DNA barcodes provide insights into the diversity and biogeography of the non-biting midge Polypedilum (Diptera, Chironomidae) in South America.

South America, particularly within its tropical belt, is renowned for its unparalleled high levels of species richness, surpassing other major biomes. Certain neotropical areas harbor fragmented knowledge of insect diversity and face imminent threats from biodiversity loss and climate change. Hence, there is an urgent need for rapid estimation methods to complement slower traditional taxonomic approaches. A variety of algorithms for delimiting species through single-locus DNA barcodes have been developed and applied for rapid species diversity estimates across diverse taxa. However, tree-based and distance-based methods may yield different group assignments, leading to potential overestimation or underestimation of putative species. Here, we investigate the performance of different DNA-based species delimitation approaches to rapidly estimate the diversity of Polypedilum (Chironomidae, Diptera) in South America. Additionally, we test the hypothesis that significant differences exist in the community structure of Polypedilum fauna between South America and its neighboring regions, particularly the Nearctic. Our analysis encompasses a dataset of 1492 specimens from 598 locations worldwide, with a specific focus on South America. Within this region, we analyzed a subset of 247 specimens reported from 37 locations. Using various methods including the Barcode Index Number (BIN), Bayesian Poisson tree processes (bPTP), multi-rate Poisson tree processes (mPTP), single-rate Poisson tree processes (sPTP), and generalized mixed Yule coalescent (sGMYC), we identify molecular operational taxonomic units (MOTUs) ranging from 267 to 520. Our results indicate that the sGMYC method is the most suitable for estimating putative species in our dataset, resulting in the identification of 75 species in the Neotropical region, particularly in South America. Notably, this region exhibited higher species richness in comparison to the Palearctic and Oriental realms. Additionally, our findings suggest potential differences in species composition of Polypedilum fauna between the Neotropical and the adjacent Nearctic realms, highlighting high levels of endemism and species richness in the first. These results support our hypothesis that there are substantial differences exist in species composition between the Polypedilum fauna in South America and the neighboring regions.

Description of two new species of Polypedilum (Asheum) and immature stages of Polypedilum (A.) curticaudatum (Diptera: Chironomidae).

Two new species of Polypedilum (Asheum) (Diptera: Chironomidae: Chironominae) are described and figured as adult males, P. (A.) sofiae sp. n. collected in the states of Mato Grosso and Rondônia and P. (A.) mayrahu sp. n. collected in the state of Bahia, Brazil. In addition, the adult male of Polypedilum (Asheum) curticaudatum (Rempel) is redescribed based on material from some localities in the Brazilian Atlantic Forest and Pantanal, and its larva and pupa are described for the first time.

Macropelopia (Macropelopia) patagonica, a new Tanypodinae (Diptera: Chironomidae) from the Patagonian Andes.

One new species of Macropelopia Thienemann (Diptera: Chironomidae: Tanypodinae), M. (Macropelopia) patagonica sp. n. is described and figured as adult male. The specimens were collected from the Patagonian Andes, at San Carlos de Bariloche, Argentina. In addition, the generic diagnosis of Macropelopia is emended for the adult male.

Procladius travassosi (Oliveira, Messias Silva-Vasconcelos, 1992) regarded as a new junior synonym of Procladius stroudi Roback 1982 (Diptera: Chironomidae: Tanypodinae).

Although recent years have seen increased activity regarding chironomid systematics in the Neotropical region (e.g. Oliveira et al. 2011, 2013, Trivinho-Strixino et al. 2013, 2015, Amora et al. 2015, Parise Pinho 2016, Andersen et al. 2017, Silva Song 2018, Trivinho-Strixino Silva 2018), particularly concerning the subfamily Tanypodinae (e.g. Oliveira Silva 2011, Silva Wiedenbrug 2015, Silva et al. 2014a,b; Siri et al. 2015, Silva Oliveira 2016, Silva Ferrington 2018), when it comes to some species-rich groups, such as Djalmabatista Fittkau, Larsia Fittkau and Procladius Skuse, the taxonomic knowledge remains fragmentary, with only a few species recorded to the Neotropics.

Chironomus rishii sp. n., an enigmatic non-biting midge (Diptera: Chironomidae: Chironominae) from Neotropical region.

A new species of Chironomus Meigen, C. rishii (Diptera: Chironomidae: Chironominae) from Brazil, is described and figured as adults male and female, pupa and larva. Adults of C. rishii sp. n. can be recognized by the prominent scutal tubercle and the hypopygium with narrow, elongated and strongly hooked superior volsella. Pupae of this new species are indistinguishable from most of the described Neotropical species, while larvae may be separated by the mentum with deeply incised trifid median tooth and 7 pairs of lateral teeth and the absence of lateral and ventral tubules. This last feature would place C. rishii sp. n. within the 'salinarius group'. However, this is not a group in the systematic sense, but an artificial grouping equivalent to a morphotype that reflects only the tubule character state. It is suggested that the absence of tubules is an adaptation for tolerating a wide range of salinity levels, however the 'salinarius group' had been also recorded in freshwater environments. Here, larvae without abdominal tubules were found in an environment with low levels of salinity, which indicates that the tubule condition may be result of further abiotic pressures, and configures a rather enigmatic scenario to this feature, particularly when considered the fact that larvae of Chironomus having tubules had also been recorded at the same habitat, living under similar conditions of C. rishi sp. n.

Oleia fieldsi sp. n., a new Orthocladiinae (Diptera: Chironomidae) species from the Brazilian Atlantic rainforest.

One new species of the genus Oleia Andersen et Mendes, 2007 (Diptera: Chironomidae: Orthocladiinae), O. fieldsi sp. n. is described and figured as adult male. The specimens were collected in a fragment of secondary forest in the Atlantic Forest, at Iguaçu National Park, on the border of Argentina and Brazil.

Sub-fossil Chironomidae (Diptera) from lake sediments in Central America: a preliminary inventory.

The chironomid diversity of Central America is virtually underestimated and there is almost no knowledge on the chironomid remains accumulated in surface sediments of lakes. Thus, in the present study we provide information on the larval sub-fossil chironomid fauna from surface sediments in Central American lakes for the first time. Samples from 27 lakes analysed from Guatemala, El Salvador and Honduras yielded a total of 1,109 remains of four subfamilies. Fifty genera have been identified, containing at least 85 morphospecies. With 45 taxa, Chironominae were the most specious and also most abundant subfamily. Tanypodinae with 14 taxa dominated in about one third of the sites. Orthocladiinae were presented by 24 taxa, but were recorded in 9 sites, being dominant in only one site. Podonominae were collected only in one locality. Head capsules of Heterotrissocladius found in the high elevation lake Magdalena, Guatemala, represent a first record for the Neotropical region. Both relative abundance and species richness of Chironominae and Orthocladiinae showed significant relationship to elevation, while Tanypodinae were indifferent. Hopefully, the list of taxa provided by our study will be a base line for future limnological and paleolimnological investigations using chironomid remains in the region.

Amazonimyia gigantea gen. n., sp. n., a new Tanypodinae (Diptera: Chironomidae) from the Neotropical Region.

A new genus, Amazonimyia, is established for a species of the tribe Pentaneurini (Diptera, Chironomidae, Tanypodinae) from the Amazon Rainforest in northern Brazil. Generic diagnoses for adult male and pupa are provided together with descriptions of a new species, Amazonimyia gigantea.

A taxonomic revision of genus Labrundinia Fittkau, 1962 (Diptera: Chironomidae: Tanypodinae).

The species of the genus Labrundinia (Diptera: Chironomidae: Tanypodinae: Pentaneurini) are revised, described and figured. Keys to known adult males, pupae and larvae are provided. Fourteen previously known species are redescribed, and 25 species from Neotropical region are diagnosed and described as new to science. These species treated are L. amandae sp. n., L. amazonica sp. n., L. becki Beck et Beck, L. carolae sp. n., L. costaricae sp. n., L. fera Roback, L. fiorelinii sp. n., L. fittkaui sp. n., L. fosteri Roback, L. hirsuta Roback, L. gregi sp. n., L. jasoni sp. n., L. johannseni Beck et Beck, L. kogilamae sp. n., L. longipalpis Goetghebuer, L. mayaca sp. n., L. meta Roback, L. multidentata sp. n., L. nathani sp. n., L. neopilosella Beck et Beck, L. nicaraguensis sp. n., L. opela Roback, L. panamensis sp. n., L. parabecki Roback, L. parafittkaui sp. n., L. parareniformis sp. n., L. paravirescens sp. n., L. paulae sp. n., L. pilosella Loew, L. reniformis sp. n., L. robacki sp. n., L. semicurvata sp. n., L. setosa sp. n., L. separata Edwards, L. sofiae sp. n., L. tenata Roback, L. trilucida sp. n., L. unicolor sp. n., L. virescens Beck et Beck. A diagnosis of the genus is presented and morphological differences to closely related genera are discussed.

Tapajos cristinae gen. n., sp. n. (Diptera: Chironomidae: Chironominae) from the Neotropical region.

A new genus of non-biting midges, Tapajos gen. n., is erected for T cristinae sp. n. from the Neotropical region, and placed in the subfamily Chironominae, tribe Chironomini. Adult males are characterized by the combination of bare eyes; antenna with 11 flagellomeres; antepronotal lobes fused medially; fore tibia with inner scale broad and rounded; superior volsella with a long sickle shaped, bare part arising from the distal lateral corner of a globose, densely trichiose base; inferior volsella sub-cylindrical, surpassing the anal point, distally setose and slightly expanded.

Thalassomya gutae sp. n., a new marine chironomid (Diptera: Chironomidae: Telmatogetoninae) from the Brazilian coast.

One new species of Thalassomya Schiner, 1856 (Diptera: Chironomidae: Telmatogetoninae), T. gutae sp. n. is described and figured as male, pupa and larva. The specimen was collected in the marine zone between tidemarks, in southeastern Brazilian coast and is the first species of this genus recorded to Brazil.