Homotrypa Ulrich, 1882

Ernst, Andrej & Carrera, Marcelo G., 2022, A cool-water bryozoan association from the La Pola Formation (Sandbian, Ordovician) of Argentine Precordillera, Geodiversitas 44 (20), pp. 563-601 : 572

Genus Homotrypa Ulrich, 1882

TYPE SPECIES. — Homotrypa curvata Ulrich, 1882 by original designation. Cincinnatian , Upper Ordovician; North America .

DIAGNOSIS. — Ramose and frondose colonies, often flattened, sometimes encrusting and irregularly massive in initial stages. Autozooecia with polygonal, rounded or oval apertures. Walls slightly thickened in exozone, integrate, diagonally and longitudinally laminated. Cystiphragms only in exozone, diaphragms commonly in exozone. Mesozooecia from rare to abundant, sometimes clustering in maculae. Acanthostyles abundant, commonly small.

OCCURRENCE. — Middle Ordovician to Lower Silurian; North America, Europe, Australia, Siberia.

COMPARISON

The genus Homotrypa Ulrich, 1882 differs from the genus Monticulipora d’Orbigny, 1850 by its branched erect colony instead of the encrusting or massive one in Monticulipora . Furthermore, cystiphragms in Homotrypa are usually concentrated in the inner exozone, whereas cystiphragms in Monticulipora occur throughout autozooecial chambers.