Francesco Mastrototaro

Biodiversity of the white coral reefs in the Ionian Sea (Central Mediterranean)

Three surveys were carried out off Cape Santa Maria di Leuca (Southern Italy). Samples were taken using an ‘ingegno’, trawl net and traps at 630–1100 m depth. The white coral biocoenosis in this area of the Ionian Sea consists of living corals mainly represented by the framework builders Lophelia pertusa and Madrepora oculata. The solitary corals Desmophyllum cristagalli and Stenocyathus vermiformis were also obtained alive. The polychaete Eunice norvegica is another characteristic species. A list of 58 species were compiled, indicating the Atlantic character of this biocoenosis and confirming Mediterranean biodiversity to be lower than that of ocean.

Deep Sequencing of Mixed Total DNA without Barcodes Allows Efficient Assembly of Highly Plastic Ascidian Mitochondrial Genomes

Ascidians or sea squirts form a diverse group within chordates, which includes a few thousand members of marine sessile filter-feeding animals. Their mitochondrial genomes are characterized by particularly high evolutionary rates and rampant gene rearrangements. This extreme variability complicates standard polymerase chain reaction (PCR) based techniques for molecular characterization studies, and consequently only a few complete Ascidian mitochondrial genome sequences are available. Using the standard PCR and Sanger sequencing approach, we produced the mitochondrial genome of Ascidiella aspersa only after a great effort. In contrast, we produced five additional mitogenomes (Botrylloides aff. leachii, Halocynthia spinosa, Polycarpa mytiligera, Pyura gangelion, and Rhodosoma turcicum) with a novel strategy, consisting in sequencing the pooled total DNA samples of these five species using one Illumina HiSeq 2000 flow cell lane. Each mitogenome was efficiently assembled in a single contig using de novo transcriptome assembly, as de novo genome assembly generally performed poorly for this task. Each of the new six mitogenomes presents a different and novel gene order, showing that no syntenic block has been conserved at the ordinal level (in Stolidobranchia and in Phlebobranchia). Phylogenetic analyses support the paraphyly of both Ascidiacea and Phlebobranchia, with Thaliacea nested inside Phlebobranchia, although the deepest nodes of the Phlebobranchia–Thaliacea clade are not well resolved. The strategy described here thus provides a cost-effective approach to obtain complete mitogenomes characterized by a highly plastic gene order and a fast nucleotide/amino acid substitution rate.

Occurrence of Paraleucilla magna (Porifera: Calcarea) in the Mediterranean Sea

The calcareous sponge Paraleucilla magna has been detected at different Mediterranean sites (Taranto, Porto Cesareo, Brindisi and Naples). Its record in well studied areas where several benthic surveys have previously been carried out suggests a recent introduction of the species into the Mediterranean Sea. Until now this sponge has only been recorded from the Brazilian coast. It shows different morphologies, varying from tubular to an irregular massive shape with several folds occurring on its surface. The colour is white-cream. The surface is smooth. The consistency is friable. The oscula are 10–20 mm in diameter and located at the top of tubular protrusions. The skeleton consists of cortical and subatrial triactines and tetractines, together with atrial triactines, differently distributed in the sponge body. Paraleucilla magna is abundant in eutrophic environments, where seasonally it may reach very high frequency values and large dimensions. It is resistant to pollution, but it is also able to live in clean waters. The inclusion of this species among Mediterranean alien invasive species is suggested.

Sponge fauna associated with a Mediterranean deep-sea coral bank

Thirty species of sponges (29 Demospongiae, 1 Hexactinellida) have been recorded in association with a white coral bank situated off Cape S. Maria di Leuca (southern Italy) at depths ranging from 430 to 1160 metres. Notwithstanding the occurrence of clearly eurybathic species, two depth-dependent sponge groups can be identified along the bathvmetric gradient. Two species, Geodia nodastrella and Plocamiopsis signata. are reported for the first time from the Mediterranean Sea. The sponge assemblage shows a higher affinity with the fauna from the Boreal region, with very low number of Mediterranean endemic species. Systematic notes concerning the poorly known and intriguing species, studied using scanning electron microscopy analysis, are reported.

Nonindigenous species along the Apulian coast, Italy

Thirty-eight nonindigenous marine species (NIS) (macroalgae, sponges, hydrozoans, molluscs, polychaetes, crustaceans, ascidiaceans and fish), are reported from the Apulian coast of Italy. Shipping, aquaculture and migration through the Suez Canal are the main pathways of introduction of the NIS. In Apulian waters, 21% of NIS are occasional, 18% are invasive and 61% are well-established. It is highly probable that more NIS will arrive from warm-water regions, because Mediterranean waters are warming. Furthermore, some of the successful NIS must have the ability to become dormant in order to survive adverse conditions, either seasonal or during long journeys in ballast waters. The identification of NIS depends greatly on the available taxonomic expertise; hence the paucity of taxonomists hinders our knowledge of NIS in our seas. We propose the creation and maintenance of a network of observatories across the Mediterranean to monitor the changes that take place along its coasts.

Hypervariability of Ascidian Mitochondrial Gene Order: Exposing the Myth of Deuterostome Organelle Genome Stability

The few sequenced mitochondrial (mt) genomes of the class Ascidiacea (Chordata, Tunicata), mostly belonging to congeneric species of the Phlebobranchia order, show extraordinary gene order rearrangements. In order to assess if this hypervariability in gene order is a general feature of Ascidiacea, we report here the gene arrangement of five ascidians belonging to the Aplousobranchia and Stolidobranchia orders. Our data show that Ascidiacea are characterized by: 1) extensive gene order rearrangements both within and between the three major lineages; 2) lack of significant similarities to the gene order of other deuterostomes; and 3) an extent of rearrangements comparable with that of Mollusca (especially the Gastropoda, Bivalvia, and Scaphopoda classes), a phylum with highly rearranged mtDNAs. The only conserved feature is the location of all genes on the same strand, which suggests that selective constraints are related to the mt transcription. Finally, a higher mobility of the tRNA genes is undetectable because of saturation effect, and only the partially conserved cox2-cob gene block seems to retain some phylogenetic signals.

Occurrence of Musculista senhousia (Mollusca: Bivalvia) in the Taranto seas (eastern-central Mediterranean Sea)

Department of Zoology,Via Orabona, 4,70125 Bari, Italy*Corresponding author, e-mail: f.mastrototaro@biologia.uniba.itThe ¢rst record of Musculista senhousia in theTaranto seas (eastern-central Mediterranean Sea) is reported.The species wasmostly found on bottoms with pleustophytic algal felt where densities up to 3800 specimens per square metre were estimated.The sizes in the sampled population ranged from 5.16 to 30.59mm. Two main modal components were detected around11.67 0.67mm and 18.00 2.38mm.Musculista senhousia (Benson in Cantor,1842) is a small musselwidespread in several regions of the earth from the Asian conti-nent (locus tipicus) to the western coast of the USA, to the NewZealand and Australian coasts, along the Israel coast to the RedSea, oi the islands of Zanzibar and Madagascar as well as inIndo-China and Japan (Lazzari & Rinaldi, 1994). This smallmussel was recorded as an immigrant species for the ¢rst time inthe western Mediterranean along the French coast (Hoenselaar& Hoenselaar,1989). Successively it was recorded in Italy, in theAdriatic Sea, in the brackish lagoons of Ravenna (Lazzari R Mistri et al., 2001) and in theTyrrhenian Sea inthe Gulf of Olbia (Savarino & Turolla, 2000).The ¢rst occurrence of M. senhousia in theTaranto seas (north-western Ionian Sea) is reported in this note.The town of Taranto is located on the coast of the north-western Ionian Sea (eastern-central Mediterranean). To thesouth-west it overlooks the open sea in the Mar Grande basinand north-eastwards the basin of the Mar Piccolo which ismade up of two smaller inlets (I and II seno) (Figure 1). TheMar Piccolo covers an area of 20.72km

The non-indigenous ascidian Distaplia bermudensis in the Mediterranean : Comparison with the native species Distaplia magnilarva and Distaplia lucillae sp. nov

Three species of Distaplia from the Mediterranean are described: D. bermudensis is a species introduced from the western Atlantic Ocean, which principally diiers from the native D. magnilarva in having hermaphroditic zooids. The new species D. lucillae diiers from the preceding ones in the structure of its stomach wall which is regularly plicated both externally and internally. Distaplia lucillae has colonies with hermaphroditic, but only male ripe, zooids and exclusively female colonies; this is a condition closely related to D. magnilarva though diierent. A key to European Distaplia is provided.

Mapping of the benthic communities in the Taranto seas using side-scan sonar and an underwater video camera

Side-scan sonar and underwater video camera records as well as dredging samples were used to map the bottom morphology and biocoenoses in the Taranto seas. A 1:20,000 scale chart has been produced with all the data recorded. Most of the study area consists of biocoenoses affected by the anthropogenic activities of the town of Taranto. Some native broadly tolerant species seem to benefit from these activities and become increasingly dominant. Environmental modifications also seem to favour the settlement of exotic species.

Ascidian Mitogenomics: Comparison of Evolutionary Rates in Closely Related Taxa Provides Evidence of Ongoing Speciation Events

Ascidians are a fascinating group of filter-feeding marine chordates characterized by rapid evolution of both sequences and structure of their nuclear and mitochondrial genomes. Moreover, they include several model organisms used to investigate complex biological processes in chordates. To study the evolutionary dynamics of ascidians at short phylogenetic distances, we sequenced 13 new mitogenomes and analyzed them, together with 15 other available mitogenomes, using a novel approach involving detailed whole-mitogenome comparisons of conspecific and congeneric pairs. The evolutionary rate was quite homogeneous at both intraspecific and congeneric level, and the lowest congeneric rates were found in cryptic (morphologically undistinguishable) and in morphologically very similar species pairs. Moreover, congeneric nonsynonymous rates (dN) were up to two orders of magnitude higher than in intraspecies pairs. Overall, a clear-cut gap sets apart conspecific from congeneric pairs. These evolutionary peculiarities allowed easily identifying an extraordinary intraspecific variability in the model ascidian Botryllus schlosseri, where most pairs show a dN value between that observed at intraspecies and congeneric level, yet consistently lower than that of the Ciona intestinalis cryptic species pair. These data suggest ongoing speciation events producing genetically distinct B. schlosseri entities. Remarkably, these ongoing speciation events were undetectable by the cox1 barcode fragment, demonstrating that, at low phylogenetic distances, the whole mitogenome has a higher resolving power than cox1. Our study shows that whole-mitogenome comparative analyses, performed on a suitable sample of congeneric and intraspecies pairs, may allow detecting not only cryptic species but also ongoing speciation events.