Austronausibius wagneri (Grouvelle) Halstead, 2020

Halstead, David G. H., 2020, New and little known Coleoptera (Silvanidae: Silvaninae) from Central and South America, Insecta Mundi 2020 (842), pp. 1-37 : 11-13

Austronausibius wagneri (Grouvelle) , new combination

( Fig. 28–38 )

Nausibius wagneri Grouvelle 1913: 316 (type examined).

Discussion. Many years ago, Dr A. O. Bachmann (MACN), following a request, kindly sent a small number of mainly unidentified Argentinian silvanids to the author. These included three male specimens which, apart from the strongly developed genae, compared well with Nausibius wagneri Grouvelle , a species described from one female collected in Argentina and not recorded since. Grouvelle’s name label on the type specimen is as follows, “Anausibius wagneri ty. Grouv.”, probably showing that at some point he had intended to erect a new genus for this beetle. The three males have the general facies of beetles placed in Austronausibius , particularly of males of A. leai Halstead and A. aemulus Halstead , and consequently N. wagneri is here transferred to Austronausibius . This genus seems to be predominantly an Australian genus as species previously placed in it are all from this continent. Austronausibius wagneri is so far the only member of the genus that has been found outside Australia and currently the only species known to occur in South America.

Diagnosis. Austronausibius wagneri is readily distinguished from other known species of Austronausibius by the form of the male genitalia, particularly the relatively straight parameres and the arrangement of their setae.

Description. The following description is based on the female type and 3 males, one larger than the other two, measurements and ratios are given for all four specimens, males in ascending order of size. Length, female 4.5 mm (Grouvelle gives 4.2 mm), males 4.2, 4.2, 5.7 mm, ratio breadth to length, female 10:36, males 10:39, 39, 43. Dark brown, head moderately shining, rest of body appearing duller due to puncturation and pubescence (cuticle shining), moderately depressed, setae golden.

Head. Genae expanded and raised, slightly in female seen ( Fig. 33 ), moderately to very strongly in males ( Fig. 28–32 ); ratio of length of head to breadth across genae female, 10:13, males, 10:27, 27, 40; clypeus and frontal region convex, depression present between this region and genae (above antennal insertions); eyes not very prominent but more so than temple, eyes dorsally separated by 9.3× (female), 7.4, 8.0, 9.9× (males) breadth of eye in dorsal view; temple less than tenth length of eye; antenna ( Fig. 29 ), ratio of length (excluding pedicel, which is largely hidden beneath gena) to that of body, female 10:58, males 10:54, 56, 64, antennomere 11 terminating in a small process; puncturation strong (punctures deep) and dense, punctures generally separated by diameter or less, except towards clypeus and vertex where separated by slightly more than diameter and at sides towards eyes where punctures become reticulate; interspaces shining. Ventrally, head with long setae, much longer than elsewhere on underside of body; large shallow cavity on each side produced by expansion of genae (for accommodation of antennae).

Pronotum. More elongate in males than in female seen, ratio of length to breadth 13, 13, 14:10 (males), 12:10 (female); puncturation dense, reticulate except along mid-line and medially before raised region where there are a few punctures more widely separated (although interspaces shining overall impression dull) basal two thirds of longitudinal mid-line slightly raised to form a weak ridge, rest of disc broadly depressed on each side of mid-line, depressions deepest towards base; anterior margin slightly raised, most obviously so at sides; lateral teeth moderately developed, anterior tooth more prominent than others, which are obtuse ( Fig. 28, 32–33 ).

Elytra. Elongate, ratio of length to breadth, female 20:10, male 21, 22, 22:10; disc convex; interstriae 3, 5 and 7 raised, 3 raised slightly on basal two thirds, others obviously raised for greater part of length; 9 forms margin of declivity, somewhat carinate; setae arranged in herringbone pattern although not very obviously so; apex slightly curved in to suture.

Legs. Male metafemora with a strong tooth on inner margin ( Fig. 31 ); tarsi simple (third tarsomere not produced beneath fourth).

Abdomen. First ventrite with femoral line very short ( Fig. 30 ).

Male genitalia ( Fig. 34–38 ). Internal sac with teeth arranged in the form of an armature ( Fig. 37 ); median strut gradually broadened to apex; area towards ostium with about 22 rods on each side; parameres long, 4 or 5 long setae at apex, shorter setae along outer margin of apical half, much shorter finer setae along inner margin; median lobe with fine short setae on dorsal surface, apex pointed; sternites 8 and 9 ( Fig. 38 ), sternite 8 with several short fine setae towards each side.

Material examined. Holotype female “Rep. Arg. Chaco Sant [green label, Grouvelle’s handwriting] / Type [orange printed label] / Museum Paris 1917 Coll. Grouvelle [recent Paris Mus. label] / Anausibius Wagneri ty. Grouv. [Grouvelle’s handwriting, see Discussion above]” ( MNHN).

Other material. (3 total) 1 male “Bańado Tucam. Weiser / Col. C. BRUCH / Mus. Arg. Cs. Nat. ” (dissected, MACN) ; 1 male “ La Cienega (Belén) Catamarca I. 1926 Weiser Wolters leg. / Col. C. BRUCH / Mus. Arg.Cs. Nat. ” (dissected, MACN) ; 1 male with same data as previous specimen except date “ XII. 1925 ” (not dissected, MACN) .

Figures

Figures 28–33. Austronausibius wagneri (Grouvelle). 28) Habitus, small male. 29) Antenna, enlarged. 30) Abdominal ventrite (right half). 31) Metafemur, part showing tooth. 32) Head and pronotum of large male. 33) Habitus, female holotype. Scale lines for Figures 28 and 32–33 = 2.0 mm.

Figures 34–38. Austronausibius wagneri (Grouvelle), male genitalia and associated sternites. 34) Genitalia without internal sac. 35) Paramere, enlarged. 36) Median lobe enlarged. 37) Internal sac. 38) Sternites 8–9. Scale lines = 0.2 mm.