Francesco Sciuto

Although coralligenous is considered a priority habitat for conservation within European directives largely considering its complex 3D structure promoting spatial and ecological heterogeneity and related high biodiversity, detailed information on species richness and composition is still scant, at least for some taxonomic groups, including bryozoans, notwithstanding their ecological relevance within the habitat. Focusing on the bryozoan community associated with six build-ups sampled between 33 and 37 m depth offshore Marzamemi (SE Sicily, SW Ionian Sea), this study contributes to improve knowledge on coralligenous bryozoan biodiversity, from a locality in the still understudied eastern Mediterranean. A total of 127 species were recorded, raising to 145 and 257 species the coralligenous bryozoan diversity currently known for Marzamemi and the entire Mediterranean, respectively, the latter representing a high proportion (44%) of the overall Mediterranean bryozoan diversity (588 species). Heterogeneity was detected at small spatial scale, among build-ups in the Marzamemi area, and at the Mediterranean scale through comparison with the scant existing literature, which mostly focused on the western basin. Facies differentiation and related ecological heterogeneity, rather than geographic distance, are considered the main drivers. Finally, our results emphasise the critical importance of microscopic and SEM examination of specimens for species detection.

Ostracods from the Upper Triassic (Carnian, Tuvalian) Mufara Formation exposed in north-west (Monti di Palermo: Reali Celsi and Torrente Cuba) and central-east Sicily (Monte Scalpello: Acquanova and Rocchette) are reported and described for the first time. The studied samples yielded 58 species, including Petasobairdia scylla n. sp. and Triadohealdia kharybdis n. sp. Ptychobairdia iudicaensis, previously described from the Monte Gambanera site, is emended and re-attributed to Petasobairdia. Following taxonomic standardization and reassignment of several previously reported species from Monte Gambanera and other sites in Monte Scalpello, 75 species are currently recognized from the Mufara Formation, including 32 formally described species and 43 in open nomenclature or compared to previously known species. The taphonomic analysis of the assemblages reported here and those from the literature indicate that they are all relatively good indicators of their depositional environment, with the exception of the largely undersampled Torrente Cuba site. The comparative analysis points to circalittoral depositional setting for all sites, with possible moderate salinity deviation in all Monte Scalpello and Monte Gambanera sites. All Monte Scalpello sites and possibly Reali Celsi correspond to the shallower sites, though more work is needed to further characterize the depositional environment of Reali Celsi.

Understanding the pre-evaporitic evolution of North African margins prior to the Messinian Salinity Crisis (MSC) remains a critical challenge. This study provides the first quantitative paleoecological analysis of Early Messinian ostracod assemblages from the Eastern Tunisian margin, based on two high-resolution sections spanning ca. 7.25–5.97 Ma. Integrating taxonomy, autoecology, lithofacies, and multivariate statistics (PCA, Two-Way Cluster Analysis), we objectively delineate three ecological phases across proximal (CRF) and distal (MEC) sections, revealing a coherent trend from marine incursion to mature ecosystems on a mixed carbonate–siliciclastic ramp. Assemblages are dominated by stenohaline taxa (Costa edwardsii, Pontocythere turbida, Keijella loricata, Carinocythereis carinata); euryhaline species and evaporitic facies are entirely absent. Depth-dependent taxa indicate a progressive transgression culminating in well-oxygenated, phytal-dominated environments at ~30 m. Chronostratigraphy is anchored by Globorotalia miotumida (MMi13 zone) co-occurring with index species Capsacythere sicula and Occlusacythereis cultrata. Crucially, ostracod data reveal no progressive environmental deterioration in Tunisian pre-MSC successions, contrasting with Spanish, Moroccan, and Cypriot basins characterized by declining diversity and restricted facies. Persistent stenohaline assemblages indicate sustained open-marine conditions, likely maintained by oceanic exchange through the Siculo-Tunisian Strait and local tectonics. This study demonstrates the value of high-resolution ostracod-based approaches for reconstructing marginal marine paleoenvironments, providing a key reference for pre-MSC Mediterranean spatial heterogeneity and highlighting ostracod biostratigraphy in settings where planktonic foraminifera are scarce or absent.

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. cavernicolasp. nov., from the semi-dark and dark zones of a submarine cave in Lesvos Island (NE Aegean Sea); F. communissp. nov., from beach-cast plastic near Palermo (NW Sicily); F. foveolatasp. nov., from Ile-Rousse Bank (Corsica); F. granulosasp. nov., from Posidonia meadows in Dhiaporia (Chios Island, Aegean Sea); F. kallistesp. nov., from outer-shelf coarse sediments off Calvi (NW Corsica); F. ovatasp. nov., from Trémies submarine cave, near Marseille (Gulf of Lion); and F. variorugosasp. 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. communissp. nov. and F. variorugosasp. 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.

Although several bryozoans are considered habitat-former species, allowing colonisation by epibionts and promoting biodiversity, studies dealt so far with only some, usually constructional, species. In this context, the present study focuses on the epibiosis found on the erect mineralised but flexible species Margaretta cereoides, contributing with some macroalgae to the canopy formation on a coralligenous build-up collected at 36.7 m depth offshore Marzamemi (Ionian Sea, Mediterranean) in the frame of the project CRESCIBLUREEF. Focusing on bryozoans and serpulids we documented high diversity (species richness) on the investigated substrata (M. cereoides, Flabellia petiolata, Peyssonnelia rubra, Osmundaria volubilis and all other fleshy algae including Phyllophora crispa). Diversity, total number of colonies/specimens hosted, and number of colonies/specimens per cm² are higher on M. cereoides than on algae, possibly in relation with the morphology, robustness and persistence of the surface offered by the bryozoan contrasting with the flexible and ephemeral nature of most algae, often provided with chemical defenses. Bryozoan and even more serpulid epibiont diversity on M. cereoides is also higher than those reported for studied species in the Mediterranean and for Flustra foliacea from North Europe.

Ostracod and foraminifera associations living on coralligenous bioconstructions, mainly generated by calcareous red algae, are analysed for the first time along the Ionian coast of SE Sicily offshore Marzamemi (SR, Italy). A total of seven samples, picked up from the surface of the bioconstructions, were collected between 33 and 37 m depth using the sorbona sampling device. Ostracod associations include 22 taxa. Clearly dominant are the specimens belonging to the genus Xestoleberis, followed by the genera Bairdia, Tenedocythere, Aurila, Loxoconcha, Urocythereis; poorly represented are the genera Carinocythereis, Paradoxostoma and Polycope. Foraminifers associations are almost exclusively represented by benthic phytal taxa and include over 3700 specimens belonging to 130 different taxa. The families quantitatively prevalent, both in terms of richness of species and abundance, are Elphidiidae, followed by Hauerinidae, Cibicididae, Ammoniidae, Homotrematidae, Planorbulinidae, Textulariidae, Cribrolinoididae, Asterigerinatidae, Rosalinidae, Spiroloculinidae and Globigerinidae are subordinate, while little represented are Astrononionidae, Haplophragmoididae, Polymorphinidae, Ammodiscidae, Ellipsolagenidae, Spirillinidae etc.