Larval morphology of Belgica antarctica Jacobs, 1900 (Diptera, Chironomidae, Orthocladiinae) from central part of the maritime Antarctic and deformities found in the larvae.

The larval morphology of the endemic species Belgica antarctica Jacobs, collected in January and February (2022) from six sites of Antarctica, was studied. The mouth apparatus and the parapods of one hundred seventy-six larvae were analyzed. No differences were found in the morphology of these structures between individuals of different sites. However, differences (with the exception of the length of 2nd antennal segment) were estimated in the sizes of the morphological features, as 2023 measurements were made of fifteen kinds of these structures and larval body. Deformities of mentum, mandible, antennal blade and antennal segments in percentage were established in larvae of almost all of the studied sites. The reasons for the differences and deformities are discussed.

External morphology of larva and polytene chromosomes of Clunio marinus Haliday, 1855 (Diptera, Chironomidae, Orthocladiinae) from two localities of the Atlantic coast.

The larva of Clunio marinus Haliday is described based on field and reared material, collected along the coast of Vigo (Spain) and Helgoland (Germany). C. marinus can be easily distinguished from other known European Clunio species on the basis of some species-specific features found in fourth instar larvae. Comparison with related known Clunio species from Europe with comments on their larval morphology are given. The characteristics of the polytene chromosomes of C.marinus from Vigo are presented. The comparative external morphological analysis of the larvae from the two localities shows a certain differentiation at the external morphological level. The reasons for this differentiation are discussed.

External Morphology of Larvae of Belgica antarctica Jacobs, 1900 (Diptera, Chironomidae) Obtained from Two Locations in Maritime Antarctica.

The external morphology of the fourth-instar larva of the Antarctic endemic chironomid midge Belgica antarctica is described. Larvae were collected from Jougla Point (Wiencke Island) and an un-named island close to Enterprise Island, off the coast of the western Antarctic Peninsula. Light microscopy was used to examine and document photographically the structures of the mouthparts (mandible, mentum, premandible, labrum), antennae, pecten epipharyngis, clypeus, frontal apotome and posterior parapods. Measurements of the mouthparts are presented. The data obtained are compared with that available in the literature. A number of differences were identified relating to the size of the larvae, the number of teeth on the mandibles, the number of antennal segments and the length of the antennal blade. Malformations of the mandible and mentum are reported for the first time in this species. Features of larvae of taxonomic value that can be used to determine the species in larval stages are presented. These are of utility in using the larvae to reveal relationships with other species. Larvae are also important in ecological and genotoxicological studies, which require accurate species level identification.

Physicochemical characteristics of the Dombrovska pit lake (Ukraine) formed in an opencast potassium salt mine and the genome response of Chironomus salinarius Kieffer (Chironomidae, Diptera) to these conditions.

This study focuses on the Dombrovska pit lake, near the city of Kalush in Ukraine, which is a former potassium salt mine filled with brine and freshwater. The water level is still increasing and as a result the salinity is decreasing. We analyzed the benthic fauna communities and the genome instability by assessing the rearrangements in the polytene chromosomes of Chironomus salinarius and the physicochemical parameters of the near-bottom water (pH, conductivity, mineralization, major ions, NO3-, NH4+, metals Cd, Pb, Cu, Mn, and Fe) and sediment (pH, organic matter and metals Cd, Pb, Cu, Zn, Mn, and Fe) at four sites. The water mineralization ranged from 17.3 to 26.2 g dm-3 which are classified as mesohaline and polyhaline waters, respectively. The biodiversity of the benthic fauna was low, and the dominant species was C. salinarius. The density of C. salinarius varied spatially and changed from 637 ind./m2 at a depth of 5 m to 8167 ind./m2 at a depth of 2.5 m. The genome instability was analyzed by examining the structural and functional changes in the salivary gland chromosomes of C. salinarius. The exposure of C. salinarius damaged the chromosomes and the activities of key structures, such as the Balbiani ring and nucleolar organizer, were partially or completely suppressed.

Prodiamesa olivacea Meigen and Prodiamesa bureshi Michailova (Diptera, Chironomidae, Prodiamesinae) as a candidate for assessing the genotoxicity of trace metals in fluvial sediments.

The genome response, realized by structure chromosome rearrangements in the polytene chromosomes of two sibling species Prodiamesa bureshi Michailova and Prodiamesa olivacea Mg., was studied. The larvae of the species were collected in May and September, 2016, from Biala Przemsza River, a metal-mine-affected site in southern Poland, where Zn, Cd, and Pb concentrations in the sediment exceeded many times the reference data and those from unpolluted sites. The water had high contents of different major ions and nutrients. A high spectrum of somatic chromosome aberrations was detected in the salivary gland chromosomes of both species, which defined a high somatic index (from 1.2 to 7), indicating the sensitivity of both genomes to anthropogenic stress. The cells with somatic rearrangements of both species were significantly higher (P. bureshi: G = 25.636, P < 0.001 May, G = 32.722, P < 0.001 September; P. olivacea: G = 47.863, P < 0.001 May, G = 38.742, P < 0.001 September) than the control. Both species from polluted and unpolluted sites showed a high frequency of ectopic conjugations, as between arms B, CD (centromere regions), and E (NOR). Some deformities of mentum and mandibles of P. bureshi (20%) and P. olivacea (35%) were detected. We postulate that the appearances of somatic chromosome aberrations are more sensitive indicators of genotoxicity in the studied species than changes in external morphology. The sensitivity of the P. olivacea and P. bureshi genomes shows that these species are good candidates for detecting the presence of genotoxic compounds in aquatic basins and evaluating their genotoxic effects.

Chironomus alchichica sp. n. (Diptera: Chironomidae) from Lake Alchichica, Mexico.

Morphological analysis of all developmental stages (except female), mitochondrial DNA sequences from cytochrome c oxidase subunit I (cox1) and cytological analysis of the polytene chromosomes were used to describe a new species of Chironomus found in the littoral and profundal zones of an endorheic, warm-monomictic lake in Mexico. Male imago is distinguished by the shape of superior volsella and by an antennal and bristle ratio lower than two. The pupa is characterized by the spur morphology of abdominal segment VIII. There is also a continuous row of hooklets on abdominal segment II. The larva is distinguished by a combination of antenna, mentum, mandible, and pecten epipharyngis characteristics, and abdominal ventral tubules. Molecular and cytological analysis supported the morphological differences found. The maximum likelihood tree obtained shows that Chironomus alchichica sp. n. clusters together with Chironomus decorus-group sp. 2 Butler et al. (1995) (bootstrap support = 92%), but genetic p-distances within C. alchichica sp. n. (0.004) were lower than the p-distances between other species of the decorus-group (C. decorus-group sp. 2, Chironomus bifurcatus Wülker et al., 2009 and Chironomus maturus Johannsen, 1908) confirming that it is a different species. The new species belongs to thummi cytocomplex, (decorus-group), with chromosome set- 2n = 8 and chromosome arm combinations: AB CD EF G. Karyologically, the species is closest to Chironomus riihimaekiensis Wülker (1973). This species has very compact salivary gland chromosomes with well heterochromatinized centromere regions in chromosomes AB CD G. Several fixed homozygous inversions distinguish arm A of the species from that of C. riihimaekiensis. Arm E differs from that of C. riihimaekiensis by simple fixed homozygous inversion. Some similarities in band sequences of this arm were found with species from the decorus-group as Chironomus blaylocki Wülker et al., 2009 and C. bifurcatus (decorus-group). The position of the key constrictions in chromosome G: Nucleolar organizer (NOR) and Balbiani rings (BRs) is similar to the species of decorus-group. C. alchichica sp. n. has been found in soft sediments rich in organic matter in well mineralized waters (where conductivity >10 mS cm-1) and with a high pH (≥9). The profundal zone is inhabited only during the mixing period, when dissolved oxygen is present.

Morphology of the adult male and pupal exuviae of Glyptotendipes (Glyptotendipes) glaucus (Meigen 1818) (Diptera, Chironomidae) using scanning electron microscope (SEM).

In this paper, a study of the morphology of the pupa and male imago of Glyptotendipes (G.) glaucus (Meigen 1818) was carried out, with the aid of a scanning electron microscope (SEM). The SEM provided additional valuable information on the morphology of the species. Adult male head, antenna, wing, leg, abdomen, hypopygium, pupal cephalothorax and abdomen were examined. It is emphasized that SEM was not often used in Chironomidae studies. The present results confirm SEM as a suitable approach in carrying out morphological and taxonomical descriptions of Chironomidae species.

Larva of Glyptotendipes (Glyptotendipes) glaucus (Meigen 1818) (Chironomidae, Diptera)-morphology by Scanning Electron Microscope (SEM), karyotype, and biology in laboratory conditions.

Larvae belonging to the family Chironomidae are difficult to identify. The aim of the present study was to describe the larval morphology of G. (G.) glaucus with the aid of a Scanning Electron Microscope (SEM), the karyotype and biology based on materials obtained from laboratory culture. Describing the morphology of larvae, special attention was paid to rarely or never described structures like the maxilla (lacinia and maxillary palp), the long plate situated below the ventromental plate, and plate X situated between lacinia and mentum. The use of SEM allowed also to obtain better images of labrum and ventromental plate. Morphological features of this species have been supplemented by karyotype and biology of larvae in laboratory conditions. Under controlled experimental conditions we found non-synchronous development of G. (G.) glaucus larvae hatched from one egg mass reflected in different lengths of larvae and emerged imagoes.

Characterization of Heterochromatin in the Salivary Gland Chromosomes of Chironomus riparius Meigen and Chironomuspiger Strenzke (Diptera, Chironomidae) by Differential and Fluorochrome Staining.

The constitutive heterochromatin of two homosequential sibling species, Chironomus riparius and Chironomus piger, was studied. The salivary gland chromosomes of both species were analyzed using three staining methods: orcein and C band staining combined with DAPI and CMA3 fluorochrome staining. Both species have the chromosome set 2n = 8, with the same banding pattern and chromosome arm combinations: AB, CD, EF, G, but they differed in number and distribution of heterochromatic bands, AT-rich sequences (DAPI+) and GC-rich sequences (CMA3+). In the polytene chromosomes of C. piger, C-bands were found in centromeres only. They contain two types of repetitive DNA sequences: DAPI+ (very weak) and CMA3+ sequences. However, the polytene chromosomes of C. riparius have many interstitial heterochromatic bands in addition to the centromeric heterochromatin. Some of these bands contain both AT-rich and GC-rich sequences, while others are either AT-rich (DAPI+) or GC-rich (CMA3+). Therefore, these closely related species differ both in the content and localization of constitutive heterochromatin. The species-specific organization of the constitutive heterochromatin can be used as an additional cytogenetic marker for species differentiation.

Chironomus amissum sp. n. (Diptera, Chironomidae) from southeastern Brazil

The paper presents a description of larva, pupa, imago (male) and karyotype of Chironomus amissum from southeastern Brazil. It belongs to pseudothummi cytocomplex with 2n=8 and chromosome arm combinations: AE BF CD G. Several fixed homozygous inversions distinguished arm A of the new species from that of Chironomus columbiensis Wülker et al. 1989 and Chironomus anonymus Williston, 1896. One homozygous inversion of arm F differentiated it from C. anonymus. Species-specific characters were presented in the larva, pupa and imago.

Neste artigo é apresentada a descrição de larva, pupa, adulto macho e cariótipo de Chironomus amissum, uma nova espécie do sudeste brasileiro. Ela pertence ao citocomplexo pseudothummi com 2n=8 e cromossomos com combinações de braços: AE BF CD G. Várias inversões homozigóticas diferem o braço A da nova espécie em relação às espécies Chironomus columbiensis Wülker et al. 1989 e Chironomus anonymus Williston, 1896. Uma inversão homozigótica do braço F diferencia essa espécie de C. anonymus. Caracteres que diferenciam a espécie nova são também apresentados para larva, pupa e adulto.

Chironomus polonicus sp. n. (Diptera: Chironomidae) from southern Poland.

The paper describes larval, pupal and adult morphology as well as the karyotype of Chironomus polonicus sp. n. from southern Poland. The material has been obtained from reared egg masses collected in Boleslaw pool, near Kraków. The species belongs to the pseudothummi cytocomplex with 2n = 8 and chromosome arm combinations AE, BF, CD, G. Several homozygous inversions distinguish arm A of the new species from that of C. pseudothummi Strenzke. Arm F is similar to that of C. aprilinus Meigen and differs from it by few steps of homozygous inversions. Few morphological differences in the pupa and adult are also presented.

Does biodiversity of macroinvertebrates and genome response of Chironomidae larvae (Diptera) reflect heavy metal pollution in a small pond?

The investigation was carried out on a small pond situated on a recent mine spoil at Boleslaw in the Olkusz region with Zn-Pb ore deposits. Water of the pond had pH 7.2-8.5 and low concentrations of heavy metals. Concentrations of Pb (487 µg g( - 1)) and Zn (1,991 µg g( - 1)) in the sediment were very high and potentially could lead to toxicological effects. In the pond, 48 taxa of macroinvertebrates belonging to Oligochaeta and water stages of Ephemeroptera, Odonata, Megaloptera, Trichoptera, Heteroptera, Coleoptera and Diptera (mainly Chironomidae family) were found. The influence of heavy metals on macroinvertebrates diversity was not found. Effect of heavy metal pollution was observed on the appearance of chromosome aberrations in the polytene chromosomes of Chironomidae larvae. It was manifested by two ways: (1) in Kiefferulus tendipediformis and Chironomus sp. chromosome rearrangements in fixed state (tandem fusion and homozygous inversions), indicated intensive process of speciation; (2) in Chironomus sp., K. tendipediformis, Glyptotendipes gripekoveni (Chironomidae) somatic chromosome rearrangements (inversions, deficiencies, specific puffs, polyploidy) affected few cells of every individual. The somatic functional and structural alterations in Chironomidae species are particular suitable as biomarkers-they can be easily identified and used for detecting toxic agents in the environment.

Somatic breakpoints, distribution of repetitive DNA and non-LTR retrotransposon insertion sites in the chromosomes of Chironomus piger Strenzke (Diptera, Chironomidae).

Structural aberrations, their frequency and distribution as well as distribution of the tandem repetitive minisatellite DNA clusters of Alu and Hinf elements and two retroelements, the LINE NLRCth1 and the SINE CTRT1, were analyzed in the genome of the chironomid C. piger Strenzke larvae from a Bulgarian population. A consistent somatic variability in the structure of the polytene chromosomes was detected, showing that the C. piger genome is more actively rearranging than supposed before. Breakpoints were concentrated in proximal parts of chromosomes significantly more often than in distal parts. By FISH analysis we could detect only one locus containing Alu elements and 38 Hinf cluster loci which appear to be dispersed equally all over the chromosomes. The retrotransposons NLRCth1 and CTRT1 are present only in a few loci, but highly variant among different individuals. The mean number of NLRCth1 sites per individual was 18.4 +/- 2.09 and of CTRT1 was 54.8 +/- 8.42. A third of breakpoint locations were close to or coincide with a locus occupied by a retroelement (either NLRCth1 or CTRT1). Nineteen percent of breakpoints coincided with Hinf repetitive DNA elements. Some breakpoints were identical in the two sibling species C. piger and C. riparius Meigen (syn.: C. thummi thummi) and are considered as conserved hot spots of chromosome breakage.

Inherited and somatic cytogenetic variability in Palearctic populations of Chironomus riparius Meigen 1804 (Diptera, Chironomidae).

Inter- and intracytogenetic variability was analyzed in 13 natural Palearctic populations of Chironomus riparius Meigen 1804 (syn. Chironomus thummi) by examining hereditary and somatic aberrations (mainly inversions) of the salivary gland polytene chromosomes. In total, 77 different types of inherited inversion sequences and 184 different types of somatic inversions were found. The median percent frequency of inherited inversions was 1.4% and karyotypic divergence between populations was very low. Most hereditary inversions were endemic and always in a heterozygous state. Only six inversion sequences, each of them shared by two very distant populations, may be considered a relic of very ancient ancestral inversions. Unlike inherited inversions, occurrence of somatic aberrations seems to increase with the overall rise in the level of heavy metal pollution of the sediments from which larvae were sampled. In contrast with what occurs in populations of other chironomid species, populations of C. riparius do not seem to undergo a process of cytogenetic differentiation.

C-heterochromatin pattern of ten species of tetrigids (Tetrigidae, Orthoptera).

The karyotypes of species belonging to the Tetrigidae is characterised by structural conservatism. The standard chromosome set of T. japonica, T. simulans, T. bolivari, P. meridionalis, U. depressus, and F. robustus consists of 2n = 13 acrocentric chromosomes in males and 2n = 14 in females, with a sex determining mechanism of X0 male and XX female. C-bands distribution often species belonging to 4 genera were studied. Differences in the position of C-bands and number of chiasma between species are discussed.

Cytogenetic alterations in Prodiamesinae species (Diptera, Chironomidae) from different polluted regions.

Changes in the salivary gland chromosomes are described in sibling species Prodiamesa olivacea Mg. and P. bureshi Michailova larvae collected from trace metal polluted and unpolluted areas in Bulgaria and the United Kingdom. Although both species from polluted and unpolluted areas show a high frequency of ectopic conjugations, those between arm B (telomere) and arm F occur at a significantly higher frequency in P. bureshi from unpolluted sites. The reasons for chromosome conjugations and their changes under stress conditions are discussed. Regression of the puffin section 2 of chromosome arm A was significantly higher in P. bureshi from polluted sites, suggesting that trace metal pollution represses transcription at that site. Also, somatic heterozygous inversions and deficiencies occur in chromosomes of both species at the polluted areas. Some deformities ofthe head capsule were observed in both species at the metal-polluted sites. However, our data shows that the genome is a much more sensitive indicator of trace metal pollution than external morphology. The present authors suggest that measuring genotoxic damage at a cellular level provides a subtle and cost-effective indicator of trace metal pollution.

Nonrandom chromosomal distribution of spontaneous breakpoints and satellite DNA clusters in two geographically distant populations of Chironomus riparius (Diptera: Chironomidae).

Two geographically distant populations of Chimnomus riparius (syn. C. thummi) from two environmentally polluted sites (Santena, Italy and Varna, Bulgaria) show numerous somatic and inherited chromosomal aberrations (inversions, deletions and deficiencies). Fifty-five percent of the observed breakpoints occurred in at least two larvae from both populations. Breakpoints occurring twice or more were considered as 'common' structural chromosomal breakpoints. We tested whether such common breakpoints in larvae of the two polluted populations had a random chromosomal distribution or occurred preferentially in specific heterochromatic regions. Distribution of common breakpoints was not random, and proximal regions of first and third chromosome had significantly more common breakpoints than distal ones. By FISH we identified and mapped 56 chromosomal sections containing clusters of two tandem-repetitive satellite DNA families called Hinf and Alu elements. Like the common breakpoints, these repetitive DNA clusters appeared to be significantly more abundant in regions of constitutive heterochromatin such as the pericentromeric regions, while in distal sections of chromosomal arms they were rare or absent. Twenty-four out of 45 common breakpoints (i.e., 53.3%) occurred in cytogenetic sections where Alu and Hinf satellite DNA probes hybridized. The frequency of co-localization between common breakpoints and repetitive DNA hybridization signals was significantly higher than expected by chance. We hypothesize that spontaneous or induced breaks occur more frequently in sections containing blocks of repetitive DNA.