Key to the species of Japanese Megaphthalmoides (male and females)

1. Large-sized, 7.8–10.0 mm in body length; postpedicel wholly yellow; arista plumose (Fig. 30)........ M. japonicus Ozerov

- Medium-sized, 5.0–6.0 mm in body length; postpedicel wholly or partly black; arista short-haired..................... 2

2. Frontal vitta with a distinct black pattern (Fig. 39); postpedicel wholly black (Fig. 40)................ M. vittatus sp. nov.

- Frontal vitta wholly yellow without a black pattern; postpedicel black in distal two-thirds and yellow in basal one-third (Fig. 34)............................................................................ M. unilineatus Zetterstedt