Keratella Bory de St. Vincent, 1822
Class Rotatoria: Order Ploimida: Family Brachionidae (ref. ID; 7097)

Synonym Anuraea Ehrenberg, 1830 (ref. ID; 3514) or 1832 (ref. ID; 2978, 3688) reported year? (ref. ID; 1345, 4593)

[ref. ID; 1663]
Dorsal surface of lorica with a pattern polygonal facets. With one, two or no posterior spine and with six short to medium anterior spine. Highly variable plankton and limnetic species. Cyclomorphic. Very common species. (ref. ID; 1663)

[ref. ID; 2891]
The genus contains, to date, approximately 16 known species which are placed in recognized, defined morphological groups principally on the basis of the variable lorica form. There are three broad Formenkreis recognized: quadrata, valga-tropica and cochlearis, however there are as well several species groups which, although they show a certain morphological stability, are not, without further study, able to be ranked, e.g. reducta, lenzi, serrulata, americana, mixta-javana. The taxonomy of most polymorphic species at present, is based on morphological lorica markings, particularly the foundation pattern (facettation), the dorsal lorica, relative length of lorica spines and the surface structure. (ref. ID; 2891)

[ref. ID; 3073]
Mode of Egg-carrying (ref. ID; 3073 , )

[ref. ID; 3114]
This genus is divided into several species based upon the following characters (Ahlstrom 1943, Gillard 1948): 1. The presence or absence of posterior spines, their number and position. 2. The pattern of dorsal sculpture on the lorica. 3. The proportions of the body, especially as regards size, shape, width and depth. 4. The number of anterior spines. 5. The ornamentation of the ventral plate. 6. The ornamentation of the dorsal plate (rather than the fundamental pattern of the dorsum). According to the Sudzuki's opinion the following characters are available for classification of the species. 1. Position of the posterior spines (terminal for cochlearis group, lateral for quadrata-valga group). 2. Features of the dorsal sculpture on the lorica (as the difference between americana and cochlearis, cochlearis and irregularis, serrulata and cochlearis, or testudo and quadrata). 3. General shape (or proportions) of the lorica (as the difference between K. valga and K. quadrata, cochlearis and faluta, or pyriformis and valga). 4. Features of the occipital spines (as the difference between taurophala and cochlearis). Such characters as presence or absence of the posterior spines, the ornamentation (except for sculpture) of the dorsal plate, however, have no taxonomic value. The number of anterior spines is so constant in this genus contrary to Brachionus, that it might serve for generic separation when it is different (cf. K. reducta). On the contrary, certain dorsal sculpture seems to be a good character for 'subspecific' distinction (as the difference between K. valga valga and K. valga tropica or between edmondsoni and quadrata or irregularis and earlinae). (ref. ID; 3114)

[ref. ID; 4593]
Brachionid rotifers with loricate body, separated into a dorsal and ventral plate. Dorsoventrally ore or less compressed. Anterior margin usually with six spines. Posterior spines often present, one or two in number, single posterior spine usually median. Dorsal plate with sculptural pattern, with or without areolate network, postulation, or fine spines. Many species in fresh water, only a few in brackish water. Keratella cruciformis cruciformis, cr. eichwaldi, quadraa platei, and cochlearis recurvispina are typical brackish-water forms. (ref. ID; 4593)