A revision of Hydraena species of the "Haenydra" lineage (Coleoptera, Hydraenidae).

Hydraena Kugelann represents the largest genus within the water beetle family Hydraenidae, and in particular within Hydraeninae, with about 900 species widely distributed all over the world and several hundreds not yet described. In a recent cladistic analysis, based on morphological characters, Hydraena s. l. was split into two subgenera: Hydraenopsis Janssens (Gondwanian) and Hydraena s. str. (Laurasian). Moreover, within Hydraena s. str., some derived and well-supported monophyletic clades were recognised, and defined as "lineages". Among them, the "Haenydra" lineage, previously considered by many authors as a valid genus/subgenus, includes 89 species distributed exclusively in western Palaearctic, from Portugal to Iran, but absent in North Africa. The main aim of the present paper is to provide a revision of the whole lineage, re-examining taxonomy, ecology, and biogeography of all known species. All species were therefore redescribed, also providing information about diagnostic characters, taxonomic and phylogenetic relationships, ecology and biogeography. A faunistic dataset, including all the known published, and many unpublished, localities for each species, with a series of detailed geographic maps for each species and species complex, was herein supplied. Finally, dichotomous keys are provided for identification of males of all the "Haenydra" species.

Tackling critical parameters in metazoan meta-barcoding experiments: a preliminary study based on coxI DNA barcode.

Nowadays DNA meta-barcoding is a powerful instrument capable of quickly discovering the biodiversity of an environmental sample by integrating the DNA barcoding approach with High Throughput Sequencing technologies. It mainly consists of the parallel reading of informative genomic fragment/s able to discriminate living entities. Although this approach has been widely studied, it still needs optimization in some necessary steps requested in its advanced accomplishment. A fundamental element concerns the standardization of bioinformatic analyses pipelines. The aim of the present study was to underline a number of critical parameters of laboratory material preparation and taxonomic assignment pipelines in DNA meta-barcoding experiments using the cytochrome oxidase subunit-I (coxI) barcode region, known as a suitable molecular marker for animal species identification. We compared nine taxonomic assignment pipelines, including a custom in-house method, based on Hidden Markov Models. Moreover, we evaluated the potential influence of universal primers amplification bias in qPCR, as well as the correlation between GC content with taxonomic assignment results. The pipelines were tested on a community of known terrestrial invertebrates collected by pitfall traps from a chestnut forest in Italy. Although the present analysis was not exhaustive and needs additional investigation, our results suggest some potential improvements in laboratory material preparation and the introduction of additional parameters in taxonomic assignment pipelines. These include the correct setup of OTU clustering threshold, the calibration of GC content affecting sequencing quality and taxonomic classification, as well as the evaluation of PCR primers amplification bias on the final biodiversity pattern. Thus, careful attention and further validation/optimization of the above-mentioned variables would be required in a DNA meta-barcoding experimental routine.