Limnophyes (Diptera: Chironomidae) from northwestern Russia

The nominal family group taxa of the Ephemeroptera are listed along with their authors, dates of publication and bibliographic references.     

Incidence of Mentum Deformities in Midge Larvae (Diptera:Chironomidae) from Northern Nova Scotia, Canada

Deformities in the mouthparts of larval Chironomidae, particularly of the teeth on the mentum, have been proposed as a bioindicator of sediment quality and environmental stress. Most work to date has concentrated on relatively few abundant, responsive genera common in soft-bottom lakes. We examined mentum deformities in 25 genera of Chironominae, Orthocladiinae and Diamesinae (one genus) from streams and a lake in rural Nova Scotia where farming and forestry are the principal land uses. Incidence of deformity at similar stream sites varied across genera from zero to >10%. Average frequencies of deformity across all three subfamilies at sites with no known sources of contamination ranged from <4% to 8%, and increased to nearly 15% at a site receiving treated municipal sewage effluent. Differences in chironomid community structure and rates of leaf litter decomposition above and below the sewage effluent outfall were congruent with the difference in mentum deformities. Frequencies of deformity observed here are an order of magnitude greater than in similar studies of rural areas. Low-level stress from agriculture or forest harvesting may be widespread in rural regions even in aquatic ecosystems that are seemingly free of industrial discharges or sediment contamination.     

Afrotropical montane midges (Diptera, Chironomidae, Diamesa)

The tribe Diamesini is a characteristic element of the chironomid fauna of the Holarctic alpine and montane areas. It is represented in the E African mountains by three species: Diamesa kenyae Freeman, Diamesa ruwenzoriensis Freeman and Diamesa freemani sp. nov. The adults of the three species, the pupa and larva of D. freemani , and the larva of D. kenyae , are all described in detail. Several morphological features indicate that the Afrotropical Diamesa are derived from a relatively plesiomorphic lineage of the genus. Other characters indicate possible sister-species occurring in the Alps, the Caucasus mountains and the Himalaya. Three lines of evidence suggest a northern origin of the Afrotropical Diamesa: the relatively young age of the E African mountain peaks, the proposed phylogeny of the genus, and the present distribution of the tribe Diamesini.     

Adaptation to an acid environment in Chironomus riparius (Diptera, Chironomidae) from Smoking Hills, NWT, Canada

The Smoking Hills in the North West Territories, Canada have burnt for centuries causing long term acidification of ponds in the vicinity. Chironomus riparius , a red chironomid larva dominated the bottom fauna in the ponds. It was investigated if it was the buffering capacity of the hemolymph rather than the oxygen binding capacity of its hemoglobin that gave these larvae a selective advantage and explained their high abundance. Canadian C. riparius larvae were compared with larvae of the same species from Sweden and with larvae of Chironomus plumosus and C. anthracinus also from Sweden. The Canadian strain of C. riparius survived 7 d exposure to pH 3.5 much better than the others. Titration curves on the hemolymph showed that the Canadian larvae had the highest buffering capacity. Within the pH range 6.0–7.0 it was 17–18 meq pH⁻¹ 1⁻¹ as compared with 13–15 meq pH⁻¹ 1⁻¹ for the others. The hemoglobin content of the Canadian larvae was found to be twice as high as that of the same species from Sweden.     

Chironomids (Diptera,Chironomidae) fauna of reservoirs in Bashkortostan

An annotated list of chironomid species from small reservoirs located in the Republic of Bashkortostan in the basins of Kama, Ural, and Ob rivers is given. The list includes 54 valid species. In addition, data on the abundance of larvae in the studied waters are presented. A total of 60 species of 31 genera from 3 subfamilies, Tanypodinae (5), Orthocladiinae (18), and Chironominae (37), are recorded. The largest number of species is registered in the Sakmara Reservoir. Palearctic species dominate.     

Molecular-cytogenetic characteristics of B-chromosomes in chironomid (Diptera, Chironomidae)

Morphological and molecular study of B-chromosomes of three Chironomus species (siblings Ch. borokensis and Ch. phumosus from plumosus group, and Ch. heterodentatus from obtusidens group) was carried out. Morphological similarity of B-chromosome banding pattern and telomer-centromeric region banding pattern of chromosome IV in Ch. borokensis was shown. Polytene B-chromosomes of Ch. borokensis and Ch. heterodentatus were microdissected, and their DNA was amplified using degenerate oligonucleotide primer polymerase chain reaction. Comparative analysis of the localization of homologous B-chromosome DNA sequences of A- and B-polytene chromosomes was made using in situ fluorescence hybridization. It has been shown that B-chromosomes in the studied species are composed mainly of repetitive DNA sequences homologous to sequences of centromeric and telomeric DNA of A-chromosomes, and also these of the mobile element NLRCthl. The B-chromosome DNA, homologous to sequences of DNA mobile element, was scattered on A-chromosomes (more than 100 sites). No ribosomal DNA repeats were identified in B-chromosome. Heterologous FISH of B-chromosome DNA to polytene A-chromosomes of Ch. thummi, a species lacking B-chromosomes, enabled us to reveal the presence of numerous sites homologous to DNA of B-chromosomes. These are mainly mobile element sites. An origin of B-chromosomes and peculiarities of their organization in chironomids are discussed.     

A review of the genusChironomus (Diptera,Chironomidae)

Two cytologically distinguishable species have been found in material ofChironomus australis. These species have been calledCh. australis andCh. duplex. Both belong to thepseudothummi-cytological grouping because they have the chromosome arm combinations AE, BF, CD, G.Ch. duplex shows a modified arm pattern due to a tandem fusion of arm G to arm E.—The banding patterns of the polytene chromosomes of the two species are compared to each other and to the Australian standard species,Ch. oppositus. Ch. australis is very close cytologically toCh. oppositus, whileCh. duplex, which is considered a derived species because of the tandem fusion, shows a number of inversion differences from the morphologically similarCh. australis. Ch. duplex is polymorphic for six inversions, four of which are simple inversions, the other two are complex involving also the transposition of some bands.Ch. australis appears to be monomorphic.     

The karyotype of Omisus caledonicus (Edwards) (Diptera, Chironomidae)

Karyotype of Omisus caledonicus with 2n = 14 is described, all chromosomes are acrocentric, heterochromatin centromere is vacuolized. The following sequence discovered: A1, A2, B1, B2, C1, C2, D1, D2, E1, F1, G1 and G2. Simple inversions are found in chromosomes A-C and G, a complex reconstruction with 3 break points are observed in chromosome D. All reconstructions are large (from 66 to 99% of bands). According to phylogenetic reconstructions for morphological characters (Saether, 1979) and data on karyotypes it may be considered that O. caledonicus is one of much more primitive species in the tribe Chironomini.     

Heterogeneity and Heterofunctionality of Hemoglobins in Bloodworms (Diptera, Chironomidae)

In electrophoretic spectra of hemoglobins of Chironomus species of plumosus group, 3 groups of fractions are arbitrarily identified: fast fractions (mobility of 0.85 and higher), fractions with intermediate mobility (0.58–0.83), and slow fractions (mobility of 0.43 and lower). The most unstable turned out to be the fast fractions; their protein content increased considerably at storage and repeated freezing–thawing of samples. Fractions with the intermediate mobility are the most numerous, have a high specific amount according to the protein content and a high peroxidase activity. The slow fractions in the majority of species were characterized by a low peroxidase activity and high protein content. An interspecies comparison of electrophoretic spectra of hemoglobins has shown that the species that are the most tolerant to oxygen deficiency have the slow fractions with the lowest mobility. The obtained data have allowed suggesting that that the identified groups of hemoglobins are functionally heterogeneous: (1) the fast fractions with mobility of 0.85 and higher are products of degradation of hemoglobins with a higher molecular mass; (2) fractions with intermediate mobility (0.58–0.83) have a high affinity to oxygen and provide its utilization at its very low concentrations in water; (3) the slow fractions with mobility of 0.43 and lower have a high mol. mass and perform the buffer function preventing disturbance of the acid-base equilibrium of internal medium at anaerobiosis.     

Karyotype structure in species of Propsilocerus genus (Diptera, Chironomidae)

Karyotype structure and polytene chromosome banding patterns were studied in two Orthocladiinae siblings--Propsilocerus akamusi (China) and Propsilocerus jacuticus (Russia). Both species have haploid number of chromosome typical for Orthocladiinae (n = 3). An unusual structure of centromeric regions was observed in all three chromosomes of karyotypes in both species. Photomaps of polytene chromosomes are presented. A comparison of karyotypes of P. akamusi and Propsilocerus jacuticus revealed a high level of homology in their banding sequences, however, the presence of fixed paracentric inversions in chromosomal arms IR, IIR, IIIR of Propsilocerus jacuticus has shown a clear-cut phylogenetic divergence. No chromosomal polymorphism was found in both species.     

Chromosomal evolution of the Hawaiian Telmatogeton (Chironomidae,Diptera)

It is only in the Hawaiian Islands that species of the otherwise marine genus Telmatogeton have evolved into freshwater. An analysis of polytene chromosomes and karyotypes of two marine species and five freshwater species revealed that paracentric inversions and centric fusions were important in chromosomal evolution. The sequence of polytene chromosome bands common to most species, established as the Telmatogeton standard sequence, is found in a population of T. torrenticola from West Maui. Most species and other populations of T. torrenticola may be derived from the standard sequence by paracentric inversions. Similarities with the standard band sequence places T. japonicus (n=7) rather than T. pacificus (n=4) in the proposed phylogeny as the species closest to the marine ancestor of the freshwater species. One of three species (T. fluviatilis from Oahu, T. torrenticola from West Maui, or an undescribed species from East Maui), each with seven pairs of chromosomes is considered to be closest to the original freshwater species. T. torrenticola is a complex species in which there is an accumulation of fixed inversions and centric fusions in stepwise fashion in populations from west to east (West Maui n=7; East Maui n=6; Kohala Mountains n=5 and Mauna Kea n=4 both from the island of Hawaii). The population of T. torrenticola from Molokai has a reduced chromosome number (n=4) and fixed inversions. T. abnormis and T. hirtus, the only species which exhibit differentiated sex chromosomes, may be derived from the standard sequency by paracentric inversions. T. abnormis (n=4) has a simple XY system and T. hirtus (n=3/4) has a complex XY₁Y₂ system. Unique sequences of bands, differences in staining intensity of puffs and bands, and an inversion form the basis for the differentiation of the various Y-chromosomes in these species.     

A review of the genus Chironomus (Diptera,Chironomidae)

Analysis of the banding pattern of the salivary gland chromosomes of Chironomus tepperi indicates that, despite a somewhat modified male hypopygium, the relationships of this species are close to the other Australian species of the genus, particularly to Ch. oppositus. No inversion polymorphism has been found in Ch. tepperi and this, together with the relatively high chiasma frequency as measured at metaphase I, would appear to be an adaptation to provide genetic variability necessary for its colonizing ability.     

Phylogeny of the endemic Baikalian Sergentia (Chironomidae,Diptera)

Fragments of two mitochondrial genes, cytochrome b (CytB) and Cytochrome c oxidase subunit I (COI) have been used as phylogenetic markers in Sergentia (Chironomidae, Diptera). The concatenated (1241 bp) sequences from both genes were used to infer the phylogenetic relationships among seven Sergentia species. Five of the species belong to the endemic fauna of Lake Baikal. Alignments of the nucleotide sequences were used for the construction of trees using Neighbor-Joining and maximum parsimony methods. Both methods yielded similar results. Monophyly of both Sergentia and the Baikalian endemic species was well supported. The date of origin of the endemic group of Sergentia was estimated as 25.7 MYA which closely coincides with the start of geological changes in the Baikal area. A cytological tree, based on 12 chromosomal characteristics, for the same set of Sergentia species showed a great similarity to the molecular phylogeny.     

Stempellina and Zavrelia from China (Diptera,Chironomidae, Tanytarsini)

The first records of the Tanytarsini genera Stempellina and Zavrelia in the Oriental Region based on adult males are presented. Two species, Stempellina clavata sp. n. and Zavrelia clinovolsella sp. n. from southern China, are described, and the generic diagnoses of the two genera are emended to accommodate the new species. A key to the male imagines of the genus Zavrelia is given.     

Phylogeny of the subfamilies of Chironomidae (Diptera)

Summary The phylogeny of the subfamilies of Chironomidae are cladistically analysed using parsimony. A data matrix is presented and some characters discussed. Different outgroup taxa, constraints and options are used, characters unordered or ordered, weighted or unweighted, the results reweighted or not and the results discussed. Telmatogetoninae in all cladograms forms the sister group of the remaining subfamilies. Aphroteniinae in some cladograms forms the sister group of all subfamilies except Telmatogetoninae, whereas in other cladograms, including the preferred cladogram, it is part of Tanypodoinae, which otherwise includes Podonominae, Usumbaromyiinae and Tanypodinae. Chilenomyiinae is basal in Tanypodoinae in some cladograms. In most cladograms, including the preferred cladogram, it is basal in Chironomoinae, which also includes Buchonomyiinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae. The preferred cladogram is compared with the relationships between different subfamilies suggested by previous authors.     

Parachironomus Lenz from China and Japan (Diptera,Chironomidae)

Members of the genus Parachironomus Lenz known from China and Japan are revised, and a key to their male adults is given. Parachironomus poyangensis sp. n. is described in this life stage. Parachironomus frequens (Johannsen) and Parachironomus monochromus (van der Wulp) are recorded from China for the first time, thus are redescribed from Chinese specimens. Parachironomus kamaabeus Sasa & Tanaka and Parachironomus toneabeus Sasa & Tanaka are new junior synonyms of Parachironomus frequens. Three Chinese or Japanese species formerly placed in Parachironomus are transferred to other genera, resulting in the new combinations Cryptochironomus inafegeus (Sasa, Kitami & Suzuki), Demicryptochironomus (Irmakia) lobus (Yan, Sæther, Jin & Wang), and Microchironomus lacteipennis (Kieffer). Chironomus sauteri Kieffer, Parachironomus kisobilobalis Sasa & Kondo and Parachironomus kuramaexpandus Sasa are removed from Parachironomus; the last of these three denotes a valid species of uncertain generic placement, the first two are nomina dubia.     

On the chironomid (Diptera,Chironomidae) fauna in Lake Sevan

An annotated list of the chironomid species collected in Lake Sevan in the first 10 days of October 2006 and 2007 is presented. Chironomid species were identified by the aquatic stages of their development (larvae and pupae) and imagoes. The list includes 26 species, among which nine species were recorded in the lake for the first time. Altogether, 53 species of chironomids have been recorded in Lake Sevan.