Procladius longistilus (Kieffer, 1916)

Brodin, Yngve, 2025, Procladius (Diptera, Chironomidae) of Europe and a global view, Zootaxa 5591 (1), pp. 1-127 : 71-73

Procladius longistilus (Kieffer, 1916)

Trichotanypus longistilus Kieffer, 1916 — Thienemann & Kieffer (1916), Sweden, adult male, description, illustrations.

Trichotanypus longistilus Kieffer, 1916 — Kieffer (1918a), Lithuania, adult male, key, description.

Trichotanypus longistilus Kieffer, 1916 — Kieffer (1924), adult male, key.

Trichotanypus longistylus Kieffer, 1916 — Goetghebuer (1927), France, adult male, key, description.

Procladius longistylus (Kieffer, 1916) — Goetghebuer & Lenz (1936a), Goetghebuer & Lenz (1936b), Sweden, adult male, key, description, illustration.

Procladius suecicus Brundin, 1949 — Brundin (1949), Sweden, adult male, key, illustration.

Procladius culiciformis (Linnaeus, 1967) — Roback (1980), United States, adult male, pupa, larva, keys, descriptions, photos, illustrations.

Procladius longistylus (Kieffer, 1916) — Ratnasingham et al. (2024), Netherlands, adult male, photo.

Procladius cf. nigriventris ( Kieffer, 1924) — Ratnasingham et al. (2024), Germany, Norway, China and Canada, adult males, adult females, pupa, larvae, photos.

Procladius sp. — Ratnasingham et al. (2024), Finland, Germany, Slovakia, China and Canada, adult males, adult females, photos.

? Trichotanypus choreus ( Meigen, 1804) — Kieffer (1924), adult male, key.

? Trichotanypus culiciformis ( Linnaeus, 1767) — Kieffer (1924), adult male, key, description.

? Procladius culiciformis ( Linnaeus, 1767) — Saether (2010), Canada, adult male in part, adult female in part, pupa in part, larva in part, keys, descriptions, illustration.

Material examined (n = 58). CHINA, 1 adult male (as P. nigriventris ), Huaping Nature Reserve , 25.56°N 109.94°E, 1 271 m a.s.l., +12 °C m.a.t., 24.vi.2020, leg. S. Zhao [ Barcode CHGX127-20 ] .— CZECHIA, 2 adult males ( NHRS), Cheb district, Lake Vodni Nadrz Skalka , 50.08°N 12.32°E, 439 m a.s.l., +7 °C m.a.t., 17.vi.1991, leg. Y. Brodin. — FINLAND, 4 adult males (as P.? nigriventris, MZHF ), Lake Kuusijärvi , 60.31°N 25.11°E, 44 m a.s.l., +5 °C m.a.t., 18.vii.1965, leg. P. Armitage ; 1 adult male (as P.? choreus, MZHF ), Lake Kuusijärvi , 60.31°N 25.11°E, 44 m a.s.l., +5 °C m.a.t., 28.vii.1966, leg. P. Armitage ; 1 adult male (as Procladius sp. , MZHF), Lake Vanajavesi, Vihdassaari Island , 61.18°N 24.03°E, 79 m a.s.l., +5 °C m.a.t., 8.vi.1978, leg. P.H. Kansanen ; 2 adult males (as P. culiciformis ), Suvakoski , small lake, 67.31°N 28.16°E, 175 m a.s.l., +1 °C m.a.t., 9.vi‒23.vii.2009, leg. L. Paasivirta ; 1 adult male (as P. culiciformis coll., ZMUO), Lake Pyhäjärvi, Säkylä , 61.00°N 22.28°E, 45 m a.s.l., +5 °C m.a.t., 4.vi.2015, leg. L. Paasivirta [ Barcode LEFIJ3517-16 ] ; 1 adult male (as Procladius sp. ), Baltic Sea, Lake Käringsund, Storskär Island , 63.43°N 21.08°E, 0 m a.s.l., +4 °C m.a.t., 15.v.2017, leg. L. Paasivirta ; 1 adult male, Tulppio, Ainijärvi , 67.76°N 29.45°E, 269 m a.s.l., 0 °C m.a.t., 10‒14.vi.2018, leg. J. Salmela ; 2 adult males, Kiikala, Lake Tervakas , 60.49°N 23.70°E, 117 m a.s.l., +5 °C m.a.t., 9.v.2023, leg. L. Paasivirta. — FRANCE, 3 adult males (as Procladius sp. 1 , LHST), Lake Gourg Nére , 42.87°N 0.18°E, 2 201 m a.s.l., +2 °C m.a.t., 10.viii.1966, leg. H. Laville ; 3 adult males ( NHRS), Corsica, Lake Melu , 42.21°N 9.02°E, 1 708 m a.s.l., +6 °C m.a.t., 25.viii.2015, leg. J. Moubayed-Breil. — GERMANY, 1 adult male (as. P. sagittalis, ZSMG ), Lake Schalkenmehrener Maar , 50.2°N 6.9°E, 422 m a.s.l., +8 °C m.a.t., 1914, leg. A. Thienemann ; 1 adult male (as P. bathocryptus, ZSMG ), Lake Schluensee , 54.19°N 10.46°E, 22 m a.s.l., +9 °C m.a.t., 1953, leg. I. Müller-Liebenau ; 1 adult male (as Procladius sp. , ZSMG), Hödinger Tobel Stauweiher , small reservoir, 47.79°N 9.13°E, 551 m a.s.l., +9 °C m.a.t., 3.vi.1966, leg. F. Reiss ; 1 adult male (as P. cf. choreus, ZSMG ), Lahnberge, near Biologisches Institut Marburg , 50.81°N 8.81°E, 340 m a.s.l., +9 °C m.a.t., 10.vi.1992, leg. A. Dettinger-Klemm ; 1 adult male (as Procladius sp. , ZFMK), Kniepow, Rügen , small lake, 54.35°N 13.35°E, 9 m a.s.l., +9 °C m.a.t., 16.viii.2014 [Barcode GBMTM0349 incomplete] ; 1 adult male (as Procladius sp. , ZFMK), Brettenbach stream, Brücke Vordere Zaismatt , 48.13°N 7.90°E, 242 m a.s.l., +10 °C m.a.t., 31.iii.2019 .— IRELAND, 2 adult males (as Procladius sp. D , UCDZ), Lacy’s canal at Lake Ennell , 53.49°N 7.37°W, 78 m a.s.l., +10 °C m.a.t., 18.iv.1974, leg. D.A. Murray. — NORWAY, 1 adult male (as P. cf. nigriventris, NTNU ), Kautokeino, Lapholuoppal , lake, 69.21°N 23.76°E, 320 m a.s.l., ‒2 °C m.a.t., 12.vi.2010, leg. T. Ekrem and E. Stur [Barcode CHRFI040-10 ] ; 1 adult male (as P. cf. nigriventris, NTNU ), Alta, Lake Sierravannet , 69.84°N 23.37°E, 43 m a.s.l., ‒1 °C m.a.t., 14.vi.2010, leg. T. Ekrem and E. Stur [Barcode CHRFI079-10 ] ; 1 adult male (as P. cf. nigriventris, NTNU ), Vardø, Lake Nedre Domsvatn , 70.32°N 31.03°E, 120 m a.s.l., ‒1 °C m.a.t., 18.vi.2010, leg. T. Ekrem and E. Stur [Barcode ATNA531-10 ] ; 1 adult male (as P. cf. nigriventris, NTNU ), Melhus, Gammelelva nature reserve , 63.22°N 10.31°E, 28 m a.s.l., +4 °C m.a.t., 22.v.2014, leg. E. Stur [ Barcode CHMNO204-15 ] ; 1 adult male (as P. cf. nigriventris, NTNU ), Bymarka, Lake Kobberdammen , 63.42°N 10.28°E, 288 m a.s.l., +3 °C m.a.t., 27.v.2014, leg. T. Ekrem and X. Lin [Barcode CHMNO097-14 ] .— RUSSIA, 1 adult male ( NHRS), Lake Khepoyarech , 60.17°N 30.56°E, 61 m a.s.l., +5 °C m.a.t., 3.vii.1980, leg. Y. Brodin ; 2 adult males ( TUSF), Lake Ladoga, Sorvala , 61.74°N 30.77°E, 4 m a.s.l., + 5 m .a.t., 4.viii.1991, leg. G. Söderman [ Barcoded ] .— SLOVAKIA, 1 adult male ( NHRS), Lake Strbske Pleso , 49.12°N 20.06°E, 1 349 m a.s.l., +3 °C m.a.t., 20.vi.1991, leg. M. Gransberg. — SPAIN, 1 adult male (as P. choreus, DEBE ), Ebro Reservoir, Burgos-Santander , 42.58°N 4.02°W, 215 m a.s.l., +13 °C m.a.t., 28.i.1975, leg. N. Prat. — SWEDEN, 1 adult male (as Tanypus sp. , ZMLU), Åreskutan , 63.4°N 13.0°E, 920 m a.s.l., ‒1 °C m.a.t., 31.vii‒4.viii.1840, leg. J.W. Zetterstedt ; 1 adult male ( NHRS), Lake Innaren , 56.98°N 14.97°E, 175 m a.s.l., +6 °C m.a.t., 21.v.1947, leg. L. Brundin ; 1 adult male ( NHRS), Lake Flarken, north of Kvarnemon , 58.56°N 13.67°E, 129 m a.s.l., +6 °C m.a.t., 1.vi.1981, leg. Y. Brodin ; 1 adult male ( NHRS), Lake Vänern, Mariestadsfjärden Bay , 58.70°N 13.77°E, 43 m a.s.l., +6 °C m.a.t., 7‒9.v.1987, leg. Y. Brodin ; 1 adult male ( NHRS), Lake Vänern, Kinneviken Bay, Truveholm , 58.50°N 13.26°E, 44 m a.s.l., +7 °C m.a.t., 21.v.1987, leg. Y. Brodin and U. Häll ; 2 adult males ( NHRS), Lake Yngern , 59.14°N 17.44°E, 41 m a.s.l., +6 °C m.a.t., 12.v.1991, leg. T. Sandberg ; 4 adult males ( NHRS), Lake Voutner , 65.65°N 19.70°E, 351 m a.s.l., +1 °C m.a.t., 1.viii.1992, leg. Y. Brodin and K. Murray ; 1 adult male ( NHRS), Kåbdalis, Kåbdalisjaure , 66.14°N 19.99°E, 330 m a.s.l., 0 °C m.a.t., vii.1993, leg. B. Viklund ; 1 adult male ( NHRS), Laggarbo wetland, west of Österfärnebo , 60.27°N 16.79°E, 62 m a.s.l., +5 °C m.a.t., 20.vi‒5.vii.2002, leg. T. Persson Vinnersten ; 2 adult males ( NHRS), Baltic Sea, Askö island, Askötorp , 58.80°N 17.67°E, 6 m a.s.l., +6 °C m.a.t., 31.v‒16.vi.2011, leg. B.E. Bengtsson. — UNITED STATES, 2 adult males (as P. culiciformis, ANSP ), Lake Lacawac , 41.38°N 75.29°W, 439 m a.s.l., +8 °C m.a.t., 7.viii.1963, leg. S.S. Roback.

Diagnostic characters. Figs. 19 , 35 , 92‒94 , key couplet 18. P. longistilus has a long gonostylus process with a GspR that overlaps that of nine other species of Procladius in Europe. Of these, P. culiciformis , P. lugubris , P. ferrugineus , P. crassinervis and P. fimbriatus are distinctly distinguished from P. longistilus by more than one other morphological character in the key and the helpdesk.

The GspR of P. longistilus considerably overlaps that of P. tenebricosus (0.25‒0.34 versus 0.23‒0.29). If overlapping, P. longistilus can be separated from P. tenebricosus by the less dark marked wing (anal cell patch absent to faint versus distinct to very distinct) and mostly larger size (wing length 2.4‒3.5 mm versus 1.8‒2.6 mm, mid leg tibia length 1.1‒1.5 mm versus 0.7‒1.1 mm, body length 4.2‒5.7 mm versus 3.2‒4.3 mm).

The GspR of P. longistilus considerably overlaps that of P. pruinosus (0.25‒0.34 versus 0.23‒0.30). P. longistilus can usually be separated from P. pruinosus by the ratio between the length of the outer phallapodeme section divided by the length of the sternapodeme (0.34‒0.46 versus 0.27‒0.36). The length of the outer phallapodeme is however frequently difficult to measure accurately and requires good slide preparation. In addition, the on average narrower gonostylus and gonostylus process of P. longistilus than that of P. pruinosus (GsmR 5.5‒6.9 versus 5.2‒ 6.3, gonostylus process length/width 1.3‒1.9 versus 1.2‒1.7) can be useful for species separation.

The GspR of P. longistilus completely overlaps that of P. frigidus (0.25‒0.34 versus 0.25‒0.33). P. longistilus can be separated from P. frigidus by combining measurements of other characters, particularly the number of median anepisternal setae (0‒6 versus 5‒26), antenna AR (1.8‒2.3 versus 2.2‒2.8) and the length of palpomere five divided with its width (9.1‒11.5 versus 8.0‒9.3).

The GspR of P. longistilus considerably overlaps that of P. floralis (0.25‒0.34 versus 0.28‒0.37). If overlapping, P. longistilus can usually be separated from P. floralis by the less marked gonostylus process divergence (5‒30° versus 30‒50°) and mostly longer body (4.3‒5.7 versus 3.6‒4.4 mm).

The pupa and larva, but not the adult female, have been described. Barcodes of adult males, adult females, pupa and larvae are available.

Geographical distribution and ecology. P. longistilus has been recorded from sites with mean annual temperature difference as much as 23 °C, ranging from about +14 °C in China to about ‒9 °C in Baffin Island in Canada. In Europe the temperature span is less extensive, ranging from +13 °C in Spain to ‒2 °C in northern Sweden.

The geographical extension of P. longistilus is also wide with findings in Europe from latitude 42°N in the island Corsica of France to 70°N in the northern mainland of Norway. Records in North America are from 41°N in the United States to 68°N in Canada, and in China from 25°N to 49°N.

P. longistilus has been reported to be present at altitudes from 5 m near the coast of the Baltic Sea in Sweden and up to 2 200 m in the Alps and Pyrenees of France. The species has also been found above 2 000 m in Tibet, China.

Almost all the 82 quality assured findings of P. longistilus are from lakes, including some defined as polyhumic with water transparency less than one and a half m. It has also been reported from lake-like reservoirs, ponds, temporarily inundated meadows and slow flowing small rivers. The lakes are mostly oligotrophic to mesotrophic, but some are ultraoligotrophic or eutrophic. Studies have shown that the larvae of P. longistilus may decrease substantially in actual and relative numbers in reservoirs experiencing eutrophication and oxygen deficiency due to human activity. Larvae are known from 1 to 4 m water depth in the littoral, e.g. with plants such as Cladophora , and down to 5 m in the profundal. One study noted that the larvae of P. longistilus feed on other small Chironomidae . Adults can be important food items of bats and songbirds such as the pied flycatcher ( Ficedula hypoleuca ). Adults have been found from early May to late September.

Countries with records of P. longistilus in Europe are Czechia, Finland, France, Germany, Italy, Lithuania, Netherlands, Norway, Poland, Russia, Slovakia, Spain and Sweden. There are also records from Canada, China, Greenland, Japan, Russia (Asia) and the United States including Alaska.

References. Anikina 2009b; Bowser & Bowser 2020; Brundin 1949; Goetghebuer 1927; Goetghebuer & Lenz 1936a; Goetghebuer & Lenz 1936b; Han et al. 2023; Ivanova & Alimov 1973; Kieffer 1918a; Kieffer 1924; Laville 1971; Lundström et al. 2010; Mossberg & Nyberg 1979; Paasivirta 2012; Ratnasingham et al. 2024; Roback 1980; Saether 2010; Sandberg 1969; Thienemann & Kieffer 1916; Verkuil et al. 2022; Vesterinen et al. 2018.

Figures

FIGURES 18‒19. Fig. 18: Dorsal view of left gonostylus of Procladius choreus, male from Romania, with characters used for calculation of GspR and GsmR indicated, cf. Table 2 G18, G22‒G23, G27‒G32. Fig. 19: Schematic oblique side view of left gonostylus of Procladius longistilus (left) and Procladius crassinervis (right) indicating upward oriented gonostylus process, cf. Table 2 G33.

FIGURES 32‒35. Male genitalia of Procladius species. Fig. 32: P. frigidus from Norway. Fig. 33: P. floralis from Czechia. 34: P. tenebricosus from Norway. 35: P. longistilus from Russia.

FIGURES 92‒94. Male genitalia left gonostylus of Procladius longistilus. Fig. 92: Norway. Fig. 93: Finland. Fig. 94: Germany.