Podischnus agenor ( Olivier 1789 )

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 : 38-42

Podischnus agenor ( Olivier 1789)

( Fig. 72-76 )

Podischnus agenor Olivier 1789: 223

Scarabaeus barbicornis Latreille 1812: 201 (synonym)

Podischnus propinquus Prell 1911: 202 (synonym)

DESCRIPTION. Length: 30.0-45.0 mm (males); 28.5-40.3 (females). Width: 15.0-22.0 mm (males); 13.0- 19.0 mm (females). Color: Ligth to usually dark reddish brown.

Males. Head: Frons with long, recurved horn, surface smooth with few setae. Apex of horn acuminate and slightly expanded on posterior margin forming a tooth-like projection ( Fig. 72 ). Eye canthus rounded, narrow, surface punctate, anterior margin weakly crenulate. Clypeus with apex broadly emarginate. Antenna with 10 segments, club subequal in length to segments 2-7. Mandibles broad, slightly bidentate at apex. Pronotum: Surface usually smooth, with some punctures; lateral margins rugopunctate, punctures large. Majors with short to moderate, broad horn, horn with apex broadly emarginate. Apical area of fovea with dense, short, fine, reddish brown setae. Base with marginal bead. Minors not seen but presumably with typical reduction. Elytra: Sutural stria strongly impressed, median half with small, moderately dense punctures. Lateral margins with incomplete rows of moderate to large, ocellate punctures; punctures decreasing in size posteriorly. Pygidium: Surface finely rugulose, with small, moderately dense punctures. In lateral view, surface convex, flat in apical third. Legs: Protibia strongly quadridentate, teeth nearly perpendicular to shaft of tibia ( Fig. 73 ), distance between 2 apical teeth less than distance between other teeth. Apex of posterior tibia with 2 teeth. Metatarsus with apex of first tarsomere long, spine-like. Venter: Prosternal process short, apex rounded, anterior surface flat. Parameres: Long, slender, base acuminated, apex rounded ( Fig. 74-75 ).

Females. As males except in the following respects: Head: Frons and clypeus with surface strongly rugopunctate. Frons with a tubercle between eyes. Pronotum: Surface rugose in anterior half and at sides, median half with some punctures. Tubercles or prominences lacking. Pygidium: Surface with small, moderately dense setae. In lateral view, dorsal half weakly convex, apical half weakly concave.

DIAGNOSIS. Podischnus agenor is easy recognized by the four teeth of the protibia projecting at nearly right angles from the tibia. This is the only Neotropical genus of Oryctini that has this configuration of protibial teeth. The long, subparallel body form is another character that helps to identify P. agenor .

DISTRIBUTION. Podischnus agenor is widely distributed, occurring from southern Mexico, Central America, Colombia, Perú, Ecuador to northern Brazil.

LOCALITY RECORDS. ( Fig. 76 ) 185 specimens examined (129 males, 56 females). Specimens were seen from the following collections : MZSP, MPEG, IBSP.

ACRE (2): Feijó, Tarauacá . AMAZONAS (176): Benjamin Constant ( Rio Javari ) , São Paulo de Olivença (Rio Solimões), Tabatinga . PARA (6): Cachimbo, Itaituba (Santaremsinho), Óbidos, Tucurui ( Rio Tocantins) . RONDÔNIA (1): Porto Velho .

TEMPORAL DISTRIBUTION. January (1), March (1), April (2), May (1), July (7), September (142), October (4), November (26), December (1).

BIOLOGY. Usually the adults of P. agenor are abundant before the beginning of the rainy season and are more active at night ( Ratcliffe 2003). This species causes great damage to sugarcane. The adults of both sexes, but especially the males, perforate the stems and excavate burrows in the median and superior areas. They use the mandibles to burrow into the plant tissues, and the pronotal and head horns help to penetrate the stem ( Eberhard 1979). The life cycle can last one year. The larva grows in the soil where it feeds on organic matter ( Eberhard 1979; Mendonça 1996). The pupa is also found in the soil. The larva develops for 4-8 months, and the pupa 2-3 months ( CENGICAÑA 2004).

The males emitted a pheromone or pungent odor, seemingly to attract females. When the female is attracted, she is often allowed to enter the burrow to feed. Combat between males occurs when another male is attracted ( Eberhard 1979). Podischnus agenor has been noted as a pest of Bambusa vulgaris Schrad in Guatemala ( Francis 1993), Bambusa guadua Humboldt and Bonpland , and Guadua angustifolia Kunth in Colombia ( Rojas 1991). It is a pest of sugarcane in Venezuela ( Rincones et al.

1991). The larvae of P. agenor are parasitized by the wasp Pelecinus polyturator Drury ( Hymenoptera : Pelecinidae ) ( Arias-Pena 2003).

In Brazilian Amazonia, P. agenor has been collected from semi-humid ombrophilous forests,

degraded vegetation areas, and floodplain areas at elevations ranging from 10-400 meters.

Podischnus sexdentatus ( Taschenberg 1870) Figure 77-78. Podischnus sexdentatus . 77) Parameres frontal view. 78) Parameres lateral view.

(Fig. 77-79)

Heterogomphus sexdentatus Taschenberg 1870: 186

Podischnus beckeri Sternberg 1907: 347 (synonym)

DESCRIPTION. Length: 35.0-47.0 mm (males); 40.5-46.3 mm (females). Width: 15.5-20.0 mm (males); 14.0- 19.7 mm (females). Color: Light to usually dark reddish brown.

Males. Head: Frons in majors coarsely rugopunctate except for smooth area along midline behind base of horn. Minors with frons longitudinally rugopunctate either side of median smooth area. Majors with long, recurved horn; horn acuminate at apex and with distinct swelling on posterior edge below apex. Male minors with small, recurved horn. Clypeus with apex broadly emarginate. Antenna with 10 segments, club subequal in length to segments 2-7. Mandibles broad, bidentate at apex. Pronotum: Surface in majors with large, scallop-shaped punctures on sides that extend to base of horn. Central third with small, sparse punctures and impressed groove extending from base of horn to anterior margin; groove with dense, moderately large punctures. Surface in front of posterior angles and base with small, sparse punctures. Anterior 2/3 weakly concave, posterior third with short, broad horn; horn projecting forward, apex broadly emarginate, venter concave and with dense, short, reddish brown setae. Base with marginal bead. Minors similar but with horn reduced to prominent tubercle, and punctures surrounding discal convexity denser, many confluent. Elytra: Majors with surface finely shagreened, with strongly impressed sutural stria, and with 3-5 short to moderate rows of large, ocellate punctures behind humerus on sides, punctures decreasing in size posteriorly. Minors similar. Pygidium: Surface transversely rugulose. In lateral view, surface convex in basal third, nearly flat elsewhere. Minors in basal third often with sparse, small punctures replacing rugosity. Legs: Protibia strongly quadridentate, teeth nearly perpendicular to shaft of tibia, distance between 2 apical teeth less than distance between other teeth. Metatibia with 3 (usually) or 4 strong teeth at apex. Metatarsus with apex of first tarsomere long, spine-like. Venter: Prosternal process subtriangular, with rounded apex, anterior surface flat. Parameres: Similar to those of P. agenor (Fig. 77-78).

Females. As males except in following respects: Head: Frons and clypeus coarsely rugose, frons with strong tubercle between eyes. Pronotum: Surface coarsely rugose in anterior fourth and at sides; elsewhere with small, sparse punctures. Armature absent. Elytra: Surface with large, dense punctures; punctures small and sparse in first interval, along lateral margins, and near apices. Pygidium: Surface with small, sparse to moderate punctures. In lateral view, basal third weakly convex, apical two-thirds weakly concave.

DIAGNOSIS. The adults of P. sexdentatus may be confused with P. agenor . In males, the punctures on the sides of the pronotum in P. sexdentatus extend to the base of the horn, while in P. agenor the pronotum is smoother and the punctures on the sides of the pronotum do not extend to the base of the horn. The prosternal process in P. sexdentatus is longer than in P. agenor .

DISTRIBUTION. Podischnus sexdentatus is known from Colombia and the Amazon region of Perú and Brazil ( Endrödi 1976, 1985).

LOCALITY RECORDS. ( Fig. 79 ) 7 specimens examined (3 males, 4 females). Specimens were seen from the following collections : INPA, UNSM.

ACRE (5): Cruzeiro do Sul. AMAZONAS (2): Manaus (AM 010 km 45, AM 60 km 23 Fazenda Esteio).

TEMPORAL DISTRIBUTION. February (1), May (1), September (5)

BIOLOGY. Nothing is known of the life history of P. sexdentatus . In Brazilian Amazonia, this species has been collected from areas of secondary vegetation and floodplain areas.

Figures

Figure 76. Distribution of Podischnus agenor in Brazilian Amazonia.

Figure 79. Distribution of Podischnus sexdentatus in Brazilian Amazonia.

Figure 72-75. Podischnus agenor. 72) Male head and pronotum. 73) Protibia (scale line: 5 mm). 74) Parameres frontal view. 75) Parameres lateral view (scale line: 2 mm).