(Kuczynski 1991 calling it as B. urceolaris urceolaris). The body is flattened dorso-ventrally. The lorica is smooth, firm and divided into a dorsal and ventral plate which are completely fused laterally. It is oval, without basal plate, rounded posteriorly, W/TL ratio 0.80-0.82, the greatest width is a little below the middle of the lorica. Lorica with a pattern of wavy lines; pointed posteriorly in lateral view. In the anterior dorsal margin six sharp pointed spines are visible. The medians are longest, medians longer than laterals, laterals longer than intermediates. The anterior ventral margin is undulate, with a shallow central sinus flanked on either side by a pointed protuberance and without spines. Posterior margin are without spines.

From Santo et al. (2005): The cingulum of Brachionus urceolaris is arranged into three lobes, with the unpaired one on the ventral side; the pseudotrochus consists of three tufts of cilia (cirri). The foot is long, transversely wrinkled, and retractile. It terminates in a couple of acute, mobile toes, perforated at the tips by the ducts of the pedal glands.

The foot, opening terminal, is annulate, with two toes and no definite foot sheath. Foot opening with a rectangular aperture dorsally and a larger oval aperture in the ventral plate.

The Mastax is malleate.

Measurements : Total length 190-270; width 140-210; 7; ALS 10; AIS 6; AMS 17. Length of dorsal foot aperture 16; length of ventral foot aperture 35; length of sinus between anterior dorsal median spines 22.

From Ahlstrom (1940): Lorica firm, oval, divided into a dorsal and a ventral plate (often indications of a basal plate as well), moderately to little compressed dorso-ventrally. Anterior dorsal margin with six spines: medians longest, laterals and intermediates about equal in length. Mental margin rigid, undulate, somewhat elevated toward the center, with a central sinus. Posterior spines not present. Lorica rises posteriorly to form an overhanging border, which may be simply rounded, or may extend to form a considerable projection. Foot opening with a sub-square to rectangular aperture in the dorsal (basal) plate, and a rather large-oval aperture ventrally. Lorica may be nearly smooth, usually with a pattern of wavy, longitudinal lines more or less distinct; pattern often foreshortened on the basal plate, giving the appearance of pitting. The four inner spines of the dorsal margin have short strengthening ridges, and two strengthening ridges also arise from the papilla-like process on either side of central sinus on mental margin.

In Berzins (1960): Total length 190-270 µm, width 140-210 µm. Lorica firm, divided into a dorsal and ventral plate. Anterior dorsal margin with six sharp pointed spines; medians longest, laterals and intermediates about equal in length. Ventral margin undulate. Posterior spines absent. Lorica with a pattern of wavy lines; pointed posteriorly in lateral view.