Oruscatus opalescens (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini) es un escarabajo coprófago, de distribución neotropical, que se encuentra ocasionalmente en colecciones y del cual se conoce muy poco su biología. En este estudio se reunió la información disponible sobre esta especie, a través del inventario de los ejemplares disponibles en colecciones entomológicas, incluyendo los de colecta reciente, y revisión de literatura. Se examinaron 107 ejemplares de nueve colecciones; 73 fueron de Colombia, 29 de Ecuador, y cinco de procedencia incierta. El rango altitudinal de la especie se estableció entre los 2.000 a 3.000 m, en el cual se asocia al estiércol, en especial de grandes mamíferos domésticos y silvestres.

Oruscatus opalescens (Coleoptera: Scarabaeidae: Scarabaeinae: Phanaeini), is the dung beetle species scarcely found in collections and very few is known about its biology. This study summarizes the available information about this species, through inventory of specimens in collections, including those more recently collected, and literature review. One hundred-seven specimens were found, in nine collections: 73 from Colombia, 29 from Ecuador and five of unknown origin. An altitudinal range of the species was established between 2,000 and 3,000 m, especially associated to large domestic and wild mammals.

The redescription of Dichotomius camposeabrai Martinez, 1974 and D. nemoricola (Pereira, 1942) is presented, including the description of the female of the first species and the male of the second so far unknown. For each species, illustrations of the male habitus, male genital organ, the sclerites of internal sac and head and pronotum of female are presented. Information about geographical distribution and some comments are available. In addition the transfer of D. camposeabrai to the bitiensis group is proposed and discussed, given the similarities of the external morphology and male genital organ with those of D. nemoricola.

Se presentan redescripciones de Dichotomius camposeabrai Martínez, 1974 y D. nemoricola (Pereira, 1942) que incluyen la descripción de la hembra de la primera especie y del macho de la segunda, hasta ahora desconocidos. Para cada especie se realizaron ilustraciones del habitus del macho, del órgano genital masculino y de los escleritos del saco interno, así como de la cabeza y pronoto de las hembras. Se proporcionan datos sobre la distribución geográfica y algunos comentarios de las especies. Además, se propone y discute la transferencia de D. camposeabrai al grupo bitiensis, dadas las similitudes de la morfología externa y del órgano genital masculino que presenta con D. nemoricola.

Este estudo disponibiliza dados sobre a fauna de Scarabaeinae que ocorre em plantio de eucalipto inserido em uma área originalmente aberta, citando quais espécies conseguem se estabelecer neste ambiente introduzido e sombreado. O levantamento de Scarabaeinae foi realizado em uma área de monocultura de eucalipto com armadilhas de interceptação de voo e armadilhas de queda iscadas com fezes humanas, banana em decomposição e carcaça, entre os meses de dezembro de 2005 e novembro de 2006. Foram capturadas 28 espécies pertencentes a 11 gêneros. Destas, 11 já foram registradas em ambientes de campo e mata nativa da região, outras 11 apenas em campo nativo, duas mostraram-se exclusivas ao plantio de eucalipto e quatro não foram identificadas a nível específico, o que não possibilitou a obtenção de maiores informações sobre registros em ecossistemas naturais da região. Os resultados obtidos mostraram que as espécies que ocorrem em eucalipto são generalistas em relação ao hábitat, apresentam preferência por ambientes sombreados e/ou são espécies "turistas". Este, contudo, representa um dos poucos levantamentos realizados na região e por isso, novos estudos são necessários a fim de obter maiores informações acerca da distribuição e resposta dos escarabeíneos aos sistemas naturais e antropizados.

This study provides data about the Scarabaeinae fauna that occurs in a eucalyptus plantation inserted in an originally open area, describing which are able to establish themselves in this introduced and shaded environment. The survey was carried in an area of eucalyptus monoculture using flight intercept and pitfall traps baited with human feces, rotten banana and carcass, from December 2005 to November 2006. Twenty-eight species were collected, belonging to 11 genera. Of these 28 species, 11 have been previously recorded in grassland and native forest environments of the region, 11 only in grasslands, two were exclusive of eucalyptus plantations and four were not identified at the specific level, which did not allow the achievement of more information on these species in the natural ecosystems of the region. The results showed that species that occur in eucalyptus are habitat generalists, have preference for shaded environments and/or are tourist species. This, however, is one of the few surveys performed in the region. Therefore, additional studies are necessary to obtain more information about the distribution and response of dung beetles to natural and anthropogenic ecosystems of the region.

Ecological theory of habitat heterogeneity and limited niche-similarity assumes that more heterogeneous environments provide a greater amount and diversity of resources than simple environments, resulting in a greater diversity of species. This study aimed to evaluate the effect of the habitat heterogeneity on the richness of dung beetles and to examine the spatial patterns of assemblage structure in relation to patterns of habitat heterogeneity. Dung beetles were collected using pitfall traps without bait in 30 points distributed in an area of cerrado sensu lato, in the region of Tangará da Serra, MT, Brazil, including areas of cerrado sensu stricto, campo sujo, cerradão and gallery forest. A total of 1,291 dung beetles were collected, distributed in 16 genera and 29 species. Overall habitat heterogeneity exerted a negative effect on patterns of dung beetles richness. Higher levels of species richness were observed in areas of cerrado campo sujo, while the areas of gallery forest were the most species poor. Regarding assembly structure, it was found that the dung beetles were separated into two major groups, one formed by the presence of specialized species in forest areas and other composed of species that occurred predominantly in cerrado. In conclusion, it was found that habitat complexity influenced the distribution of dung beetles, but the level of turnover in species composition along the heterogeneity gradient was relatively weak.

In a tropical forest patch of Southeastern Brazil, adult Scarabaeidae beetles were used to test the hypothesis that fungivorous guilds have a higher proportion of generalist species than either frugivorous, necrophagous or coprophagous ones. No significant differences were found between guilds in relation to either the proportion of generalists or niche breadths of the component species. Only two fungivorous specialist species were sampled. These results indicate that sporocarps eaten by Scarabaeidae are not as rare as literature suggests. Fungi may help maintain high species diversity of Scarabaeidae in tropical forests.

En un fragmento de bosque tropical en Minas Gerais, sureste de Brasil, se estudió la proporción de generalistas en escarabajos adultos de la familia Scarabaeidae. A partir de los resultados obtenidos, se rechazó la hipótesis de que el gremio de los fungívoros de escarabeidos adultos tendría una mayor proporción de generalistas que los gremios frugívoro, necrófago o coprófago. No se encontraron diferencias significativas entre los gremios, ni en relación a la proporción de generalistas, ni en la amplitud de nicho de sus especies componentes. Solo dos especies fungívoras especialistas se encontraron en este estudio. Aunque se trata de un caso puntual, este resultado indicaría que los esporocarpos consumidos por miembros de la familia Scarabaeidae no son tan raros como lo sugiere la literatura. Posiblemente, los hongos ayuden al mantenimiento de la diversidad de Scarabaeidae en bosques tropicales americanos, donde no hay abundancia de excrementos de grandes mamíferos.