Procladius imicola Kieffer, 1922

Procladius imicola Kieffer, 1922 View in CoL

Procladius lugubris ( Zetterstedt, 1838) View in CoL — Lundström (1916), Finland, adult male, illustration.

Procladius imicola Kieffer, 1922 View in CoL — Kieffer (1922), Germany and Poland, adult male, adult female, description.

Procladius imicola var. nigriventris Kieffer, 1922 View in CoL — Kieffer (1922), Germany, adult male, key, description.

Procladius bathyphilus Kieffer, 1922 View in CoL — Kieffer (1922), Germany, adult male, description.

Procladius imicola Kieffer, 1922 View in CoL — Goetghebuer (1927), Germany, adult male, adult female, key, description.

Psilotanypus imicola Kieffer, 1922 View in CoL —Goetghebuer & Lenz (1936), Germany, adult male, adult female, key, description, illustration.

Procladius imicola Kieffer, 1922 View in CoL — Brundin (1947), Sweden, adult male, description, illustration.

Procladius imicola Kieffer, 1922 View in CoL — Brundin (1949), Sweden, adult male, key.

Procladius lugens Kieffer, 1915 View in CoL — Coe (1950), England and Scotland, adult male, adult female, key, description, illustration.

Psilotanypus imicola Kieffer, 1922 View in CoL — Muragina-Koreneva (1957), Russia, adult male, adult female, pupa, larva, keys, descriptions, illustrations.

Procladius nietus Roback, 1971 View in CoL — Roback (1971), Canada, adult male, key, description, illustrations.

Procladius imicola Kieffer, 1922 View in CoL — Pankratova (1977), Russia, pupa, larva, illustrations.

Procladius nietus Roback, 1971 View in CoL — Wrubleski & Roback (1987), Canada, adult male, adult female, pupa, larva, description, illustrations.

Procladius nietus Roback, 1971 View in CoL — Saether (2010), Canada, adult female, larva, key.

Procladius imicola Kieffer, 1922 View in CoL — Ratnasingham et al. (2024), Finland and Netherlands, adult males, photos.

? Procladius lugubris Zetterstedt, 1838 View in CoL — Kieffer (1918a), adult male, key, description.

? Procladius latifrons Kieffer, 1922 View in CoL — Goetghebuer (1927), Germany and Poland, adult male, adult female, key, description.

? Psilotanypus latifrons Kieffer, 1922 View in CoL — Goetghebuer & Lenz (1936a), Germany and Poland, adult male, adult female, key, description.

? Psilotanypus imicola Kieffer, 1922 View in CoL — Shilova (1969), Russia, adult male, key.

Material examined (n = 18). CANADA, 1 adult male (Holotype of P. nietus, CNCC ), Atlin , 59°N 133°W, 670 m a.s.l., 0 °C m.a.t., 9.vi.1955, leg. H. Hackel GoogleMaps ; 1 adult male (as P. nietus, CNCC ), Lake Manitoba, Bone Pile Pond , 50.11°N 98.19°W, 248 m a.s.l., +3 °C m.a.t., 18.v.1980, leg. D.A. Wrubleski GoogleMaps ; 1 adult male (as P. nietus, ANSP ), Lake Manitoba, Bone Pile Pond , 50.11°N 98.19°W, 248 m a.s.l., +3 °C m.a.t., 11.vii.1980, leg. D.A. Wrubleski. GoogleMaps — FINLAND, 1 adult male (as P. appropinquatus, ZMUO ), Lake Littoistenjärvi , 60.46°N 22.38°E, 36 m a.s.l., +6 °C m.a.t., 20.v.2013, leg. L. Paasivirta GoogleMaps [ Barcode LEFIJ5880-17 ] ; 1 adult male ( ZMUO), Hamarijärvi, Salo , 60.21°N 22.94°E, 34 m a.s.l., +6 °C m.a.t., 18.v.2014, leg. L. Paasivirta GoogleMaps [ Barcode LEFIJ3836-16 ] ; 2 adult males ( ZMUO), Tammela, Lake Suujärvi , 60.77°N 23.85°E, 97 m a.s.l., +4 °C m.a.t., 5.v.2015, leg. L. Paasivirta GoogleMaps [ Barcode LEFIJ3665-16 and LEFIJ3666-16 ] .— GERMANY, 1 adult male (as P. flavifrons, ZSMG ), River Unterer Schierenseebach , 54.3°N 10.0°E, 6 m a.s.l., +8 °C m.a.t., 13.v.1985, leg. U. Holm. GoogleMaps — NETHERLANDS, 1 adult male (as P. lugens, NMNL ), Leiden , 52.2°N 4.5°E, 1 m a.s.l., +11 °C m.a.t., 2014 GoogleMaps .— RUSSIA, 3 adult males ( IBIB), Rybinsk Reservoir , 58.1°N 38.6°E, 97 m a.s.l., +4 °C m.a.t., vii.1972, leg. A.I. Shilova. GoogleMaps — SCOTLAND, 1 adult male (as P. lugens, BMNH ), Aviemore , 57.19°N 3.83°E, 214 m a.s.l., +7 °C m.a.t., 16.v.1947 GoogleMaps .— SWEDEN, 1 adult male ( NHRS), Lake Tullan , 59.22°N 17.70°E, 25 m a.s.l., +6 °C m.a.t., 16.v.1989, leg. M. Gransberg GoogleMaps ; 2 adult males ( SLUU), Mälaren, Drottningholm , 59.33°N 17.87°E, 3 m a.s.l., +6 °C m.a.t., 21.v.1991, leg. L. Eriksson GoogleMaps and T. Wiederholm ; 1 adult male ( NHRS), Tärnsjö, Nordmyra , temporary inundated wetland, 60.16°N 16.89°E, 64 m a.s.l., +5 °C m.a.t., 1.v.2007, leg. A. Hagelin GoogleMaps ; 1 adult male ( NHRS), Eriksberg nature reserve, Lake Gårdsjön , 56.17°N 15.00°E, 14 m a.s.l., +7 °C m.a.t., 1.v.2017, leg. J. Wolgast GoogleMaps [ Barcoded ] .

Diagnostic characters. Figs. 10 View FIGURES 9‒10 , 46 View FIGURES 44‒46 , 125‒127 View FIGURES 125‒127 , key couplet 26. P. imicola has an almost unidentifiable to very short gonostylus process with a GspR that overlaps that of four other species of Procladius in Europe. Of these, P. flavifrons , P. simplicistilus and P. appropinquatus are easily separated from P. imicola by several characters including gonostylus form, setae on katepisternum, size and numbers of macrotrichia on the wing membrane.

The only similar species in Europe is P. lugens . The genitalia of P. imicola is very similar that of P. lugens , but the outer margin of the base section of the gonostylus is usually distinctly angled in P. imicola , while rounded in P. lugens . P. imicola is on average larger (wing length 2.6‒3.4 mm versus 2.1‒2.8 mm, mid leg tibia length 1.1‒1.4 mm versus 0.8‒1.1 mm, body length 4.8‒5.5 mm versus 3.5‒4.6 mm) and has an antenna AR only slightly overlapping (2.2‒2.6 versus 1.7‒2.3) that of P. lugens .

P. imicola has mostly been correctly identified in taxonomic literature. The adult female, pupa and larva have been described. Barcodes of adult males are available.

Geographical distribution and ecology. The known geographical distribution of P. imicola in Europe extents from the Netherlands and England at 52°N to Finland at 66 °N, encompassing sites with mean annual temperature which range from +11 to +2 °C. Down to ‒4 °C mean annual temperature is reached in Asian Russia and Canada. P. imicola has been found at altitudes from 2 m to about 700 m above sea level in Europe. Findings in Canada are up to 1 020 m, while about 1 640 m in Mongolia. The smaller but morphologically very similar P. lugens is only known from altitudes up to 540 m above sea level.

A great majority of the 28 sites with quality assured findings of P. imicola are oligotrophic to hypereutrophic lakes or lake-like reservoirs. Findings of P. imicola larvae are often from the profundal zone from 2 m down to 30 m, while its close relative P. lugens has mostly been found in the littoral and not known from more than 5 m depth in the profundal.

P. imicola can be among the most abundant species of the macroscopic bottom fauna in deep water of eutrophic and hypereutrophic lakes and reservoirs, showing a profound ability to withstand low oxygen conditions. More than 1 000 individuals of 3 rd to 4 th stage larvae per m 2 and about 1 g wet weight per m 2 have been reported. Rapid growth of the larvae may take place in autumn due to improved oxygen conditions after summer stagnation. Larvae of P. imicola are also known from littoral bottoms with different kinds of vegetation including mosses, Cladophora , Potamogeton , Typha and Phragmites .

There are scattered findings of P. imicola from habitats other than freshwater lakes or reservoirs, namely temporary ponds of an inundated wetland, rivers and canals with slowly floating water and a mountain lake with salinity equal to or even higher than typical seawater.

P. imicola have been observed to feed on animals such as Cladocera, Copepoda, Ostracoda and other Chironomidae , but also algae such as diatoms, fungal spores and detritus. Experiments have suggested that the larvae cannot or have difficulties to complete development to adults without some animal food.

Adults of P. imicola have been found from mid-April to mid-August. Synchronized emergence during about one week has been reported. Swarming of males over light-coloured objects has been observed. Larvae have been reported to overwinter in their last fourth instar.

Countries or autonomous regions with records of P. imicola in Europe are England, Estonia, Finland, Germany, Latvia, Lithuania, Netherlands, Poland, Russia, Scotland and Sweden. Records are also known from Canada, Mongolia and Russia (Asia).

References. Anikina 2009b; Balushkina 1987; Brodin & Wolgast 2019; Brundin 1947; Brundin 1949; Cannings & Scudder 1978; Coe 1950; Erbaeva & Safronov 2016; Goetghebuer 1927; Goetghebuer & Lenz 1936a; Izvekova 1975; Izvekova 1980; Kajak & Dusoge 1970; Kajak et al. 1968; Kansanen 1985; Kahlert et al. 2024; Kieffer 1918a; Kieffer 1922; Koreneva 1959; Lenz 1936; Lundström 1916; Muragina-Koreneva 1957; Paasivirta 2012; Pankratova 1977; Ratnasingham et al. 2024; Roback 1971; Saether 2010; Samietz 1999; Sandberg 1969; Shcherbina 1989; Shilova 1969; Shilova 1976; Sokolowa 1966; Sokolowa 1968b; Sokolowa 1971; Timm et al. 1996b; Vallenduuk & Moller Pillot 2007; Wiederholm 1974; Wrubleski & Roback 1987; Zetterstedt 1838; Zetterstedt 1850.