Coelosis biloba ( Linnaeus 1767 )

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 : 8-11

Coelosis biloba ( Linnaeus 1767)

( Fig. 8-13 )

Scarabaeus biloba Linnaeus 1767: 544

Geotrupes bilobus Fabricius 1801: 7 (redescription)

Coelosis biloba Hope 1837: 82 (redescription)

Coelosis biloba lepesmei Bourgin 1944: 129 (unavailable name, described as aberration of C. biloba biloba )

Coelosis biloba incana Bourgin 1944: 129 (unavailable name, described as aberration of C. biloba biloba )

Coelosis biloba cacica Bourgin 1944: 131 (unavailable name, described as aberration of C. biloba biloba )

Coelosis biloba tibialis Bourgin 1944: 132 (synonym, described as subspecies)

Coelosis biloba tibialis pauliani Bourgin 1944: 134 (unavailable name, described as variation of C. biloba tibialis )

DESCRIPTION. Length: 29.5-37.8 mm (males); 25.6-35.5 mm (females). Width: 15.41-19.8 mm (males); 13.41-18.7 mm (females). Color: Shiny reddish brown.

Males. Head: Horn short to long, recurved; apex acuminate, posterior margin with small, tooth-like swelling near apex. Eye canthus rounded at apex, anterior margin crenulate with row of setae. Clypeus elongate, subtriangular, surface strongly rugose, apex with 2 teeth. Mandibles with 3 strong, sharp teeth. Antenna with 10 segments, club subequal in length to segments 2-7. Pronotum: Surface smooth in anterior third, with small punctures. Sides strongly rugose, central region smooth. Male majors ( Fig. 9 ) with large, broad, bifurcate, dorsally flattened (almost laminar) horn on posterior half of pronotum. Male minors with horn variably reduced. Anterior angles elongated. Fovea prominent, surface smooth. Elytra: Surface with 5 punctate striae, punctures deep, oblong, ocellate. Sides similar. Pygidium: Surface convex at base in lateral view, without setae, densely punctate and slightly wrinkled. Apex with small setae. Legs: Protibia elongate, slender, lateral edge with 3 subequally spaced teeth. Apex of posterior tibia weakly crenulate, without teeth. Posterior tarsus with apex of first tarsomere triangularly produced. Venter: Prosternal process short, rounded, anterior half without setae, with a pronounced furrow. Parameres: Broad, apices obtusely acuminated, upper third convex with lateral striae, central third concave, lower third broad ( Fig. 11-12 ).

Females. As males except in the following respects: Head: Frons with surface totally rugose. Pronotum: Surface without horns or tubercles, sides with deep punctures, discal area smooth ( Fig. 10 ). Pygidium: Surface with dense, small punctures.

DIAGNOSIS. Coelosis biloba is easily recognized by its clypeus that has two strong teeth, the tridentate mandibles, elytra with rows of punctures, and a broad, horizontal, bifurcate pronotal horn.

DISTRIBUTION. Of the seven 7 species in the genus, Coelosis biloba has the largest distribution, occurring from central Mexico to southern Argentina.

LOCALITY RECORDS. ( Fig. 13 ) 144 specimens examined (89 males, 55 females). Specimens were seen from the following collections : INPA, CZPB, MZSP, MPEG, UNSM.

ACRE (11): Cruzeiro do Sul, Feijó, Purús, Rio Branco, Tarauacá. AMAPÁ (2): Mazação. AMAZONAS (92): Barcelos, Benjamin Constant (Rio Javarí), Carauari (Porto Gavião), Coari (Rio Urucu), Itacoatiara (Fazenda Aruanã, Am 10 km 215), Itamarati (Monte Calavário), Juruá (Mineruazinho), Manaus (Am 10 km 26, Am 60 km 23, BR 164 km 130, BR 174 km 60, INPA, Reserva Ducke), Maraã (Rio Japurá Maguari), Novo Airão (Refúgio Arambóia), Novo Aripuaná, Presidente Figueredo (Rio Urubu), Parque Nacional do Jaú, São Gabriel da Cachoeira (Querari), São Paulo de Olivença (Rio Solimões), Taracuá (Rio Uaupés), Tefé. MATO GROSSO (5): Aripuaná, Barra do Tapirapé, Reserva Humboldt, Xingú. PARÁ (25): Abaetutuba, Belém, Benevides, Cachimbo, Itaituba (Rio Tapajós), Óbidos (Canta Galo), Redenção (Ribeirão de Fogo), Parauapebas (Serra Norte: Manganês, Pojuca), Tapana. RONDÔNIA (6): Príncipe da Beira, Porto Velho (Rio Madeira). RORAIMA (3): Ilha de Maracá, Pacaraima.

TEMPORAL DISTRIBUTION. January (14), February (7), March (15), April (12), May (11), June (11), July (14), August (9), September (3), October (8), November (29), December (11).

BIOLOGY. Adults are nocturnal and attracted to lights, especially mercury vapor lights and ultraviolet lights, during the first months of the year, when the populations of beetles are high. Females of C. biloba lay eggs in leaf mulch of the preparation chambers of leafcutter ants, Atta sexdens (L.). The eggs are transported by the ants to the fungus gardens, where the scarab larvae feed on the organic matter that grows there ( Eidmann 1937). Coelosis biloba has also been found in nest of Atta cephalotes (L.), Atta mexicana (Smith) ( Bruch 1917; Navarrete-Heredia 2001) and Atta columbica Guerin ( Neita et al. 2006) . Pardo-Locarno et al. (2006) found larvae, pupae, and pre-pupae in the nest of Atta sp. in Colombia. The larvae of C. biloba may be parasitized by wasps of the genera Campsomeris Guérin and Scolia Fabricius ( Hymenoptera : Scoliidae ), which visit the nests of A. sexdens ( Pardo-Locarno et al. 2006) . They also observed cannibalism by adults feeding on third instar larvae. Adults can occasionally be collected with Malaise traps or with flight intercept traps.

In the Brazilian Amazon, this species is associated with degraded ecosystems dominated by plants of genus Vismia Vandelli , agriculture areas, semi-humid ombrophilous forests, savannahs, and flooded areas. It is found from the sea level to 400m.

Figures

Figure 13. Distribution of Coelosis biloba in Brazilian Amazonia.

Figure 8-12. Coelosis biloba. 8) Habitus. 9) Male head and pronotum (scale line: 5 mm). 10) Female pronotum dorsal view. 11) Parameres frontal view. 12) Parameres lateral view (scale line: 1 mm).