ABSTRACT
Salicornia is a highly taxonomically problematic genus due to the reduced morphological observable characters. Ten Eurasian species are currently recognized: S. alpini, S. europaea, S. fruticosa, S. hispanica, S. lagascae, S. perennans, S. perennis, S. persica, S. procumbens, and S. pruinosa. In addition, eleven subspecies are accepted, mainly based on their distribution areas. Along the Venetian coasts and in Sardinia, in the past, an endemic species called S. veneta was recognized, but this name was later synonymized with S. procumbens subsp. procumbens. The aim of the present research is investigating different Italian Salicornia populations by a molecular point of view, using the nuclear ribosomal external transcribed spacer ETS and the plastid psbA-trnH intergenic spacer. A particular focus is on the comparison between Venetian (including those occurring in locus classicus of S. veneta) and Sardinian S. procumbens and other Italian populations of this species. The molecular analyses based on the plastid marker highlight that the Italian S. procumbens populations form two well distinct groups. In particular, some of the Venetian (Locus classicus of S. veneta) and all the Sardinian specimens are genetically distinct (=plastid haplotype 1) from the other investigated populations (=plastid haplotype 2). This indicates that the psbA-trnH haplotype 1 glassworts represent a distinct entity, which we suppose to coincide with the former S. veneta. Therefore, we suggest to recognize this taxonomic entity at the subspecies rank, as S. procumbens subsp. veneta comb. and stat. nov. However, contrary to the results found with the plastid psbA-trnH intergenic spacer, the ETS locus does not show a separation into two distinct clades for S. procumbens, probably due to a different evolution of the two loci. Nevertheless, in the ETS phylogenetic reconstruction, the Sardinian specimens (=ribotypes 2 and 3) are placed, together with a Moroccan sample, in a subclade separated from all the other S. procumbens. These results suggest that the Sardinian populations can represent a subspecies/incipient speciation process, probably due to geographic isolation. In the light of this, morphometric analyses (k-means, MANOVA, PCA, DA, and Box-Plot) have been carried out on the Sardinian and Venetian populations to verify if this distinction is detectable also by a morphological point of view. The morphometric analyses highlight the existence of two groups, concerning both the nuclear and plastid trees. Six characters were found to be diagnostic.
ABSTRACT
The present study describes a new species of spionid polychaete, Streblospio eridani n. sp., from the Italian coasts of the Northern Adriatic Sea (Mediterranean Sea). This new spionid species was recorded from shallow lagoon and marine habitats: the soft bottoms of the Sacca di Goro (Po River Delta), on October 2017, and the Lido di Dante (Emilia Romagna), between 2016 and 2017. The re-assessment of spionid specimens from other lagoon systems (the Valli di Comacchio and the Valle di Gorino) led us to recognize the presence of this species in the northern Adriatic Sea since 2009. Streblospio eridani n. sp. had low occurrence and density at the marine site Lido di Dante and at the lagoon sites Valli di Comacchio and Valle di Gorino; whereas it reached the highest density of 21,213.3 ind. m-2 at the Sacca di Goro. Morphologically this new species is characterized by dorsal (occipital) papilla on the first chaetiger, sabre chaetae and hooded hooks first appearing on chaetigers 7, hooks with 4-5 pairs of small secondary teeth, pygidium with ventral lappets, and brooding branchiate structures between chaetigers 13 and 28. In the phylogenetic reconstruction, based on the mitochondrial cytochrome c oxidase subunit I (COI) gene, the Adriatic taxon results clearly indicate that this is distinct from the other species of the genus and formed a well-supported clade with other Streblospio sp. specimens from India. Nucleotide divergences calculated between the Adriatic specimens and the other Streblospio species are higher than the intraspecific range reported for the genus and support the description of a new species. Morphological characters important for differentiation of the new species herein described from congeneric species are discussed and an updated key for Streblospio species is provided.
Subject(s)
Polychaeta , Animals , Mediterranean Sea , PhylogenyABSTRACT
Ulva Linnaeus (Ulvophyceae, Ulvales) is a genus of green algae widespread in different aquatic environments. Members of this genus show a very simple morphology and a certain degree of phenotypic plasticity, heavily influenced by environmental conditions, making difficult the delineation of species by morphological features alone. Most studies dealing with Ulva biodiversity in Mediterranean waters have been based only on morphological characters and a modern taxonomic revision of this genus in the Mediterranean is not available. We report here the results of an investigation on the diversity of Ulva in the North Adriatic Sea based on molecular analyses. Collections from three areas, two of which subject to intense shipping traffic, were examined, as well as historical collections of Ulva stored in the Herbarium Patavinum of the University of Padova, Italy. Molecular analyses based on partial sequences of the rbcL and tufA genes revealed the presence of six different species, often with overlapping morphologies: U. californica Wille, U. flexuosa Wulfen, U. rigida C. Agardh, U. compressa Linnaeus, U. pertusa Kjellman, and one probable new taxon. U. californica is a new record for the Mediterranean and U. pertusa is a new record for the Adriatic. Partial sequences obtained from historical collections show that most of the old specimens are referable to U. rigida. No specimens referable to the two alien species were found among the old herbarium specimens. The results indicate that the number of introduced seaweed species and their impact on Mediterranean communities have been underestimated, due to the difficulties in species identification of morphologically simple taxa as Ulva.
