Megalotomus (Fieber, 1860)

Yi, Wenbo, Wang, Shijun, Zhang, Hufang & Bu, Wenjun, 2022, Notes on Megalotomus Fieber, 1860 in the Palaearctic Region (Hemiptera, Heteroptera, Alydidae), Zootaxa 5128 (2), pp. 211-224 : 220-221

Key to the species of Megalotomus occurring in the Palaearctic region

1. Small sized, usually not surpassing 12.0 mm in length; pronotum with a conspicuous triangular or cuneiform dark black hairless region................................................................ M. angulus ( Hsiao, 1965) comb. nov.

- Moderate or large sized, usually surpassing 12.0 mm in length; pronotum normal, without any black hairless region...... 2

2. Body almost entirely black, with vertex and pronotum consistent black........................................... 3

- Body yellowish brown or reddish brown, vertex or pronotum brownish, never entirely dark black...................... 4

3. In male genital capsule, surcapsular spine with narrow and straight spike arising in middle, paramere split into two lobes at apex............................................................................... M. costalis Stål, 1873

- Surcapsular spine with small and broad projection close to the proximal part, paramere with two pointed apices at the terminal part, not divided into lobes......................................................... M. junceus ( Scopoli, 1763)

4. Body size large, over 15.0 mm in length; anterior lobe of pronotum black and posterior lobe reddish brown; posterior angle of pronotum acute and pointed, with a sharp apex......................................... M. castaneus Reuter, 1888

- Body size moderate, less than 15.0 mm in length; pronotum uniformly brownish; posterior angle of pronotum upturned but not acute............................................................................................... 5

5. All femora reddish yellow, with dense red speckles..................................... M. zaitzevi Kerzhner, 1972

- Femora brownish, with black punctures.................................................................... 6

6. Conspicuous, light-coloured spot on forewing, shaped somewhat like a split arrow; paramere expanded apically, with 5–8 projections around apex............................................................... M. ornaticeps ( Stål, 1858)

- Light-coloured spot small and inconspicuous, parameres tapering towards apex, without apical projections........................................................................................... M. acutulus Liu & Liu, 1998