Microplinthus, Zherichin, 1987

Meregalli, Massimo, 2020, Revision of the Nepalese genus Microplinthus Zherichin, 1987 (Coleoptera: Curculionidae: Molytinae), with description of 25 new species, Zootaxa 4794 (1), pp. 1-63 : 52-54

Key to the species of Microplinthus

In order to accommodate a few cases of doubt or difficult recognition of a character, some species appear at more than one place in the key.

1. Claws simple........................................................................................ 2

- Claws with an inner tooth, sometimes very small, microscopic................................................ 19

2. Elytra with humps or tubercles on intervals................................................................. 3

- Elytra lacking humps or tubercles, intervals more or less convex, but smooth..................................... 15

3. Pronotum lacking a median keel......................................................................... 4

- Pronotum with at least a trace of a median keel visible in anterior half........................................... 5

4. Larger (body length 3.9–4.3 mm.). Pronotum as long as wide, densely punctured, matt, sides broadened to apical third, anterior margin of pronotum in lateral view not prominent on the head. Kathmandu, Phulchowki......... M. phulchowkianus n. sp.

- Smaller (body length 2.9–3.0 mm). Pronotum subcylindrical, glossy, sparsely punctured, sides scarcely broadened, anterior margin of pronotum in lateral view prominent on the head. Western Nepal, Pokhara............... M. wolfgangi Meregalli

5. Elytral punctures irregularly impressed.................................................................... 6

- Elytral punctures regularly impressed, intervals linear, continuous............................................... 8

6. Rostrum not thickened basad, regularly curved in lateral view; elytra oval, sides moderately curvilinear; pronotum as long as wide, apex of penis rounded. Body length 3.6 mm. Pokhara, Pothani............................... M. kaskianus n. sp.

- Rostrum strongly thickened basad and sharply curved downwards; elytra oblong, sides subparallel; pronotum longer than wide; apex of penis slightly prominent medially.................................................................. 7

7. Setae on tibia perpendicularly erect. Body length 2.9–3.5 mm. Northern India (Sikkim, Darjeeling)... M. bhaktai (Meregalli)

- Setae on tibia recumbent against integument. Body length 4–4.5 mm. Eastern Nepal, Northern India (Darjeeling).......................................................................................... M. ausobskyi (Zherichin)

8. Elytral setae spatulate, as long as wide, generally recumbent................................................... 9

- Elytral setae slender, much longer than wide, not spatulate, erect............................................... 10

9. Rostrum slender, ratio l/w ca. 3, with large round punctures; pronotum with small punctures, interspaces as wide as punctures. Body length 4.4–4.6 mm. Pokhara, Kali-Gandakhi valley........................................ M. letheensis n. sp.

- Rostrum short, ratio l/w ca. 2.5, punctures small, separated by raised glossy longitudinal lines; pronotum with dense large punctures, interspaces much smaller than punctures, linear. Body length 3.6 mm. Kathmandu, Phulchowki. M. godawaricus n. sp.

10. Elytra oval, convex, pronotum subquadrate, finely and regularly densely punctured, sides slightly linearly broadened to apical quarter. Body length 4.35 mm. Northern India (Darjeeling)...................................... M. shiva Meregalli

- Elytra oblong, scarcely convex, pronotum subrectangular, variously sculptured, sides subparallel..................... 11

11. Setae on elytra broadened apicad, shorter than one interval width, recumbent on integument......................... 12

- Setae on elytra slender, barely broadened apicad, as long as one interval width.................................... 13

12. Smaller (body length 3.8–4.2 mm.), rostrum short, ratio l/w <3; funicle antennomere 1 globose, 2 as long as wide; pronotum as long as wide. Northern India (Darjeeling)................................................. M. laurae Meregalli

- Larger (body length 5 mm); rostrum slender, ratio l/w ca. 3.5, first 2 funicle antennomeres distinctly longer than wide; pronotum longer than wide. Eastern Nepal, Ilam District........................................... M. maior (Zherichin)

13. Rostrum thick in lateral view, ratio of thickness from dorsum to upper margin of scrobe / rostrum thickness 0.77. Body length 4.8 mm. Central Nepal, Gamesh Himal....................................................... M. ganesha n. sp.

- Rostrum slender in lateral view, ratio of thickness from dorsum to upper margin of scrobe / rostrum thickness <0.60..... 14

14. Female sternum VIII with very short branches; elytra with setae limited to odd intervals and grouped in tufts on humps; femur with a minute internal tooth. Body length 4.9–5.1 mm. Eastern Nepal, Taplejung District.......... M. morimotoi Zherichin

- Female sternum VIII with very long branches; elytra with some setae present also on even intervals, setae evenly placed, not grouped in tufts on humps; femur with a sharp tooth. Body length 4.6 mm. Western Nepal, Manaslu Himal..................................................................................................... M. schmidti n. sp.

15. Basal half of rostrum glossy red, thickened in lateral view, with small and shallow punctures. Body length 3 mm. Eastern Nepal, Ilam District......................................................................... M. minor (Zherichin)

- Basal half of rostrum brown or dark ferruginous, matt, not or moderately thickened in lateral view, with dense punctures and longitudinal lines.................................................................................... 16

16. Funicle antennomeres 1 and 2 very short, globose or conical, not longer than wide................................. 17

- Funicle antennomeres 1 and 2 longer than wide, conical...................................................... 18

17. Pronotum with a distinct median line in anterior part. Body length 3.1–3.3 mm. Central Nepal, Bagmati District ............................................................................................. M. helambuensis n. sp.

- Pronotum lacking a distinct median line in anterior part. Body length 2.9 mm. Western Nepal, Kaski District................................................................................................ M. minimus Zherichin

18. Sides of pronotum broadened towards apical third, constricted at apex. Body length 4.2 mm. Western Nepal, Gorkha District.................................................................................. M. setulosus Zherichin

- Sides of pronotum subparallel, moderately converging at apex. Body length 3.7 mm. Western Nepal, Dhawalagiri District ................................................................................... M. kaligandaki Meregalli

19. Rostrum strongly curved downwards; anterior margin of pronotum in lateral view strongly prominent above head........ 20

- Rostrum moderately curved downwards; anterior margin of pronotum in lateral view linear or only weakly prominent above head............................................................................................... 29

20. Pronotum with a distinct median line at least in anterior half.................................................. 21

- Pronotum lacking a median line......................................................................... 25

21. Tibia with long, erect setae............................................................................. 22

- Tibia with setae curved or recumbent against integument..................................................... 23

22. Funicle antennomeres 1 and 2 very short, not longer than wide; inner teeth of claws minute. Body length 2.9–3.5 mm. Northern India (Sikkim, Darjeeling)............................................................. M. bhaktai (Meregalli)

- Funicle antennomeres 1 and 2 slender, longer than wide; inner teeth of claws strongly developed. Body length 3.9 mm. Eastern Nepal, Koshi Province .................................................................. M. koshianus n. sp.

23. Elytra oval, ratio length/width 1.3. Body length 4.2 mm. Eastern Nepal, Solokhumbu District................ M. yeti n. sp.

- Elytra elongate, ratio length/width 1.7–1.8................................................................ 24

24. Smaller (body length 3.2 mm), odd intervals lacking raised humps. Eastern Nepal, Lamjura District.... M. leptus (Meregalli)

- Larger (body length 4.0– 4.5 mm), odd intervals with humps. Northern India (Sikkim, Darjeeling)... M. roggeroi (Meregalli)

25. Inner teeth of claws indistinct, only visible as a tiny inner spine. Body length 2.9–3.0 mm. Western Nepal, Pokhara......................................................................................... M. wolfgangi Meregalli

- Inner teeth of claws fully developed, clearly visible......................................................... 26

26. Larger (body length 5.4–6.2 mm); elytral tubercles very high, prominent, densely covered with yellow setae appressed to in- tegument; eye large, with more than 50 ommatidia. China, Mt. Emei...................... M. phoenicopterus (Meregalli)

- Smaller (body length <5 mm); elytral tubercles moderately raised, not more densely covered with yellow setae; eye small, with less than 50 ommatidia................................................................................ 27

27. Rostrum in lateral view strongly thickened at base, tapering to apex. Body length 3.4–4.3 mm. China, Mt. Emei........................................................................................ M. emeishanicus (Meregalli)

- Rostrum in lateral view of uniform thickness from base to apex................................................ 28

28. Pronotum sparsely and shallowly sculptured, punctures individually impressed, interspaces almost flat. Body length 4.3 mm. Kathmandu, Phulchowki............................................................... M. newarorum n. sp.

- Pronotum densely and deeply sculptured, punctures not clearly distinct, merged in groups, interspaces raised, convex. Body length 4.9–5.8 mm. Eastern Nepal, Khandbari District............................................ M. sherpa n. sp.

29. Pronotum lacking a clearly delimited median line or keel..................................................... 30

- Pronotum with a more or less raised, but clearly delimited, median line......................................... 32

30. Elytral intervals convex, lacking clearly differentiated humps, excepting at apex of intervals 3 and 5; elytra slender, blackish, almost glossy, pronotum with large isolated punctures....................................................... 31

- Elytral intervals with clearly differentiated humps along most of length; elytra oblong, brownish, matt................. 28

31. Elytra oblong, ratio l/w 1.7; punctures on pronotum deep, isolated, interspaces as wide as punctures. Body length 3.6 mm. Western Nepal, W Pokhara.................................................................. M. jaegeri n. sp.

- Elytra elliptical, ratio l/w 1.9; punctures on pronotum shallowly impressed, dense, confused. Body length 4.4 mm. Western Nepal, Manaslu Himal................................................................. M. longipennis n. sp.

32. Elytra oval, much broader than pronotum, ratio l/w <1.15–1.35................................................ 33

- Elytra oblong, scarcely broader than pronotum, ratio l/w>1.45................................................ 37

33. Elytra shortly oval, ratio length/width 1.15; elytral intervals densely rugose, striae deep, punctures not distinct, almost furrows- like, with a series of glossy small granules. Body length 4 mm. Eastern Nepal, Solukhumbu............. M. rugosus n. sp. - Elytra oval, ratio length/width 1.30–1.35; elytral intervals not rugose, striae with punctures distinct................... 34

34. Elytra with smooth and matt integument, punctures on striae small, evenly spaced, very regular, intervals smooth, with small low humps, and relatively short setae inserted in a single row. Body length 5.2 mm. Mid-western Nepal, Karnali Province ...................................................................................... M. karnalicus n. sp.

- Elytra with sculpture irregular, integument slightly glossy, surface of intervals not smooth and regular, setae often on groups .................................................................................................. 35

35. Rostrum strongly curved, particularly in basal part. Body length 3.5–3.7 mm. Eastern Nepal, Panchtar district................................................................................................... M. messneri n. sp

- Rostrum weakly curved, almost straight in basal part........................................................ 36

36. Inner teeth of claws small, broadly triangular; ventrites 1 and 2 smooth, unpunctured except near sides. Body length 3 mm. Western Nepal, Manaslu Himal.......................................................... M. brevipennis n. sp.

- Inner teeth of claws robust, sharply acute; ventrites 1 and 2 deeply and densely punctured. Body length 4.0– 4.5 mm. Eastern Nepal. Khandbari District................................................................. M. arunensis n. sp.

37. Elytra with raised tubercles............................................................................ 38

- Elytra lacking tubercles, at most with low humps on declivity................................................. 41

38. Pronotum with punctures regularly and individually impressed................................................ 39

- Pronotum with punctures densely and confusedly impressed, not individually delimited, interspaces of punctures narrowly and linearly raised....................................................................................... 40

39. Punctures on pronotum dense, reticulate, interspaces between punctures linear, smaller than punctures. Body length 4.4 mm. Central Nepal, Helambu Himal............................................................... M. gupta n. sp.

- Punctures on pronotum sparse, interspaces between punctures broad, flat, as wide as punctures. Body length 3.1–3.7 mm. West- ern Nepal, Kali-Gandakhi valley.............................................................. M. franzi n. sp.

40. Pronotum as long as wide, glossy, base truncate. Body length 3.5 mm. Western Nepal, Ghorepani........... M. durga n. sp.

- Pronotum longer than wide, moderately glossy, base slightly angularly prominent towards elytra at middle. Body length 3.8–4.3 mm. Central Nepal, Janakpur Province ....................................................... M. tamanus n. sp.

41. Pronotum with very shallow punctures, poorly delimited, spaced, integument completely matt. Body length 4.1 mm. Mid-west- ern Nepal, Karnali District ............................................................... M. kaumarya n. sp.

- Pronotum with dense punctures, deeply impressed, well delimited, integument slightly glossy....................... 42

42. Elytra with sparse setae, recumbent against integument, scarcely visible. Body length 4.4–4.7 mm. Eastern Nepal, Khandbari District.......................................................................... M. khandbariensis n. sp.

- Elytra with raised, erect setae, clearly distinct.............................................................. 43

43. Pronotum with dense and deep sculpture, punctures merged in irregular rows; penis with narrow apex. Body length 3.8–3.9 mm. Western Nepal, N Pokhara.......................................................... M. annapurnae n. sp.

- Pronotum with clearly delimited punctures, reticulate........................................................ 44

44. Larger (body length 5 mm); apex of pronotum, in lateral view, with ocular lobes weakly developed but present; female sternum VIII with long arms and branches, X-shaped. Western Nepal............................... M. schawalleri (Zherichin)

- Smaller (body length 4.1-4.3 mm); apex of pronotum, in lateral view, straight, lacking ocular lobes; female sternum VIII with short branches, laterally directed. Western Nepal, Parbat District............................. M. parbatensis Meregalli