Eleusis humilis ( ERICHSON, 1840 )

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 : 284-285

Eleusis humilis ( ERICHSON, 1840)

Figs 3 A-C, 28D, 35a

Isomalus humilis ERICHSON, 1840: 839

Type material examined: female, Lectotype: Brazil: Blumenau (labelled as ‘ex type’ in IRSNB); the type specimen in IRSNB was selected as lectotype, because the holotype of E. humilis in ZMUH is lost.

Additional material examined: Brazil: Rio de Janeiro, female, leg. Squires ( BMNH) ; Nova Teutonia , 2 males, 8 females, 17.7.1944,.2., 20.2., 24.2., 26.2., 6.3.1950, leg. F. Plaumann ( BMNH) ; Paraguay: Cazaapa, Hermosa, prop. Sosa family, San Rafael Reserve (26°19.15'S, 55°44.55'W), 90 m elev., fermenting tree wound, 7 males, 9 females, 4.12.2000, 5.12.2000, leg. Z.H. Falin #PAR1F04 (14 KNHM, 2 UIC) ; Argentina: Tucumán, 19.12.1928, leg. H.E. Box ( BMNH) .

Diagnosis: E. humilis resembles E. interrupta in shape and colouration. It is slightly smaller and lighter than E. interrupta . Aedeagus slenderer and the medial triangular prominence more elongate. The species can be identified by the long setae of the apical transparent lobe of the paramere. A syntype of E. indica KRAATZ, 1859 was studied that was deposited in the IRSNB. Although the overall habitus of the species extremely resembles the other small species of the E. humilis-group, e.g. E. humilis , E. fauveli , E. boliviana , the aedeagus shows that E. indica is a valid species, distinctly different from the other species of the group ( Fig. 10A ). The medial process of the central lobe resembles that of E. boliviana , but is thicker and shorter.

Description: Length: 2.5 – 3.0 mm. Colouration: light brown; head darker brown; posterior margin of elytra indistinctly darker; legs and antennae yellow.

Head: 0.32 mm long, 0.31 mm wide; eyes large; slightly prominent; nearly twice as long as temples; on average, EL/HL = 0.34; temples shortly narrowed to neck in smooth curve; preocular sides shortly parallel to base of antennae; supraocular groove from anterior edge of eyes to neck; front edge of clypeus prominent; in sinuate curve to centre; punctation fine and irregularly sparse; interstices between punctures two to four times as long as diameter of punctures; on vertex, microsculpture with elongate striae; on clypeus with transverse striae; microsculpture on vertex much deeper than on clypeus; surface on vertex matt; on clypeus shiny.

Antennae as long as head and pronotum combined; first to sixth antennomeres longer than wide; first antennomere slightly thicker than following antennomeres; second to sixth antennomere decreasing in length; sixth antennomere only slightly longer than wide; seventh antennomere quadrate; following antennomeres increasing in width; approximately quadrate; sixth to eleventh antennomere pubescent; all antennomeres with yellow apical setae.

Pronotum: 0.26 mm long, 0.31 mm wide; widest close to anterior angles; shortly rounded to anterior angles; anterior angles smoothly curved; posterior 2/3 rd evenly narrowed to posterior angles; posterior margin 0.7 times as wide as anterior margin; in dorsal aspect, lateral margin not visible; punctation similarly deep and sparse as on head; close to anterior angles on each side with three larger punctures; each puncture with long seta; some more punctures with setae along lateral margin; sides interrupted in posterior half; marked by deep setiferous puncture; in posterior half with indistinct midline; microsculpture with longitudinal striae; partly curved; surface slightly shiny.

Elytra: 0.41 mm long, 0.38 mm wide; widest close to posterior angles; continuously narrowed to rounded humeral angles; punctation thicker and denser than on head and pronotum; interstices between punctures as wide as to twice as wide as diameter of punctures; along lateral and anterior margin with large setiferous punctures; microsculpture with longitudinal striae; still finer than on pronotum; surface shiny.

Abdomen sparsely punctate; several setiferous punctures on each segment; few setae extremely long; nearly as long as segmental length; microsculpture weak; transverse; close to base of each segment with parts of isodiametric microsculpture.

Aedeagus slightly narrowed to apex; apex smoothly rounded; in central position of apical part with carinate prominence; along apical midline with row of sensillae; at carinate prominence sensillae denser than apically; more sensillae at lateral part of apex; paramere shorter than central lobe; widened to apical transparent lobe; transparent lobe with several extremely fine sensillae; one larger sensilla with longer seta.

Figures

Fig. 2–6: Eleusis interrupta (2), E.humilis (3), E. nigerrima (4), E. boliviana (5), E. andina (6); aedeagus in lateral (A) and ventral (B)

Fig. 7–12: Eleusis fauveli (7), E. hondurana (8), E. nigrita (9), E. indica (10), E. castanea (11), E. genieri (12); aedeagus in lateral (A)