Holarctic Chironomus (s.l.) - Einfeldia pagana larva

Species 2k. Einfeldia pagana (Meigen, 1838)

Originally Chironomus paganus
Syn: Einfeldia synchrona Oliver 1971 (Oliver et al. 1990)

Adult of North American specimens described by Townes (1945) as Tendipes (Einfeldia) paganus, and by Oliver (1971) as E. synchrona.

Male: Wing length 2.4 - 3.8 mm; VR 1.02 - 1.09; LR 1.45; AR 2.67 - 3.06; frontal tubercles variable in size,
fore tarsus with a rather short beard.
Light pea green, with thoracic markings, etc. ochraceous but occasionally brown or black; legs green, brown towards their apices.
The inflated style abruptly constricted near the apex and the broad anal point are distinctive.
Head: Frontal tubercles variable in size depending on locality, with those from British Columbia about 3 times the length of those from Ontario (Sublette, unpubl. data); with a seta approx. 4 times the length of the smaller tubercle. Clypeus with 18 - 30 setae.

Frontal tubercles of E. pagana from Ontario (left) and British Columbia (right).

Palp segment lengths (2-5) (µm) 50-80 : 190-300 : 130-220 : 200-280.
Thoracic setae: Acrostichals 5 - 11; Dorsocentrals 12 - 28, uni - to biserial; Prealars 5 - 6; Prescutella 1;
Scutellar 7 - 13, uniserial laterally to multiserial medially. Scutellum with a small central hump.
Legs with sparse beard, BR 3 - 5. Front LR 1.39 - 1.56; Mid LR 0.55 - 0.62; Hind L.R. 0.61 - 0.67.
First tarsal segment of mid and hind legs with row of apically curved setae on anterior margin.

Female: As male, but the thoracic markings, etc., are never darker than pale brown.
Antennal flagellum 5-segmented, segment lengths (µm) 140-169 : 101-112 : 112-120 : 101-112 : 198-234.
Head: Clypeus with 6 - 24 setae. Palp segments 2-5 (µm) 50-60 : 150-210 : 150-180 : 220-300.
Thoracic setae: Acrostichals 7 - 8; Dorsocentrals 16 - 21; Prealars 5 - 6; Scutellar 12 - 14.
Wing length 2.6 - 3.0; VR 1.10 - 1.18.
Legs Front LR 1.66 - 1.79; Mid LR 0.50 - 0.54; Hind L.R. 0.57 - 0.62.
Genitilia: Cercus quadrate.

Larva not a Chironomus type but small (11.8 - 12.7 mm; 2 males) with only one pair of short ventral tubules (abt 0.56 - 0.66mm) and no postero-lateral tubules.  Anal tubules about 300 µm long and 2.5-3 times longer than wide (ventral pair may be thicker).
Gula and frontal apotome pale, just slight darkening of the posterior margin.  Frontal sclerite with a large indistinct oval pit with a large rugose area anterior to it.
Mentum with pointed teeth apart from central tooth which may be worn in the available specimen, c2 teeth little more than notches (type I); 4th laterals in line with other lateral teeth (type I).
Ventromentum with a sharply downturned inner edge and a wavy anterior margin.  Pecten epipharyngis with about 12 rather irregular teeth.
Premandible with two teeth of about equal lengthBasal segment of antenna relatively short (AR = 0.8) about 3.3x as long as wide; A3 relatively long, A4/A3 about 0.8.
Mandible with pigmented and clearly separated third inner tooth.

Cytology: 4 polytene chromosomes with no obvious indication of Keyl pattern.
Chromosome 4 with a terminal nucleolus which pairs, otherwise unpaired. A smaller nucleolus is sometimes developed close to the centromere of one of the long chromosomes. However a visible nucleolar envelope is only visible in some cells, sometimes very large and fused between the two nucleoli. Centromeres heterochromatic.

Found: British Columbia - (Sublette, unpubl.).
Manitoba - Lake Winnipeg (Sæther 2012)
Ontario - White Lake, Three Mile Bay (48.70; -85.75); Ottawa (45.40; -75.87), and South March (Type locality E. synchrona) (44.88; -85.75), Carleton Co. .
Idaho - Cataldo (Townes 1945).
Michigan - Isabella Co. (Townes 1945).
New York - Canadaroago Lake; Milford Center; Otsego Lake (Townes 1945).
Ohio - (Bolton 2012)
South Dakota - Waubay (Townes 1945).

Also found in the Palearctic (Belgium - region of Liége; Type locality). and claimed to occur in Asia, at least in Japan.

Recorded from shallow eutrophic pools.

DNA analyses:
MtCOI barcode sequence is available from larvae from White Lake, Ontario. This sequence has 99% or better similarity to a large number of sequences in GenBank which are only identified as Einfeldia sp. or Chironomidae sp.

The difference in adult cephalic tubercles reported by Sublette (see above) could indicate the presence of different species under this name in the east and west of North America. The specimens of Curry (quoted in Oliver 1971) with scale like teeth is Einfeldia species A of Epler (2001) (see species 5b). The adult and pupa of this species are presumably similar to E. pagana, as Epler notes that J. E. Sublette identified an an adult and pupa of species A as E. pagana.
Larval description recorded in Oliver (1971), largely as the synonym E. synchrona.

See also E. species 2y, E. species A (Epler 2001), B. bruneipennis.

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