Scapomegas gibbus Marseul, 1855

Leivas, Fernando W. T., Bicho, Carla L., Degallier, Nicolas & Moura, Daniel P., 2012, Revision of the genus Scapomegas Lacordaire, 1854 (Coleoptera: Histeridae: Omalodini), Zootaxa 3482, pp. 33-46 : 44

Scapomegas gibbus Marseul, 1855

Scapomegas gibbus Marseul, 1855: 132 –133 (original description); Marseul, 1887: CXXV (as S. gibbosus ); Mazur, 2010: 142 (new record of distribution); Santos et al., 2010 (ecological data); Mazur, 2011: 75 (catalogue).

Diagnosis. Pronotum with a short lateral stria, absent at the posterior region, anterior margin sinuous behind the head; elytra with outer subhumeral stria present on the posterior half; propygidium with strong punctuation on the anterior half and with few and strong points on the lateral and posterior margin, posterior region weakly elevated; 8th sternite in ventral view with only one, rarely two bristles on lateral-posterior region.

Redescription. Length (pronotum+elytra): 4.2–4.6 mm; elytral width: 3.8–4.24 mm.

Color dark or dark-brown. Basal segment of the antennal club with a concave region on the inner side. Anterior margin of pronotum sinuous behind the head ( Figs. 1 C; 5B); lateral stria widely interrupted at the posterior half ( Fig. 5 B). Prosternal lobe with strong punctuation laterally. Elytra with outer subhumeral stria present at the posterior half ( Fig. 2 B), inner subhumeral stria absent; 1st dorsal stria complete, 2nd dorsal stria not beginning at the anterior margin, 3rd dorsal stria weak and present only at the basal third, sutural stria complete ( Fig. 1 C). Mesosternum with marginal stria widely interrupted at the middle ( Fig. 1 D). Metasternum with lateral stria sometimes interrupted, postmesocoxal stria present. Middle and hind tibiae with the submarginal stria on the inner margin variable. Third visible abdominal sternite with strong punctuation and without a sulcus ( Fig. 1 D). Propygidium with strong punctuation on the anterior half and with fewer on the lateral and posterior margin; posterior region slightly elevated. Pygidium with strong punctuation at the anterior margin and angles ( Fig. 10 A). Male terminalia. Eighth sternite in ventral view usually with only one, rarely two bristles on lateral-posterior region ( Fig. 6 B). Basal margin of the parameres, in ventral view with a truncated emargination and in dorsal view with an acuminated or rounded emargination ( Fig. 7 B).

Remarks. Unlike what Marseul described for this species (3rd dorsal stria indicated only at the apex), we observed that the 3rd dorsal stria is present at the basal third. The pronotal punctuation can be slightly stronger on the sides in the population from the north of Paraná and Paraguay. The antescutellar stria is not present in this species as mentioned in its original description, S. gibbus presents a weak antescutellar fovea which can be represented by a vertical line but not a stria.

Distribution and ecological data. Currently known from elevations of 160–213 m in Paraguay and 0–650 m in Brazil. In Brazil the species is collected in Tropical Rain Forest and Seasonal Semideciduous Tropical Forest, both components from the Atlantic Forest biome.

Type material. The specimen labeled: “2 Scapomegas gibbus m 3 Rio-Jan ...63” (handwritten green round label) / “MUSEUM PARIS COLL. DE MARSEUL 2842-90 (printed label)” / ” TYPE (red printed label)” / 3 (handwritten)” is herein designed as the LECTOTYPE of the species. L = 3.48 mm; l = 3.22 mm ( MNHN). The specimen labeled: "G. Lewis Coll. B.M. 1926-369" (printed) / " Scapomegas gibbus m…Jan…" (handwritten on green paper, in part illegible) / "Marseul's type fr. Coll. Chrevolat [sic]" (Lewis's handwriting) / " Type " (redbordered printed, circular, Museum label) is herein designated as a PARALECTOTYPE ( BMNH).

Additional examined material. BRAZIL: Minas Gerais, Viçosa, 20° 45’S 42° 53’W, FIT, X/1998, F. Z. Vazde-Mello col., 1 ex. ( SBMN); Espírito Santo, Conceição da Barra, 22/XI/1969, C. T. & C. Elias col., 1 ex.; Córrego Itá, W. Zikan col., XI/1954, 5 ex. ( MNRJ); Rio de Janeiro: Rio de Janeiro (Corcovado), XII/1959, Alvarenga & Seabra col. 1 ex.; Represa Rio Grande (Guanabara), 20/X/1967, F. Oliveira col., 1 ex. ( DZUP); Rio de Janeiro (Floresta da Tijuca), 15/XI/1985, E. D. Thocaz col., 3 ex. ( MPEG); Rio de Janeiro (Parque da Cidade), X/1991, 3 ex.; X/1991, A. Bello col., 1 ex. ( CPAB); Paraná, Ibiporã (Fazenda Doralice, I-1 D), 17/XII/2005, A. A. Santos col., 1 ex.; (Fazenda Doralice, B-1D), 30/XII/2005, A. A. Santos col. 1 ex.; (Fazenda Doralice, M-1D), 14/I/2006, A. A. Santos col., 6 ex.; (Fazenda Doralice, B-2D), 11/II/2006, A. A. Santos col., 1 ex.; (Fazenda Doralice, I-1 D), 25/III/2006, A. A. Santos col., 1 ex.; (Fazenda Doralice, B-1D), 08/IV/2006, A. A. Santos col., 1 ex.; (Fazenda Doralice, B-3D), 21/IV/2006, A. A. Santos col., 1 ex. ( DZUP). PARAGUAY: Caazapa (Estero Cristal), 20-25/XI/ 1999, J. Jensen col., 5 ex.; Concepcion (Cororo), 23/XII/1999, C. Aguilar col., 2 ex. ( SBMN).

Figures

FIGURE 1. Dorsal and ventral habitus. A – B. Scapomegas auritus Marseul; C – D. Scapomegas gibbus Marseul; E – F. Scapomegas aurifer Marseul. Scale 1 mm.

FIGURE 2. Lateral habitus. A. Scapomegas auritus Marseul; B. Scapomegas gibbus Marseul; C. Scapomegas aurifer Marseul. Scale 1 mm.

FIGURE 5. Pronotum. A. Scapomegas auritus Marseul; B. Scapomegas gibbus Marseul; C. Scapomegas aurifer Marseul. Scale 1 mm.

FIGURE 6. Eighth sternite of the male terminalia with detail of the bristles on the sides of the posterior margin (A – C, scale 0.5 mm and 0.125 mm, respectively) and ninth sternite and tergite (D – F, scale 0.5 mm). A, D. Scapomegas auritus Marseul; B, E. Scapomegas gibbus Marseul; C, F. Scapomegas aurifer Marseul.

FIGURE 7. Aedeagus in ventral and dorsal view, respectively. A. Scapomegas auritus Marseul; B. Scapomegas gibbus Marseul; C. Scapomegas aurifer Marseul. Scale 0.5 mm.

FIGURE 10. Propygidium and pygidium in posterior view. A. Scapomegas gibbus Marseul; B. Scapomegas aurifer Marseul. Scale 0.5 mm.