Miridiba, Reitter, 1902

Pham, Phu Van, Keith, Denis, Pham, Nhi Thi & Cao, Nga Quynh Thi, 2022, Threenew species ofthe genus MiridibaReitter, 1902 (Scarabaeidae: Melolonthinae) from Vietnam along with a new country record, Zootaxa 5205 (4), pp. 331-342 : 341

Key to Vietnamese species of Miridiba .

Based on the key of Gao & Coca-Abia (2021), modified and updated

1. Antennae 9-segmented................................................................................ 2

- Antennae 10-segmented................................................................................ 9

2. At least some part of dorsum (head, pronotum or elytra) with pubescence......................................... 3

- Dorsum glabrous, at most, with tiny setae in each puncture, hardly visible even at high magnification.................. 5

3. Pronotum with pubescence conspicuously arranged in a longitudinal tuft in the centre of the surface. Head and elytra glabrous.................................................................................. M. sus (Moser, 1912)

- Dorsal pubescence present on whole dorsum (head, pronotum and elytra)........................................ 4

4. Pronotum with anterior margin moderately concave at lateral ends...... M. apicespinosa P.V. Pham & Keith , new species

- Pronotal anterior margin without concavities at lateral ends.............................. M. pilosella (Moser, 1908)

5. Frontal carina moderately developed..................................................................... 6

- Frontal carina sharp and strongly developed................................................................ 7

6. Posterior pronotal margin pubescent, clypeo-frontal suture not visible, antenna club almost equal length of antennomeres 2–6 combined...................................................................... M. hanoiensis Keith, 2006

- Posterior pronotal margin glabrous, clypeo-frontal suture visible, antenna club longer than length of antennomeres 2–6 combined................................................. M. quangnamensis P.V. Pham & Keith , new species

7. Pronotum with anterior margin pubescent....................................... M. tuberculipennis (Moser, 1913)

- Pronotum with anterior margin glabrous................................................................... 8

8. Metatibia with interrupted transverse carina........................................ M. ciliatipennis (Moser, 1913)

- Metatibia with complete transverse carina...................................... M. bannaensis Gao & Fang, 2018

9. Pronotal surface scattered punctate (distance between punctures greater than diameter of a single puncture)............. 10

- Pronotal surface densely punctate (distance between punctures equal or smaller than diameter of a single puncture)....... 11

10. Sutural costae of elytra developed; each elytron with 4 longitudinal flat stripes............. M. longiuscula (Moser, 1909)

- Sutural costae of elytra developed....................................................................... 12

11. Pronotal surface irregularly and coarsely punctate.................................. M. schoolmeestersi Keith, 2010

- Pronotal surface regularly punctate................................................... M. scutata (Reitter, 1902)

12. Meso-and metatibia without spines on inner margin of dorsal surface....................... M. longula (Moser, 1912)

- Meso- and metatibia with spines developed to a greater or lesser extent on inner margin of dorsal surface.............. 13

13. Parameres shorter, stout, and with several banches, the dorsal branches asymmetrical.......... M. enigmatica Keith, 2020

- Parameres longer, more or less slender, and with two symmetrical branches (dorsal and ventral branches).............. 14

14. Parameres with dorsal and ventral branches separated in lateral view........................................... 15

- Parameres with dorsal and ventral branches completely or partially fused by a membrane in lateral view............... 16

15. Parameres with flat collum ..................................................... M. lamellata Gao & Fang, 2019

- Parameres without collum....................................................... M. saigonensis (Moser, 1912)

16. Pronotal posterior margin pubescent in front of scutellum.............................. M. quasisinensis Keith, 2020

- Pronotal posterior margin glabrous...................................................................... 17

17. Parameres with dorsal and ventral branches only partially fused by a membrane in lateral view... M. axanensis Keith, 2020

- Parameres with dorsal and ventral branches completely fused in lateral view...................................... 8

18. Tip of parameres moderately or profusely elongated........................................................ 19

- Tip of parameres not elongated.......................................................................... 20

19. Tip of parameres moderately elongated, branches with two lobes in dorsal view ............. .. M. sinensoides Keith, 2020

- Tip of parameres profusely elongated, branches with one lobe in dorsal view............... M. parasinensis Keith, 2020

20. Parameres with angulation on interior margin in dorsal view, C-shape in lateral view............ M. sinensis (Hope, 1842)

- Parameres without angulation on interior margin in dorsal view, ½ C-shape in lateral view...................................................................................... M. ngoclinhensis P.V. Pham & Keith , new species