Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study.

The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna complexity and diversity in barrens rather than in macroalgal forests, and have allowed estimating the differences in levels of diversity and the consistency of variability across Mediterranean sites. Some peculiar patterns in barrens, related to both abundance of specific taxa and to high values of beta diversity, have been evidenced.

The interrelationships of proseriata (Platyhelminthes: seriata) tested with molecules and morphology.

Proseriate flatworms are common members of the interstitial benthic fauna worldwide, predominantly occupying marine environments. As minute animals, having relatively few characters useful for cladistic analysis, they have been difficult to present in a phylogenetic framework using morphology alone. Here we present a new morphological matrix consisting of 16 putatively homologous characters and two molecular data sets to investigate further this major group of free-living members of the Platyhelminthes. Complete 18S rDNA (representing 277 parsimony-informative characters) from 17 ingroup taxa and partial 28S rDNA spanning variable expansion regions D1 to D3 and D1 to D6 (representing 219 and 361 parsimony-informative characters, respectively) from 27 and 14 ingroup taxa, respectively, were determined and aligned as complementary data sets. Morphological and molecular data sets were analyzed separately and together to determine underlying phylogenetic patterns and to resolve conflict between published scenarios based on morphology alone. The monophyly of the Proseriata cannot be confirmed categorically with any of these data sets. However, the constituent taxa are confirmed as basal members of the Neoophora, and a sister group relationship with Tricladida is rejected. Similarly, the monophyly of one of the two subtaxa of the Proseriata, the Lithophora, could not be confirmed with molecules. Concerning intragroup relationships, we could reject one of the two phylogenetic trees formerly proposed, as well as the clade Otoplanidae + Coelogynoporidae. However, a clade Otoplanidae + Archimonocelididae + Monocelididae (to which the Monotoplanidae belong) was supported, and the position of the genus Calviria shifted from the Archimonocelididae to the Coelogynoporidae.

A reappraisal of the systematics of the monocelididae (Platyhelminthes, Proseriata): inferences from rDNA sequences.

The current classification system for the Monocelididae which is based on the character "presence or absence of an accessory prostatoid organ" divides the family into two subfamilies, namely the Minoninae and the Monocelidinae. However, other characters relating to the structure of the male copulatory bulb and to karyotypes do not support this division. Monocelidid male copulatory bulbs can be either of the simplex or the duplex-type, and if this character is mapped onto the current classification, then both subfamilies contain species with either type of copulatory bulb. We therefore decided to construct an independent phylogeny for the Monocelididae using nucleotide-sequence data of the gene coding for the 26/28S rDNA. Distance-and parsimony-based analyses resulted in phylogenetic trees that strongly supported a division of the Monocelididae based on characters of the male copulatory bulb and not on the accessory prostatoid organ. Thus, all species possessing a simplex-type copulatory bulb cluster together into one monophyletic group, the Monocelidinae (sensu Midelburg), whereas species characterized by a duplex-type copulatory bulb constitute a paraphyletic assemblage.