Eleusis, LAPORTE, 1835

Irmler, Ulrich, 2017, The Neotropical species of the genus Eleusis LAPORTE, 1835 with description of the new genus Eleusima (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 67 (2), pp. 275-318 : 302-303

Key to species of the genus Eleusis second; third antennomere nearly twice as long as second; following antennomeres shorter than third and increasing in width; fourth antennomere nearly twice as long as apical width; tenth as long as apical width; fourth to eleventh antennomeres pubescent and with few long apical setae.

Pronotum: on average, 1.28 mm long, 1.43 mm wide; sides in anterior half parallel; in posterior half continuously narrowed to posterior angles; at posterior angles only half as wide as at anterior angles; short groove at each side margined by sharp ridge; central part slightly prominent posteriad; at anterior angles with deep short groove; anterior angles emarginate; depth of emargination varying corresponding to depth of groove; punctation as deep and sparse as on posterior vertex of head; on average, interstices between punctures three times as wide as diameter of punctures; setiferous punctures in anterior grooves, along lateral margin, and one large setiferous puncture at beginning of posterior third; pairs of setiferous punctures at anterior margin close to anterior angles; elongate microsculpture similarly dense and deep as on head; surface moderately matt.

Elytra: on average, 1.52 mm long, 1.52 mm wide; slightly widened to posterior angles; humeral angles obtusely angled; punctation similarly dense and deep as on pronotum; setiferous punctures along lateral margin; one setiferous puncture in central position on each side of suture; elongate microsculpture as dense and deep as on pronotum; surface moderately matt.

Abdomen impunctate except transverse rows of setiferous punctures on each abdominal segment; transverse reticulate microsculpture weak; surface shiny.

Aedeagus elongate; in lateral view aspect, shortly acute; central lobe in anterior half with numerous sensillae and in apical third with minute diagonal striae; in ventral aspect, apex slightly emarginate; parameres slightly shorter than central lobe; with widened transparent apical lobe; at apical margin with minute setae; few sensillae on transparent apical lobe and at base of scape.

Etymology: The species name honours Tim Struyve, who found the species in Panama.

1 Sides of pronotum interrupted by a short emargination followed by short tooth. ..................................................... 2

– Sides not interrupted; posterior half continuously narrowed to posterior angles. ................................................... 16

2 Elytra with at least two pairs of setiferous punctures. .................................................................................................. 14

– Elytra with one pair of setiferous punctures. ................................................................................................................... 3

3 Larger than 5.0 mm, elytra reddish brown. ..................................................................................................................... 4

– Not longer than 4.5 mm, elytra reddish or light brown to yellowish with dark posterior margin or totally dark brown to blackish. ............................................................................................................................................................... 5

4 Antennae shorter, as long as head and half of pronotum combined, aedeagus thick and stout, in ventral aspect, apex rounded. ................................................................................................................................... E. castanea spec. nov.

– Antennae longer, as long as head and pronotum combined; aedeagus slenderer, in ventral aspect, apex triangular. ..................................................................................................................................................... E. ecuadoriensis spec. nov.

5 Elytra light reddish brown, with dark spot along suture, pronotum with narrow impunctate midline, elytra distinctly longer than wide. ................................................................................................................................................................. 6

– Elytra dark brown without darker spot or pale with darker posterior margin and sides; pronotum without impunctate midline, elytra quadrate, wider than long or only slightly longer than wide. ...................................................... 7

6 Head and pronotum with pairs of impressions, slightly smaller, 3.8 – 4.0 mm long. .......... E. rufipennis spec. nov.

– Head and pronotum without impressions; slightly larger, 4.2 mm long. .................................... E. genieri spec. nov.

7 First antennomere black; prominence of aedeagus short and close to apex. ....................... E. hondurana spec. nov.

– First antennomere yellow; prominence of aedeagus in central position, triangular or extremely elongate. .......... 8

8 Prominence of aedeagus slender and elongate; nearly as long as apex of parameres. ........... E. boliviana spec. nov.

– Prominence of aedeagus widely triangular or nearly absent. ........................................................................................ 9

9 Aedeagus stout and broad; apical half of central lobe as wide as or wider than basal half; apex broadly obtuse. .... 10

– Aedeagus slender; apical half of central lobe smaller than or equally wide as basal half; apex semicircular or slightly acute. ................................................................................................................................................................................... 11

10 Apex of aedeagus broadly obtuse. ................................................................................. E. interrupta ( ERICHSON, 1840)

– Apex of aedeagus with wide lobes. .................................................................................................... E. andina spec. nov.

11 Smaller, 2.2 – 2.9 mm long, elytra yellow to light brown with blackish posterior margin, with at least slight central prominence of aedeagus. .................................................................................................................................................. 13

– Larger, 3.1 – 3.5 mm long. ................................................................................................................................................ 12

12 Elytra as black as head and pronotum, central prominence of aedeagus nearly absent, only marked by concentration of sensillae, apex of paramere without sensillae. ..................................................................... E. nigrita spec. nov.

– Elytra dark brown to yellowish with black posterior margin, central prominence of aedeagus large, nearly semicircular, apex of paramere with fringe of short setae. ........................................................ E. nigerrima FAUVEL, 1864

13 Smaller, 2.2 – 2.4 mm, head and pronotum brown, central prominence of aedeagus extremely weak. ..................... ................................................................................................................................................................ E. fauveli spec. nov.

– Larger, 2.5 – 2.9 mm, head and pronotum blackish, central prominence of central lobe weak, apex of parameres without marginal setae. .......................................................................................................... E. humilis ERICHSON, 1840

14 Totally black, punctation of head weak. ................................................................................... E. breviceps SHARP, 1887

– At least with few yellow parts, extremely variable in colouration, but never totally black. ..................................... 15

15 Head coarsely punctate, interstices between punctures less than half as wide as diameter of punctures. ................. .......................................................................................................................................................... E. insignis SHARP, 1887

– Punctation of head weaker, interstices between punctures at least as wide as diameter of punctures. ...................... ................................................................................................................................................................ E. scita SHARP, 1887

16 Slender species, not depressed in dorso-ventral direction; left mandible with broad and thick tooth. ...................... ............................................................................................................................................................. E. elongata spec. nov.

– Species depressed in dorso-ventral direction, left mandible with acute tooth. ........................................................ 17

17 Totally black. ...................................................................................................................................................................... 18

– Only partly black, variable in colouration, but never totally black. ........................................................................... 19

18 Head with dense microsculpture and without punctuation. .............................................. E. panamaensis spec. nov.

– Head with polished parts and distinctly punctate. ................................................................. E. frater (FAUVEL, 1865)

19 Pronotum reddish, elytra in anterior half reddish, in posterior half dark, smaller than 5.0 mm. .............................. ............................................................................................................................................................. E. rufula SHARP, 1887