Unlocking Mediterranean bryozoan diversity: seven new species unveiled after fixing a neotype for Fenestrulina malusii (Audouin & Savigny, 1826) (Cheilostomatida, Fenestrulinidae)

Fenestrulina malusii (Audouin & Savigny), the type species of Fenestrulina Jullien, is among the most widely reported bryozoans globally. Following the loss of the original type material, presumed Mediterranean in origin based on Savigny’s depiction on Sargassum, we designate a neotype from a colony on deep Laminaria blades off Ustica Island (Tyrrhenian Sea). Additionally, seven new species are described from various habitats across the Mediterranean: F. cavernicola sp. nov., from the semi-dark and dark zones of a submarine cave in Lesvos Island (NE Aegean Sea); F. communis sp. nov., from beach-cast plastic near Palermo (NW Sicily); F. foveolata sp. nov., from Ile-Rousse Bank (Corsica); F. granulosa sp. nov., from Posidonia meadows in Dhiaporia (Chios Island, Aegean Sea); F. kalliste sp. nov., from outer-shelf coarse sediments off Calvi (NW Corsica); F. ovata sp. nov., from Trémies submarine cave, near Marseille (Gulf of Lion); and F. variorugosa sp. nov., from Posidonia rootlets off Formica Isle (Egadi Archipelago, near the Sicily Strait). Five of these species are currently known only from their type localities, while F. communis sp. nov. and F. variorugosa sp. nov. occur elsewhere. An additional species with distinct features is described but left in open nomenclature owing to the absence of an ovicell. A comprehensive review of the published images of the 77 species currently assigned to Fenestrulina, with the identification of new diagnostic features, including kenozooids, has led to a revised diagnosis of the genus.