Hexagonella, Waagen and Wentzel, 1886

Ernst, Andrej, 2016, Bryozoan fauna from the Permian (Artinskian-Kungurian) Zhongba Formation of southwestern Tibet, Palaeontologia Electronica (1946) 51 (9), pp. 1-59 : 14

Genus HEXAGONELLA Waagen and Wentzel, 1886

Type species. Hexagonella ramosa Waagen and Wentzel, 1886 . Upper Permian ; Pakistan.

Diagnosis. Colonies consisting of compressed to subcylindrical bifoliate branches. Mesotheca straight, three-layered, with central granular and granular-prismatic outer layers. Autozooecia recumbent, widely isolated by vesicular skeleton throughout the colony. Diaphragms rare, planar. Lunaria well-developed in exozone, consisting of granular-prismatic material. Vesicles large, irregular in endozone, box-like in inner exozone, blister-like and low in outer exozone. Stereom of granular-prismatic material well-developed, containing tubules. Autozooecial walls granular-prismatic. Monticules consisting of central cluster of vesicular skeleton and radiating rows of autozooecia with lunaria directed towards the centre of the monticule. Each monticule surrounded by elevated ridges of vesicular skeleton producing hexagonal pattern.

Remark. Hexagonella Waagen and Wentzel, 1886 differs from Coscinotrypa Hall and Simpson, 1887 by colony form and presence of crests on the colony surface. Some species placed in Hexagonella do not have typical crests of the colony surface (e.g., H. australis { Bretnall, 1926]).

Occurrence. Twenty-five species have been reported from the Permian of Australia, Asia, and Northern Russia. The genus seems to be absent in North and South America.