Malcus

Wang, Shujing & Bu, Wenjun, 2020, A key to species of genus Malcus Stål, with descriptions of four new species from China (Hemiptera: Heteroptera: Malcidae), Zootaxa 4759 (1), pp. 31-48 : 32-33

Key to the species of Malcus

1. Head and pronotum without any erect hair................................................................. 2

- Head and pronotum with erect hair, erect hairs always clearly visible in lateral view............................... 11

2. Pronotum with distinct posterolateral tubercles.............................................................. 3

- Pronotum only slightly protruding posterolaterally but not form as distinct tubercles............................... 10

3. Pronotum with distinct posteromedial tubercle.............................................................. 4

- Pronotum without posteromedial tubercle, or only slightly protruding posterolaterally but not forming as tubercle................................................................................ Malcus gibbus Zheng, Zou & Hsiao

4. Body dark brown and small (<4.6mm); abdominal laterotergite VII triangular or trapezoidal.......................... 5

- Body black and large (> 4.6mm); abdominal laterotergite VII large and rounded.................................... 9

5. Posterolateral tubercle of pronotum elevated strongly........................ Malcus noduliferus Zheng, Zou & Hsiao

- Posterolateral tubercles of pronotum elevated relatively weakly................................................. 6

6. Pygophore with 2 divergent fork-like parandria ( Fig. 27 ), outline of posteromedial tubercle in frontal view elevated relatively weekly.............................................................................................. 7

- Pygophore without 2 divergent fork-like parandria, ouline of posteromedial tubercle in frontal view elevated strongly...... 8

7. Protonum dark brown with obviously contrasting black callar region and black median.......... Malcus bacillus sp. nov.

- Protonum (except collum and posterior margin) black, with a shallowly grooved mid-line............. Malcus similis Štys

8. Posteromedial tubercle of pronotum elevated strongly, outline obtuse in frontal view; 7 th ventrite of male without processes................................................................................. Malcus tuberculatus Štys

- Posteromedial tubercle of pronotum relatively weakly, outline cuspidal in frontal view; 7 th ventrite of male with processes.................................................................. Malcus subauriculatus Zheng, Zou & Hsiao

9. Body smaller (<4.7mm); posterolateral tubercles more prominent; 1st antennal segment much shorter (ratio of length of body: first segment=10.17)........................................................... Malcus vasarhelyii Kondorosy

- Body larger (> 5mm); posterolateral tubercles not prominent in the posterior pronotal outline; 1st antennal segment longer (ratio of length of body: first segment about 9.2)................................ Malcus japonicus Ishihara & Hasegawa

10. Pygophore with lob-like parandria ( Fig. 29 )............................................. Malcus auriculatus Štys

- Pygophore with 2 divergent fork-like parandria, long and thick................................. Malcus furcatus Štys

11. Pronotum with distinct big posterolateral tubercles.......................................................... 12

- Pronotum without distinct posterolateral tubercles.......................................................... 17

12. Abdominal laterotergites all narrow, laterotergite V and laterotergite VI nearly invisible............................. 13

- Abdominal laterotergites not narrow, all abdominal laterotergites easily visible................................... 14

13. 1st antennal segment outside with distinct small tubercles, in callar region of pronotum near median with a pair of small spines....................................................................... Malcus spinosus Kondorosy

- 1st antennal segment outside without any tubercles, in callar region of pronotum near median without any spines............................................................................................ Malcus dentatus Štys

14. Posterolateral tubercles of pronotum not strongly elevated, anterolateral margin of abdominal laterotergite VI arched in dorsolateral view, abdominal laterotergite VII without distinct notch in the middle........ Malcus elevatus Zheng, Zou & Hsiao

- Posterolateral tubercles of pronotum strongly elevated; abdominal laterotergites VI triangular, abdominal laterotergite VII with a distinct notch in the middle........................................................................... 15

15. Body larger (> 4.5mm); Pronotum distinctly wide (maximal width of pronotum> 1.85mm), lateral margin of posterior pronotal outline sloping under a sharp angle, posterolateral tubercles outline oval in frontal view............................ 16

- Body smaller (3.9–4.15 mm); pronotum relatively narrow (maximal width of pronotum =1.5–1.58), lateral margin of posterior pronotal outline sloping relatively weakly, posterolateral tubercles outline semicircle in frontal view..................................................................................... Malcus denticulatus Zheng, Zou & Hsiao

16. Body pale; pronotum wider (maximal width of pronotum = 2.29 mm)........................... Malcus alatus sp. nov.

- Body dark; pronotum relatively narrow (maximal width of pronotum= 2.10 mm)................. Malcus thoracicus Štys

17. Pronotum flat, slightly declivent, angle with body axis less than 30 degrees...................................... 18

- Pronotum declivent, the angle with body axis more than 30 degrees............................................ 21

18. Abdominal laterotergites V & VI unconspicuous, or only like a tooth........................................... 19

- Abdominal laterotergites V & VI conspicuous.............................................................. 20

19. Body obviously elongate, body length: 4.05–4.49 mm; abdominal laterotergite VII sickle-like...... Malcus elongatus Štys

- Body not elongate, body length: 3.56–3.81mm; abdominal laterotergite VII trapezoidal............ Malcus planus sp. nov.

20. Corium with long erect hairs; erect hairs of 2nd and 3rd antennal segments three times as long as diameter of segments......................................................................................... Malcus setosus Štys

- Corium without long erect hairs; erect hairs of 2nd and 3rd antennal segments twice as long as diameter of segments...................................................................................... Malcus externus sp. nov.

21. 1st antennal segement remarkably thick, especially in males.................................................. 22

- 1st antennal segement not thick......................................................................... 23

22. Abdominal laterotergites narrow; abdominal laterotergite VII flatly arched, with tiny teeth; pygophore with 2 teeth ( Fig. 30 )................................................................................ Malcus inconspicuus Štys

- Abdominal laterotergites not narrow, abdominal laterotergite VII not arch-shaped, with strong teeth; pygophore without any teeth............................................................................ Malcus stysi Kondorosy

23. 2nd antennal segement very short (<0.7mm)................................................. Malcus sinicus Štys

- 2nd antennal segement normal (> 0.7mm)................................................................. 24

24. Abdominal laterotergites not narrow..................................................................... 25

- Abdominal laterotergites narrow........................................................................ 32

25. Abdominal laterotergite VII arch-shaped.................................................................. 26

- Abdominal laterotergite VII not arch-shaped............................................................... 28

26. Membrane not elongate (length of membrane: length of body =0.49–0.5); posterior margin of abdominal laterotergite VII with teeth.............................................................................................. 27

- Membrane distinctly elongate (length of membrane: length of body =0.52); posterior margin of abdominal laterotergite VII straight without teeth.................................................................. Malcus mishimi Štys

27. Body large (4.5–4.6 mm); margin of abdominal laterotergite VII not completely arched, usuaully with notch in the middle......................................................................... Malcus piceus Zheng, Zou & Hsiao

- Body small (4.03–4.3 mm); margin of abdominal laterotergite VII completely arched Malcus arcuatus Zheng, Zou & Hsiao

28. Posterolateral angle of pronotum with markedly 3 big teeth.................................... Malcus indicus Štys

- Posterolateral angle of pronotum without big teeth.......................................................... 29

29. With long erect hairs, erect hairs on head and pronotum distinctly longer than the length of eye...... Malcus insularis Štys

- Erect hairs not long, erect hairs on head and pronotum as long as the length of eye................................. 30

30. All anterior part of pronotum (not including collar) black, formed a distinct transversal black band Malcus nigrofaciatus Štys

- All anterior part of pronotum of the ground color, or only with darkened callar, forming two darkened spots............ 31

31. Body slender and narrow; whole body light yellow-brown..................................... Malcus pallidus Štys

- Body robust and less narrow; brown or dark brown......................................... Malcus flavidipes Stål

32. Membrane distinctly elongate, abdominal laterotergite VII with few teeth....................... Malcus nigrescens Štys

- Membrane not elongate, abdominal laterotergite VII with more densely teeth.................. Malcus idoneus Horváth

Figures

FIGURES 21–30. Malcus spp., pygophore, ventral views: 21 & 25, M. planus sp. nov.; 22 & 26, M. externus sp. nov.; 23 & 27, M. bacillus sp. nov.; 24 & 28, M. gibbus Zheng, Zou & Hsiao; 29, M. auriculatus Štys; 30, M. inconspicuus Štys.