Eunausibius tenebrionoides (Grouvelle)

Halstead, David G. H., 2020, New and little known Coleoptera (Silvanidae: Silvaninae) from Central and South America, Insecta Mundi 2020 (842), pp. 1-37 : 27

Eunausibius tenebrionoides (Grouvelle)

( Fig. 91–94 )

Nausibius tenebrionoides Grouvelle 1896: 193 (type examined).

Eunausibius tenebrionoides (Grouvelle) ; Grouvelle 1913: 314.

Diagnosis. See “Diagnosis” for Nausibius jatahyensis new species, a very similar species.

Description. Eunausibius tenebrionoides is known only from the male holotype. Length 6.4 mm, elongate, total length to elytral breadth ratio 43.8:10.0, general appearance sub-cylindrical, dark brown, moderately shining, dorsum glabrous.

Head. Slightly transverse (10.0:10.9), moderately raised medially on anterior half, slight depressions above antennal insertions, punctures small and separate on middle of head becoming larger and confluent laterally towards eyes; eyes in dorsal view flat, small, length: head length, 10:36, separated from front of head by 2× length of eye; antenna with 4-segmented club, last segment small, first antennal segment hidden beneath genal margin.

Pronotum. Elongate, 13.3:10.0; lateral margins straight, parallel; lateral rim fine, inwardly produced as very short fine line below anterior angle; anterior angle slightly curved before apical margin; densely punctured, punctures confluent producing predominantly longitudinal rugosity, particularly obvious laterally where punctures become obsolete (pronotum without an obvious medial, longitudinal impunctate region).

Elytra. Elongate, 24.4:10.0, sub-cylindrical, glabrous (at least in type); 9 rows of punctate striae on each elytron, including 2 on lateral declivity; interstriae mostly with single row of very small punctures, surface uneven with deep micro-reticulation as in E. jatahyensis ; arrangement of elytral punctures similar to that of E. jatahyensis (see Fig. 102 ) but setae absent; fine impressed line present along sutural side of first punctate stria, near elytral apices ( Fig. 91 ).

First abdominal ventrite. Femoral line strongly produced, extending to apical third of ventrite ( Fig. 92 ).

Legs, male. Metafemora with extremely small tooth, all tibiae with fine striae on inner side ( Fig. 91 ).

Male genitalia. ( Fig. 93–94 ) With median strut and internal sac similar to E. elongatus (see Fig. 108 ), also rods similar but 25–26 on each side; median lobe short, deeply emarginate and with 4 comparatively long setae on each side; parameres moderately long, setae present along outer margin and apical third of inner margin, those at apex very long ( Fig. 94 ); sternites 8 and 9 transverse, 8 rounded at sides, not produced ( Fig. 93 ).

Taxonomic notes. The specimen in the MNHN labelled as “tenebrionoides” also “ Eunausibius tenebrionoides ” by Grouvelle, and bearing an old printed “Type” label (as other Grouvelle types) is a male (as figured by Grouvelle in the original description). It has the character states described by Grouvelle, of which the pronotal puncturation is particularly significant, but the locality of Bahia, which is on the specimen, is wrong for that recorded by Grouvelle (1896) who gives “Matusinhos (Minas Geraes)”. However, the specimen is here accepted as the holotype because there is no evidence to suggest that Grouvelle based his description on more than one specimen and the published locality record seems to be a mistake.

Material examined. Holotype male “ S. Antonio da Barra Pr. de Bahia Gounelle 11-12. 88 [printed] / Type [printed] / Nausibius tenebrionoides Grouv. [handwritten on squared paper] / tenebrionoides Grouv. [Grouvelle’s handwriting on green label] / Eunausibius tenebrionoides Grouv. [Grouvelle’s handwriting on green label]” ( MNHN).

Distribution. Brazil.

Figures

Figures 91–97. Eunausibius spp. 91–94) E. tenebrionoides (Grouvelle), male holotype. 91) Habitus, inset enlarged view of metafemoral spine. 92) First abdominal ventrite. 93–94) Genitalia and associated sternites. 93) Sternites 8–9. 94) Parameres and median lobe. 95–97) E. jatahyensis, new species, male holotype. 95) First abdominal ventrite. 96–97) Genitalia and associated sternites. 96) Sternites 8–9. 97) Parameres and median lobe. Scale lines for Figures 91, 92 and 95 = 2.0 mm, for Figures 93–97 (94 and 97 to same scale) = 0.5 mm.

Figures 98–102. Eunausibius jatahyensis, new species, types. Dots on pronotal disc show position of narrow, medial impunctate region. 98) Habitus, holotype male (Jatahy). 99) Habitus, paratype female (Jatahy). 100) Head, paratype female with smaller eyes dorsal view (Minas Gerais). 101) Head of holotype, ventral view to show eyes plus deep antennal grooves. 102) Elytron, small part enlarged (margin of suture on left) to show strial punctures, also very short, fine setae. Scale lines = 2.0 mm.

Figures 103–110. Eunausibius elongatus (Grouvelle), male. 103) Habitus, dots on pronotal disc show position of narrow, medial impunctate region. An example of the pronotal puncturation is included. 104) First abdominal ventrite. 105) Elytron, small part enlarged (margin of suture on left) to show strial punctures with associated comparatively long, conspicuous setae, each above a strial puncture and similar setae in a line on interstriae. 106) Antenna, enlarged. 107) Pronotal punctures, an enlargement of some of those near the anterior margin to show their setae. 108–110) Genitalia and associated sternites. 108) Genitalia without internal sac. 109) Internal sac. 110) Sternites 8–9. Scale lines for Figure 103 (104 also to same scale) = 2.0 mm, for Figures 108–110 = 0.2 mm.