Check-list of the Nudibranchs (Mollusca Gastropoda) from the biodiversity hot spot "Scoglio del Corallo" (Argentario promontory, Tuscany)

The Mediterranean nudibranch (Mollusca Gastropoda) fauna is part of complex communities belonging to the Mediterranean endemic "Coralligenous". This important ecosystem shows a high species richness and functional diversity with assemblages of species tied together by major trophic and ecological relationships. A first check-list for the biodiversity hot spot "Scoglio del Corallo", located along the coast of the Argentario promontory (Tuscany, Tyrrhenian Sea) is here reported

Crustaceans and Marine Heterobranchia: A New Symbiotic Relationship in the Mediterranean Sea

The "solar-powered" Elysia timida (Risso, 1818) is an endemic Mediterranean sacoglossan living in rocky substrates at shallow water. During a scuba dive, one E. timida was photographed and collected. The observation revealed the presence of a small crustacean of the Pinnotheridae family. It was not possible to assign the crustacean to a genus, but it shares typical ecological and external morphological features with other Pinnotherinae species. This is the first report of a pea crab hosted by a non-shelled Heterobranchia and the first case of a symbiotic association between crustaceans and marine Heterobranchia reported in the Mediterranean Sea

First record of Calma gobioophaga Calado and Urgorri, 2002 (Gastropoda: Nudibranchia) in the Mediterranean Sea

Specimens of the nudibranch genus Calma were observed under stones at two Croatian localities while feeding on gobiid eggs. Some ambiguous morphological features compared with the original descriptions of the known species of the genus, C. glaucoides and C. gobioophaga, hampered an easy identification. Genetic data (COI and 16S sequences) confirmed the distinction between the two species of the genus Calma, and allowed to unambiguously identify the Croatian specimens as Calma gobioophaga. This is the first record of this species for the Mediterranean and extends remarkably its distribution range. Finally, the eggs fed by the Croatian specimens have been taxonomically identified by using the 12S rDNA marker as Gobius cobitis

A new perspective on the distribution of Camachoaglaja africana (Pruvot-Fol, 1953) and Biuve fulvipunctata (Baba, 1938) (Gastropoda, Cephalaspidea) in the Mediterranean and the NE Atlantic

During underwater monitoring, one specimen of Camachoaglaja africanaand one of Biuve fulvipunctata were found at the ‘Tavolara Punta Coda Cavallo’ Marine Protected Area, allowing to expand the known Mediterranean range of distribution of these two species. The finding of both species constitutes the first report for NE Sardinia and the whole Tyrrhenian Sea. By coupling data obtained from the analysis of social media and those present in the bibliography it was also possible to speculate on alternative pattern of distribution of these two species at a global scale. Finally, it is also confirmed the importance of repeated monitoring activities over time on the mooring buoys which act as steppingstone habitats for epifauna or for larval settlement and that are capable to provide important additional information on local biodiversity

What are you doing here? Investigating on an unexpected association in shallow Mediterranean dark caves sheds new light on the diet of Marionia blainvillea (Mollusca, Gastropoda, Nudibranchia)

In a shallow dark cave along the coast of Capo Palinuro (Campania, Italy), the finding of an unusual aggregation of individuals belonging to Marionia blainvillea (Gastropoda, Nudibranchia) has allowed to identify a population of Cervera atlantica (Cnidaria, Anthozoa, Alcyonacea) and to add this latter to the list of the hosts preyed by this tritoniid nudibranch. This association was confirmed by a second observation in a dark shallow cave in the Island of San Pietro (Sardinia, Italy). Moreover, a subsequent internet data mining shed light on the diet of M. blainvillea adding useful ecological notes on the scarcely known trophism characterizing Marionia species. Cervera atlantica is reported for the first time along the continental coast of Italy

Integrative Taxonomy of the Bubble Snails (Cephalaspidea, Heterobranchia) Inhabiting a Promising Study Area: The Coastal Sicilian Faro Lake (Southern Italy)

The worldwide diffused bubble snails, Haminoeidae, although characterized by an extreme morphological homogeneity, display the most diverse radiation inside the order Cephalaspidea. This hidden diversity within the family Haminoeidae was recently unraveled by molecular studies, which helped to understand the evolutionary history of this group by clarifying some aspects of its systematics. In fact, the type genus Haminoea W. Turton and Kingston (1830) was proved to be polyphyletic and, consequently, the genus Haminoea sensu stricto was restricted to the Mediterranean, Atlantic and East Pacific species, with the Mediterranean Haminoea hydatis Linnaeus (1758) as the type taxon. However, at the specie rank, many aspects need to be clarified, especially concerning the Mediterranean fauna. Due to low reliability of macro-morphological characters, the minimal quantity of molecular data currently available on Mediterranean specimen adds to the lack of molecular comparison in most reports. Based on such considerations, Haminoea species from an interesting Mediterranean study area, Faro Lake, a Sicilian coastal lake that is considered a hot spot for both alien and endemic marine Heterobranchia, have been studied using an integrative taxonomic approach. Eleven Mediterranean specimens belonging to four Haminoea bubble snails have been collected, identified and compared with samples from other localities, integrating ecological, morphological, anatomical (reproductive apparatus) and molecular data. Based on molecular investigations carried out on three different molecular markers (H3, 16S and COI), the morphological identifications of the species collected in the Faro Lake have been confirmed, and 37 new sequences are provided for future comparisons. Furthermore, results from this integrative systematic study shed light on the phylogenetic relationships occurring in this group of bubble snails that could be useful in identifying valid diagnostic morphological characters. Haminoea hydatis and H. navicula were confirmed to be close to each other, with H. orteai as sister to them and with H. orbignyana as the basal taxon. Given external morphological features are unreliable with species identification in Haminoea genus open questions on the geographical distribution of the species and on their ranges of intraspecific variability have yet to be addressed and further in-depth studies are needed. Finally, the presence of three sympatric Haminoea species, two of which are considered native or long-time naturalized, along with other occasional congeneric species, and the absence of the introduced invasive Haloa japonica, reflects both the resilience and stochastic space-temporal dynamics of Faro Lake. This confirms it as an inexhaustible source of case-studies

A Rather Unusual ”Pearl”: Biological Observations of the Hidden Pearlfish Carapus acus (Brünnich, 1768) and Its First Report from Apulian Waters (Salento Peninsula, Southern Italy)

The Salento peninsula in southern Italy (Mediterranean Sea) is a strip of land between the Adriatic and the Ionian Seas, both characterized by local regimes of currents, different geological and physical backgrounds, and quite diversified fauna. In this area, specimens of the sea cucumber Holothuria tubulosa (Brünnich, 1768) (Echinodermata) were collected at four stations in the spring and autumn of 2020 to investigate a possible symbiotic association with the inquiline fish Carapus acus (Brünnich, 1768). Among the collected holothurians, five pearlfish specimens were found in the body cavity of four H. tubulosa collected at 10 m of depth, in autumn, at “Grotta Verde” in Marina di Andrano, Lecce (Ionian Sea). More than half of the sea cucumbers from the latter station hosted the symbiont, suggesting the presence of a shallow population of C. acus inhabiting this coastal area. Furthermore, morphometric analysis carried out on the collected fish helped to shed light on the population dynamics characterizing this neglected species. This is the first report of C. acus from Apulian waters, allowing us to unite previously disjoined areas and providing essential baseline knowledge for planning future in-depth analysis of this difficult-to-study fish in a geographical area that is strategic in terms of the conservation of Mediterranean biodiversity. Furthermore, the range of preferred host species is extended, as C. acus was previously known to prefer other sea cucumber species such as Parastichopus regalis (Cuvier, 1817) instead of H. tubulosa. Finally, the finding of C. acus in a single station and in only one season is not trivial and delivers baseline useful information for future conservation purposes

Različit, ali isti: uz pomoć DNA identifikacije otkrivena iznenađujuća obojenost primjeraka Sredozemnog morskog puža stražnjoškržnjaka (Mollusca: Nudibranchia)

A peculiar eolid nudibranch showing an unknown chromatic array was found in a rocky bottom of Santa Maria al Bagno, in the Salento peninsula, Ionian Sea (Central Mediterranean Sea). This specimen, initially identified as Piseinotecus sp., was observed in situ and photographed while feeding and laying eggs close to individuals belonging to the Mediterranean Piseinotecus soussi. To assess the identity of this unexpected Piseinotecus ‘white morph’, a DNA identification approach was carried out using mitochondrial cytochrome c oxidase subunit I (COI), as it is the molecular marker mostly used to distinguish nudibranchs species. The molecular analysis unambiguously identified this specimen as Piseinotecus soussi and helped to shed lights on the striking intraspecific colour variability characterizing this rare species.Neobični primjerak eolidnog morskog puža stražnjoškržnjaka s dosad nezabilježenim obojenjem pronađen je na stjenovitom dnu lokaliteta Santa Maria al Bagno na poluotoku Salentu u Jonskom moru (središnje Sredozemno more). Ovaj primjerak, prvobitno identificiran kao Piseinotecus sp., promatran je i fotografiran dok se hranio i polagao jaja u blizini jedinki koje pripadaju sredozemnoj vrsti Piseinotecus soussi. Kako bi se otkrio identitet ovog neobičnog „bijelog oblika“ Piseinotecus sp. primjerka, provedena je identifikacija DNA pomoću mitohondrijske podjedinice citokrom c oksidaze I (COI), budući da je to molekularni marker koji se uglavnom koristi za razlikovanje vrsta stražnjoškržnjaka. Molekularna analiza nedvojbeno je identificirala ovaj primjerak kao Piseinotecus soussi i pomogla da se rasvijetli upečatljiva intraspecifična varijabilnost obojenja koja karakterizira ovu rijetku vrstu

Tritonia nilsodhneri Marcus Ev., 1983 (Gastropoda, Heterobranchia, Tritoniidae): prvi nalaz za Jadransko more i novi podaci o ekologiji i distribuciji mediteranske populacije

The nudibranch Tritonia nilsodhneri, usually feeding on a variety of gorgoniacean species, is known from different localities of the eastern Atlantic Ocean and the Mediterranean Sea. Knowledge of the host preferences of the Mediterranean populations is still scarce. Few records of this nudibranch have been reported from the eastern Mediterranean basin. With this report, the occurrence of T. nilsodhneri within the Mediterranean basin is extended to the Adriatic Sea. Furthermore, the list of the host species associated to the Mediterranean populations for feeding habits is increased from two up to five. Mediterranean specimens of T. nilsodhneri were observed for the first time feeding and spawning on Leptogorgia sarmentosa, Eunicella cavolini and E. labiata. Finally, these last two Gorgoniidae species are also reported here as a new host species for T. nilsodhneri.Morski puž golać, Tritonia nilsodhneri, poznat je s različitih lokaliteta istočnog Atlantskog oceana i Sredozemnog mora, a obično se hrani raznim vrstama gorgonija. Podatci o domaćinima za ovu vrstu u Sredozemlju su još uvijek rijetki. Postoji nekoliko zapisa o ovom pužu u istočnom dijelu Sredozemlja. Ovim radom zabilježena je nazočnost vrste T. nilsodhneri u Jadranskom moru. Nadalje, popis vrsta domaćina koji su povezani sa hranjenjem i mriještenjem sredozemne populacije se povećao sa dva na pet. Sredozemni primjerci T. nilsodheri su po prvi put zabilježeni tijekom hranjenja i mriješćenja na vrstama Leptogorgia sarmentosa, Eunicella cavolini i E. labiata. Ove posljednje dvije spomenute vrste Gorgonida su u ovom radu po prvi put zabilježene kao nova vrsta domaćina za T. nilsodheri

Collective exploitation of large prey by group foraging shapes aggregation and fitness of cnidarian polyps

Group living is widespread and beneficial to metazoans. It improves protection and survival opportunities, reinforcing interspecific competitiveness. Benthic cnidarians often colonize large surfaces. Evidence of collective capture and exploitation of large prey by small, clumped polyps suggests that aggregation is functional to access food resources hardly achievable by isolated individuals. In turn, the chance to catch large prey may represents a driver of aggregation in polyps, whether beneficial to their fitness. Here, the effects of group foraging on aggregation, asexual reproduction, and growth rates of Aurelia coerulea von Lendenfeld 1884 polyps were experimentally tested by providing them with either small or large prey, or a mix of both to simulate the co-occurrence of preys at sea. As expected, some polyps were not able to reach the large prey. Hence, the population was a posteriori divided into group-foragers and solitary-feeders. In general, the large prey diet resulted in higher population fitness and when simultaneously supplied with the small prey represented an energetic booster resulting beneficial for all group-members. The decrease of interindividual distances was reported among group-foragers, that converged towards each other. Cnidarians are basal in metazoan evolution, and the comprehension of their collective foraging behavior, as well as the processes leading to the selective feature driving them to forage in group or not, may be essential to better understand the evolution and spread of social foraging in animals. Moreover, the access to large prey by sessile polyps of Aurelia coerulea could be pivotal in determining the increase in abundance of adult bloom-forming medusae