1,720,977 research outputs found
Morphology and histology of the mouthparts and gut system of Macarorchestia remyi (Schellenberg, 1950) (Amphipoda, Talitridae
No full textMacarorchestia remyi lives in beached logs, where it makes its tunnels by eating the wood. Hence, this wood-feeding species has a peculiar diet compared with other Mediterranean talitrid amphipods. We carried out a morphological analysis of its mouthparts and a mainly histological investigation (transverse sections) of its gut regions (foregut, midgut and hindgut). The ectodermal foregut and hindgut regions are typically lined with cuticle, finely elaborated into various structures. Near the distal end of the oesophagus are the lateralia, provided with two rows of setae and several stout spines. The primary filter, including two parallel channels, is located ventrally in the first region of the foregut, while the secondary filter lies ventrally in the posterior foregut chamber, composed on each side of two longitudinal channels covered by densely arranged parallel setae. In the hindgut, the lining folded cuticle of the cylindrical epithelium shows unspecialized spines. In the endodermal midgut, the fine materials extracted from the upper foregut chambers through the filter systems are conveyed from the ventral channels to two pairs of ventrally located hepatopancreatic tubules; all these lobes, surrounding the midgut and partially the hindgut, are characterized by large vacuolated cells in their proximal regions. The midgut caeca includes the paired tubular pyloric caeca lateral to the secondary filter and a single caecum dorsal to the midgut. Two posterior caeca, originating in the distal part of the midgut, are located dorsolaterally and partially surround the hindgut. Finally, we observed layers of peritrophic membranes in the lumen of the midgut. In summary, the molar surface morphology appears to agree with the trend previously hypothesized for talitrid taxa with an increasing landward habitat and shifting toward a typical terrestrial diet. However, our data suggest that M. remyi, despite its particular feeding preference, shows no major differences in the main gut structures from other talitroid species. This relatively uniform morphology can be considered close to the ground pattern of the gammaridean amphipods, probably representing the early stage of Amphipoda evolutio
Pattern of genetic structuring and gene flow in four talitrid species in the Mediterranean sea (Crustacea, Amphipoda)
No full textriassunt
Victoriomyces antarcticus gen. nov., sp. nov., a distinct evolutionary lineage of the Cephalothecaceae (Ascomycota) based on sequence-based phylogeny and morphology
No full textIn this study, we propose a new genus, Victoriomyces, with a new species, Victoriomyces antarcticus, isolated from soil samples collected in Victoria Land, Antarctica. To determine its taxonomic status and evolutionary relationships, a phylogenetic analysis was performed on DNA sequences from the nuclear 18S rRNA, 28S rRNA, and the second largest subunit of RNA polymerase II (RPB2) genes. Victoriomyces antarcticus constitutes one well-supported distinct lineage within the Cephalothecaceae (family incertae sedis in Sordariomycetes), in which the only recognised anamorphs belong to the genus Phialemonium and to Acremonium thermophilum. Victoriomyces antarcticus can be clearly distinguished from these taxa by means of a DNA sequence analysis and its morphological traits that consist in having a Metarhizium-like anamorph, dark red-coloured like-disk structures, immature bodies, and the production of an intense red pigment in the growth media. Finally, we inferred the divergence time of V. antarcticus and the Cephalothecaceae using Bayesian analysis and secondary calibration. The type strain of V. antarcticus is FBL 165T = MUT 3686 = CCF (number pending); an additional strain of the species is FBL 577. The MycoBank number is MB 823713 for the genus and MB 823714 for the species
FILOGENESI MOLECOLARE DI AMPHIPODA (CRUSTACEA) DI AMBIENTI ACQUATICI ED INQUINAMENTO IDRICO.
No full textStruttura genetica e livelli di differenziamento tra popolazioni e specie di Orchestia (Amphipoda, Talitridae) del Mediterraneo.
Full text linkStrutturazione genetica e pattern di flusso genico in quattro specie di anfipodi talitridi sopralitorali dell'area egea.
Full text link- …
