DNA barcoding of the Italian anecic Octodrilus species in rural (vineyard) and forested areas with description of Octodrilus zicsiniello sp. nov. (Clitellata, Megadrili).

DNA barcoding of 172 anecic Octodrilus specimens collected in NE Italy and bordering Croatia has been carried out. The Bayesian phylogenetic tree showed high support for almost all currently recognized species, however, some unexpected results also appeared. The clade representing Oc. pseudocomplanatus contains a highly advanced subclade, which morphologically resembles Oc. slovenicus. The highly supported Oc. tergestinus clade consists of four unresolved divergent lineages of which the first corresponds to Oc. istrianus and the second resembles Oc. mimus morphologically; the third and fourth clades show typical tergestinus characters. The widely distributed Oc. complanatus consists of three highly divergent subclades which are sister to a new species, Oc. zicsiniello sp. nov., hereunder described.

A unique midgut-associated bacterial community hosted by the cave beetle Cansiliella servadeii (Coleoptera: Leptodirini) reveals parallel phylogenetic divergences from universal gut-specific ancestors.

BACKGROUND: Cansiliella servadeii (Coleoptera) is an endemic troglobite living in deep carbonate caves in North-Eastern Italy. The beetle constantly moves and browses in its preferred habitat (consisting in flowing water and moonmilk, a soft speleothem colonized by microorganisms) self-preens to convey material from elytra, legs, and antennae towards the mouth. We investigated its inner and outer microbiota using microscopy and DNA-based approaches. RESULTS: Abundant microbial cell masses were observed on the external appendages. Cansiliella's midgut is fully colonized by live microbes and culture-independent analyses yielded nearly 30 different 16S phylotypes that have no overlap with the community composition of the moonmilk. Many of the lineages, dominated by Gram positive groups, share very low similarity to database sequences. However for most cases, notwithstanding their very limited relatedness with existing records, phylotypes could be assigned to bacterial clades that had been retrieved from insect or other animals' digestive traits. CONCLUSIONS: Results suggest a history of remote separation from a common ancestor that harboured a set of gut-specific bacteria whose functions are supposedly critical for host physiology. The phylogenetic and coevolutionary implications of the parallel occurrences of these prokaryotic guilds appear to apply throughout a broad spectrum of animal diversity. Their persistence and conservation underlies a possibly critical role of precise bacterial assemblages in animal-bacteria interactions.