The distribution of Heterotrissocladius oliveri Saether (Diptera: Chironomidae) in Lake Michigan

Fifty one chironomid species were identified from 504 samples collected at depths ranging 8 to 267 m in Lake Michigan, U.S.A. Heterotrissocladius oliveri Saether occurred in 32% of these samples and had an average abundance of 22 m^–2 which was similar to other estimates from the Great Lakes. Maximum average lake-wide density was at 30 to 60 m (41 m^–2). At depths 60 m, H. oliveri was the dominant chironomid species comprising 75% of total Chironomidae. The substrate preference of H. oliveri differed within each depth regime considered: at 30–60 m, 2–3 ; at 60–120 m, 3–5 , 7–9 ; and at 120–180 m, 6–8 . Abundance was notably reduced at all depths in substrates characterized as medium silt (5–6 ). On a lake-wide basis, the distribution pattern suggested H. oliveri was most numerous from 30 to 60 m along the southwestern, eastern, and northern shorelines and at 60–120 m depths along the southern and eastern shorelines. Increased abundance in the South Basin was concurrent with evidence of increased sedimentation at 60 to 100 m. However, in several other areas of the lake, high densities were associated with medium to very fine sands relatively free of silts and clays. This observation suggested occurrence of H. oliveri was minimally affected by sediment type.Widely variable, but generally elevated water temperatures likely prevent H. oliveri from establishing a substantial population density at depths < 30 m. With increased depth, temperature fluctuation is negligible and food is more stable, though the source is variable. Factors limiting abundance of H. oliveri at depths 30 m were related to decreased food supply due to distance from shore, food sources of lower value (clays), and, most importantly, to reproductive replenishment.Although still oligotrophic in nature, high density occurrences in both high and low sedimentation areas of the lake suggest the trophic indicator status of H. oliveri might be broader than previously thought.     

Identification of instars and species in some larval Polypedilum (Polypedilum) (Diptera: Chironomidae)

Instars II and III of Polypedilum aviceps Townes, Polypedilum convictum (Walker), and Polypedilum illinoense (Malloch) can be identified to species by associating them with instar IV because key taxonomic characters remain relatively unchanged from instar to instar. Instars I cannot be identified to species or genus unless they are associated with older, identifiable larvae reared from the same egg masses. No single character evaluated on slide material can be used to clearly separate instars in all three species. Larvae of P. aviceps can be separated into instars based on any four of seven characters; P. convictum by either of two characters; and, P. illinoense by a combination of two characters. Changes in structures of instars II, III, and IV are described for all three species. Growth ratios for some structures are compared and discussed with regard to Dyar's Rule.     

New records of Polypedilum Kieffer (Diptera: Chironomidae) from India

Adult males of Polypedilum (Polypedilum) exterflexus n. sp., P. (Tripodura) rectangulum n. sp. and life stages of P. (Tripodura) pruina Freeman are described from India. In addition, one species, Polypedilum clavipennae n. sp. with all the life stages not assigned to any one of the existing subgenera is also described, and it may be justified to erect it as a new subgenus in future.     

Karyotype and karyofund of chironomids Polypedilum (Pentapedilum) sordens (Diptera, Chironomidae)

Karyotypes and karyofund of chironomids P. Polypedilum (Pentapedilum) sordens (Van der Wulp, 1874) from four water bodies of Saratov region have been analysed. 2n = 6, I (GAB) > II (CD) > III (EF). A cytophotochart of polytene chromosomes of this species was composed, and discovered inversions were identified on its base. The level of inversion polymorphism is high. There are 18 chromosome sequences in the karyofund. The frequency of heterozygote inversions is 1.6-2.5 per specimen. On the base of this cytochart it is possible to produce chromosome charts of other species of subgenus Pentapedilum.     

Afrotropical Polypedilum subgenus Tripodura, with a review of the subgenus (Diptera: Chironomidae)

Vårdal, H., Bjørlo, A. & Sæther, O. A. (2002). Afrotropical Polypedilum subgenus Tripodura, with a review of the subgenus (Diptera: Chironomidae). —Zoologica Scripta, 31, 331–402. A subgeneric diagnosis for all stages of the subgenus Tripodura Townes, 1 945 of the genus Polypedilum Kieffer, 1 912 is given. Nine new Afrotropical species of Tripodura are described: P.(T.)chelum Vårdal sp. n., P.(T.)amplificatus Bjørlo sp. n., P.(T.)patulum Bjørlo sp. n., P.(T.)spinalveum Vårdal sp. n., P.(T.)ewei Bjørlo sp. n., P.(T.)ogoouense Bjørlo sp. n., P.(T.)akani Bjørlo sp. n., P.(T.)dagombae Bjørlo sp. n., and P.(T.)amputatum Bjørlo sp. n.; all as male imagines only. P.(T.)alboguttatum Kieffer, P.(T.)albosignatum Kieffer, P.(T.)tropicum Kieffer, P.(T.)pruina Freeman, P.(T.)quinqueguttatum Kieffer, P.(T.) aegyptium Kieffer, P.(T.) tridens Freeman, P.(T.)allansoni Freeman, P.(T.)longicrus Kieffer, P.(T.)annulatipes Kieffer and P.(T.)abyssiniae Kieffer are re‐described as male and female imagines, while P.(T.)majiis Lehmann, P.(T.)subovatum Freeman, P.(T.)griseoguttatum Kieffer, P.(T.)aferum Lehmann and P.(T.)kijabense Freeman are re‐described as male imagines only. Keys to the male and the known female imagines of the 30 Afrotropical species in the subgenus are presented. A phylogenetic analysis based on all available information on Tripodura from all over the world (135 species) is presented and discussed. The monophyly of the subgenus Tripodura is confirmed. The subgenus can be divided into 20 groups with the acifer group forming the sister group of two larger assemblages of groups in the order acifer (titicacae (ginzansecundum ((aferum (ewei (malickianum (floridense (halterale, pullum)))))) (subovatum (labeculosum ((parascalaenum (allansoni (apfelbecki (udominatum, parvum))))) ((((alboguttatum, aegyptium) quinqueguttatum) annulatipes)). Only in the titicacae, halterale, pullum and apfelbecki groups are the larvae of more than one species described, while one larva is known in each of the subovatum, parascalaenum, aegyptium and quinqueguttatum groups. Three or more pupae are known only from the halterale, pullum, apfelbecki and aegyptium groups. Thus, the tentative nature of the group divisions is obvious. Geographical co‐evolutionary analyses (Brooks parsimony analyses) of the subgenus as a whole and of the major groups are performed and the areas most likely to be part of the original areas estimated. Most probably, eastern South America and Africa were part of the ancestral area. There are multiple sister‐group relationships and generalized tracks between South and East Asia and Africa, between Africa and the Palaearctic region, between South and East Asia, between tropical Brazil and Africa, between East Asia and North America across a former Beringian land bridge, and between the Indo‐West Pacific region and New Zealand, but no evidence for transantarctic relationships.     

Production of Cricotopus ornatus (Meigen) (Diptera: Chironomidae) in Waldsea Lake,Saskatchewan

Cricotopus ornatus was the predominant chironomid in meromictic, saline Waldsea Lake. Annual production of C. ornatus larvae in the mixolimnion was estimated to be 107 mg m^-2 (dry weight) in 1974, 66.5 mg m^-2 in 1975 and 69.5 mg m^-2 in 1976. These estimates are similar to those for chironomids in Canadian arctic lakes and deep-water areas of the Great Lakes. Annual P/B ratios were 5.4 in 1974, 6.8 in 1975 and 6.8 in 1976. These ratios are in the middle of the range reported for chironomids. The major factors limiting chironomid production in Waldsea Lake appear to be: (1) restriction of the habitable zone because of meromixis with accompanying loss of mobile first and second instars that are swept out of the mixolimnion (2) the relatively narrow zone of good C. ornatus habitat, i.e. areas of dense macrophyte or benthic algal growth and (3) predation by nine-spine stickleback and damselfly naiads.     

Succession of Chironomus Meigen Species (Diptera,Chironomidae) in Newly Filled Ponds

The colonization by Chironomus spp. of two ponds filled after a dry period was investigated. Field data were collected by means of quantitative benthic samples and emergence traps. C. melanescens. C. annularius, C. riparius, C. piger, C. luridus, C. obtusidens, C. plumosus, C. dorsalis and Camptochironomus tentans were determined cytotaxonomically in ponds investigated. C. melanescens and C. annularius appear to be the most characteristic species colonizing in high numbers in newly filled ponds. Larvae of C. annularius grew more slowly in ponds compared with the former one which resulted in a characteristic succession of both larval types. Most species mentioned disappeared completely from the ponds investigated after the metamorphosis of a single cohort. They were replaced by C. plumosus which was often attended by C. annularius in smaller ponds.     

中国多足揺蚊属指名亚属一新种(双翅目:摇蚊科)

记述中国多足摇蚊属指名亚属Polypedilum (s. str.) Kieffer 1新种——等跗多足摇蚊Polypedilum (Polypedilum) aequabe, sp. nov.,该新种雄虫可借以下组合特征与本亚属其它已知种类相区别:后足第 2 与第 3 跗节等长,肛尖具侧毛,上附器外侧毛位于近端部,下附器端部膨大。模式标本存放在南开大学生命科学学院摇蚊研究室。正模:♂,四川乡城硕曲河,2 700 m,1996-Ⅵ-12,灯诱,王新华采;副模:18♂♂,同正模;1♂,云南丽江石鼓冲江河,1750m,1996-Ⅴ-25,灯诱,周长发采。     

Identification of larvae of European species of Chironomus Meigen (Diptera: Chironomidae) by morphological characters

Abstract Variation in the morphology of larvae of twenty-six cytologically identified species of Chironomus Meigen from Europe is described. Characters studied include tubules on posterior abdominal segments, head pigmentation, mental size and teeth, mandibular and epipharyngeal teeth and antennae. A key to the species, based on these characters and ventromental plate features, is presented.     

Grazing rate determination of Corynoneura scutellata Winnertz (Chironomidae: Diptera)

Corynoneura scutellata Winnertz (Chironomidae: Diptera) grazing rates were determined radiometrically at different temperatures. The resulting temperature-grazing function was used to calculate C. scutellata grazing rates in the littoral zone of a Rhode Island lake. These grazing rates were compared to periphyton net accumulation rates, grazing rate: accumulation rate ratios ranged from 3–15% with a maximum of 70%.     

Some immature stages of the subgenus Chironomus (Meigen) (Diptera:Chironomidae) from Malawi,Central Africa

An account is given of the diagnostic characters of the larvae and pupae of 10 of the 18 African species of the subgenus Chironomus Meigen from a wide range of habitats in southern Malawi.     

Cadmium,zinc, lead and copper inChironomus riparius (Meigen) larvae (Diptera,Chironomidae): uptake and effects

Cadmium, Zn, Pb and Cu uptake and effects in larvae ofChironomus riparius (Meigen) were studied in an integrated laboratory investigation, in which metal analyses in different instar stages, uptake kinetics and effects on development and growth were considered in three separate experiments.In short-term experiments with fourth instar larvae, it was demonstrated that only a minor portion of metals was adsorbed on the larval exoskeletons. No conclusive evidence on the uptake mechanism was found, but active uptake of trace metals seemed highly unlikely.In partial life cycle experiments, all four metals studied were readily accumulated in chironomid larvae. Uptake could be described satisfactorily utilizing a first-order one-compartment uptake model which incorporated growth. In all cases steady state conditions were approached and high uptake and elimination rate constants were estimated. Distinct differences between essential (Zn and Cu) and non-essential (Cd and Pb) metals were noted. Larval growth was significantly impaired upon exposure.Finally, long-term exposure experiments with low Cd concentrations (0.010 and 0.025 mg 1^{–1) resulted initially in growth impairment and high mortality in first instar stages, but surviving larvae restored growth and adults emerged even before control adults. In similar experiments with Zn (0.1 and 1.0 mg 1–1}), development of larvae was significantly retarded. High Zn concentrations in larvae were noted and almost no adult midges emerged.     

Comparative morphology of the larval ventromental plates of European species of Chironomus Meigen (Diptera: Chironomidae)

Abstract. The ventromental plates of larvae of twenty-six cytologi-cally identified species of Chironomus Meigen from Europe are described. Variation in plate features, including size, striae, inner and outer hook series, and ventral surface ornamentation, is reported. A principal components analysis based on plate characters is undertaken, and the taxonomic composition of the resulting groupings is discussed.     

A new method for establishing a permanent laboratory culture of Chironomus riparius Meigen (Diptera: Chironomidae)

A new technique for the establishment of a permanent laboratory culture of Chirono-mus riparius is described. Larvae and pupae were reared in plastic tanks containing tap water, filamentous algae and a commercially prepared fishfood. The tanks were aerated, maintained at a constant temperature of 24°C and subjected to a constant lighting regime of 13 h of light followed by 11 h of darkness. Adults flew freely in a modified handling box, mated, and oviposited on strips of filter paper placed in the plastic tanks containing the aquatic stages. It has proved unnecessary to change the water or medium, which has saved both time and effort. Moreover, larvae established themselves in ail parts ofthe alga, and therefore more could be kept in each tank than when, as in previous methods, they are provided only with a substratum on the floor of the container.     

A structural study of the anal papillae of the midge Chironomus riparius Meigen (Diptera: Chironomidae)

Larvae of the midge, Chironomus riparius Mg., have four anal papillae arranged as two pairs, one dorsal to and the other ventral to the anus. Structural study with light and electron microscopes has revealed that their integument consists of a thin cuticle overlaying a thick, syncytial epidermis which is specialised to facilitate ion transport. There is a distinct neck or collar region at the junction of each papilla with the rest of the body wall. Although in many respects these structures resemble those in mosquitoes, there are both morphological and physiological features which suggest that differences exist in the means by which ion exchange with the environment is controlled and effected in the two families.     

Water quality and the occurrence of Chironomus riparius Meigen (Diptera: Chironomidae) in a stream receiving sewage effluent

SUMMARY. The effects of a sewage effluent in Moat Brook, Staffordshire, were determined from regular collections of water and biological samples from directly comparable stations above and below the sewage outfall.
The eutrophic conditions below the outfall result in the replacement of Polypedilum laetum by Chironomus riparius (except in the spring) as the dominant member of the Chironominae. Continuous recruitment of first instar larvae to the population of C. riparius in summer and autumn results in much overlap of generations, but emergence trap captures suggest at least five generations in the year.
The usefulness of C. riparius as an indicator of enriched conditions in lotic ecosystems should be considered in relation to oviposition behaviour and the occurrence and seasonal variation in density of the adults and aquatic stages (including the more conspicuous third and fourth instar larvae).     

The effect of mercury chloride on morphofunctional parameters in Chironomus riparius Meigen (Diptera, Chironomidae) larvae

The effects of various mercury chloride (HgCl₂) concentrations associated with bottom sediments on mercury accumulation in chironomid larvae and the modifications of morphofunctional parameters (mortality, growth, and structure of the mouth apparatus) have been studied. It was shown that, upon exposure, the larvae accumulated mercury in amounts exceeding its sediment concentrations. The mortality rate and metamorphosis duration increased with an increase in metal concentrations, while the animal size remained unaffected. Among all investigated morphological structures, the antennae were the most heavily effected.     

Polypedilum digitifer Townes andPolypedilum griseopunctatum (Malloch) (Diptera,Chironomidae): Redescription of adult males with a description and separation of the immature stages

Polypedilum (Tripodura) digitifer Townes andPolypedilum (Tripodura) griseopunctatum (Malloch) are morphologically similar species of Chironomidae. Using associated material from New York State, the adult males for both species are redescribed (adding previously ignored characters) and the mature larva and pupa are thoroughly described for the first time. Traits for distinguishing these species from each other and possibly from other Nearctic species ofPolypedilum (Tripodura) are provided.