Larvae of the genus Pseudodiamesa Goetghebuer, which includes 12 described valid species and is divided by Makarchenko and Makarchenko (1999) into two species groups, Pseudodiamesa branickii group and Pseudodiamesa nivosa group, are widespread in lakes and running waters of cold, high-latitude and high-altitude areas of the Northern Hemisphere. Larval remains of the genus are often found in subfossil assemblages from these cold regions, but intra-genus morphotypes usually are not distinguished by palaeoecologists. Current knowledge of the ecology of the species indicates that the Pseudodiamesa nivosa group is more cold-adapted than the Pseudodiamesa branickii group and, therefore, these two intra-genus morphotypes cannot be amalgamated into a larger taxonomic unit without losing substantial information. Here we present the morphological characters of head capsules of Pseudodiamesa larvae attributed to the different speciesgroup morphotypes, which are clearly visible in subfossil specimens. The information summarized in this paper will help provide more reliable chironomid-based palaeoclimatic inferences from lake sediment records covering colder phases through the late Quaternary in the Northern Hemisphere.

This special issue provides an overview of recent advances in the study of chironomids (Diptera chironomidae), as an outcome of the 20th International Symposium on Chironomidae held in Trento (Italy), in July 2017. it includes 27 selected papers, representative of the six topics of the symposium: genetics and cytogenetics, taxonomy and systematics, autecology and physiology, toxicology and adaptive biology, ecology and biomonitoring, palaeolimnology. Most papers emphasise the value of chironomids in the monitoring programmes, mainly on Europe and case histories from South America and Africa. however, as our title indicates, the reported contemporary studies represent a range from the genetic through the autecological to the ecosystem scale. the aim of the volume is to give new insights on ecology and biology of non-biting midges, the freshwater insect family that comprises the highest number of species in the world, in both lentic and lotic habitats.

Chironomids of the subgenus Chaetocladius s. str. from the Amur River basin are revised using both morphological characters and molecular data. Three new species, C. egorych sp. nov., C. lopatinskiy sp. nov. and C. yavorskayae sp. nov., are described and figured. The pupa of C. fedotkin is described for the first time. Adult males of C. ligni and C. piger, little-known in the Far East, are redescribed and annotated, and key to males of the Chaetocladius s. str. from the Amur River basin is provided. A reference 658 bp barcode sequence from a fragment of the mitochondrial gene cytochrome oxidase I (COI) was used as a tool for species delimitation. Comparisons with corresponding regions of COI between 5 species in the subgenus produced K2P genetic distances of 8.3-12.6%, values well associated with interspecific variation. Molecular data were also used for the reconstruction of the phylogenetic relationships within the subgenus Chaetocladius s. str.

Резюме. Приведены иллюстрированные описания с российского Дальнего Востока двух новых для науки видов-Eukiefferiella captiosa sp.n. по трём стадиям развития и E. bykova sp.n. по имаго самцу и куколке. Впервые описаны куколка и личинка для E. convexa Makarchenko et Makarchenko, а также дано переописание куколки E. devonica (Edwards), указанного впервые для российского Дальнего Востока и краткое описание неопределенной куколки Eukiefferiella sp., которая наиболее близка виду E. ilkleyensis Edwards. Для всех видов сделаны таксономические замечания со сравнительной характеристикой для близкородственных видов и уточнено распространение.

The male, pupa, and larva of a new species, Arctodiamesa marinae, from the Russian Far East are described and figured. Keys to males, pupae, and fourth-instar larvae of known species of the genus are presented.