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Meiofauna includes an astonishing diversity of organisms, whose census is far from being complete. Most classic ecological studies have focused on hard-bodied Ecdysozoan taxa (notably Copepoda and Nematoda), whose cuticle allows determination at species-level after fixation, rather than soft-bodied, Spiralian taxa, which most often lose any diagnostic feature in fixed samples. Yet, metabarcoding studies have recently revealed a species-richness of soft-bodied taxa comparable, and in cases superior, to that of Copepoda and Nematoda together. However, given objective difficulties inherent to their study, which necessarily has to be performed on living individuals, and their limited utilisation for ecological and applicative research, taxonomic expertise on soft-bodied organisms has declined over the years, and diversity of these phyla in most areas of the world is presently completely unknown. Here we present an expert-based survey of current knowledge on the composition and distribution of soft-bodied meiofaunal taxa in Italy, with special references to the predominantly or exclusively meiobenthic phyla Gastrotricha, Gnathostomulida, Platyhelminthes, Rotifera, Xenacoelomorpha, and macrofaunal taxa with conspicuous meiofaunal representatives (Annelida, Mollusca and Nemertea). A total of 638 described species have been reported from Italian coasts; furthermore, the existence of a large number of undescribed species is mentioned. Knowledge of Annelida, Gastrotricha, and Rotifera appears particularly detailed, placing Italy among the best-known country worldwide. In contrast, knowledge of Platyhelminthes and Xenacoelomorpha appears patchy, and limited to few areas. Sampling effort has been uneven, with most species recorded from the Tyrrhenian Sea, while large sections of the Adriatic and Ionian seas have been poorly explored. Results highlight the role that Marine Biological Stations, notably the Zoological Station "Anton Dohrn" in Naples, have had in promoting the study of soft-bodied taxa in Italy. [ABSTRACT FROM AUTHOR]

Ruditapes decussatus (Linnaeus, 1758) (Veneridae) is an Atlanto-Mediterranean bivalve whose populations have experienced reductions and, in some instances, hybridisation with allochthonous R. philippinarum. Acquisition of additional genetic knowledge concerning the present R. decussatus populations is essential to address adequate conservation plans for this species. For this purpose, we analysed a portion of the mtDNA cytochrome c oxidase subunit I (COI) region in populations from the western Mediterranean, where this species represents a harvested fishery resource. Our analyses revealed an overall lack of genetic structure within the western Mediterranean area, and the occurrence of mtDNA substructuring between the Aegean and Marmara seas and the remaining populations from the whole Mediterranean basin and the South European Atlantic coast. The results obtained for populations from Sardinia, where extensive restocking programmes have not been reported and where R. philippinarum is rare and localised, suggest that intensive harvesting and potential dispersal alone may have been able to shape the genetic variation identified in the local R. decussatus populations. [ABSTRACT FROM AUTHOR]

Esox cisalpinus(Teleostea: Esocidae) (syn.Esox flaviae) is an Italian freshwater autochthonous fish, whose originary range is limited to the Northern and Central Italy. However, this species has historically been introduced in several areas of Southern Italy, mainly for recreational purposes. In this paper we report the first record ofE. cisalpinuson the Sardinia island (Western Mediterranean, Italy), where the species has been recently introduced at least in one lake. The species identification and the population dynamics analysis were performed using mitochondrial markers. The level of genetic variability, compared to those of other peninsular populations ofE. cisalpinus, was surprisingly high, and several never-before-described haplotypes were found. A total of 10 mtDNA haplotypes were found. Demographic analysis is suggestive of a population expansion. We hypothesise thatE. cisalpinushas been introduced in the Sardinian lake by the releasing of a conspicuous number of individuals. Given the conservational and recreational interest thatE. cisalpinusarouses, it would be advisable that Sardinian government focuses in the near future also on management measures of its Sardinian population. [ABSTRACT FROM AUTHOR]

The Mediterranean Lessepsian migrations excite the interest of biologists who are devoted to inferring the effects of selection on the genetic structure of immigrants. The bluespotted cornetfishFistularia commersoniiis an Indo-Pacific species that was first recorded in the Levantine cost of Mediterranean, and within a few years, it rapidly expanded throughout the entire basin. Studies on its genetic variability, performed via mitochondrial sequencing of the Mediterranean specimens, suggest that a limited number of mitochondrial lineages passed through the Suez Canal. However, nuclear markers provide a scenario, with a high genetic variability among the MediterraneanF. commersoniimigrants, along with the occurrence of haplotype sharing between the Mediterranean and the Red Sea. The aim of this study was to enlarge the number of Mediterranean sites in order to evaluate if the rapid expansion and different patterns of spread ofF. commersoniiin the basin could have led to a genetic structuring. The analysis was carried out by sequencing mitochondrial D-loop I in individuals from Sardinia, Sicily, Tunisia, Lampedusa, Libya and Lebanon. Sequences available from previous studies were included in the data set, allowing us to obtain a data set that likely represents the entire distribution range of the species. Results suggest the possible occurrence of two mitochondrial lineages involved in the Mediterranean invasion ofF. commersonii, a bottleneck may have caused a loss in the genetic variation, leading to the fixation of specific lineages as an adaptive response to the new environmental conditions. [ABSTRACT FROM AUTHOR]

Patella ulyssiponensis s.l. is widely distributed in the Mediterranean as well as in the north-eastern Atlantic, from southern Norway to north-western Africa, including Macaronesia. Throughout its range, P. ulyssiponensis s.l. shows a high degree of variability in the shape and colour pattern of the shell and in the colour pattern of the foot. In addition, the species demonstrates widely overlapping morphological parameters with the coexisting P. caerulea (in the Mediterranean), P. vulgata (in north-eastern Atlantic) and P. candei (in the Macaronesian islands). Thus P. ulyssiponensis s.l. identification proves to be difficult. So far, method to unequivocally identify uncertain specimens of P. ulyssiponensis s.l. from the coexisting species was using a molecular taxonomy approach based on the Cytochrome c Oxidase subunit I (COI) sequences analysis. The aim of the present study was to identify specific PCR-RFLP (Restriction Fragment Length Polymorphism PCR-based) markers on the COI sequences which could be used as an alternative and fast diagnostic tool for the discrimination of P. ulyssiponensis s.l. from P. caerulea, P. vulgata and P. candei, when the morphology of the coexisting individuals provided equivocal information. First, we sampled 65 Patella spp. and classified these by means of the COI sequencing. Then, we selected the TaqI endonuclease for the specific RFLP reaction, which produced a combination of RFLP electrophoretic bands, allowing an unequivocal identification of the individuals of P. ulyssiponensis s.l. [ABSTRACT FROM PUBLISHER]

Owing to technical problems and difficult taxonomic identification, meiofauna have been generally less studied than macrofauna. However, the role of meiofauna in marine ecosystem functioning, and their effective and rapid response to anthropogenic alterations and climatic changes have recently been acknowledged, leading to increasing scientific and applied interest. At present, systematic and biogeographic knowledge of the meiofauna of the Adriatic Sea is extremely heterogeneous, because most of the data are limited to a few taxa and the sampled areas are scattered, being located mainly in the coastal areas of the northern basin. Analysis of the composition and distribution of meiobenthic groups in the Adriatic Sea highlights the presence of several endemisms. Meiofauna also include bioindicator taxa, which allow assessment of the quality of marine sediments; this is particularly useful in systems characterised by the synergistic effect of different forms of anthropogenic impact, such as the Adriatic basin. Current knowledge about the ecology of the meiofauna and use of this component in applied ecological studies, along with the availability of a standardised protocol for the analysis of meiofaunal assemblages, allows us to recommend formal acknowledgement of the need to integrate information derived from the analysis of macrofauna with information derived from the study of meiofauna. Future research based on the simultaneous use of both of these benthic components will allow faster and more accurate evaluation of the response of coastal marine ecosystems to anthropogenic disturbance. [ABSTRACT FROM AUTHOR]

A new species of mesopsammic polyclad, Theama mediterranea sp. nov., from lower intertidal habitats of the Mediterranean Sea, is described. The species differs from congeneres found in the tropical Pacific and the Atlantic coast of South America, in terms of size, structure of the male copulatory organ and number of eyes. T. mediterranea sp. nov. has a short pelagic juvenile phase, while adults are strictly interstitial; the life cycle is annual. Based on observation of the type material of Theama evelinae Marcus, 1949, the genus Eutheama Faubel, 1983 is synonymized with Theama Marcus, 1949. [ABSTRACT FROM AUTHOR]

Pseudomonocelis ophiocephala (Schmidt, 1861), a mesopsammic proseriate, is common in a variety of shallow water habitats in the Mediterranean. The genetic relationships between morphologically indistinguishable populations across the Mediterranean were surveyed by means of combined allozyme and Random Amplified Polymorphic DNA (RAPD) analysis. Genetic distances, UPGMA cluster analysis and F-statistics based on 27 allozyme genetic loci and 68 RAPD primer fragments were consistent in showing that the taxon Pseudomonocelis ophiocephala is a complex of sibling species, consisting of four taxonomic units. The four species differ in distribution and habitat: sibling A is widespread in lower intertidal habitats of the Mediterranean, in well-sorted, medium- to coarse-grained sand; siblings B, C and D show a restricted distribution (Corsican–Sardinian region and Elba Island, west and east coast of Greece, respectively) in low-energy marine habitats. Given that the species of the complex are morphologically indistinguishable, the type material is absent, and that there are two siblings in the type locality (Corfu Island, Greece), a neotype is designated for P. ophiocephala. The three further siblings are named; species descriptions are based on non-morphological characters (karyotype, allozymic and RAPD patterns). Distributions and reconstruction of phylogenetic relationships based on allozyme data suggest that both allopatric and ecological speciation have played a role in the evolutionary history of the species complex. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 87, 553–576. [ABSTRACT FROM AUTHOR]

Six new species of Nematoplana are described from eastern Australia. They are distinguished on the basis of the morphology of sclerotized structures, chromosome number and morphology, and pigmentation. Six further unguiphorid species were only found immature, and cannot be formally described. They none the less have distinct morphological and/or karyological features. The Unguiphora as a whole, and the genus Nematoplana in particular, are species-rich in eastern Australia. The high diversity of the group appears due both to narrow-range endemics, and to the narrow ecological niche of many of the species. [ABSTRACT FROM AUTHOR]

Presents and discusses research findings in eastern australia which has revealed an abundance and diversity of Polystyliphora species. Factors attributed to the abundance of the species of platyhelminthes in eastern Australia; Comparison of the number of sympatric species in Australia to those in other parts of the world.