Anhydrobiosis represents an extreme example of tolerance adaptation to water loss, where an organism can survive in an ametabolic state until water returns. Here we report the first comparative analysis examining the genomic background of extreme desiccation tolerance, which is exclusively found in larvae of the only anhydrobiotic insect, Polypedilum vanderplanki. We compare the genomes of P. vanderplanki and a congeneric desiccation-sensitive midge P. nubifer. We determine that the genome of the anhydrobiotic species specifically contains clusters of multi-copy genes with products that act as molecular shields. In addition, the genome possesses several groups of genes with high similarity to known protective proteins. However, these genes are located in distinct paralogous clusters in the genome apart from the classical orthologues of the corresponding genes shared by both chironomids and other insects. The transcripts of these clustered paralogues contribute to a large majority of the mRNA pool in the desiccating larvae and most likely define successful anhydrobiosis. Comparison of expression patterns of orthologues between two chironomid species provides evidence for the existence of desiccation-specific gene expression systems in P. vanderplanki.

Non‐biting midges (Diptera: Chironomidae) adapt to species‐specific environmental conditions and hence are promising bioindicators for aquatic and ecotoxicological monitoring. Although their utility for these purposes was historically limited by difficulties in their morphological identification, DNA barcoding offers a possible solution. Here, eight Japanese species of the genus Chironomus, which is characterized by its worldwide distribution and abundance among Chironomidae, were subjected to DNA barcoding using cytochromec oxidase subunit I (COI). To examine whether this DNA barcode is a useful indicator for Japanese species of Chironomus, we calculated genetic distances within and between the COI sequences of Chironomus species both from this study and worldwide and constructed phylogenetic trees. Based on 415 bp COI sequences and the Kimura two‐parameter model, the average genetic distances within 37 species and between 72 species were 2.6% and 17.2%, respectively. Although the ranges of genetic distances within and between species overlapped from 0.8% to 17.3%, 99.7% of average genetic distances between species were >3.0%. Some of this overlap is attributable to distances within species that were “too large” as well as those between species that were “too small”. Of eight Japanese species examined, two showed genetic distances between species that were below a 3.0% threshold, and four had distances within species that were greater than 3.0%. These results suggest a possible reclassification of these species and the need for further sampling to unveil biogeographic variations among different countries and regions.

A revision of mapping of main and alternative banding sequences in chromosome III (EF) has been made for 14 species of the Chironomus plumosus group. In total, new versions of mapping are presented for 18 banding sequences of arm E and 18 banding sequences of arm F. A new way of tracing the origins of banding sequences in chromosome III of the Ch. plumosus group in comparison with basic banding sequences of the genus Chironomus is suggested. The presented data indicate that h’pluE2 in arm E and p’borF2 in arm F are the closest to banding sequences of Ch. piger Strenzke, 1959 and thus should be considered the most ancient among banding sequences of chromosome III in the Ch. plumosus group. Phylogenetic relationships of banding sequences of chromosome III are discussed.

Variation and divergence patterns of the multilocus genome markers in twelve Chironomus species belonging to the plumosus and piger sibling-species groups were examined by use of polymerase chain reaction with arbitrary primers (RAPD method). The chironomid species showed high levels of the RAPD markers polymorphism. The genetic distances (GD) were determined between the species within the group of closely related species, as well as between the species from different groups. The estimates obtained characterized the divergence levels between the sibling species (GD = 0.739) and morphologically distinct species (GD = 0.935). Comparison of the variation and divergence levels of the RAPD markers with those for the other genome markers, namely, the enzyme-coding genes and chromosomes (gene linkage groups) have demonstrated different divergence rates for different genome components during speciation of chironimids. GENERAL GENETICS

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