Osoriellus

Irmler, Ulrich, 2014, The Neotropical species of the genus Osoriellus FAGEL, 1959 (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 64 (2), pp. 231-354 : 291-294

Key to the species of the Osoriellus - s. str. -group

1. Species smaller than 2.9 mm. ............................................................................................................................................ 2

- At least 3.0 mm long. .......................................................................................................................................................... 6

2. At least head dark red or brown. ....................................................................................................................................... 3

- Fore-body totally lighter, yellow, apical margin of clypeus with distinct acute teeth at outer angle. ....................... 5

3. Totally black, only elytra slightly dark brown, apical lobe of aedeagus acute. .......................... O. punctatellus n. sp.

- Yellow, head and posterior margin of elytra slightly darker, apical lobe of aedeagus obtuse. ................................... 4

4. Apical lobe of aedeagus slender, punctation of pronotum slightly finer. ....................... O. exiguus ( NOTMAN, 1925)

- Apical lobe of aedeagus thick, triangular, punctation of pronotum slightly deeper. ................ O. indescriptus n. sp.

5. Eyes small, half as long as temples and not prominent, sides of pronotum continuously narrowed from anterior to posterior angles. ...................................................................................................................................... O. coruscus n. sp.

- Eyes larger, as long as temples and slightly prominent, sides of pronotum slightly emarginate in front of posterior angles. ............................................................................................................................................................ O. luteus n. sp.

6. Smaller than 4.0 mm. .......................................................................................................................................................... 8

- Longer than 4.0 mm. ......................................................................................................................................................... 24

7 Punctation of fore-body and abdomen extremely dense and coriaceous. ...................................... O. asperatus n. sp.

- Punctation of fore-body and abdomen not coriaceous or only head coriaceously punctate. ................................... 8

8 Punctation of head densely coriaceous. .............................................................................................. O. coriaceus n. sp.

- Punctation of head dense or sparse, but not coriaceous. ............................................................................................... 9

9 Shape of protibia asymmetric, trapezoid. .......................................................................................... O. latitibialis n. sp.

- Shape of protibia more or less symmetric, nearly semi-circular. ................................................................................ 10

10. Pronotum with isodiametric microsculpture, surface matt or slightly shiny. ........................................................... 11

- Pronotum without or with weak microsculpture or remains of microsculpture, surface shiny or polished. ....... 15

11. Eyes distinctly prominent, pronotum with extremely large punctures, partly depressed rows adjacent to midline. ........................................................................................................................................................ O. grossopunctatus n. sp. - Eyes not or only very slightly prominent; row of punctures adjacent to midline not large and deep and forming partly a furrow. .................................................................................................................................................................. 12

12. 6 th antennomere nearly two times wider than long, only slightly narrower than 7 th antennomer. ........................ 13

- 6 th antennomere slightly wider than long and distinctly narrower than 7 th antennomere, posterior angles of pronotum widely rounded. ................................................................................................................... O. micros ( SHARP, 1887)

13. Eyes prominent. ................................................................................................................................ O. surinamensis n. sp.

- Eyes not prominent. .......................................................................................................................................................... 14

14. Pronotum lighter brown than head and evenly narrowed from anterior angles to posterior angles. ........................ ............................................................................................................................................ O. brevicornis ( NOTMAN, 1920)

- Pronotum and head black, pronotum more strongly narrowed in posterior half than in anterior half. .................... ........................................................................................................................................... O. lewisi ( BLACKWELDER, 1943)

15. Punctures of pronotum large, along impunctate midline in irregular rows, not more than 12 punctures in the row adjacent to midline. ........................................................................................................................................................... 16

- Pronotum on both sides of impunctate midline with irregular finer punctation, punctures not in rows, irregular line of punctures adjacent to midline at least with 12 to 15 punctures. ..................................................................... 23

16. On average larger, 3.5 – 3.9 mm long, pronotum with weak microsculpture and micro-punctation. .................. 17

- Not longer than 3.5 mm, surface of pronotum polished and with fine micro-punctation. .................................... 20

17. Head and pronotum with iridescent shine. ................................................................................................................... 18

- Head without iridescent shine, punctation of pronotum denser and deeper, distance between punctures shorter than diameter of punctures. ............................................................................................................................................. 19

18. Punctation of pronotum sparse, distance between punctures as wide as diameter of punctures. .............................. .................................................................................................................................................................... O. flaveolus n. sp.

- Punctation of pronotum denser, distance between punctures in row adjacent to midline shorter than diameter of punctures. .................................................................................................................................................. O. huggerti n. sp.

19. Head without microsculpture, but coriaceous punctation on vertex, irregular row of pronotal punctures depressed. ........................................................................................................................................................ O. salvini ( SHARP, 1887)

- Head with microsculpture, punctation on vertex dense, but not coriaceous, row of pronotal punctures not depressed. ................................................................................................................................................................ O. obtusicollis n. sp.

20. Dark brown, punctation of pronotum sparser and less deep, distance between punctures within row as wide as diameter of punctures. ................................................................................................................................... O. levyi n. sp.

- Light or dark reddish and punctation denser, distance between punctures within row shorter than diameter of punctures. ........................................................................................................................................................................... 21

21. Pronotum with weaker punctation and remains of microsculpture. .................................................... O. loksai n. sp.

- Pronotum with dense and deep punctation and without remains of microsculpture; surface polished. .............. 22

22. Anterior angles of pronotum obtuse, not produced to short teeth. .................................................... O. bicolor n. sp.

- Anterior angles of pronotum acute, produced to short teeth. ................................................................. O. ashei n. sp.

23. Punctation of fore-head as dense as on vertex, apex of aedeagus acute. ................... O. eggersi ( BERNHAUER, 1904)

- Punctation of fore-head sparser than on vertex, apex of aedeagus obtuse. .................................... O. humicola n. sp.

24. Between 4.0 and 4.9 mm long. ........................................................................................................................................ 25

- Longer than 4.9 mm. ......................................................................................................................................................... 33

25. Pronotum with dense microsculpture, surface matt or slightly shiny. ....................................................................... 30

- Pronotum without or very weak microsculpture, surface polished and shiny. ......................................................... 26

26. Eyes slightly prominent, punctation of pronotum dense, but not coriaceous. ............................ O. boliviensis n. sp.

- Eyes not prominent. .......................................................................................................................................................... 27

27. Pronotum sparsely punctate, distance between punctures at least as wide as diameter of punctures. .................. 28

- Pronotum densely punctate, interstices between punctures smaller than diameter of punctures, longer, 4.6 – 4.8 mm long. ..................................................................................................................................................................................... 29

28. Smaller, 4.1 – 4.2 mm long, row of punctures adjacent to impunctate midline not more than 6 punctures. ............ ....................................................................................................................................................... O. parumpunctatus n. sp.

- Larger, 4.4 mm long, row of punctures adjacent to impunctate midline at least 9 punctures. .................................... ............................................................................................................................................. O. franckei ( WENDELER, 1955)

29. Pronotum quadrate, posterior angles of pronotum obtuse, elytra longer than wide. ....................... O. tuxtlae n. sp.

- Pronotum wider than long, posterior angles of pronotum widely rounded, elytra quadrate. ..................................... .................................................................................................................................................... O. minor ( NOTMAN, 1925)

30. Eyes thick and prominent, interstices between setiferous punctures of pronotum less than half as wide as diameter of punctures. ................................................................................................................................. O. multipunctatus n. sp.

- Eyes smaller and not or only slightly prominent; pronotal punctation less dense, interstices between punctures maximum less shortly wide than diameter of punctures. ............................................................................................ 31

31. Pronotum trapezoidal, clypeus with two short lateral granules. ................................................. O. triangulatus n. sp.

- Sides of pronotum smoothly rounded; clypeus without or with one short lateral denticle. ................................... 32

32. Pronotum with dense microsculpture, surface matt, irregular line of punctures adjacent to midline with more than 12 punctures. ............................................................................................................... O. rugipennis ( BERNHAUER, 1910)

- Pronotum with weaker microsculpture, surface slightly shiny, irregular line of punctures adjacent to midline with 10 to 12 punctures. ...................................................................................................... O. haitiellus ( DARLINGTON, 1937)

33. Pronotum with microsculpture, surface matt or slightly shiny. .................................................................................. 40

- Pronotum without microsculpture, surface polished or with remains of weak microsculpture, surface shiny. ....... .............................................................................................................................................................................................. 34

34. Longer, 7.8 mm long, punctate line adjacent to impunctate midline depressed, disc of pronotum irregularly punctate. ................................................................................................................................................ O. crassus ( SHARP, 1887)

- Smaller, not longer than 6.5 mm. .................................................................................................................................... 35

35. Sides of pronotum in anterior half nearly parallel; anterior edge only 1.3 times wider than posterior edge. ........... ......................................................................................................................................................... O. frater ( LYNCH, 1884)

- Sides of pronotum strongly narrowed from anterior to posterior angles, anterior edge at least 1.5 times wider than posterior edge, posterior angles obtuse. ......................................................................................................................... 36

36. Smaller species of 5.3 – 5.4 mm. ................................................................................. O. latipes (GRAVENHORST, 1802)

- Longer than 5.5 mm. ......................................................................................................................................................... 37

37. Head with distinct or weak isodiametric microsculpture, surface matt or slightly shiny. ...................................... 38

- Head without microsculpture, surface polished and shiny. .................................. O. mexicanus ( BERNHAUER, 1910)

38. Pronotum more strongly trapezoid, anterior edge nearly 2 times wider than posterior edge. .................................... ........................................................................................................................................... O. brevipennis ( NOTMAN, 1925)

- Pronotum less narrowed to posterior edge, anterior edge only 1.5 times wider than posterior edge. .................. 39

39. Eyes distinctly prominent and longer than temples. ....................................................................... O. tunariensis n. sp.

- Eyes not prominent and as long as temples. ........................................................... O. argentinus ( BERNHAUER, 1911)

40. At least 6.7 mm long. ........................................................................................................................................................ 41

- Smaller than 6.5 mm. ........................................................................................................................................................ 42

41. Sides of pronotum evenly narrowed to posterior angles in smooth curve. ......................... O. parcus ( SHARP, 1887)

- Sides of pronotum evenly narrowed to posterior angles, pronotal shape nearly trapezoidal, lateral margin close to posterior angles widened. ................................................................................................................... O. majusculus n. sp.

42. Smaller, 4.9 – 5.4 mm long, microsculpture of pronotum weak, surface shiny. ....................................................... 43

- Longer than 5.5 mm, microsculpture of pronotum dense, surface matt. .................................................................. 46

43. Sides of pronotum narrowed to posterior angles in even curve. ................................................................................ 45

- Sides of pronotum evenly narrowed from anterior angles to posterior angles, shape trapezoid. .......................... 44

44. Posterior angles of pronotum obtuse and rounded, sides of fore-head narrowed to anterior angles in slight sinuate curve. ..................................................................................................................................................... O. trapezoides n. sp.

- Posterior angles of pronotum nearly rectangular, sides of fore-head narrowed to anterior angles in deep emarginate curve. .................................................................................................................................................... O. rubripennis n. sp.

45. More slender, sides of pronotum nearly parallel in anterior half, lateral margin fine throughout its total length. .. ......................................................................................................................................................... O. debilis ( SHARP, 1887)

- Broader, sides of pronotum also curved in anterior half, lateral margin slightly widened close to posterior angles. ...................................................................................................................................................................... O. seriatus n. sp.

46. Pronotum evenly narrowed from anterior to posterior angles; shape of pronotum trapezoidal. ............................... .................................................................................................................................................................. O. verhaaghi n. sp.

- Shape of pronotum different, pronotal sides curved. ................................................................................................... 47

47. Sides of pronotum emarginate close in front of posterior angles; sides shortly in front of posterior angles nearly parallel, lateral margin in front of posterior angles distinctly widened, two very similar species. ........................ 48

- Sides of pronotum narrowed to posterior angles in even curve, posterior angles obtuse, lateral margin in front of posterior angles not widened. .......................................................................................................................................... 49

48. Slightly larger, 6.4 mm long, microsculpture less distinct and surface slightly shiny, apex of aedeagus obtuse. ...... ................................................................................................................................................................... O. fumarius n. sp.

- Slightly shorter. 6.0 mm long, microsculpture deeper and surface matt, apex of aedeagus acute. ............................. ................................................................................................................................................................ O. caliginosus n. sp.

49. Pronotum mostly with longitudinally reticulate microsculpture, only near anterior edge with netlike microsculpture; elytra with weak ground sculpture, punctation distinctly visible. ............................................... O. rougemonti n. sp.

- Pronotum with isodiametric microsculpture; surface matt, ground sculpture of elytra more distinct and, thus, punctation less visible. ...................................................................................................................................................... 50

50. Elytra with dense and deep microsculpture, surface extremely matt, inner edge of apical aedeagus with numerous sensillae. ....................................................................................................................................................... O. opacus n. sp.

- Elytra with ground sculpture, but without dense and deep microsculpture, surface more or less shiny, aedeagus at inner edge with single row of few sensillae. ..................................................................... O. schwarzi ( NOTMAN, 1925)

Pronotum: 0.88 mm long, 0.88 mm wide; widest at anterior angles; slightly convergent to posterior angles; posterior angles smoothly rounded; lateral margin fine; in dorsal aspect, visible in its total length; punctation coarse and dense; in irregular rows of 10 to 12 setiferous punctures; on average, interstices between punctures narrower than half of diameter of punctures; wide midline impunctate; sparse micro-punctures between coarse setiferous punctures; without distinct microsculpture; only with remains of weak striae; in most parts, surface shiny and polished.

Elytra: 1.00 mm long, 0.88 mm wide; densely and coarsely punctate; on average, interstices between setiferous punctures half as wide as diameter of punctures.

Abdomen as densely and coarsely punctate as elytra; with wide impunctate midline.

Protibia: 0.50 mm long, 0.15 mm wide; 9 spines at lateral edge; WLR: 5.0; in posterior aspect, comb of inner emargination widely covered; posterior face with moderately dense setation.

Aedeagus angulate; apical lobe thin and elongate; 1.5 times as long as basal lobe and with acute apex.

Etymology: The specific name refers to the region of Tuxtla, where the species was collected.