Systematic revision and scanning electron microscopic study of some critical cheilostome bryozoan species of Arthur Waters from the Pleistocene of Brucoli (Siracusa, Sicily)

In 1878, Arthur Waters described a bryozoan fauna from a Pleistocene (Calabrian) outcrop, at that time considered as Pliocene, located near the town of Brucoli in southeast Sicily (Italy). Waters’ work on bryozoans was based on the material collected four years earlier by Theodor Fuchs, curator of the Imperial-Royal Mineralogical Court-Cabinet in Vienna, now the Natural History Museum, and currently housed in the palaeontological collection of the same museum. Since its first description, Waters’ material has never been revised and his new species never recorded again. Here, we employ scanning electron microscopy (SEM) to study Waters’ new species that are still valid today, and some other critical taxa present in the same collection. Based on this revision, Eschara lunaris Waters, 1878 is synonymized with Microporella verrucosa (Peach, 1868), and Lepralia auriculata var. leontiniensis Waters, 1878 is confirmed to be a valid species, i.e., Stephanotheca leontiniensis (Waters, 1878) comb. nov. We also highlight that Biflustra rhynchota Waters, 1878 fits better in the genus Amphiblestrum, showing a close affinity with A. lyrulatum (Calvet, 1907). Additional specimens in Waters’ collection identified as Onychocella angulosa (Reuss, 1847) were compared with Reuss’ Miocene syntypes to confirm their identification and the distinction of this species from the Recent Onychocella marioni (Jullien, 1882). Lastly, a specimen identified by Waters as Busk’s Microporella morrisiana (Busk, 1859) from the Pliocene Coralline Crag is now regarded as M. appendiculata Heller, 1867, a common Pliocene-to-Recent Mediterranean species, after comparison with a topotypic colony of the former species.