Pontine Archipelago Research Articles

Chromosome-Level Reference Genome of the Ponza Grayling (Hipparchia sbordonii), an Italian Endemic and Endangered Butterfly.

Islands are crucial evolutionary hotspots, providing unique opportunities for differentiation of novel biodiversity and long-term segregation of endemic species. Islands are also fragile ecosystems, where biodiversity is more exposed to environmental and anthropogenic pressures than on continents. The Ponza grayling, Hipparchia sbordonii, is an endemic butterfly species that is currently found only in two tiny islands of the Pontine archipelago, off the coast of Italy, occupying an area smaller than 10 km2. It has been classified as Endangered (IUCN) because of the extremely limited area of occurrence, population fragmentation, and the recent demographic decline. Thanks to a combination of different assemblers of long and short genomic reads, bulk transcriptome RNAseq, and synteny analysis with phylogenetically close butterflies, we produced a highly contiguous, chromosome-scale annotated reference genome for the Ponza grayling, including 28 autosomes and the Z sexual chromosomes. The final assembly spanned 388.61 Gb with a contig N50 of 14.5 Mb and a BUSCO completeness score of 98.5%. Synteny analysis using four other butterfly species revealed high collinearity with Hipparchia semele and highlighted 10 intrachromosomal inversions longer than 10 kb, of which two appeared on the lineage leading to H. sbordonii. Our results show that a chromosome-scale reference genome is attainable also when chromatin conformation data may be impractical or present specific technical challenges. The high-quality genomic resource for H. sbordonii opens up new opportunities for the accurate assessment of genetic diversity and genetic load and for the investigations of the genomic novelties characterizing the evolutionary path of this endemic island species.

Putting the dead to work: A new method to assess the autochthony of marine Ostracoda death assemblages

Sedimentary and paleontological records can be powerful means of reconstructing ecological and physical environmental changes, by using a variety of records extending proxies to extend chronologies beyond the reach of instrumental or manual records. Ostracods are often used as paleoenvironmental proxies. Estimating the population age structure could be a useful tool for assessing the influence of some environmental parameters on death assemblages and for determining the autochthoneity or allochthoneity of the species that make up the thanatocoenosis. In the literature, several methods based on population age structure have been proposed to distinguish autochthonous and allochthonous components of life/death ostracod assemblages.The Adult:Juveniles ratio analysis of a rich and well-preserved ostracod assemblage from one site in the circalittoral zone of Pontine Archipelago, in the central-eastern Tyrrhenian Sea, is presented. The new Specific Population Stage Index (SPS) is proposed, built upon the measurements of all growth stages in the assemblage. The population structure using the new SPS Index on three different grain sizes is tested against a list of putative in situ and transported ostracod specimens. The analysis on the small grain size (maximum heigth >63 µm) proved the most effective in describing the putative life ostracod assemblage, whereas in the largest grain size (maximum height >180 µm) the young instars of the smaller species are under-represented. This includes species generally under-represented in the fossil record of the Mediterranean, probably due to sample processing bias and not to the rarity of the species itself. Assessing the autochthoneity of modern/fossil assemblages has great potential for acquiring baseline information on ecosystems before the onset of human activities, making this an extremely powerful approach essential to evaluating anthropogenic impacts. This approach seeks to identify the in situ life assemblages within an ostracod population to ensure that paleoenvironmental interpretations are not biased by transported allochthonous elements.

Characterization of rhodolith beds-related backscatter facies from the western Pontine Archipelago (Mediterranean Sea)

Rhodoliths (nodular calcareous red algae) are considered one of the most important bioengineers in the Mediterranean Sea, making rhodolith beds ecologically relevant ecosystems. On the insular shelf surrounding the western Pontine Archipelago (depth from 43 to 112 m), rhodolith beds were identified through the analysis of an extensive dataset of grab samples and videos to ground-truth the backscatter acoustic facies. Six acoustic facies (low backscatter, dishomogeneous low-backscatter, dishomogeneous high-backscatter, high-backscatter, rocks and high backscatter, and rocks and medium backscatter) were recognized. We studied how rhodoliths characteristics (density, morphotype, size and structure) differently influence the backscatter signature. At the western Pontine Archipelago, rhodolith beds are mainly represented by facies dishomogeneous high backscatter, high backscatter, high backscatter with rocks, and medium backscatter with rocks. The obtained results increase both the knowledge on the heterogeneous structure of such ecologically relevant benthic habitat and highlight the use of distinctive acoustic facies for their identification. Finally, the used approach could be considered a useful method for indirect detection and mapping of rhodolith beds.

Benthic Foraminiferal Assemblages and Rhodolith Facies Evolution in Post-LGM Sediments from the Pontine Archipelago Shelf (Central Tyrrhenian Sea, Italy)

The seabed of the Pontine Archipelago (Tyrrhenian Sea) insular shelf is peculiar as it is characterized by a mixed siliciclastic–carbonate sedimentation. In order to reconstruct the Late Quaternary paleoenvironmental evolution of the Pontine Archipelago, this study investigates the succession of facies recorded by two sediment cores. For this purpose, benthic foraminifera and rhodoliths assemblages were considered. The two cores (post-Last Glacial Maximum in age) were collected at 60 (CS1) and 122 m (Caro1) depth on the insular shelf off Ponza Island. The paleontological data were compared with seismo-stratigraphic and lithological evidence. The cores show a deepening succession, with a transition from a basal rhodolith-rich biodetritic coarse sand to the surface coralline-barren silty sand. This transition is more evident along core Caro1 (from the bottom to the top), collected at a deeper water depth than CS1. In support of this evidence, along Caro1 was recorded a fairly constant increase in the amount of planktonic foraminiferal and a marked change in benthic foraminiferal assemblages (from Asterigerinata mamilla and Lobatula lobatula assemblage to Cassidulina carinata assemblage). Interestingly, the dating of the Caro1 bottom allowed us to extend to more than 13,000 years BP the rhodolith record in the Pontine Archipelago, indicating the possible presence of an active carbonate factory at that time.

Alteration and Mineralization Products of the Zannone Giant Pockmark (Zannone Hydrothermal Field, Central Tyrrhenian Sea)

The Zannone Giant Pockmark (ZGP) is a shallow-water (<−150 m) giant depression located on the shelf off Zannone Island (Pontine Archipelago, central Tyrrhenian Sea, Italy), hosting active hydrothermal vents. The ZGP seabed displays different fluid-venting morphologies (pockmarks, lithified pavements, mounds, and cone-shaped structures) and widespread bacterial communities. In this study, we analyzed ROV (Remote Operated Vehicle) images to gain information on seabed geology and the textural, mineralogical, and geochemical composition of authigenic crusts and gravel-sized clasts sampled close to active emissions. ROV images show authigenic dome-shaped crusts composed of native sulfur associated with barite, gypsum, amorphous silica, and secondary hydrothermal minerals (illite–montmorillonite). The gravel-sized clasts are mostly rhyolites strongly affected by hydrothermal alteration (Alteration Index > 88; depletion of some mobile elements and enrichment of some base metals), causing feldspar-destruction, silicification, formation of hydrothermal phyllosilicates, and precipitation of disseminated pyrite. More intense alteration implying the complete obliteration of the primary mineralogy or fabric is represented by quartz-pyrite samples. ZGP seabed morphology and petro-geochemical features of deposits point to the possible occurrence of a sulfide system linked to the degassing of magma similar to that feeding the Pleistocene products of Ponza Island.

Assessment of rodenticide resistance, eradication units, and pathogen prevalence in black rat populations from a Mediterranean biodiversity hotspot (Pontine Archipelago)

Biological invasions are a growing threat to biodiversity. The black rat, one of the worst pest in the world, is responsible for extensive population decline of many autochthonous and endemic species, particularly in island ecosystems. A number of rat eradication campaigns have been conducted, however, such endeavors do not always result in a complete removal of the pest. This may be due to the occurrence of individuals resistant to common rodenticides and/or a re-invasion of the same environment from interconnected areas when appropriate eradication units are not defined before starting an eradication campaign. Our study is a multidisciplinary approach whereby genetic and epidemiological methods were used to provide background information for successful eradication of black rats. We investigated the occurrence of mutations in the VKORC1 gene known to confer resistance to rodenticides and evaluated the spread of zoonoses across three islands of the Pontine Archipelago, an Italian hotspot of endemic Mediterranean biodiversity and a possible mainland source of invasion. As part of an eradication campaign, we also assessed patterns of genetic diversity at 10 microsatellite loci in order to identify eradication units. We recorded a strong population structure and revealed at least two distinct eradication units. Some degree of admixture was recorded on Ponza, the largest island and likely the main source of rats invading the other two islands. We did not record the occurrence of rats resistant to anticoagulants, but we revealed transmission of vector-borne pathogens in commensal habitats of the Archipelago.

Podarcis siculus latastei (Bedriaga, 1879) of the Western Pontine Islands (Italy) raised to the species rank, and a brief taxonomic overview of Podarcis lizards

In recent years, great attention has been paid to many Podarcis species for which the observed intra-specific variability often revealed species complexes still characterized by an unresolved relationship. When compared to other species, P. siculus underwent fewer revisions and the number of species hidden within this taxon may have been, therefore, underestimated. However, recent studies based on genetic and morphological data highlighted a marked differentiation of the populations inhabiting the Western Pontine Archipelago. In the present work we used published genetic data (three mitochondrial and three nuclear gene fragments) from 25 Podarcis species to provide a multilocus phylogeny of the genus in order to understand the degree of differentiation of the Western Pontine populations. In addition, we analyzed new morphometric traits (scale counts) of 151 specimens from the main islands of the Pontine Archipelago. The phylogenetic analysis revealed five principal Podarcis groups with biogeographic consistency. The genetic distinctiveness of the Podarcis populations of the Western Pontine Islands is similar or even more ancient than those observed in numerous other pairs of Podarcis sister species. In the light of these evidences we raise the Western Pontine lizards to specific rank; thus they should be referred to as Podarcis latastei.

Magmatic Signature in Submarine Hydrothermal Fluids Vented Offshore Ventotene and Zannone Islands (Pontine Archipelago, Central Italy)

Geochemical investigations carried out on submarine hydrothermal fluids vented offshore the Pontine Islands (Tyrrhenian Sea) revealed the existence of gas vents to the W of Zannone Island and SW of Ventotene Island. The geochemical features of the CO2-rich gas samples show a clear mantle-derived signature with3He/4He of 3.72-3.75 Ra and 1.33 Ra at Zannone and Ventotene, respectively. Gas geochemistry denotes how CO2-rich gases undergo fractionation processes due to CO2dissolution to a variable extent favoring enrichment in the less soluble gas species, i.e., CH4, N2, and He. The carbon isotope composition of CO2, expressed asδ13C vs. V-PDB, ranges from -0.71 and -6.16‰ at Zannone to 1.93‰ at Ventotene. Preliminary geothermometric and geobarometric estimations indicate equilibrium temperatures in the range of 150-200°C at Zannone and >200°C at Ventotene besides H2O pressures in the range of 5 bar and 20 bar at Zannone and Ventotene, respectively. Although the latest volcanic activity at the Pontine Archipelago is dated Middle Pleistocene, the combination of the new geochemical information along with geothermometric estimations indicates that cooling magmas are likely releasing enough thermal energy to form an efficient hydrothermal system.

Coralline algae on hard and soft substrata of a temperate mixed siliciclastic-carbonatic platform: Sensitive assemblages in the Zannone area (western Pontine Archipelago; Tyrrhenian Sea)

In the Mediterranean Sea, coralline algae assemblages (i.e. rhodolith beds and coralligenous assemblages) are considered biodiversity hotspots comparable to tropical reefs. However, information regarding their environmental distribution is still poor. In this view, relevant international actions have been adopted by the European Union to fill this gap.This work represents one of a few cases of predictive (fine-scale) habitats distribution map obtained through an integrated semi-automatic approach based on bathymetry, backscatter, seismic profiles, video, and sampling data. The used method has permitted the identification of nine morphological zones, four backscatter facies, and four benthic habitats distributed on the Zannone seafloor (western Pontine Archipelago; Tyrrhenian Sea). In particular, the finding of widespread sensitive habitats (i.e. coralligenous assemblages and rhodolith beds) reveals as the marine area off the western Pontine Archipelago (Tyrrhenian Sea) is highly suitable for their development (distance from the mainland, lack of river mouths), confirming the relevant ecological value of the Zannone area. Therefore, such information constitutes an update to the Mediterranean habitats distribution inventory, highlighting the need for the application of protection actions possibly targeted in the establishment of a Marine Protected Area.

On the coral-feeding habit of the sea star Peltaster placenta

The predatory activity of the asteroid Peltaster placenta (Muller and Troschel, 1842) on the black coral Parantipathes larix (Esper, 1790) is here described for the first time based on video footage obtained during a Remotely Operated Underwater Vehicle (ROV) survey conducted in the Pontine Archipelago (Southern Tyrrhenian Sea, Mediterranean Sea). Feeding is carried out on the living coenenchyme of the basal axis and pinnules of the antipatharian and is confirmed by the occurrence of its cnidocysts in the sea star gut content. The chitinous skeletal parts of the black coral are left intact as bare tissue, which helps to relate colonies to the predation event. Among all black coral species present in the research area, P. placenta was observed grazing exclusively on P. larix, similarly to other goniasterids known to be deep-sea corallivores with a marked selectivity for their prey. The predatory behaviour of P. placenta was previously unknown. The extent of its feeding traces suggests a significant influence on benthic trophic relationships and, ultimately, on the functioning, structure and health status of deep Mediterranean black coral forests.

Control of invasive species for the conservation of biodiversity in Mediterranean islands. The LIFE PonDerat project in the Pontine Archipelago, Italy

We present the EU LIFE PonDerat project, which is aimed at restoring the natural ecosystems of the Pontine Archipelago, a group of islands located off the western coast of Italy. The spread of invasive species is a major environmental threat on these islands, which are rich in rare habitats and endemic species and are important sites for the conservation of Mediterranean biodiversity. The project focuses on the conservation of species and habitats that are protected by EU laws but are currently threatened by introduced plants and animals. The main targets of the control measures are black rats, feral goats, mouflons and invasive plants of the genus Carpobrotus. Conservation measures focus on the shearwaters Puffinus yelkouan and Calonectris diomedea, which are endemic to the Mediterranean and are listed in Annex I of the European Bird Directive. Conservation measures also focus on island habitats of great biogeographical value, which are listed in Annex I of the European Habitats Directive and are seriously threatened by introduced herbivores and by invasive plants. The main outcome expected from this project is that the restoration of ecosystem functions will enhance the breeding success and population size of shearwaters and lead to the recovery of target habitats.

Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

AbstractDiscoveries from multibeam bathymetry and geochemical surveys performed off Zannone Island (western Pontine Archipelago, Tyrrhenian Sea) provide evidence of an undocumented hydrothermal field characterized by ongoing fluid emissions and morphologically complex giant depressions located in shallow water (<150 m water depth). Based on a detailed morpho‐bathymetric study we identify the seabed morphologies produced by hydrothermal fluid emission activity. We recognize five giant depressions (length >250 m) that host pockmarks, mounds, small cones, and active fluid vents, which are interpreted as complex fluid‐escape features developed both through vigorous‐explosive events and steady seepage. Their spatial distribution suggests that the NE‐SW trending faults bounding the Ponza‐Zannone structural high and the shallow fractured basement are favorable conditions for the upward migration of hydrothermal fluids. Moreover, we performed a detailed geochemical study to investigate the source of the hydrothermal fluids. The geochemical signature of the collected fluids provides information of active CO2‐dominated degassing with a significant contribution of mantle volatiles, with measured 3He/4He values > 3.0 Ra that are similar to those recorded at Stromboli and Panarea volcanoes. The hydrothermal system produces volatiles that may originate from residual magma batches, similar to the Pleistocene trachytes cropping out in the SE sector of Ponza Island that were probably intruded in the shallow crustal levels and never erupted. The discovery of the Zannone hydrothermal field updates the record of active hydrothermal areas of the Mediterranean Sea. Moreover, the recognition of several giant hydrothermal depressions characterized by a complex morphology is peculiar for the Mediterranean Sea.

Environmental factors controlling the distribution of rhodoliths: An integrated study based on seafloor sampling, ROV and side scan sonar data, offshore the W-Pontine Archipelago

The effects of different environmental factors controlling the distribution of different morphologies, sizes and growth forms of rhodoliths in the western Pontine Archipelago have been studied. The analysis of 231 grab samples has been integrated with 68 remotely operated vehicle (ROV) videos (22h) and a high resolution (<1m) side scan sonar mosaic of the seafloor surrounding the Archipelago, covering an area of approximately 460km2. Living rhodoliths were collected in approximately 10% of the grab samples and observed in approximately 30% of the ROV dives. The combination of sediment sampling, video surveys and acoustic facies mapping suggested that the presence of rhodoliths can be associated to the dishomogeneous high backscatter sonar facies and high backscatter facies. Both pralines and unattached branches were found to be the most abundant morphological groups (50% and 41% of samples, respectively), whereas boxwork rhodoliths were less common, accounting only for less than 10% of the total number of samples. Pralines and boxwork rhodoliths were almost equally distributed among large (28%), medium (36%) and small sizes (36%). Pralines generally presented a fruticose growth form (49% of pralines) even if pralines with encrusting-warty (36% of pralines) or lumpy (15% of pralines) growth forms were also present. Morphologies, sizes and growth forms vary mainly along the depth gradient. Large rhodoliths with a boxwork morphology are abundant at depth, whereas unattached branches and, in general, rhodoliths with a high protuberance degree are abundant in shallow waters. The exposure to storm waves and bottom currents related to geostrofic circulation could explain the absence of rhodoliths off the eastern side of the three islands forming the Archipelago.

The response of benthic meiofauna to hydrothermal emissions in the Pontine Archipelago, Tyrrhenian Sea (central Mediterranean Basin)

Recent investigations highlighted the occurrence of a giant depression related to hydrothermal activity off the Pontine Archipelago (central Mediterranean Sea, Italy). The new record of a giant seeping depression (Zannone Giant Pockmark, ZGP) in shallow-water provides the opportunity to study fluid vent impact on meiobenthic communities. The micropaleontological analyses on living (Rose Bengal stained) and dead assemblages recorded inside and outside the Zannone Giant Pockmark, allow to highlight changes in the structure and composition of the foraminiferal community that suggest variations of fluid emissions in different sectors of the study area. Inside the ZGP, under the direct influence of venting activity, a very peculiar living foraminiferal assemblage is found. It consists of agglutinated species (Spiculosiphon oceana, Jaculella acuta, Deuterammina rotaliformis) never found or very rare in the Mediterranean Sea. On the contrary dead assemblage testifies the changes on foraminiferal assemblages under carbonate dissolution process. Outside the pockmark in the nearby area of ZGP, the integrated meiofaunal and geochemical data suggest a transitional condition between vent influenced sedimentation and the typical carbonate sedimentation recorded in the rest of the Pontine Archipelago. In particular a possible spread of the venting activity in the northern and southern sectors of the study area, towards the edge of the Zannone insular shelf, is inferred.The impact of fluid emissions on foraminiferal assemblages can be summarized in the following observations: reduced biodiversity, increase of agglutinated species with predominant siliceous component in the test structure, limited distribution of living specimens inside the sediment, disappearance of porcelaneous taxa and presence of carbonate loss tests. As the result, the venting activity is likely to be the main environmental driver on the meiofaunal distribution.We also report, at the emission sites in the Pontine Archipelago, the presence of agglutinated species such as Spiculosiphon oceana, Jaculella acuta, Deuterammina rotaliformis, never found earlier in the Mediterranean Sea.

New insights on the petrology of submarine volcanics from the Western Pontine Archipelago (Tyrrhenian Sea, Italy)

The Pontine Islands form a volcanic archipelago in the Tyrrhenian Sea. It consists of two edifices, the islands of Ponza, Palmarola and Zannone and the islands of Ventotene and Santo Stefano, respectively. The Archipelago developed during two main volcanic cycles in the Plio-Pleistocene: 1) the Pliocene episode erupted subalkaline, silica-rich volcanic units, which constitute the dominant products in the western edifice (Ponza and Zannone Islands); 2) the Pleistocene episode erupted more alkaline products, represented by evolved rocks (trachytes to peralkaline rhyolites) in the islands of Ponza and Palmarola and by basic to intermediate rocks in the eastern edifice (Ventotene and Santo Stefano Islands). In this paper we present new geochemical and petrological data from submarine rock samples collected in two oceanographic cruises and a scuba diving survey. The main result is the recovery of relatively undifferentiated lithotypes that provide further insights on the magmatic spectrum existing in the Pontine Archipelago, allowing modelling of the whole suite of rocks by fractional crystallization processes. New major and trace element data and thermodynamic constrains (by the software PELE) indicate the existence of three distinct evolutionary trends corresponding to a HK calcalkaline series in the Pliocene, followed by a transitional and then by a shoshonite series in the Pleistocene. In particular, the transitional series, so far overlooked in the literature, is required in order to explain the genesis of several peralkaline felsic rocks recognized in the Archipelago. On the whole, the new geochemical data i) confirm the orogenic signature of the suites, ii) allow to rule out an anatectic origin for both subalkaline and peralkaline rhyolites and iii) indicate highly heterogeneous mantle sources, due to crustal components variously recycled in the mantle via subduction.

Obsidians artefacts from Renaghju (Corsica Island) and the Early Neolithic circulation of obsidian in the Western Mediterranean

The site of Renaghju has the largest excavated area of any Neolithic site on the island of Corsica (Western Mediterranean). Its lowest layer, exposed over a few hundred meters square contained a rich Early Neolithic Cardial ceramic and lithic industry dated by 14C to the second half of the 6th millennium BC. Obsidian, a raw material exogenous to the island, comprises ca. 15 % of the chipped stone industry. The provenance of 622 obsidian artefacts (84 % of the total assemblage) was determined through a combination of visual characterization, together with noninvasive particle-induced X-ray emission spectroscopy (PIXE) and energy dispersion spectrometer of a scanning electron microscope (SEM-EDS) on millimeter-sized polished fragments. This is, by far, the largest sample of obsidian artefacts analyzed from a Corsican Neolithic site. All but one of the artefacts was found to be made of obsidian from sources associated with the volcanic complex of Monte Arci on the nearby island of Sardinia. Obsidian from each of the three major Monte Arci sources exploited during the Neolithic were identified, with a predominance of obsidians of the SA and SB2 types over the SC type. Only one artefact was shown to be made of obsidian from another source, namely, that on the island of Palmarola, in the Pontine Archipelago. The Monte Arci obsidian were procured in the form of small nodules that were then reduced on site, the knappers primarily producing flakes using an expedient and intensive technology. This tradition involved the production of very few types of formal implements, including geometrics and carving/boring tools, forms that are typical of the Tyrrhenian Cardial Early Neolithic. This is the earliest Neolithic culture on Corsica, whose appearance coincides with a major colonization of both Corsica and Sardinia. The significant presence of Sardinian obsidians in the southwestern Corsican site of Renaghju attests to early contacts between groups inhabiting these islands from the 6th millennium BC, while the Palmarola obsidian indicates occasional contacts with groups living on the Italian Peninsula. Alternatively, this “exotic” raw material’s presence at Renaghju might be viewed as the result of frequent and intensive movements of the first colonists in the Tyrrhenian area.

NEW OBSERVATIONS ON AMMOLAGENA CLAVATA (JONES AND PARKER, 1860) FROM THE MEDITERRANEAN SEA

One hundred and sixty specimens of Ammolagena clavata (Jones and Parker), encrusted on various bioclastic substrates, were collected from recent foredeep sediments of the Pontine Archipelago (Tyrrhenian Sea). Numerous specimens were measured, photographed, and analyzed, using energy dispersive spectrometry (EDS). The wall of A. clavata is composed of an agglutinated layer between two organic films. An EDS analysis showed high concentrations of Si and, subordinately, Al, both in the agglutinated and organic layers; the latter also contain high amounts of Fe. The presence of an incipient lip (pseudoseptum) at the beginning of the tubular chamber confirms the pseudo-bichambered architecture of the test. Its most problematic morphological feature is a second aperture at the base of the first chamber (proloculus). The variable morphology of the second pseudochamber is interpreted to be an adaptive behavior for avoiding occlusion of its aperture by the sediment. The presence of coccoliths and coccospheres within the chambers suggests that A. clavata is a suspension feeder. The upper limit of its bathymetric range in the Mediterranean Sea coincides with the upper limit of Mediterranean Levantine Intermediate Water.

Repeated events of hardground formation and colonisation by endo-epilithozoans on the sediment-starved Pontine continental slope (Tyrrhenian Sea, Italy)

Abstract Rock samples dredged offshore the Pontine Archipelago (400–2000 m water depth) were studied by palaeontological analyses of planktic foraminifera and endo-epilithozoan faunas colonising Fe–Mn crusts and by petrographic analyses of volcanic samples. Palaeontological and petrographic analyses have revealed a complex Plio-Pleistocene depositional history controlled by hemipelagic sedimentation and volcanic activity with episodic non-depositional phases. The sedimentary deposits are associated with ferromanganese hardgrounds, more or less colonised by endolithic and epilithozoan organisms. The presence of foraminifera typical of tropical and subtropical waters (such as Globigerinoides ruber , Globigerinoides trilobus , Pulleniatina obliquiloculata and Sphaeroidinella dehiscens ) indicates that the micritic deposition occurred during warm climatic periods, whilst micrite cementation and hardground formation are here attributed to colder climates. The depositional processes recognised on the Pontine continental slope reveal a sediment-starved condition that locally resemble those of seamount environment. The slope sedimentation found in the Pontine Archipelago can be helpful in the interpretation of ancient deposits from seamounts and continental slope depositional environments, characterised by hardground and hiatuses.

Mixed carbonate-siliclastic sediments and benthic foraminiferal assemblages from Posidonia oceanica seagrass meadows of the central Tyrrhenian continental shelf (Latium, Italy)

Sedimentological and micropaleontological characterisation of bottom sediments from two Latium continental platform areas (central Tyrrhenian Sea) was carried out. The two studied areas are Santa Marinella in northern Latium and Ponza Island in southern Latium (Pontine Archipelago), characterised by the presence of Posidonia oceanica seagrass, but with different sediment inputs. In the Santa Marinella area, where seagrass ends at 15 m water depth, there are both siliciclastic sediments from fluvial run-off and carbonate lithoclasts originated by coastal erosion. In the Pontine Archipelago, in which P. oceanica meadows end at 35-40 mwd, terrigenous clasts originate only from coastal erosion and, consequently, carbonate production prevails. On the whole, grain size analysis shows a strong predominance of sandy fraction, whereas mud and gravel are subordinate. The very low frequencies of muddy fraction can be attributable to re-suspension processes and the lack of aragonitic components that produce mud-sized particles. The better sorting of Santa Marinella seagrass substrate with respect to Ponza Island is related to the origin of terrigenous sediments, which are mainly provided by rivers and so are previously sorted. Facies analysis was performed using component analyses, grain size percentage, sorting and carbonate content, complemented with the observations obtained from artificially-hardened sediments and, finally, tested with a Q-mode cluster analysis. Consequently, 4 sedimentary facies have been recognised. Facies F1, limited to the Santa Marinella area (7.5-13.5 mwd), is characterised by sand-sized wellsorted sediments, and dominated by the terrigenous fractions. Facies F2 represents the shallowest seagrass environment (5-7 mwd), and it is restricted to the Ponza area. In this environment the sedimentation is still dominated by terrigenous components, while the carbonate sediment contribution is due principally to red algae. Facies F3 has the widest water depth interval (8-34 mwd), and principally occurs in the Ponza site, while only two samples are from the Santa Marinella. The terrigenous fraction is conspicuous, however there is an increase of carbonate sediment produced mainly by the epiphytes (foraminifera, bryozoans) and, subordinately, by benthic organisms (foraminifera, molluscs). Facies F4, occurring in the Ponza site (17-29 mwd), is the most carbonate rich facies with a carbonate sediment produced by epiphytic (foraminifera, bryozoans, serpulids, red algae) as well as benthic (foraminifera, red algae, molluscs) biota. Q-mode cluster analysis performed on the most abundant benthic foraminiferal species led to the identification of 4 assemblages, dominated by epiphytic foraminifera. The A1 assemblage was found only in the Ponza site (5-12 mwd) and is dominated by Lobatula lobatula, Peneroplis pertusus and Miliolinella subrotunda. The A2 assemblage (10-34.5 mwd), characterised by L. lobatula and Rosalina bradyi, is mainly limited to Ponza Island, with only one sample from Santa Marinella. The B1 (7.5-9 mwd) and B2 (8-13.5 mwd) assemblages were found only in the Santa Marinella area and are dominated by L. lobatula, R. bradyi and Conorbella hexacamerata and by Asterigerinata mamilla and R. bradyi, respectively. The calculated diversity indices (α-Fisher and Shannon index) are very similar in both areas, whereas the dominance percentage is higher in the Santa Marinella site. The lack of the symbiont-bearing foraminifer P. pertusus in the Santa Marinella samples may be linked to less favourable environmental conditions. In this area, the prevalent siliciclastic sedimentation and the water turbidity, which decreases the light penetration, are the limiting factors also for the seagrass growth. The comparison between the foraminiferal assemblages of two areas may be used to estimate the health of present-day and fossil seagrass.

Taxonomic Notes on theGenista ephedroidesGroup (Fabaceae) from the Mediterranean Area

Abstract. A revision of the taxa belonging to the Genista ephedroides group (Fabaceae, Cytiseae) occurring in the Tyrrhenian area is presented. The study, carried out on the basis of the literature, herbarium material, and field and karyological investigations, allows the recognition of 13 taxa. Eight are already known: G. cilentina Vals., G. demarcoi Brullo, Scelsi & Siracusa, G. dorycnifolia Font Quer, G. ephedroides DC., G. gasparrinii (Guss.) C. Presl, G. numidica Spach, G. tyrrhena Vals., and G. valsecchiae Brullo & De Marco, and five are new to science. Genista bocchierii Bacch., Brullo & Feoli Chiapella, G. insularis Bacch., Brullo & Feoli Chiapella, G. insularis subsp. fodinae Bacch., Brullo & Feoli Chiapella, and G. ovina Bacch., Brullo & Feoli Chiapella are described from Sardinia, Italy, while G. tyrrhena subsp. pontiana Brullo & De Marco is described from the Pontine Archipelago of Latium, Italy. Karyologically, most of the taxa are characterized by the somatic number 2n = 48 (G. bocchierii, ...