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Freshwater mussels are essential for the integrity of freshwater ecosystems but numbers of these organisms are declining rapidly at regional and global scales. The phylogenetic and biogeographic aspects of the rich unionoid fauna of the Indo-Burma region are becoming increasingly well understood. Guangxi is part of the Chinese portion of the Indo-Burma biodiversity hotspot but regional studies of the freshwater mussel diversity are scarce. In this study, we report a new genus and species of freshwater mussel from Guangxi, China. Genetic datasets including three genes (COI, 16S rRNA and 28S rRNA) and complete maternal mitogenomes were compiled to infer the phylogenetic history of the group. Molecular phylogenetic analyses showed that the new species formed a monophyletic group and was closely related to Obovalis and Ptychorhynchus in the tribe Gonideini of the subfamily Gonideinae. Morphological and molecular evidence supported that these specimens represent an undescribed genus and species that we describe as Postolata guangxiensisgen. nov., sp. nov. The discovery of this new taxon adds to the known level of endemism of freshwater mussels in Guangxi and a detailed survey of uncharted areas should reveal new diversity in the future. We also suggest that complete mitogenomes or even genome-scale nuclear data should be used for phylogenetic reconstructions when proposing major taxonomic changes.
Males of the South American spider genus Mecolaesthus Simon, 1893 are characterised by a dorsally ‘inflated’ prosoma or hump. Here we describe the first representatives of the genus from Ecuador. A phylogenetic analysis of molecular sequence data suggests that the new species are part of an Amazonian-West Indian clade. Whether this clade is sister to ‘true’ (northern Venezuelan) Mecolaesthus or not remains unclear. The two clades occupy different major Neotropical biogeographic regions. Our phylogenetic reanalysis of Mecolaesthus and related genera greatly expands the taxon sampling compared to previous analyses (from 9 to 46 species representing the ‘Venezuelan clade’ of genera) but remains ambiguous regarding the monophyly of Mecolaesthus. In addition, we present first micro-computed tomography (µ-CT) data of the unique prosoma ‘inflation’, showing that these ‘inflations’ are tightly packed with muscles inserted at the leg coxae, mainly of legs 2 and 3. Male (but not female) leg length is negatively correlated with body size and this is highly unusual in Pholcidae. We predict that male–male fights in Mecolaesthus rely on powerful leg movements of legs 2 and 3 rather than on using legs 1 to assess the opponent’s body size. Finally, we document structural genital asymmetry in females of three of the four new species and in M. putumayo Huber, 2000 (of which the female is newly described). This constitutes the fourth known case of structural genital asymmetry in Pholcidae.
Nemognathinae is the most widespread subfamily of Meloidae, with ~600 species, and includes the only blister beetles distributed in Australia and on islands of the western Pacific. Four tribes are recognised based on morphology: Stenoderini, Palaestrini, Horiini and Nemognathini. Using two mitochondrial (16S, COI) and three nuclear markers (CAD, 28S, ITS2), and both maximum likelihood and Bayesian approaches, this study describes the evolutionary history of Nemognathinae based on molecular data for the first time. We provided a fossil-calibrated phylogeny that unravels the phylogenetic relationships among the tribes and among most of the genera, and a reconstruction of the biogeographic history using a parametric approach. Our results recognised the four tribes that were described previously based on morphology and revealed the presence of another well-differentiated clade corresponding to the genus Zoltanzonitis. Phylogenetic relationships among the tribes are well supported, with Stenoderini as the most ancient lineage, followed by Zoltanzonitini, Palaestrini, Horiini and Nemognathini. A few long-standing genera within Nemognathini (Nemognatha, Zonitis, Stenoria) and the nominate subgenus Stenodera (Stenodera) were recovered as polyphyletic. In addition, biogeographic analyses revealed the origin of the subfamily in the Old World during the Eocene, and the associated diversification into the five tribes astride the Eocene and Oligocene between 46 and 30 Ma. Based on these results we propose the new tribe Zoltanzonitini, and the elevation of the subgenus Pronemognatha to genus level, new status. In addition, Zonitoschema breveapicalisnew comb., Z. curticepsnew comb. and Z. pulchellanew status are proposed.
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