Influence of ecoregion and river type on neotropical Chironomidae (Diptera) from humid mountain to semiarid lowland

Introduction: Chironomidae (Diptera) is the most widespread and abundant aquatic insect family in freshwater ecosystems. Chironomids are considered good indicators of water quality but are seldom identified at the genus level in broad spatial scale studies. Objective: To identify environmental conditions associated with chironomids in an altitudinal gradient. Methods: We compared ecoregions, river types, and seasons, for chironomids in neotropical streams and rivers (18 river sites; 2014-2018; Yungas rainforest and Western Chaco dry forest, Argentina). We used non-metric multidimensional scaling, dissimilarity, envfit analysis and rank-abundance curves. Results: Chironomid "assemblages''matched both ecoregions and river types. However, ecoregions presented a better fit with species composition. The stenothermal taxa of Orthocladiinae were dominant at high elevations and the eurythermal Chironominae in lowland rivers. Altitude, water temperature and conductivity were important. Seasonal differences were smaller than ecoregional differences. Conclusions: Ecoregions, altitude, water temperature and conductivity correlated with chironomid communities. Orthocladiinae were dominant at high elevations and Chironominae in lowland rivers.

Introducción: Chironomidae (Diptera) es la familia de insectos acuáticos más extendida y abundante en los ecosistemas dulceacuícolas. Los quironómidos se consideran buenos indicadores de la calidad del agua, pero rara vez se identifican a nivel de género en estudios de amplia escala espacial. Objetivo: Identificar las condiciones ambientales asociadas a los quironómidos en un gradiente altitudinal. Métodos: Comparamos ecorregiones, tipos de ríos y estaciones para quironómidos en arroyos y ríos neotropicales (18 sitios en ríos; 2014-2018; en un bosque tropical de Yungas y un bosque seco del Chaco Occidental, Argentina). Utilizamos escalamiento no métrico multidimensional, disimilitud, análisis de envfit y curvas de rango-abundancia. Resultados: Los "ensamblajes''de quironómidos coincidieron tanto con las ecorregiones como con los tipos de ríos. Sin embargo, las ecorregiones presentaron un mejor ajuste con la composición de especies. Los taxones estenotérmicos de Orthocladiinae fueron dominantes en las elevaciones altas y los euritermales de Chironominae en los ríos de las tierras bajas. La altitud, la temperatura del agua y la conductividad fueron importantes. Las diferencias estacionales fueron menores que las diferencias ecorregionales. Conclusiones: las ecorregiones, la altitud, la temperatura del agua y la conductividad se correlacionaron con las comunidades de quironómidos. Orthocladiinae fue dominante en los sitios altos y Chironominae en los ríos de tierras bajas.

Mitogenomes provide new insights of evolutionary history of Boreheptagyiini and Diamesini (Diptera: Chironomidae: Diamesinae).

Mitogenomes have been widely used for phylogenetic reconstruction of various Dipteran groups, but specifically for chironomid, they have not been carried out to resolve the relationships. Diamesinae (Diptera: Chironomidae) are important bioindicators for freshwater ecosystem monitoring, but its evolutionary history remains uncertain for lack of information. Here, coupled with one previously published and 30 new mitogenomes of Diamesinae, we carried out comparative mitogenomic analysis and phylogenetic analysis. Mitogenomes of Diamesinae were conserved in structure, and all genes arranged in the same order as the ancestral insect mitogenome. All protein-coding genes in Diamesinae were under stronger purifying selection than those of other nonbiting midge species, which may exhibit signs of adaptation to life at cold living conditions. Phylogenetic analyses strongly supported the monophyly of Diamesinae, with Boreheptagyiini deeply nested within Diamesini. In addition, phylogenetic relationship of selected six genera was resolved, except Sympotthastia remained unstable. Our study revealed that the mitogenomes of Diamesinae are highly conserved, and they are practically useful for phylogenetic inference.

New or little-known Boreoheptagyia (Diptera, Chironomidae) in China inferred from morphology and DNA barcodes.

The male adult of Boreoheptagyia zhengi Lin & Liu, sp. nov. is described and illustrated based on material collected in China. Associated morphological characteristics and reference to its DNA barcode are provided. Boreoheptagyia kurobebrevis (Sasa & Okazawa, 1992) is newly recorded from China based on both a male and female, with additional associated data on the DNA barcode of the male adult. A neighbor-joining tree based on available Boreoheptagyia DNA barcodes and a key to the adults of Boreoheptagyia from China are given.

New species and findings of emPagastia/em Oliver (Diptera: Chironomidae: Diamesinae) from Central Asia, with DNA barcoding of known species of the genus.

Chironomids of the genus Pagastia Oliver (Diamesinae, Diamesini) from the mountains of Central Asia are revised using both morphological characters and molecular data. Illustrated descriptions of the adult male Pagastia (P.) caelestomontana sp. nov. from Kirgizstan and Tajikistan, P. (P.) hanseni sp. nov. from Tajikistan, and record of a finding apparently a new species P. (P.) aff. lanceolata (Tokunaga) from Tajikistan as well as an updated a key to the determination of the adult males of all known species of Pagastia are provided. A phylogenetic framework is reconstructed based on two mitochondrial genes cytochrome oxidase subunit I (COI) sequences of 34 samples belonging to 7 species of the genus Pagastia and cytochrome oxidase subunit II (COII) available for most samples. Phylogenetic trees of some known species of the genus Pagastia were reconstructed using the combined dataset and Bayesian inference (BI) and Maximum Likelihood (ML) methods. The interspecific K2P distances between seven Pagastia species including P. (P.) caelestomontana sp. nov., P. (P.) hanseni sp. nov. and undescribed P. (P.) aff. lanceolata (Tokunaga) are 6.3-13.2 which corresponding to species level.

Pagastia (P.) donoliveri sp. nov.-a new Nearctic alpine stream chironomid species (Diptera: Chironomidae: Diamesinae) from the Beartooth Mountains, Wyoming, U.S.A.

An illustrated description of the adult male of Pagastia (P.) donoliveri sp. nov. from the Beartooth Mountains, Wyoming, of North America is provided. An updated key to the determination of all known Holarctic species of Pagastia Oliver for males is also provided.

Review of the genus Shilovia Makarchenko (Diptera: Chironomidae: Diamesinae: Boreoheptagyiini) from the mountains of Central Asia, with morphological description and DNA barcoding of known species.

Chironomids of the genus Shilovia Makarchenko (Diamesinae, Boreoheptagyiini) from the mountains of Central Asia are revised using both morphological characters and molecular data. Illustrated descriptions of the adult male Shilovia xinhuawangi sp. nov. from Xinjiang Uygur Autonomous Region of China, S. yakovlevi sp. nov. from East Kazakhstan and redescription of S. rara Makarchenko from Tajikistan and Kyrgyzstan are provided. The result of morphological study is congruent with DNA barcoding analyses using COI sequences. The average K2P interspecific nucleotide distances within S. xinhuawangi sp. nov. and S. yakovlevi sp. nov. are 0.03% and 0.3% respectively. The nucleotide distances between the two new species and S. rara can be considered interspecific. Phylogenetic analysis using Maximum likelihood (ML) and Bayesian inferences (BI) support the placement of S. xinhuawangi sp. nov. and S. yakovlevi sp. nov. within the monophyletic genus Shilovia.

New or little-known Diamesinae (Diptera: Chironomidae) from Oriental China.

Morphological description for adult male of a new species Diamesa qiangi sp. nov. and redescription for adult males of the little-known species Linevitshia prima Makarchenko and Sasayusurika nigatana (Tokunaga) of subfamily Diamesinae from the Oriental Region of China are given.

Review of the genus Pagastia Oliver (Diptera: Chironomidae: Diamesinae) from North America, with description of P. (P.) subletteorum sp. nov.

Illustrated description of the adult male of Pagastia (P.) subletteorum sp. nov., redescription of the pupa and adult male of P. (P.) orthogonia Oliver and P. (P.) partica (Roback), with redescription of the adult male of P. (Hesperodiamesa) sequax (Garrett) from North America are provided. An emended generic diagnosis and a key to determination of adult males of all known species of Pagastia Oliver are also provided.

The species of the genus Diamesa (Diptera, Chironomidae) known to occur in Italian Alps and Apennines.

Some rare species from Italian Alps, belonging to the genus Diamesa Meigen, 1835 (Diptera, Chironomidae) are here redescribed as adult males, because only old, incomplete descriptions are available for these taxa. Terminology of male genitalia is reviewed, diagnostic features are illustrated in detail, and notes on biology and geographical distribution of the examined species are provided. An identification key to the known adult males is presented.

Why on the snow? Winter emergence strategies of snow-active Chironomidae (Diptera) in Poland.

A long-term study of adult non-biting midges (Chironomidae) active in winter on the snow in mountain areas and lowlands in Poland yielded 35 species. The lowland and mountain communities differed significantly in their specific composition. The mountain assemblage was found to be more diverse and abundant, with a substantial contribution from the subfamily Diamesinae, whereas Orthocladiinae predominated in the lowlands. Orthocladius wetterensis Brundin was the most characteristic and superdominant species in the winter-active chironomid communities in both areas. Only a few specimens and species of snow-active chironomids were recorded in late autumn and early winter. The abundance of chironomids peaked in late February in the mountain and lowland areas with an additional peak in the mountain areas in early April. However, this second peak of activity consisted mainly of Orthocladiinae, as Diamesinae emerged earliest in the season. Most snow-active species emerged in mid- and late winter, but their seasonal patterns differed between the 2 regions as a result of the different species composition and the duration of snow cover in these regions. Spearman's rank correlation coefficient tests yielded positive results between each season and the number of chironomid individuals recorded in the mountain area. A positive correlation between air temperature, rising to +3.5 °C, and the number of specimens recorded on the snow in the mountain community was statistically significant. The winter emergence and mate-searching strategies of chironomids are discussed in the light of global warming, and a brief compilation of most important published data on the phenomena studied is provided.