. Always laterally compressed, elliptical in cross section. Pseudostome ranging from linear to strongly curved, with or without thickened organic lip. Test hyaline, composed of self-secreted square plates.

Differential diagnosis. Quadrulella differs from Nebela and Hyalosphenia by the use of square, siliceous self-secreted plates in the construction of the test. It may be confused with Mrabella , which has similar test shape and square plates. The most distinctive characteristic is the presence of a lateral pronounced hollow keel in the genus Mrabella (although Q. alata also exhibits a lateral keel, we consider it to be flat and not hollow, even if this detail is not mentioned in the original description of the species), and the fact that square plates of Quadrulella are self-secreted, while the origin of square plates of Mrabella is unclear (see Discussion section above). For more detailed information on the differential diagnosis of genera in Hyalospheniidae see the synoptic key to hyalosphenid genera in Supplementary Material 1.

Type species. Quadrulella symmetrica (Wallich 1864) Cockerell 1909 .

Included taxa. Q. acuminata , Q. alata, Q. camerounensis , Q. elegans , Q. elongata , Q. quadrigera , Q. madibai , Q. scutellata , Q. tropica , Q. symmetrica and Q. variabilis .