The first detailed systematic study on the tanytarsine chironomids recorded in the Eocene amber from the Rovno region (Ukraine) revealed seven new taxa. Archistempellina gen. nov., represented by A. bifurca sp. nov. (type for the genus, male) and A. falcifera sp. nov. (male), displays characters similar to those found in Stempellina Thienemann et Bause, and is recognized as one of probable basal lineages in the subtribe Stempellinina Shilova. Corneliola gen. nov., represented by C. avia sp. nov. (male, female), combines features known from several genera of the tribe Tanytarsini, and tentatively is regarded as the closest relative of Constempellina Brundin. Rheotanytarsus alliciens sp. nov. (male), featuring a long hypopygial digitus, is considered to be the oldest species of the genus. Tanytarsus congregabilis sp. nov. (male) is the first known Eocene representative of the lugens systematic species group. A complemented description of the male of Tanytarsus serafini Giłka is provided as well.

Aims:The main aim of this study was to fill a gap in barcoding data of the European Chironomidae of the Balkan region, developing and testing the efficiency of a reference DNA barcode library for ancient Lake Skadar basin species (Montenegro/Albania), a region of Europe never before subjected to barcoding studies on Chironomidae.Another aim was to test the efficiency of DNA barcoding for the identification of European Chironomidae, including the estimation of optimal identification thresholds, using >12,000 barcodes.Location: Lake Skadar basin and adjacent area (Montenegro/Albania).Methods: Through this study, 770 individuals of Chironomidae from the Lake Skadar region were barcoded, both at adult and pre-imaginal stages. Adults were morphologically identified, while larvae were assigned to species by molecular identification, using different methods, of which the efficiency was tested, for a total of 97 different barcoded species. Results:The identification efficiency of the reference dataset developed for the Lake Skadar region was 98.6%, a value in line with that obtained when the identification efficiency for European Chironomidae was evaluated (95.8%), which confirms the accuracy of DNA barcoding for the identification of these insects. Moreover, we found that the optimal threshold for the molecular identification of the family is 1.6% nucleotide distance, though more specific thresholds are suggested for the identification of species belonging to Chironomidae subfamilies, since they are related to lower identification errors than to the use of a general threshold. The analysis of inconsistency between molecular and morphological identification shed light on taxonomic issues within European Chironomidae. Previously postulated species synonyms were confirmed, and also further cases requiring deeper investigation were detected.Main conclusions: Our de novo DNA barcode library was shown to have a high identification efficiency. Taxon-specific thresholds increase the efficacy of molecular identification. Hypothesized species synonyms could be validated through molecular techniques.

Here we provide evidence for the presence of non-biting midges of the subfamily Chironominae in the Mesozoic, based on descriptions of exceptionally rare amber inclusions. The subfamily has already been reported, but based on a single and unspecified record from Late Cretaceous Taimyr amber (~84 Mya). That record is here revised and confirmed. Moreover, a new find in Burmese amber locates the temporal boundary of the subfamily back to the mid-Cretaceous (probably ~100 Mya). We describe two new genera assigned to the tribe Pseudochironomini: Mesoacentron gen. nov. with the species Mesoacentron kaluginae sp. nov. (Taimyr amber) and Palaeocentron gen. nov. with the species Palaeocentron krzeminskii sp. nov. (Burmese amber), the oldest known representative of the subfamily. The systematic position of the new taxa is discussed, and a key to the identification of adult males of extinct and extant Pseudochironomini genera is presented. Insights in the phylogeny and diversification tempo of the Chironominae and Pseudochironomini in the past are also provided.

A new fossil chlronomid, Tanytarsus serafini, found in Baltic amber is described and illustrated based on adult males. The new species and similar extant species of the genus Tanytarsus van der Wulp are compared. Due to several distinct characters of wing, legs and hypopygium, a new species group for Tanytarsus serafini is proposed, and its diagnostic features are evaluated.

Non-biting midges of the tribe Tanytarsini collected in the Museum of Amber Inclusions, University of Gdańsk, Poland, are reviewed. Among over 1500 chironomid specimens examined (inclusions in Baltic amber), 44 Tanytarsini individuals were found, of which 27 well preserved specimens were determined to 7 species, including 3 species described as new. Stempellinella electra sp. nov. (male) displays morphological hypopygial characters unique for the genus, and the antenna composed of 13 flagellomeres. A new checklist of fossil and extant species of this genus is also given, including Stempellinella sofiae (Fusari et Lamas, 2014) comb. nov. Tanytarsus glaesarius sp. nov. (male) is the only Eocene species of the genus with a reduced number of antennal flagellomeres. Tanytarsus protogregarius sp. nov. (male) is the oldest known representative of the gregarius species group. Notes on phylogenetic relations of the new species with their extant congeners are also provided.