Procladius simplicistilus Freeman, 1948

Brodin, Yngve, 2025, Procladius (Diptera, Chironomidae) of Europe and a global view, Zootaxa 5591 (1), pp. 1-127 : 83-84

Procladius simplicistilus Freeman, 1948

Procladius simplicistilus Freeman, 1948 — Freeman (1948), England, adult male, description, illustration.

Procladius simplicistilus Freeman, 1948 — Coe (1950), England, adult male, adult female, key, illustration.

Procladius ruris Roback, 1971 var. grandis — Roback (1971), Canada, adult male, key, description, illustrations.

Procladius simplicistilus Freeman, 1948 — Pinder (1978), England, adult male, key, illustrations.

Procladius PE 1— Langton (1991), pupa, key, illustration.

Procladius ruris Roback, 1971 var. grandis — Roback (1980), Canada, adult male, pupa, key, description, photos, illustrations. Procladius simplicistilus Freeman, 1948 — Langton & Visser (2003), pupa, key, illustration.

Procladius simplicistilus Freeman, 1948 — Langton & Pinder (2007), England, adult male, key, illustrations.

Procladius simplicistilus Freeman, 1948 — Langton et al. (2013), pupa, key, illustration.

Procladius simplicistilus Freeman, 1948 — Ratnasingham et al. (2024), Finland and Norway, adult males, adult female, photos. Procladius sp. 1 — Ratnasingham et al. (2024), Slovakia and Canada, adult males, adult females, larvae, photos.

Material examined (n = 18). BELGIUM, 1 adult male (as Procladius sp. , ZSMG), Épioux Reservoir , 49.8°N 5.3°E, 383 m a.s.l., +9 °C m.a.t., v.1964 .— CANADA, 2 adult males (as P. ruris var. grandis, CNCC ), Lake Altin , Altin, 59.35°N 133.42°W, 670 m a.s.l., 0 °C m.a.t., 9.vi.1955, leg. Huckel. — ENGLAND, 1 adult male (Holotype of P. simplicistilus, BMNH ), Hawkshead , Three Dubs Tarn, 54.37°N 2.96°W, 218 m a.s.l., +7 °C m.a.t., 7‒15.v.1947 , leg. T. T. Macan ; 1 adult male (Paratype of P. simplicistilus, BMNH ), Hawkshead , Three Dubs Tarn, 54.37°N 2.96°W, 218 m a.s.l., +7 °C m.a.t., 7‒15.v.1947 , leg. T. T. Macan .— FINLAND, 2 adult males (as Procladius sp. , LMMR), Enontekiö , Lake Toskaljärvi, 69.19°N 21.46°E, 704 m a.s.l., ‒5 °C m.a.t., 4‒15.vii.2010, leg. L. Kakko ; 2 adult males ( 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 CHIFI292-16 and CHIFI293-16 ] .— FRANCE, 3 adult males (as Procladius sp. , 1, LHST), Lake Long , 42.82°N 0.12°E, 2 094 m a.s.l., +3 °C m.a.t., 13.viii.1967, leg. H. Laville. — IRELAND, 2 adult males ( UCDZ), Lake Sillan , 54.01°N 6.92°W, 89 m a.s.l., +9 °C m.a.t., 14.iv.1978, leg. D.A. Murray ; 1 adult male ( NMID), Lake Sandy , 54.35°N 8.17°W, 333 m a.s.l., +8 °C m.a.t., 28.iv.2005, leg. D.A. Murray and J.- R. Baars .— NORWAY, 1 adult male (as Procladius sp. , NHRS), Caerro , Lake Isejavri, 69.67°N 24.21°E, 390 m a.s.l., ‒3 °C m.a.t., 26.vi‒ 30vii.1980, leg. K.J. Loine. — SWEDEN, 1 adult male (as P. sagittalis, NHRS ), Njulja pond, 68.37°N 18.70°E, 995 m a.s.l., ‒5 °C m.a.t., 15.vii.1936, leg. A. Thienemann. — SWITZERLAND, 1 adult male ( MCSN), Lake Leman , 46.37°N 6.27°E, 372 m a.s.l., +10 °C m.a.t., 7.v.2009, leg. B. Lods-Crozet.

Diagnostic characters. Figs. 27 , 68‒70 , key couplet 9. Male P. simplicistilus and P. appropinquatus have an only slightly indicated gonostylus process which separates them from all other European Procladius species with wing macrotrichia.

The gonostylus process of P. simplicistilus is on average somewhat shorter than that of P. appropinquatus (GspR 0.02‒0.06 versus 0.04‒0.10). P. simplicistilus is larger than P. appropinquatus exemplified by wing length (3.7‒4.6 mm versus 2.5‒3.7 mm), body length (6.5‒8.1 mm versus 4.3‒6.0 mm) and gonocoxite width (377‒451 µm versus 282‒350 µm).

The antenna AR-ratio of P. simplicistilus is mostly higher than that of P. appropinquatus (AR 2.5‒3.2 versus 1.8‒2.6). Hairiness is often also useful to distinguish P. simplicistilus from P. appropinquatus (scutellum 74‒117 setae versus 40‒73 setae, wing vein Cu stem 0‒4 setae versus 4‒36 setae).

P. simplicistilus is the largest Procladius known worldwide. The pupal exuvia has been described, but probably not the female and larva. Barcodes of adult males, adult females, and larvae are available.

Geographical distribution and ecology. P. simplicistilus is known from southern France at latitude 43°N to northern Norway at latitude 70°N. The species seems to be rather common in Ireland and Northern Ireland, but otherwise less common or rare. Sites with records cover a mean annual temperature interval from +10 to ‒5 °C, with the coldest conditions in the northern mountains of Finland and Sweden, and globally ‒7 °C in Canada. The species has an altitude range from 5 m to 2 090 m above sea level .

P. simplicistilus has only been reported from lakes and smaller water bodies with standing water such as ponds and gravel pits. Records of up to 1 400 individuals per m 2 are present from 0 to 4 m water depth in the littoral with plants such as Potamogeton , Myriophyllum or Elodea . There are a few records of P. simplicistilus larvae in the profundal, where they have been reported from depths down to 78 m.

Ultraoligotrophic to eutrophic conditions exist in the lakes with findings of P. simplicistilus . The lakes are classified as oligohumic to polyhumic with pH from 5.5 to 8. Food items of the larvae are not known. P. simplicistilus adults fly from mid-April to mid-August.

Countries or autonomous regions with records of P. simplicistilus in Europe are Belgium, Denmark, England, Finland, France, Ireland, Lithuania, Netherlands, Northern Ireland, Norway, Poland, Russia, Scotland, Slovakia, Sweden and Wales. The species has also been recorded from Canada.

References. Anikina 2009b; Charles et al. 1974; Charles et al. 1976; Davids et al. 1980; Freeman 1948; Langton 1991; Langton & Pinder 2007; Langton et al. 2013; Langton & Visser 2003; Laville 1971; Mol 1984; Moubayed-Breil et al. 2019; Murray & Baars 2006; Murray et al. 2018; Paasivirta 2012; Pinder 1978; Ratnasingham et al. 2024; Roback 1971; Roback 1980; Ruse 2013; Shcherbina 1989; Titmus 1979; Tomlin et al. 2024.

Figures

FIGURES 24‒27. Male genitalia of Procladius species. Fig. 24: P. signatus from Sweden. Fig. 25: P. tatrensis from France. Fig. 26: P. simplicistilus from Norway. Fig. 27: P. appropinquatus from Finland.

FIGURES 68‒70. Male genitalia left gonostylus of Procladius appropinquatus. Fig. 68: Finland. Fig. 69: Sweden. Fig. 70: Norway.