Einfeldia pagana (Meigen, 1838)

The description by Yamamoto (1995) seems to be the best description of Japanese material in English.  Yamamoto refers to a description in Japanese by Sasa (1993).  Some information on the larvae is given Yamamoto et al. (2015), but for the pupa, descriptions of European material must be used.

Adult:

Pupa: The only information for the pupa seems to be that for European specimens (e.g. Langton and Visser 2003) - sex of exuviae not stated but likely includes both males (smaller specimens with larger cephalic tubercles) and females (larger specimens with smaller cephalic tubercles):
Length of exuvia 7.5-9.0 mm.  Cephalic tubercles large, conical, curved, 145-190 µm long and 120-155 µm wide (in males about 3 times longer than width at base; in females about as long as width at base).
Abdomen: Hook row of segment II entire, length of row 0.43-0.52x width of the tergite. Armament of tergites II-IV an undivided, usually extensive patch of strong points, on seg. II extending forward at least as far as setae D1.  The patch on tergite VI is more of less reduced. Lateral tainiae of segments V-VIII: 4,4,4,5.  Comb, or spur, of segment VIII of 4.5 (2-7) small teeth on a short base that does not exceed the margin of the segment.  Fringe of anal lobe with 63-86 taeniae.

Larva: In 2006, Yamamoto published some brief notes on the larva:
One pair of ventral tubules, antepronotum distinctly divided at middle by a conspicuous V-shaped notch, scutal tubercle indistinct, acrostichals normally developed.  In 2015, Yamamoto et al. further noted the large oblong fenestra in the frontoclypeal apotome, a feature noted and illustrated for European specimens by Pinder and Reiss (1983) and S5 setae well anterior to the "ring organ" of the dorsal head; the rugosity anterior to the fenestra has not been confirmed in Asian specimens.
The description of North American specimens gives the coloration of the mentum and frontoclypeus as pale.
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 (A) with a sharply downturned inner edge and a wavy anterior margin. PE (D) with about 12 rather irregular teeth. Premandible (see D) with two teeth of about equal length, inner tooth wider than outer tooth (, below).Antenna (B) with basal segment relatively short, AR = 0.8, about 3.3x as long as wide; A3 relatively long, A4/A3 about 0.8. Mandible (C) with pigmented and clearly separated third inner tooth (type IIIC).  No furrows on outer surface near the base.

Cytology:  No information is available for Japanese populations.

Other descriptions of Einfeldia pagana indicate that it is a paler species, but it appears that Yamamoto is justified in considering this to be a seasonal variation of color – his specimens were collected in May.  However, there is doubt as to whether this material is actually E. pagana, since Yamamoto illustrates the antepronotum to have a distinct V-shaped notch, while the Holarctic keys indicate that the antepronotum is fused.  This, together with the fact that there is no Oriental specimen in the same BOLD Bin as the North American specimens, suggests that this material requires a new name.
The presence of this darker form may help explain why the species is confused with the generally dark Benthalia species.

Found: - a Holarctic species.
            Japan - Yamaguchi, Honshu; Okinawa Island; Kyushu; Lake Hibera, Fukushima;Yoshimi, Shimonoseki (abt 33.9°N, 130.95°E),
            Yamaguchi Pref.
            There appear to be no specimens in the Chironomid DNA Barcode Database (at January 2020)
            Holarctic distribution (Belgium - region of Liége; Type locality).