Eleusis dybasi, Irmler, 2019

Irmler, Ulrich, 2019, Additions to the Neotropical species of the genusEleusis LAPORTE, 1835 with description of new species (Coleoptera, Staphylinidae, Osorinae), Beiträge Zur Entomologie = Contributions to Entomology 69 (1), pp. 71-77 : 74-75

Eleusis dybasi spec. nov.

urn.lsid:zoobank.org.act: ED409CD2-1674-4C51-94AE-A2AB6D54B066

Figs 2 a-c, 4B

Type material: Holotype, male: Panama, Chiriqui Prov., nr. Nueva California , W of Finca Palo Santo, in torn fibers of wounded tree, 5000 ft., 10.3.1959, lg. H. Dybas ( FMNH) . Paratypes: male, same location, collector and date as holotype; 2 males, same location and collector as holotype, but 9.3.1959; Chiriqui Prov., Finca Lerida nr. Boquete , in split sapling, 5650 m elev., male, 14.3.1959, leg. H. Dybas (3 FMNH, 1 UIC) .

Diagnosis: Eleusis dybasi resembles E. humilis (ERICHSON, 1840) and E. fauveliana in size, colouration and in the shape of the aedeagus. On average, it is slightly larger than E. fauveliana and the central prominence of the aedeagus is more distinct, as in E. humilis . The elongate elytra are the most specific character. In E. humilis and E. fauveliana the elytra are quadrate or slightly shorter than wide, whereas in E. dybasi the elytra are longer than wide (ratio: 1.15).

Description: Length: 2.6 mm. Colouration: Blackish to dark brown; elytra light yellow with indistinct infuscate apex; abdomen lighter brown than head and pronotum; legs and antennae light brown; base of antennae yellowish.

Head: 0.31 mm long; 0.33 mm wide; eyes large, slightly prominent; approximately twice as long as postocular space; widely rounded to neck; preocular sides parallel; as long as postocular space; sides slightly divergent from base of antennae to posterior angles; sides of clypeus shortly sinuate; narrowed to straight anterior margin; supraocular groove short with setiferous puncture on each end; two additional setiferous punctures at sinuate part of clypeus; punctation moderately sparse and deep; interstices between punctures varying; on average three to five times as wide as diameter of punctures; microsculpture distinct; on vertex approximately longitudinally striate; on clypeus and neck transversely striate; surface moderately shiny; posterior angles without microsculpture; surface nearly polished.

Antennae: first antennomere thicker than four following antennomeres; second antennomere one third shorter than first, approximately as long as conical third antennomere; following antennomeres increasing in width and decreasing in length; fourth antennomere longer than wide; tenth antennomere wider than long; antennomeres four to eleven pubescent and with long yellow apical setae.

Pronotum: 0.30 mm long; 0.33 mm wide; widest close to anterior angles; anterior angles widely rounded; sides strongly convergent posteriad; space between anterior angles nearly twice as wide as between posterior angles; lateral sides at central convergent part deeply interrupted; interruption marked by setiferous puncture; along lateral, anterior and posterior margins with additional setiferous punctures; with pair of large deeply depressed punctures close to anterior angles at anterior margin; punctation similarly deep and sparse as on head; microsculpture similarly distinct as on head; longitudinally striate on central disc; wavily striate close to anterior angles; surface moderately shiny.

Elytra: 0.45 mm long, 0.39 mm wide; humeral angles distinct; sides slightly divergent posteriad; posterior angles widely rounded; posterior margin smoothly rounded with slight incision at suture; one larger setiferous puncture on central disc; several more setiferous punctures along lateral margin; punctation slightly deeper but similarly sparse as on head and pronotum; microsculpture as deep and dense as on head and pronotum; longitudinally striate; surface moderately striate.

Abdomen sparsely punctate; microsculpture transversely striate.

Aedeagus with central lobe in lateral aspect moderately thick with acute apex; slightly rounded; at inner side straight with weak central prominence; in ventral aspect wide; prominence narrow with numerous sensillae; more sensillae close to prominence but nearer to base; paramere distinctly shorter than central lobe; moderately thick with wide apical transparent lobe; transparent lobe with numerous micro-sensillae and with short seta at apex.

Etymology: The species name honours the collector H. Dybas, who collected extensively in South and Central America.

Figures

Figs 1–3:Eleusis mazureki (1), E. dybasi (2), E. chiriquensis (3); aedeagus lateral (a) and ventral (b) aspect, antenna (c); scale bar 0.1 mm. –Fig. 4: Forebody showing shape and colouration ofEleusis mazureki (A), E. dybasi (B), E. chiriquensis (C); scale bar, 0.5 mm.