Eleusis breviceps SHARP, 1887

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 : 289-290

Eleusis breviceps SHARP, 1887

Figs 15 A-C, 30A-B, 35e

Eleusis breviceps SHARP, 1887: 731

Type material examined: female, Lectotype: Guatemala: Verapaz, Senahu, leg. Champion ( BMNH). According to Sharp, two syntypes exist. One syntype labelled additionally with a type label was examined. This specimen was selected and labelled as lectotype.

Additional material examined: Costa Rica: Puntarenas Prov., Las Alturas Biol. Sta. (8°56.17'N, 82°50.01'W), 1660 m elev., under bark, male, 1.6.2004, leg. J.S. Ashe, Z. Falin, I. Hinojosa #CR1AFH04071 ( KNHM) ; Cartago Prov., Tapanti Nat. Park , visitors cabin (9.76112 N, 83.7848 W), 1283 m elev., under bark, male, 17.3.2010, leg. Z.H. Falin, #CR10-0317-ZF13 ( KNHM) ; Panama: Panama Prov., Santa Fé, Piedra Alta (8°52'N, 81°13'W), dead wood, 4 males, 5 females, 26.4.2014, leg. T. Struyve (4 TSC, 5 UIC) .

Diagnosis: The species can be differentiated from the other two species of the group by its black colouration. In this respect, it resembles E. frater of the E. bicolor-group. However, E. frater has only one pair of elytral setiferous punctures and no interrupted pronotal lateral margin. E. breviceps is additionally differentiated from E. scita and E. insignis by the weak punctation and microsculpture of head and pronotum. The head shape described by SHARP (1987) based on the female specimen studied by SHARP. The higher number of specimens studied here shows that the head shape of E. breviceps varies extremely and is no valuable character separating the species from E. scita and E. insignis .

Description: Length: 3.9 mm long. Colouration: totally black, except abdominal segments VII and VIII dark yellow; legs brown; antennomeres 1-3 brown, 4-11 black.

Head: on average, females: 0.61 mm long, 0.96 mm wide; males: 0.78 mm long, 1.24 mm wide (sexual dimorphism statistically significant: t-test: t=-3.8, p=0.004); eyes not prominent; short; sides of temples divergent; in females, 1.5 times to more than two times longer than eyes; in males, 2.5 times as long as eyes; head width and length of temples varying; supraocular groove deep; straight; pointing to outer edge of neck; not parallel to outer line of temples; preocular sides sinuate; strongly narrowed in front of base of antennae; central part of clypeus prominent; punctation weak and sparse; on average, interstices between punctures, two to four times as wide as diameter of punctures; one setiferous puncture at each end of supraocular groove; another pair of setiferous punctures on each side of clypeal prominence; elongate microsculpture weak; on clypeus, transversely striate; on vertex, longitudinally striate; surface slightly shiny.

Antennae as long as head and pronotum combined; first antennomere thicker than following antennomeres; second antennomere only half as long as first; third antennomere nearly as long as first, but narrower; following antennomeres longer than wide; decreasing in length and increasing in width; fourth antennomere approximately twice as long as apical width; tenth antennomere only slightly longer than wide; fifth to eleventh antennomere pubescent; all antennomeres with long apical setae.

Pronotum: 0.58 mm long, 0.85 mm wide; widest close to anterior angles; continuously narrowed to posterior angles; lateral margin interrupted in posterior half by short emargination followed by a tooth-like prominence; posterior angles obtuse; close to anterior angles with deep and short groove; in front of groove deeply emarginate; narrowed to anterior angles; as weakly and sparsely punctate as on head; with several setiferous punctures; one in anterior groove, few along lateral margin, pair of deeply impressed setiferous punctures on each side of midline at anterior margin; elongate microsculpture as weak as on head; longitudinally striate; surface slightly shiny.

Elytra: 0.79 mm long; 0.79 mm wide; sides nearly parallel; humeral and posterior angles nearly rectangular; punctation slightly deeper than on pronotum, but as sparse as on pronotum; several setiferous punctures along lateral margin; on disc, two pairs of setiferous punctures; one pair in anterior half; one pair on central disc; elongate microsculpture slightly deeper than on pronotum; longitudinally striate; surface slightly shiny.

Abdomen weakly punctate; each segment with transverse row of setiferous punctures; elongate microsculpture transversely striate.

Aedeagus thick; in lateral aspect, ventral edge approximately straight; apex with deep incision; apex with fringe of short setae; in ventral aspect, approximately parallel; apical opening rectangular; in apical half with numerous sensillae; parameres approximately as long as central lobe; slightly widened to apex; transparent lobe elongate; with numerous apical setae.

Figures

Fig. 13–17: Eleusis rufipennis (13); E. ecuadoriensis (14), Eleusis breviceps (15), E. insignis (16), E. scita (17); aedeagus in lateral (A)