Ignatov, M.S., A. Schäfer-Verwimp, E.E. Perkovsky & J. Heinrichs. Mosses from Rovno amber (Ukraine), 3. Pottiodicranum, a new moss genus from the Late Eocene
Arctoa (2016) 25: 229–235
Pottiodicranum gen. nov. is described based on an inclusion in Late Eocene Rovno amber. The fossil is characterized by an acrocarpous habit, common for many genera of haplolepideous mosses, but differs from all known Paleogene amber fossils of acrocarpous mosses in the presence of several high solid papillae above the lumen of the lamina cells. The papillae are present on the dorsal and ventral side of the lamina and resemble modern Pottiaceae species. However, Pottiodicranum papillosum has a striate dorsal costa surface consisting of low ridges similar to those of some species of Dicranaceae s.l., especially Campylopus and Dicranum. However modern Dicranaceae lack this kind of papillae, while Pottiaceae may have lamellae on the ventral side of the costa, but not on the dorsal side. Thus the Eocene moss fossil possesses a unique combination of characters and apparently belongs to an extinct group of Dicranidae, while the family relationships remain unclear.