Rocky shore molluscan assemblages from natural and artificial substrata in the Maltese Islands

This work was partially funded through the European Social Fund under the Strategic Educational Pathways Scholarship (STEPS) scheme grants.The mediolittoral macrofaunal assemblages associated with concrete jetties and natural rocky substrata in two Maltese bays were compared to assess potential differences in the molluscan assemblages between artificial and natural hard substrata. The whole extent of the mediolittoral zone was sampled and the molluscs present were identified and counted. Overall species richness was significantly lower on jetties. Densities of species common on the natural rock, such as Cerithium spp. and Eatonina spp., were lower on jetties; however, the densities of Patella spp. were higher.peer-reviewe

Not all that clear cut : intraspecific morphological variability in Squalus blainville (Risso, 1827) and implications for identification of the species

Of the three species of the genus Squalus that occur in the Mediterranean Sea, S. blainville and S. megalops are very difficult to distinguish. This study assesses the variability in morphological features that have been used to differentiate between these species. Squalus were collected from stations within the 25-nautical mile Fisheries Management Zone around the Maltese Islands; 349 specimens were dissected and categorized into male and female, mature and immature, and individuals were randomly selected from each category to make up a sample of 169 specimens. For each individual, total length and first dorsal fin parameters were measured, and morphology of denticles isolated from the laterodorsal area, of the upper and lower teeth and of the chondrocranium was analysed. The first dorsal spine was shorter that the fin base in 93% of the specimens, which is typical of S. megalops; this character was not related to either gender or maturity. Chondrocrania with one lateral process (typical of S. blainville) and two lateral processes (typical of S. megalops) were present. Teeth from the same individuals showed morphological features that overlap between S. blainville and S. megalops. Both unicuspid (typical of S. megalops) and tricuspid denticles (typical of S. blainville) were observed on the same individuals. Twelve specimens (six having one and six having two lateral chondrocranial processes) were analysed genetically by sequencing of the mtDNA marker Cytochrome Oxidase Subunit I (COI). All resulted to be S. blainville showing that intraspecific variability in supposedly diagnostic morphological features is large enough to render these unreliable to tell apart these two species, especially in the field.peer-reviewe

Puzzling over spurdogs : molecular taxonomy assessment of the Squalus species in the Strait of Sicily

The actual occurrence of Squalus megalops in the Mediterranean Sea has recently been questioned. Several research works which sought to assess available morphological and meristic features that differentiate S. megalops from other Squalus species in the Mediterranean Sea, revealed poor discriminatory power and high variability of the assessed characters, especially when comparing S. megalops and S. blainville. The application of molecular tools does not support the presence of S. megalops. In the present study, we screened spurdog species from the Strait of Sicily using a molecular taxonomy approach based on two mitochondrial DNA markers and we report the occurrence of two Squalus lineages characterizing specimens collected from the stretch of sea between Tunisia, southern Sicily, Malta and Libya. The results support the hypothesis that a common species, S. blainville, currently inhabits the Mediterranean Sea, while a second and rare species is probably an occasional visitor with high morphological similarity to the S. megalops and S. blainville but is genetically distinct from both. Within this perspective, the occurrence of S. megalops in the Mediterranean Sea is not confirmed and our study highlights the taxonomic uncertainties in relation to the occurrence and distribution of Squalus species in this region. We encourage the establishment of a coordinated international effort to implement a comprehensive and integrated taxonomic assessment on this genus which represents an irreplaceable component of the biodiversity of the area.peer-reviewe

Improving the conservation of Mediterranean Chondrichthyans : the ELASMOMED DNA barcode reference library

Cartilaginous fish are particularly vulnerable to anthropogenic stressors and environmental change because of their K-selected reproductive strategy. Accurate data from scientific surveys and landings are essential to assess conservation status and to develop robust protection and management plans. Currently available data are often incomplete or incorrect as a result of inaccurate species identifications, due to a high level of morphological stasis, especially among closely related taxa. Moreover, several diagnostic characters clearly visible in adult specimens are less evident in juveniles. Here we present results generated by the ELASMOMED Consortium, a regional network aiming to sample and DNA-barcode the Mediterranean Chondrichthyans with the ultimate goal to provide a comprehensive DNA barcode reference library. This library will support and improve the molecular taxonomy of this group and the effectiveness of management and conservation measures. We successfully barcoded 882 individuals belonging to 42 species (17 sharks, 24 batoids and one chimaera), including four endemic and several threatened ones. Morphological misidentifications were found across most orders, further confirming the need for a comprehensive DNA barcoding library as a valuable tool for the reliable identification of specimens in support of taxonomist who are reviewing current identification keys. Despite low intraspecific variation among their barcode sequences and reduced samples size, five species showed preliminary evidence of phylogeographic structure. Overall, the ELASMOMED initiative further emphasizes the key role accurate DNA barcoding libraries play in establishing reliable diagnostic species specific features in otherwise taxonomically problematic groups for biodiversity management and conservation actions.peer-reviewe

Nikteb...

Ġabra ta’ poeżiji u proża li tinkludi: L-iben il-ħali ta’ David Agius Muscat – Kaptan ta’ Kit Azzopardi – Il-lanterna ta’ Charles Bezzina – Li kelli mmur lura ta’ Ġorġ Borg – Firda ta’ Ġorġ Borg – Garden fairy ta’ Charles Briffa – Sejf jinfidlek ruħek ta’ Charles Briffa – Waqt ta’ Joseph Buttigieg – Vjaġġ ta’ John Caruana – Ċaqlembuta ta’ Antoine Cassar – Ħaġa tqila ta’ Carmel G. Cauchi – F’tarf il-blat ta’ Leanne Ellul – Int ta’ Victor Fenech – Pippin u l-bojja ta’ Charles Flores – L-arloġġ ta’ Joe Friggieri – Il-fjur tal-ġakaranda ta’ Joe Friggieri – Fjur tal-kaktus ta’ Joel Galea – Biss is-skiet ta’ Joel Galea – Għalissa ta’ Maria Grech Ganado – Ilsna ta’ Maria Grech Ganado – Is-sried ixoqqna fin fin ta’ Adrian Grima – Ħsieb ħalliel... ta’ Patrick Sammut – Lament lil ommi ta’ Salv Sammut – Hekk kif tinħass ġol-arja x-xitwa ta’ Lillian Sciberras – F’għajnejha, il-ħarsa siekta ta’ Clare Azzopardi – Għad jagħdab l-irdum ta’ Paul P. Borg – Forsi...xi darba ta’ Charles Casha – Faxxa ngħas ta’ Sergio Grech – Il-mejda tal-mogħdija ta’ Pierre J. Mejlak – Min jaf bi Stojan Kurepa? ta’ Immanuel Mifsud – L-eħrex jum tal-gwerra ta’ Maurice Mifsud Bonnici – Il-vażett tal-bewsiet ta’ Rita Saliba – Pjanu ta’ Trevor Żahra – Il-ħalliel ta’ Guy de Maupassant, traduzzjoni ta’ Toni Aquilina – Salvu tal-pasturi ta’ Francis Ebejer, traduzzjoni ta’ Steve Borg – Sunetti ta’ William Shakespeare, traduzzjoni ta’ Oliver Friggieri – Nikteb... ta’ Nizar Qabbani, traduzzjoni ta’ Kevin Saliba.peer-reviewe

Puzzling over spurdogs: molecular taxonomy assessment of the Squalus species in the Strait of Sicily

The actual occurrence of Squalus megalops in the Mediterranean Sea has recently been questioned. Several research works which sought to assess available morphological and meristic features that differentiate S. megalops from other Squalus species in the Mediterranean Sea, revealed poor discriminatory power and high variability of the assessed characters, especially when comparing S. megalops and S. blainville. The application of molecular tools does not support the presence of S. megalops. In the present study, we screened spurdog species from the Strait of Sicily using a molecular taxonomy approach based on two mitochondrial DNA markers and we report the occurrence of two Squalus lineages characterizing specimens collected from the stretch of sea between Tunisia, southern Sicily, Malta and Libya. The results support the hypothesis that a common species, S. blainville, currently inhabits the Mediterranean Sea, while a second and rare species is probably an occasional visitor with high morphological similarity to the S. megalops and S. blainville but is genetically distinct from both. Within this perspective, the occurrence of S. megalops in the Mediterranean Sea is not confirmed and our study highlights the taxonomic uncertainties in relation to the occurrence and distribution of Squalus species in this region. We encourage the establishment of a coordinated international effort to implement a comprehensive and integrated taxonomic assessment on this genus which represents an irreplaceable component of the biodiversity of the area

Puzzling over spurdogs: molecular taxonomy assessment of the Squalus species in the Strait of Sicily

The actual occurrence of Squalus megalops in the Mediterranean Sea has recently been questioned. Several research works which sought to assess available morphological and meristic features that differentiate S. megalops from other Squalus species in the Mediterranean Sea, revealed poor discriminatory power and high variability of the assessed characters, especially when comparing S. megalops and S. blainville. The application of molecular tools does not support the presence of S. megalops. In the present study, we screened spurdog species from the Strait of Sicily using a molecular taxonomy approach based on two mitochondrial DNA markers and we report the occurrence of two Squalus lineages characterizing specimens collected from the stretch of sea between Tunisia, southern Sicily, Malta and Libya. The results support the hypothesis that a common species, S. blainville, currently inhabits the Mediterranean Sea, while a second and rare species is probably an occasional visitor with high morphological similarity to the S. megalops and S. blainville but is genetically distinct from both. Within this perspective, the occurrence of S. megalops in the Mediterranean Sea is not confirmed and our study highlights the taxonomic uncertainties in relation to the occurrence and distribution of Squalus species in this region. We encourage the establishment of a coordinated international effort to implement a comprehensive and integrated taxonomic assessment on this genus which represents an irreplaceable component of the biodiversity of the area

Puzzling over spurdogs : molecular taxonomy assessment of the Squalus species in the Strait of Sicily

The actual occurrence of Squalus megalops in the Mediterranean Sea has recently been questioned. Several research works which sought to assess available morphological and meristic features that differentiate S. megalops from other Squalus species in the Mediterranean Sea, revealed poor discriminatory power and high variability of the assessed characters, especially when comparing S. megalops and S. blainville. The application of molecular tools does not support the presence of S. megalops. In the present study, we screened spurdog species from the Strait of Sicily using a molecular taxonomy approach based on two mitochondrial DNA markers and we report the occurrence of two Squalus lineages characterizing specimens collected from the stretch of sea between Tunisia, southern Sicily, Malta and Libya. The results support the hypothesis that a common species, S. blainville, currently inhabits the Mediterranean Sea, while a second and rare species is probably an occasional visitor with high morphological similarity to the S. megalops and S. blainville but is genetically distinct from both. Within this perspective, the occurrence of S. megalops in the Mediterranean Sea is not confirmed and our study highlights the taxonomic uncertainties in relation to the occurrence and distribution of Squalus species in this region. We encourage the establishment of a coordinated international effort to implement a comprehensive and integrated taxonomic assessment on this genus which represents an irreplaceable component of the biodiversity of the area.</p

Cases of specimens’ misidentification by FAO fishing division.

<p>The number of misidentified individuals over the total number of barcoded individuals is given in parenthesis.</p

Haplotype parsimony networks of <i>Raja miraletus</i>, <i>Raja asterias</i>, <i>Raja polystigma</i>, <i>Raja radula</i> and <i>Torpedo marmorata</i> reconstructed using ELASMOMED COI barcode sequences.

<p>Each circle represents one haplotype and its size is proportional to frequency. Colours indicate the origin of samples according to FAO fishing divisions. Mutations and positions characterizing each haplotype, as well as the size (bp), and the number of the sequences included in each species network, are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0170244#pone.0170244.s004" target="_blank">S4 Table</a>.</p