Centropyxis minima, after Bonnet, 1959
Centropyxis minima Bonnet, 1959 *)
Basionym: Centropyxis deflandriana Bonnet var. minima Bonnet, 1959
Diagnosis: Ovoid test, light gray, with circular cross section. Pseudostome in position as eccentric as in the type, with visor strongly thrown back. Wall covered with amorphous siliceous particles, and, in general, more regular than in the type.
Dimensions: Long axis 35-40 µm, small axis 28-34 µm, visor height 5-7 µm, total height 40-47 µm.
Habitat: Like the type, this species is extremely aerophilic. It is very common in the rhizosphere of rupicolous grasses on limestone, rarer on siliceous rocks. Its optimum pH is around 7, compared to 6 for C. deflandriana which is also very rare on limestone substrate.
*) Centropyxis deflandriana Bonnet var. minima Bonnet, 1959 changed to Centropyxis minima Bonnet, 1959.
Note: A formal change is not required in this case according to the International Code of Zoological Nomenclature: (1) According to article 45.6.3, as the name was published before 1961 using the abbreviation var., it is deemed to be subspecific rather than infra-subspecific and therefore falls under rulings for species-group nominal taxa (Chapter 10). (2) According to article 46.1, names established at either species ranks (species or subspecies) are simultaneously established at the other rank, with same author and same type. Authority thus is unchanged.