Abstract The enigmatic genus Stenocrates Burmeister has 52 species that are widely distributed from Mexico to Argentina, but mainly in South America. In the present study, the larva of the third instar and pupa of Stenocrates agricola Dechambre & Hardy, 2004 are described and illustrated based on specimens from Argentina, this being the first description of immatures for the genus. The adult is also redescribed, significantly expanding the number of characters and providing information on the natural history of this species. In addition, 28 species of Cyclocephalini and 20 species of Pentodontini are morphologically compared, emphasizing the most useful larval characters used among these beetles. Stenocrates agricola shows frequent and common characters of Pentodontini species but scarce (and even absent) characters typical of Cyclocephalini species, including some considered diagnostic for this tribe. Accordingly we consider that the tribal position of Stenocrates remains controversial and more study is needed to clarify the tribal status of Stenocrates. We believe that larval morphology provides important information in systematics studies that can clarify tribal relationships within the Dynastinae.

Dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) compete intensively for dung resources, and most species forage in the understory. Here, we describe the unique behavior of one dung beetle species, Canthon aff. quadriguttatus (Olivier), associated with two species of monkeys from Peru. We observed this beetle species on the genital and anal regions of the brown titi monkey, Callicebus brunneus (Wagner), and subsequently falling with dung as the monkeys defecated. The same association was also observed with the bald-faced saki monkey, Pithecia irrorata irrorata (Gray). Using the " sit and wait" at the source behavior, C. quadriguttus may arrive first at the dung resource, possibly out-competing other dung beetle species. This paper is the first report of this behavior for C. aff. quadriguttatus on the brown titi monkey and bald-faced saki monkey from southeastern, Amazonian Peru. We discuss this behavior in the context of competition and resource partitioning, and also speculate as to why C. aff. quadriguttatus has been found on both monkey species.

Los Escarabajos del estiércol (Coleoptera: Scarabaeidae: Scarabaeinae) compiten intensamente por excrementos, un recurso escaso por el cual muchas especies forrajean en el sotobosque en bosques tropicales. En este artículo describimos el comportamiento particular de una especie de escarabajo del estiércol, Canthon aff. quadriguttatus (Olivier), asociado a dos especies de primates en Perú. Observamos esta especie de escarabajo en la región genital y anal de monos " tocones" , Callicebus brunneus (Wagner), y subsecuentemente cayendo con excrementos que los monos defecaron. De manera similar, observamos individuos de esta especie de escarabajo asociados a monos " huapos" , Pithecia irrorata irrorata (Gray). Mediante un comportamiento de " sentarse y esperar" a la fuente, C. aff. quadriguttatus llega primero a la fuente de excremento y aparentemente supera a otras especies de escarabajos en la competencia por el mismo recurso. Este artículo representa el primer registro de C. aff. quadriguttatus en asociación a dos especies de primate en la Amazonía del sureste de Perú. Discutimos este comportamiento en el contexto de competencia y distribución de recursos y especulamos sobre la razón por la cual este escarabajo está asociado a ambas especies de primates.

The larva and pupa of Aspidolea singularis (Scarabaeidae: Dynastinae: Cyclocephalini) are described for first time based on specimens from Colombia. A key to the known third instar larvae of genera in the tribe Cyclocephalini is included. Data on the larval biology of Aspidolea singularis are provided.

The knowledge of the diversity of scarabs in Colombia in some areas is still very little studied, in order to extend this information the fauna of Scarabaeidae (Pleurosticti) of the lowlands of the tropical rain forest of the Choco-Biogeografico zone was characterized, during the years 2001-2003. Five sampling sites with different composition and degrees of intervention were selected (primary forest, secondary forest, high stubble and agroforestal parcels), corresponding to the municipalities of Itsmina, Lloró, Quibdó, Tado and Union Panamericana, located between the 43 and 150 meters. The capture of the scarabs was made manually and with the use of nets, black light and modified coke-traps, rotten trunk of Brosimum utile H.B.K, Lecythis ampla Miers, Pouteria caimito Radlk, Apeiba aspera Aubl., Inga spp., Cedrela odorata L. and Jacaranda hesperi Dugand among others were explored. A total of 17,840 specimens in 65 species, distributed in 4 subfamilies, 12 tribes and 38 genera were collected. Pelidnota chiriquina Bates, Spodochlamys cupreola Bates, Gymnetis pardalis (G & P), Gymnetis vandepolli (Bates), Hoplopyga ocellata (G & P) and Guatemalica hueti (Chevrolat) are record for Colombia for the first time. The richest subfamily in number of species was Dynastinae with 26 species, followed of Rutelinae with 25, Cetoniinae with 11 and Melolonthinae with 3 species. The richest genera were: Cyclocephala Dejean, 1821: C. amazona (Linné), C. carbonaria Arrow, C. melanocephala (Fabricius), C. pardolocarnoi Dechambe y C. fulgurata Burmeister; Anomala Samouelle, 1819: Anomala cincta Say, A. medellina Ohaus, A. undulata Melsheimer; Gymnetis MacLeay, 1819: Gymnetis coturnix (Burmeister), G. stellata (Latreille), G. holosericea (Voet) and Rutela Latreille, 1802: Rutela heraldica Perty, R. pygidialis Ohaus y R. sanguinolenta Waterhouse. A taxonomic key to identify the 65 species gathered is included. Biological and ecological comments for these species are also provided.

Con el objetivo de ampliar el conocimiento de la diversidad de escarabajos en Colombia en áreas hasta ahora poco estudiadas, se caracterizó la fauna de Scarabaeidae (Pleurosticti) de la selva baja del bosque pluvial tropical del Chocó-Biogeográfico colombiano, durante los años 2001-2003. Se seleccionaron cinco sitios de muestreo en ecosistemas con diferentes procesos de intervención (bosque primario, bosque secundario, rastrojo bajo y dos parcelas agroforestales), correspondiente a los municipios de Itsmina, Lloró, Quibdó, Tadó y Unión Panamericana, ubicados entre los 43 y 150 metros de altitud. La captura de los escarabajos se realizó mediante jama, trampas de luz negra, captura manual y carpotrampas modificadas. Igualmente, se exploraron troncos en proceso de descomposición de las especies vegetales como Brosimum utile H.B.K, Lecythis ampla Miers, Pouteria caimito Radlk, Apeiba aspera Aubl., Inga spp., Cedrela odorata L. y Jacaranda hesperi Dugand entre otros. Se colectaron e identificaron un total de 17,840 especímenes pertenecientes a 65 especies, distribuidas en 4 subfamilias, 12 tribus y 38 géneros. La subfamilia con mayor número de especies fue Dynastinae con un total de 26 especies, seguida de Rutelinae con 25, Cetoniinae con 11 y Melolonthinae con 3 especies. De estos Pelidnota chiriquina Bates, Spodochlamys cupreola Bates, Gymnetis pardalis (G & P), Gymnetis vandepolli (Bates), Hoplopyga ocellata (G & P) y Guatemalica hueti (Chevrolat) son nuevos registros para Colombia. Los géneros con mayor riqueza de especies fueron: Cyclocephala Dejean, 1821: C. amazona (Linné), C. carbonaria Arrow, C. melanocephala (Fabricius), C. pardolocarnoi Dechambe y C. fulgurata Burmeister; Anomala Samouelle, 1819: Anomala cincta Say, A. medellina Ohaus, A. undulata Melsheimer; Gymnetis MacLeay, 1819: Gymnetis coturnix (Burmeister), G. stellata (Latreille), G. holosericea (Voet) y Rutela Latreille, 1802: Rutela heraldica Perty, R. pygidialis Ohaus y R. sanguinolenta Waterhouse. Se incluye una clave taxonómica para la identificación de las 65 especies. Se aportan comentarios de la biología y ecología de las especies observadas.

Resumo Trichillum hirsutum Boucomont (Coleoptera: Scarabaeidae: Scarabaeinae) é redescrito porque a descrição original estava errada. Apresentam-se novos registros de distribuição no Brasil para Trichillum hirsutum Boucomont, ipselissus alvarengai Pereira and Martinez (novos registros do estado), Trichillum boucomonti Saylor, e Cryptocanthon peckorum Howden (novos registros do país).

Abstract Trichillum hirsutum Boucomont (Coleoptera: Scarabeidae: Scarabaeinae) is redescribed because of errors in the original description. New distribution records are presented for Trichillum hirsutum Boucomont, Ipselissus alvarengai Pereira and Martinez (new state records); and Trichillum boucomonti Saylor and Cryptccanthon peckorum Howden (new country records for Brazil).

Abstract Six new species of Stenocrates (Scarabaeidae: Dynastinae) are described from the Amazon Basin of Brazil: S. rionegroensis, S. varzeaensis, S. inpai, S. amazonicus, S. ariasi, and S. laceyi. The females of S. haackae Ratcliffe and S. popei Endrödi are reportd for the first time and briefly characterized. Stenocrates popei is listed from Brazil and constitutes a new country record.

Resumo É descrita uma nova espécie de Troginae — Trox juglans (Coleoptera: Scarabaeidae) da Bacia Amazônia brasileira. Foram encontradas novas localidades de distribuição para as espécies Trox fulglnosus Robinson, T. loxus Vaurie. T. punctatus Germar, T. tomentosus Robinson, e T. variolatus Melsheimer.

Abstract Trox juglans is described as new from the Amazon Basin in Brazil, and new distribution records are given for Trox fulginosus Robinson, T. loxus Vaurie, T. punctatus Germar, T. tomentosus Robinson, and T. variolatus Melsheimer.

Resumo Quatro novas espécies de Cyclocephalini (Coleoptera: Scarabaeidae) são descritas. Estas são: Aspidolea lindae, da Colômbia; Mimeoma englemani, do Panamá; Stenocrates rabbanii, do Brasil; e Stenocrates haacki, também do Brasil.

Abstract Four new species of Cyclocephalini are described. These are Aspidolea lindae from Colombia, Mimeoma englemani from Panamá, Stenocrates rabbanii from Brazil, and Stenocrates haacki, also from Brazil.