Stream restoration in the Mid-Atlantic USA is intended to reduce delivery of nutrients and sediment to Chesapeake Bay. However, the macroinvertebrate communities of urban streams have shown little improvement following restoration. To detect biological responses to restoration of Cloisters Branch, two sampling methods and two analytical approaches were compared. The restoration minimized disturbance of the existing forest buffer and wetlands to the extent possible during construction. Concurrent sampling using benthic D-net and collection of floating chironomid pupal exuviae (CPEX) occurred once pre- (2013) and twice post-restoration (2023 and 2024) at five stations on Cloisters Branch. Additional CPEX sampling of Cloisters Branch and three non-restored control streams, for two years pre- and post-restoration, in a Before-After-Control-Impact design allowed us to distinguish a restoration response from other sources of interannual variation. Multimetric analysis of D-net samples indicated declines of biotic integrity post-restoration. In contrast, multivariate analyses of D-net and CPEX samples showed significant taxonomic responses to restoration. Lower conductivity in Cloisters Branch facilitated a strong increase in CPEX diversity and abundance of Chironominae. Post-restoration increase in stability and abundance of epilithic algae suggests that restoration improved physical habitat stability. Temporal and spatial variation in conductivity showed that road salt deicers were a greater biotic stressor than nutrients.
The genus Claudiotendipes Andersen, Mendes & Pinho (2017) includes species from Brazil, Costa Rica, and Bolivia typically occurring at altitudes between 220 and 1,525 m a.s.l. To date, no records of the genus exist for Colombia, and molecular data for the group remain absent from public databases. During a large-scale survey of 52 high Andean streams sites spanning Peru, Ecuador, and Colombia (altitudinal range: 2,200–4,500 m a.s.l.) we sorted hundreds of chironomid specimens and collected a single larva exhibiting this unique morphotype. This specimen came from the Cauca River basin (Caldas, Colombia) at 2,515 m a.s.l. We examined the specimen morphologically and sequenced the barcode region of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Morphological characters—including the six-segmented antenna with alternate Lauterborn organs and the mentum with four pale median teeth—place the specimen within Claudiotendipes. This record extends the known altitudinal range of the genus above 2,000 m a.s.l. and represents the first record for Colombia. The partial COI sequence (GenBank: PX924818) provides the first DNA barcode for the genus. Maximum Likelihood analysis confirms its position as a distinct lineage within the Chironomini, clustered in a clade with Oukuriella and an unidentified Chironomidae sequence, though the deeper nodes supporting these relationships remain weak. This study contributes to the knowledge of Neotropical chironomid biodiversity and provides a molecular baseline for future taxonomic and ecological studies of Claudiotendipes in the Andes.
Heterotrissocladius bipartitus sp. n. is described from Finland. The species is known from 12 geographical provinces in southern and central Finland. According to DNA barcode data, the species also occurs in the United Kingdom. The description is based on the adult male, male pupal exuviae and molecular data. The adult male of the new species can be assigned to the H. marcidus species group, but its pupal exuviae do not fit well with any of the three species groups (subpilosus-, maeaeri- and marcidus group). Molecular data suggest that H. marcidus is the closest relative of H. bipartitus. Males are recognizable by the inferior volsella having a posteriorly directed lobe. Characteristic features of pupal exuviae are prominent frontal warts on frontal apodeme, three lateral taeniae on VII, five on VIII and 23-26 taeniae on anal lobe. A key to the pupal exuviae of West Palaearctic species and a key to the adult males of Heterotrissocladius species of the world are provided.
A modified and updated diagnosis of Parametriocnemus adult males is provided by examining 13 morphological characters to separate the genus from the other 32 genera of Orthocladiinae worldwide with macrotrichia on the wing membrane. Consequently, seven species assigned to Parametriocnemus are transferred to other genera. Parametriocnemus tenuiapicalis is recognized as a new species based on a description including drawings of a species from Turkey addressed as Parametriocnemus sp. in a publication by Caspers and Reiss 1989. A provisional identification key to the males of the 31 species of Parametriocnemus of the world is presented, assisted by a table containing data for 19 characters of each species. The shape of the hypopygium inferior volsella was found to be the most important character to distinguish species.
Parakiefferiella ferringtoni sp. n., previously recorded as the provisional taxon Orthocladiinae Genus 5 sensu Coffman and Ferrington (2008), is described based on larval, pupal, pharate male and female material. This species resides in the Pacific Northwest region of the Nearctic. The morphology of P. ferringtoni sp. n. blurs the lines between genera of the Parakiefferiella group. We review the state of generic taxonomy of the Parakiefferiella group, with an emphasis on providing explicit morphological synapomorphies to delineate each genus, although Parakiefferiella Thienemann and Lappokiefferiella Tuiskunen have no unambiguous synapomorphies.
Male adults and pupae of the genus Lopescladius from the Nearctic are reviewed. The morphologies of adult male and pupal Lopescladius (Cordiella) hyporheicus Coffman and Roback, 1984, are reexamined and compared to the Neotropical Cordiella. The pupa of Lopescladius (Lopescladius) inermis Sӕther, 1983, is described, along with comments on the adult male. Three additional pupal morphotypes are described. Keys are included for adult males and pupal exuviae from the Nearctic. Large range expansions are reported for several species.
A gut content analysis (GCA) was performed to quantify the relative use of food resources by larvae of chironomids (Diptera: Chironomidae) inhabiting different Alpine freshwater habitats fed by meltwater (kryal), groundwater (krenal) and mixed waters (glacio-rhithral, proglacial pond) in the Italian Alps (Trentino). GCA was performed on the 13 most frequent and abundant taxa in these habitats: Diamesa bertrami, Diamesa latitarsis, Diamesa steinboecki, Diamesa zernyi, Pseudokiefferiella parva, Eukiefferiella minor, Metriocnemus eurynotus gr., Parametriocnemus stylatus, Thienemanniella clavicornis, Tvetenia calvescens, Macropelopia sp., Zavrelimyia sp., Micropsectra atrofasciata gr. Guts were removed, mounted in Canada Balsam, and examined under a microscope (1000x). The gut of each individual was assumed to be 100% full, and proportions of the different food items were estimated using a 10x10 grid designed with the NIS-BR software. Food items were divided into 10 categories: Mineral Material, Animal Tissue, Algae (except diatoms), Diatoms, Plant tissue, Amorphous detritus, Lichens, Bryophytes, Fungi, and Pollen. The gut content of different taxa contained significantly different (p < 0.05) food categories based on a non-parametric statistical test. Differences in the diet were observed between species living in the same habitat type and classified into the same trophic category (detritivores, grazers, or predators) and individuals belonging to the same species living in different habitat types. A certain trophic flexibility and omnivory was found, which may facilitate the adaptation of chironomids to changes in available resources due to glacier retreat.
The Chironomidae are one of several groups of aquatic insects with representatives that possess cold hardening strategies that allow pronounced hibernal activity, including species that complete their life and reproduce only during the coldest months of the year. Although these winter-active species are often ignored in aquatic studies, relatively recent research has demonstrated that these insects are not only interesting, but they can also be an important and diverse element of aquatic insect communities. This review synthesizes existing literature on winter-emerging Chironomidae, focusing largely on Holarctic species emerging from temperate streams that are at least partially ice-free throughout the winter season. We found that there are currently at least 215 chironomid taxa present during winter, predominated by Orthocladiinae (n = 127), Chironominae (n = 42) and Diamesinae (n = 35). Our review highlights cold hardening strategies, such as supercooling, that permit winter activity, and we also discuss growth and emergence for species that have been extensively studied, such as Diamesa mendotae Muttkowski. Winter-active species tend to be long-lived at cold temperatures, and we discuss how consequences of climate change, including warmer temperatures and reduced snowpack, may negatively impact certain winter-active species. Although there is a growing base of studies featuring winter-active species, our review demonstrates that research is largely restricted to a handful of localities, and autecology studies are limited to only select species. We emphasize the importance of extending field work into the winter season and expanding research on winter Chironomidae to a broader geographic range to better gauge species accounts and enhance our understanding of the importance of winter-emerging Chironomidae.
The Prairie Pothole Region (PPR) in North America is characterized by a high density of wetlands that can range from temporary habitats to small lakes. Much of the PPR has been converted to agriculture resulting in outright habitat loss, eutrophication, sedimentation, introduction of agrochemicals, and the introduction of invasive plants and animals. We compared two prairie pothole lakes, Cottonwood Lake and Page Lake, to assess the functional roles and trophic structure of the macroinvertebrate communities in this highly altered landscape. We collected macroinvertebrate samples from littoral and profundal regions of each lake with an Ekman grab sampler in winters of 2007-2008. In fall 2012, 15 samples were collected from the near shore aquatic vegetation of Cottonwood Lake using D-frame nets. Macroinvertebrates, including Chironomidae, were identified to genus or morphospecies and assigned to functional feeding groups (FF-groups). Taxon richness of littoral and profundal samples were comparable in Cottonwood Lake but was significantly lower in the profundal zone of Page Lake. Macroinvertebrate abundance was significantly lower in Page Lake. Chironomidae made up 55% and 38% of the abundance in Cottonwood and Page Lakes, respectively and the similarity in chironomid composition was only 53%. Significantly more shredders, including the chironomid Glyptotendipes, occurred in Cottonwood Lake, including in the profundal zone. Macrophytes in Cottonwood Lake support additional taxa and shed light on the importance of near-shore sources of organic matter as a food resource. The FF-group distribution in Cottonwood Lake suggests that macroinvertebrates are taking advantage of a continuum of available organic matter resources that is dominated by coarse particulate organic matter (CPOM) near shore and by fine particulate organic matter (FPOM) in habitats farther from shore. In contrast, Page Lake had limited sources of organic matter; very few shredders were collected from littoral samples in Page Lake. In profundal samples most taxa were collector gatherers (Chironomus) or predators (Procladius and other Tanypodinae). Macroinvertebrates in Page Lake appear to be resource limited suggesting that the extensive algal blooms that characterize this eutrophic lake do not provide a comparable food source to that found in Cottonwood Lake. Analysis of the macroinvertebrate communities allowed us to discern the functional role of macroinvertebrates, including the Chironomidae, in processing organic matter in these highly impacted systems.
Winter is typically viewed as a time when insects are thought to be inactive; however, some aquatic insects (e.g., chironomid flies, stoneflies, and mayflies) have species which complete multiple life stages and emerge as active, terrestrial adults during winter. These insects have adaptations that permit survival at low temperatures and are known to occur in seasonally cold environments worldwide. However, awareness and education around these specialized insects are lacking partially due to the limited research and education centered around winter aquatic ecology. The Bugs Below Zero project, started in 2019, aims to enhance awareness and increase appreciation for winter-adapted aquatic insects, providing opportunities for the public to engage in community science efforts collecting data on these insect groups. The program has received positive reception in classroom and outreach settings and has successfully provided multimedia educational materials to hundreds of educators and data collection opportunities to numerous volunteer groups and classrooms. With the help of volunteers, the Bugs Below Zero team aims to add to the body of scientific knowledge about winter active insects and to continue educating students and community members about these organisms, their role in food webs, and their conservation needs.
In non-perennial aquatic habitats, dry periods influence the aquatic community by filtering organisms based on their ability to survive periods of drying or to recolonize the habitat quickly. Although intermittent streams often support interesting, specialized species, they often support a less species-rich community compared to perennial habitats. I collected Chironomidae from an intermittent, 3rd order stream biweekly for 6 years using surface floating pupal exuviae. The stream regularly dried in the summer every year, but the duration of the dry period varied among years (15-146 days). In total, 158 non-biting midge taxa were identified, but many species (65) were rare and only occurred in 1-2 samples. Most common taxa had regular seasonal emergence patterns, but some taxa had irregular emergence patterns that differed year to year. Following dry periods, Chironomidae resumed emergence within 2-3 weeks after the stream began flowing again and, in some years, sample richness was higher after flow resumed than before. The length of the dry period in the stream did not affect annual taxa richness, but lower annual taxa richness was observed in years with higher accumulated discharge and more frequent summer spates. Comparison of midge communities from this intermittent site to a downstream perennial site found no difference in taxonomic richness. However, the emergence period was shorter and the number of taxa present in individual samples was lower at the intermittent site. The equivalent richness was achieved in the intermittent site through higher temporal β diversity. This pattern may have been the result of higher disturbance in the intermittent site due to spates and drying which could contribute to greater habitat heterogeneity and promote colonization of new taxa. Most taxa at the perennial site were also found in the intermittent site indicating that many midge taxa in these habitats are facultative. Intermittent streams are usually expected to only support a depauperate community of facultative species, but these habitats can support interesting and diverse communities that should be conserved.
Northern European Corynoneura species with the combination of comparatively short extension of the hind tibia apex and a thick transverse stern-apodeme are morphologically similar to species in Thienemanniella. Moreover, the generic placement of Corynoneurella paludosa Brundin has been debated. We present results from morphological and molecular analyses that clarify the taxonomy of C. paludosa. Consequently, we regard Corynoneurella as a junior synonym of Corynoneura, move Corynoneurella paludosa to Corynoneura and return Corynoneurella afra (Lehmann) to Thienemanniella. Our observations also conclude that Corynoneurella paludosa sensu Langton is morphologically different from C. paludosa (Brundin) and is best placed in Thienemanniella as Thienemanniella langtoni sp. n. Corynoneura ferringtoni sp. n. and Corynoneura minimagna sp. n. are described and diagnosed based on adult male morphology and DNA barcodes. We redescribe Corynoneura minuscula Brundin, discuss Corynoneura magna Brundin, and suggest a solution for the identity of Corynoneura celeripes Winnertz. Finally, we provide an identification key to adult males of Holarctic Corynoneura species with a short hind tibial extension.
Washington State, USA has extensive coastal habitats that extend from marine or estuarine ecosystems upstream to the upper mixing zone where tidal surge and freshwater meet. We document a rare maritime chironomid genus, Eretmoptera Kellogg, 1900, from these habitats. The larvae of Eretmoptera were identified from 21 samples composed of 17 sites in the Puget Lowlands and Coast Range ecoregions based on a total of 1067 samples examined. Larvae were compared to reference material to confirm identification. We document Eretmoptera from low order forested streams in urban and private lands. Many sites sampled were near marine habitat and likely experienced saltwater intrusion while at least six sites were far from saltwater intrusion and were likely fully freshwater. We compare larval habitat for Eretmoptera in this study to larval habitat of the sub-Antarctic and Antarctic E. murphyi Schaeffer, 1914, the only species in the genus for which larvae have been associated. The georeferenced data provided in this study should spur further research to find and associate all life stages for Eretmoptera in Washington State to verify the genus identification and to help solve its taxonomic position within maritime and terrestrial Orthocladiinae.
In this study, we confirm the status of Parachaetocladius lenferringtoni Bouchard et Namayandeh, 2024, using molecular evidence. Using distance-based ABGD, ASAP, and K2P techniques, we determined that the minimum interspecific distance between sequences of P. lenferringtoni and Parachaetocladius abnobaeus (Wülker, 1959) was 14.8%, sufficient to maintain the species level. Based on the results obtained, we suggest that the threshold of 3% is sufficient to set the species limit for the Parachaetocladius species. Therefore, our molecular analyses of P. lenferringtoni specimens further support its status as a new Nearctic species distinguished from Parachaetocladius abnobaeus (Wülker, 1959).
Two strange species are described and illustrated here based on adult males collected from China and Malaysia respectively. The combination of conventional diagnostic character states is unusual in both species, and we cannot allocate either into any currently recognized genera. We propose that these represent two new genera in the tribe Chironomini. Here we adopt ‘Chironomini taxon 1’ and ‘taxon 2’ as coded unresolved names for further discussion.
We investigated the taxonomic status of Cryptotendipes usmaensis (Pagast, 1931), a cryptic species of Chironomidae (Insecta, Diptera), focusing on its morphological and molecular characteristics. We found discrepancies in the descriptions of adult males and pupal exuviae, suggesting the possibility of multiple species or significant polymorphism within C. usmaensis. Studies of recent collections from Finland revealed two distinct pupal morphotypes of C. usmaensis coexisting in the same habitat. DNA barcoding of adult males from Finland and other countries suggest the existence of two genetically distinct groups of the species. The findings emphasize the need for a comprehensive taxonomic review of C. usmaensis and suggest that species identification in some Chironomidae may require a different approach, i.e. combination of pupal morphology and molecular data, rather than relying solely on adult male morphology.
