Synobius lobatus (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 : 3-4

Synobius lobatus (Grouvelle)

( Fig. 1–8 , 123 )

Nausibius lobatus Grouvelle 1896: 207 (type examined).

Synobius lobatus (Grouvelle) : Grouvelle 1913: 371.

Synobius reichenspergeri Nevermann (manuscript name, unpublished - see below).

Diagnosis. See S. lobicollis .

Description. This description, including measurements, is based on 7 specimens with data label information as recorded below. Length 4.60–5.24 mm; length to breadth ratio (breadth, maximum across elytra) 27.5–29.5:10.0; dark red-brown, moderately shining, sub-depressed; fine, short, recumbent golden pubescence present, most obvious on elytra.

Head. Breadth (across eyes) to length ratio, 14.1–16.3:10; punctures fine, setiferous; sides in front of eyes initially straight then forming obtuse angle, raised above antennal insertions; transverse, weakly arcuate impression across greater part of head between frons and vertex; clypeal region somewhat convex; temples absent; eyes small, separated dorsally by 10–12× width of eye in dorsal view; antennae, length to total body length ratio 10: 39–44, slightly clubbed, antennomere 11 (apical) very small, 8–10 (particularly 9 and 10) a little broader than 3–7 ( Fig. 3 ); ventral prominence beneath antenna slightly broader than that of S. lobicollis (see Fig. 12 for S. lobicollis ).

Pronotum. ( Fig. 1 , 7–8 ) Slightly to more obviously transverse (not trapezoidal in specimens seen), medial breadth to midline length, 10.6–13.8:10.0, transversely less convex than elytra; margins with narrow rim; anterior angles forming lobes, laterally rounded, in front slightly declivous, smaller compared with pronotum than lobes of S. lobicollis ; side margins of pronotum very shallowly, irregularly undulating; posterior angles only slightly produced; very shallow (inconspicuous) depressions on each side of disc towards anterior and posterior angles, a more obvious transverse depression towards base.

Tarsi. ( Fig. 2 ) Simple, not lobed, basal three tarsomeres each slightly smaller than previous one, tarsomere 4 very small, pretarsus about as long as basal three.

Elytra. Ratio of length to greatest breadth (latter across basal quarter), 18.2–17.4:10.0, gradually curved to apex from greatest breadth; very narrowly explanate at sides before marginal rim; not obviously striate, 9 rows of punctures present although obscured by rows of very fine golden, recumbent setae (3 rows between each row of punctures) originating in low tubercles; humeri with short, curved, impressed line. Scutellar shield with transverse ridge joining raised basal margin of elytra.

Male genitalia. Parameres ( Fig. 4–6 ) long, sides almost parallel for much of length, 6 × as long as broad, setae restricted to apical part, outer margin with longest setae (6 or 7 in specimens seen), apex with a few shorter setae, inner margin bearing much shorter and finer setae ( Fig. 6 ); median lobe longer than broad ( Fig. 4–5 ), gradually tapered from base to rounded apex, degree of taper variable, a few small fine setae across middle; median strut very broadly expanded and almost semi-circular at apex then strongly narrowed to basal bifurcation where one thirteenth of breadth across apex; tegminal struts also broad at their apical junction; about 16 rods on each side towards ostium; internal sac with spines and, near ejaculatory duct, sclerites as in S. lobicollis ( Fig. 16 ); sternites 8 and 9 similar to those of S. lobicollis ( Fig. 17 ), with caudal margins straight, mainly short setae along them, at corners a few long setae (3 or 4 in specimens examined).

Material examined. Holotype male “ Rio Grande do Sul / Type / TYPE / Museum Paris 1917 Coll.Grouvelle / lobatus ty Grouv [Grouvelle’s handwriting, black ink] / Synobius lobicollis Sharp v. prob . [handwritten, purple ink]” [dissected] ( MNHN).

Other material. (7 total) 7 specimens labelled by Nevermann “ Synobius Reichenspergeri new species m.” [manuscript name, unpublished] as follows: 1 male, “ Brasilien Est. Paraná Rio Negro 26. v. 36 slg. Nevermann [top of green label] Wilte O. F. M. col. Reichensperger ded. 10. viii. 36 [reverse of this label, all handwritten / Nest von Trigona [cream label, handwitten] / Cotype [pink print] / Synobius Reichenspergeri new species m. / det. Nevermann 1936 / 49 / Nevermann Collection 1940 / USNM 2045653” ( USNM); 4, including male and female mounted together plus two separately mounted females, sex written on the cards, all with data as above but without “49” and with date on top of green label “15. vii. 36” and that on reverse of this label “19. x. 36” ( USNM); 1 male, (on card male sign and “No. 94a”) “ Brasilien Est. Paraná Rio Negro 15. vii. 36 [top of green label] San Antonio Coleg. A. Reichensperger leg. Erh. 19. x. 36 [reverse of this label] / im Nest von Trigona / TYPE [red label] / Nevermann Collection 1940 / Synobius Reichenspergeri new species m. det. Nevermann 1936 / USNM 2045653” ( USNM); 1 male, genitalia mounted on a separate card beneath card point holding specimen “ Paraná Rio Negro 15. vii. 36 Collegia San Antonio [on top of green label] Erhalten 19.x. 36 A. Reichensperger leg. [on reverse of this label] / im nest von Trapua Bienc Trigona / Cotype [pink label] / Nevermann Collection 1940 / Synobius Reichenspergeri new species m. det. Nevermann 1936 / USNM 2045653” ( USNM).

Figures

Figures 1–6. Synobius lobatus (Grouvelle), male. 1) Habitus. 2) Metatarsus. 3) Antenna, enlarged (1–3 holotype). 4–6) Genitalia. 4–5) Parameres and median lobes to show variation. 4) Narrower median lobe, specimen from Brazil, Est. Paraná, Rio Negro. 5) Broader median lobe, holotype specimen from Brazil, Rio Grande do Sol. 6) Paramere, enlarged apical region. Scale lines for Figure 1 = 2.0 mm, for Figures 4 and 5 = 0.2 mm.

Figures 7–10. Synobius spp. pronota. 7–8) S. lobatus (Grouvelle). 7) Male, 8) Female. 9–10) S. lobicollis Sharp, both male. Scale line = 2.0 mm.

Figures 123–124. Color habitus photographs.123) Synobius lobatus (Grouvelle). 124) Pensus hirtus, new species.

Figures 11–17. Synobius lobicollis Sharp, male. 11) Habitus. 12) Head, anterior lateral region showing antennal base and eye. 13) Antenna, enlarged. 14–17) Genitalia and associated sternites. 14) Genitalia, without internal sac. 15) Paramere, enlargement of apical half. 16) Internal sac, apical third. 17) Sternites 8 and 9. Scale lines for Figure 11 = 2.0 mm, for Figures 14 and 16–17 = 0.5 mm.