Osoriellus weberi ( BLACKWELDER, 1943 ), 2014

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 : 310-311

Osoriellus weberi ( BLACKWELDER, 1943) new combination

( Figs 119 A-C, 125A)

Osorius weberi BLACKWELDER, 1943: 198

Type material examined: Trinidad: 12 miles N of Arima (61°16W, 10°37'N), male, 23.6.1935, leg. N.A. Weber (holotype in MCZ) .

Description: Length: 3.1 mm. Colouration: Brown; pronotum and elytra at shoulders reddish; legs, antennae, and anterior margin of clypeus yellow.

Head: 0.37 mm long, 0.58 mm wide; eyes not prominent and as long as temples; sides of fore-head sinuate; anterior edge of clypeus even; without lateral granules; width of anterior edge smaller than width of head in front of eyes; on vertex, setiferous punctation dense and coarse; interstices between punctures half as wide as diameter of punctures; irregular midline impunctate; impunctate midline without microsculpture; surface polished and shiny; on punctate areas of vertex with remains of microsculpture; surface matt or slightly shiny.

Further material examined: Brazil: Amazonas, Manaus, INPA / Smithsonian Res. 2 (59°50'W, 2°25'S), leaf litter of terra firme forest, collected by Winkler method, 1 male, 4 females, 3.1994, 1.1994, 2.1994, leg. R. Didham ( BMNH) ; Peru: Dept. Loreto, Campamento San Jacinto (75°51.77'W, 2°18.75'S), collected by flight intercept trap, 175-215 m elevation, male 7.7.1993, leg. R. Leschen ( KNHM) ; Huanuco, Panguana (74°56'W, 9°37"S), cut forest, female, 3.8.1975, leg. W. Hanagarth ( UIC) .

Antennae short; slightly longer than head; second antennomere thick and oval; distinctly longer than conical third antennomere; following 3 antennomeres slightly increasing in width and distinctly wider than long; antennomeres 7 to 11 distinctly thicker than preceding antennomeres; antennomere 10 only slightly wider than long.

Diagnosis: The species is characterised by the iridescent shine of the head and the digitate protibia. Other species with iridescent shine are smaller and have no digitate protibia. Similarly large species with digitate protibia, e.g. O. lescheni , have no iridescent shine on the head. The thick apical lobe of the aedeagus narrowed abruptly to the acute apex. In ventral aspect, the aedeagus resembles that of O. lescheni and O. loreti , since the circular basal lobe is much thicker than the apical lobe. In the male specimen from Peru, the apical lobe is thicker than in the Central Amazon or Trinidad males, but this may be within the range of the species.

Pronotum: 0.53 mm long, 0.56 mm wide; widest at anterior angles; sides evenly convergent to posterior widely rounded angles; lateral margin fine; in dorsal aspect, visible throughout its total length; setiferous punctation distinctly finer and sparser than on head; interstices between punctures approximately as wide as diameter of punctures; between normal punctures with sparse micropunctation and weak remains of microsculpture; surface mostly polished and shiny.

Description: Length: 4.5 mm. Colouration: Dark brown; elytra lighter reddish brown; abdomen, legs and antennae still lighter yellowish brown.

Elytra: 0.68 mm long, 0.59 mm wide; ground-sculpture deep and coarse; coarse setiferous punctation nearly invisible in ground-sculpture; surface matt.

Head: 0.52 mm long, 0.84 mm wide; eyes slightly prominent; nearly twice as long as temples; fore-head convergent to anterior angles in smooth concave curve; anterior edge of clypeus even; setiferous punctation weak and moderately sparse; punctures partly granulate; punctures close to neck and on supraocular area larger; yellow setae as long or slightly longer than interstices between punctures; isodiametric microsculpture weak and dense; surface with iridescent shine; on supraocular area and on lateral neck, microsculpture slightly deeper.

Abdomen with coarse setiferous punctation; similar to elytral punctation; surface matt, except impunctate shinier midline.

Protibia: 0.30 mm long, 0.10 mm wide; on outer edge with 8 long spines; 3 apical spines inserted on short digits; WLR: 1.00; posterior face covered with sparse setae; in posterior aspect, inner emargination distinctly visible; in middle, partly covered by posterior inner edge.

Aedeagus with thick apical lobe ending in widely rounded obtuse apex; along inner edge with groups of several sensillae.

Key to the remaining species

1. Smaller than 6.0 mm. .......................................................................................................................................................... 7

- Longer than 6.5 mm. ......................................................................................................................................................... 17

2. Eyes thick and nearly semicircular. ................................................................................................................................... 3

- Eyes less thick, only slightly prominent or not prominent. ........................................................................................... 4

3. Punctation of pronotum sparse, but punctures very large, surface with microsculpture, sides only slightly narrowed to posterior angles, lateral and posterior margin of pronotum and elytra yellowish brown. ......... O. orbiculatus n. sp.

- Punctation of pronotum denser, punctures smaller, surface without microsculpture, sides evenly narrowed to posterior angles in smooth curve, colouration dark brown. ................................................................ O. opticus n. sp.

4. Protibia with extremely long digits, WLR smaller than 0.35. ....................................................................................... 5 - Protibia with moderately long digits; WLR higher than 0.60. .........................................................................................

5. Smaller than 4.0 mm, anterior angles of pronotum not produced to acute teeth, posterior angles of pronotum rounded. ................................................................................................................................................... O. digitatus n. sp.

- Longer than 5.0 mm, anterior angles produced to distinct acute teeth, posterior angles obtuse, but distinctly angulate. ................................................................................................................................................................ O. acutus n. sp.

6. At least 4.0 mm long. .......................................................................................................................................................... 8 - Smaller than 3.5 mm. .......................................................................................................................................................... 7

7. Setiferous punctation of pronotum dense and coarse, interstices between punctures distinctly shorter than diameter of punctures. .................................................................................................................... O. carinicollis ( NOTMAN, 1925)

- Setiferous punctation of pronotum sparser and finer, interstices between punctures as wide as diameter of punctures. ............................................................................................................................ O. trinitatis ( BLACKWELDER, 1943)

8. Shoulders with rectangular angle. ..................................................................................................................................... 9 - Shoulders rectangular, but rounded. .............................................................................................................................. 11

9. Black, sides of pronotum evenly narrowed to posterior angles. .................................................. O. rectangulus n. sp. - Light reddish brown, sides of pronotum slightly emarginate in middle, nearly parallel in posterior half. ........... 10

10. Head with weak microsculpture, surface moderately shiny, pronotum without microsculpture or only with remains of microsculpture, surface shiny. ........................................................................................................... O. rufescens n. sp.

- Head with dense and deep microsculpture, surface matt, pronotum with dense, but weak microsculpture, surface moderatly shiny. ............................................................................................................................................ O. loreti n. sp.

11. At least 5.3 mm long. ........................................................................................................................................................ 15 - Smaller than 4.8 mm. ........................................................................................................................................................ 12

12. Pronotum with deep and dense microsculpture, surface matt. .......................................................... O. adustus n. sp. - Pronotum without or with weak microsculpture, surface shiny. ................................................................................ 13

13. Head with dense microsculpture, surface with iridescent shine. ........................... O. weberi ( BLACKWELDER, 1943) - Head without or with weak microsculpture, surface without iridescent shine. ....................................................... 14

14. Light brown, surface of pronotum polished and shiny. ....................................................................... O. lescheni n. sp. - Dark brown, surcface of pronotum with weak microsculpture, moderately shiny. ..................... O. infuscatus n. sp.

15. Pronotum with dense and finer punctation, without impunctate midline. ...... O. cordovensis ( BERNHAUER, 1910) - Pronotum with sparser or coarser punctation and with wide impunctate midline. ................................................ 16

16. Light red, angles of clypeus produced to acute teeth, punctation of pronotum sparser, interstices between punctures tree to four times as wide as diameter of punctures ................................................ O. notmani ( DARLINGTON, 1937)

- Dark brown, angles of clypeus produced to granules, punctation of pronotum denser, two times as wide as diameter of punctures. .............................................................................................................. O. neotropicus ( BERNHAUER, 1908)

17. Sides of pronotum strongly narrowed in distinct curve to posterior angles, pronotum with weak or without microsculpture, surface shiny or polished. .............................................................................................................................. 19

- Sides evenly and straightly narrowed to posterior angles; pronotal shap trapezoidal, pronotum with dense and deep microsculpture, surface matt. .......................................................................................................................................... 18

18. Anterior angles of clypeus only produced short granules, microsculpture of pronotum dense, surface matt. ......... ................................................................................................................................................................. O. opacinotus n. sp.

- Anterior angles of clypeus produced to short and acute teeth, microsculpture of pronotum less dense, surface moderately matt. ....................................................................................................................................... O. sticticus n. sp.

19. Punctation of pronotum sparse, interstices between punctures at least twice as wide as diameter of punctures. .... ................................................................................................................................... O. sexpunctatus ( BERNHAUER, 1912)

- Punctation of pronotum denser, interstices between punctures as wide as diameter of punctures or slightly wider. ................................................................................................................................................... O. germanus ( SHARP, 1887)

Antennae as long as head and half of pronotum combined; second antennomere oval and distinctly longer than wide; as long as conical third antennomere; antennomeres four to six slightly increasing in width; following antennomeres distinctly wider than preceding antennomeres, but all quadrate.

Pronotum: 0.84 mm long, 0.93 mm wide; widest close to anterior angles; sides convergent to obtuse posterior angles in even curve; posterior angles widely rounded; lateral margin distinct; in dorsal aspect, visible throughout its total length; slightly widened posteriorly; setiferous punctation larger and deeper than on head; moderately sparse; on average, interstices between punctures as wide as diameter of punctures; in irregular row adjacent to impunctate midline denser; impunctate midline in anterior half narrower than in posterior half; yellow setae as long as or slightly longer than interstices between punctures; between normal coarse punctures, with sparse micro-punctation; isodiametric microsculpture weak and less dense than on head; surface without iridescent shine; slightly shiny.

Elytra: 1.01 mm long, 0.95 mm wide; shoulders rounded; sides slightly widened to posterior third; setiferous punctation similarly dense and large as on pronotum; in irregular rows; coriaceous ground-sculpture coarse; surface less shiny than pronotum.

Abdomen with denser setiferous punctation than on forebody; yellow setae much longer than interstices between punctures; narrow midline impuncate; netlike microsculpture weak; surface shiny.

Protibia: 0.42 mm long, 0.13 mm wide; with seven spines at outer edge; apical spines inserted on long digits; WLR: 0.60; in posterior aspect, inner emargination with comb visible in its total length; posterior face sparsely covered by long yellow setae.

Aedaegus angulate in nearly rectangular angle; symmetric; with thick apical lobe; close to apex, apical lobe suddenly narrowed to acute apex; two lateral sensillae at base of apical lobe; at inner edge of apical lobe with row of sensillae close to apex and second row of four sensillae close to base.

Figures

Fig. 119-122: Remaining-species-group: Osoriellus weberi (119), O. infuscatus (120), O. rectangulus (121), O. rufescens (122); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.