Search

The early origin and evolutionary radiation of graptolites (Hemichordata:Pterobranchia) is a story told almost entirely in the fossil record, but for four extant species of the genus Rhabdopleura Allman, 1869. Here we report the discovery of a fifth species, Rhabdopleura recondita, sp. nov., at a depth range of 2–70m from the Adriatic and Ionian Seas, always associated with bryozoans in coralligenous habitats. This is the first pterobranch record in Italian waters, and the second in the Mediterranean Sea. The new species is characterised by: (1) tubaria with smooth creeping tubes adherent to the inside of empty bryozoan zooecia; (2) erect outer tubes with a graptolite, fusellar-like organisation; and (3) zooids that extend from a black stolon, which is free from the creeping tube. Each of the paired feeding arms has two rows of tentacles that do not extend to the arm tip. The distal ends of the arms, the collar and the cephalic shield are replete with black granules. Phylogenetic analyses of individual and concatenated gene sequences of mitochondrial 16S rDNA and nuclear 18S rDNA support the validity of R. recondita as a new species. Finally, we discuss the global biogeographic and habitat distributions of the extant Rhabdopleura representatives. http://zoobank.org/urn:lsid:zoobank.org:pub:82C6A51E-F8F4-44AF-AD8F-16873BE80D03

Molecular analyses have led to an increased knowledge of the number and distribution of morphologically cryptic species in the world's oceans and, concomitantly, to the identification of non-indigenous species (NIS). Traditional taxonomy and accurate delimitation of species' life histories and autecology lag far behind, however, even for the most widely distributed taxa, such as the moon jellyfish Aurelia (Cnidaria, Scyphozoa) species complex. Here we analysed mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal RNA (28S) gene sequences to assign polyps, ephyrae, and medusae collected in the Mediterranean Sea to different phylogenetic species. We find evidence for three Aurelia species, none of which are referable to the type species of the genus, Aurelia aurita (Linnaeus, 1758), and describe the anatomical, morphometric, and developmental variation within and between them. We identify Aurelia coerulea von Lendenfeld, 1884 and Aurelia solida Browne, 1905 as established non-indigenous species in the Mediterranean Sea. We describe Aurelia relicta sp. nov., an endemic species currently unique to a population in the marine lake of Mljet (Croatia). These results demonstrate the usefulness of integrative approaches in resolving taxonomic uncertainty surrounding cryptic species complexes, identifying patterns of marine biodiversity, and recognizing non-indigenous species in marine ecosystems.

Submarine caves are environments of great ecological interest because of the occurrence of peculiar conditions, such as the attenuation of light and reduced water turnover, which can determine oligotrophic conditions from the entrance to the interior part of the cave. These environmental gradients may influence the distribution of the communities inhabiting submarine caves. In this study we investigated the meiofaunal community and nematode assemblages from the sediments inside and outside two submarine caves in Ustica Island Marine Protected Area (southwest Italy): Grotta Falconiera and Grotta dei Gamberi. Consistently with a general pattern of distribution reported by several studies on benthic organisms, our results showed a decrease in the abundance and changes in the taxa composition of the meiofaunal community along the exterior-interior axis of the caves, also highlighting the dissimilarity between the dark and semi-dark communities. We found a significant influence of the availability of organic matter (i.e. phytopigment concentrations) on the distribution and composition of both the meiofauna and the nematode community inside the caves. Different nematode assemblages characterized the inside and the outside of the two caves, with species occurring exclusively in the sediment of both caves, particularly in the dark portions, and completely absent in the external sediments. Environmental features of submarine caves may affect food resources inside the caves and consequently trophic nematode assemblages. Our results showed a difference in feeding strategies between nematodes inhabiting the caves and those living outside, suggesting that in the two caves investigated, bacteria might represent the most important food source for nematodes.

A bloom of an unknown semaestome jellyfish species was recorded in the North Adriatic Sea from September 2013 to early 2014. Morphological analysis of several specimens showed distinct differences from other known semaestome species in the Mediterranean Sea and unquestionably identified them as belonging to a new pelagiid species within genus Pelagia. The new species is morphologically distinct from P. noctiluca, currently the only recognized valid species in the genus, and from other doubtful Pelagia species recorded from other areas of the world. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal DNA genes corroborate its specific distinction from P. noctiluca and other pelagiid taxa, supporting the monophyly of Pelagiidae. Thus, we describe Pelagia benovici sp. nov. Piraino, Aglieri, Scorrano & Boero.