Megaceras crassum Prell 1914

Alvarez, Héctor Jaime Gasca, da, Claudio Ruy Vasconcelos, Fonseca & Ratcliffe, Brett C., 2008, Synopsis of the Oryctini (Coleoptera: Scarabaeidae: Dynastinae) from the Brazilian Amazon, Insecta Mundi 2008 (61), pp. 1-62 : 28-29

Megaceras crassum Prell 1914

( Fig. 46-50 )

Megaceras crassum Prell 1914: 213

Megaceras punctatostriatum Prell 1934: 57 (synonym)

DESCRIPTION. Length: 37.1-42.5 mm (males); 29.5 mm (females). Width: 23.1-25.1 mm (males); 18.2 mm (females) (Species range for females. Length: 31.0- 38 mm ( Endrödi 1985)). Color: Black.

Males. Head: Frons with recurving horn; horn weakly bilobed at apex, posterior margin of horn with small, tooth-like swelling near apex ( Fig. 46 ). Eye canthus with rounded apex, anterior margin weakly crenulate. Clypeus truncate, reflexed, surface punctate ( Fig. 47 ). Antenna with 10 segments, club subequal in length to segments 2-7. Mandibles with 2 teeth, external tooth elongated, internal tooth truncate with apex subquadrangular. Pronotum: Prominence moderately high, bifurcated, apex with 2 small, subparallel horns, curving downward ( Fig. 46 ). Surface almost smooth, opaque, with sparse punctures, lateral margins with a band of spaced rugae, rugae connected to areola apposita. Scutellum: Smooth , triangular, apex rounded. Elytra: Smooth or with micropunctures. Sutural stria impressed, wrinkled. Pygidium: Surface punctate to finely punctate. Base with a band of long setae. Lateral angles finely rugose. In lateral view, surface convex. Legs: Protibia tridentate. Apex of posterior tibia with a spur. First tarsomere of posterior tarsus triangular, apex extend into long spine. Venter: Prosternal process high, slightly convex, apex rounded. Parameres: Circular, sides strongly curved, apex slightly curved ( Fig. 48-49 ).

Females. As males except in the following respects: Head: Frons with single, strong, conical tubercle at middle, surface rugose. Pronotum: Surface smooth, 2 strong, acuminate tubercles behind anterior margin, with a slight furrow between them, sides punctate.

DIAGNOSIS. Adults of M. crassum can usually be recognized by the small size of the body, horns of pronotum parallel to subparallel, and the circular form of parameres. Males of M. crassum could be confused with the males of M. laevipenne , and only the form of the parameres can separate these two species.

DISTRIBUTION. Megaceras crassum is widely distributed in Ecuador, Peru, Colombia, Bolivia and southern Brazil. The specimens listed below from Amazonas and Pará states represent NEW RECORDS from the Brazilian Amazon.

LOCALITY RECORDS. ( Fig. 50 ) 7 specimens examined (6 males, 1 female) Specimens were seen from the following collections : MZSP and UNSM.

AMAZONAS (6): Benjamin Constant ( Rio Javarí ); Hupda Maku (Serra dos Porcos), Taracuá . PARÁ (1): Cachimbo.

TEMPORAL DISTRIBUTION. June (2), July (2), August (1), September (1).

BIOLOGY. Little is known about the life history of this species. According to Dufour (1987), the Tukanoan Indians of the northwest Amazon in the Colombian Vaupes region eat the larvae of M. crassum , and these are preferred over the adults. In Brazilian Amazonia, this species has been collected from semi-humid ombrophilous forests and areas of seasonal whitewater inundation forest (várzea) at elevations of 60-400 meters.

Figures

Figure 50. Distribution of Megaceras crassum in Brazilian Amazonia.

Figure 46-49. Megaceras crassum. 46) Male head and pronotum (lateral view). 47) Male head (dorsal view) (scale line: 5 mm). 48) Parameres frontal view. 49) Parameres lateral view (scale line: 2 mm).