RESUMO
Costa Rica emerged from the seas as a new geological territory during the Miocene as an insular archipelago. It later became part of a continental area once it became a segment of Central America. Two dung beetle genera that colonized this new territory from South and North America, Canthidium and Onthophagus (Coleoptera: Scarabaeidae: Scarabaeinae), are here studied, in the first analysis of a volcanic paleo-archipelago, colonized from its emergence, and then later becoming terra firma. To assess their biodiversity distribution patterns, we analyzed the effect of biogeography, ecosystem origins, and body size on their altitudinal distribution patterns in three geographic basins of Costa Rica. Based on 32 years of collecting representing more than 158,000 specimens from 1017 localities, we undertook Generalized Linear Models of the two dung beetle genera to assess the effects of biodiversity and biogeographical distribution patterns. Canthidium and Onthophagus species ranged from 0 to 3000 m a.s.l., with an abrupt diversity decline at altitudes above 1500 m. Endemic species tended to show a higher altitudinal mean with a narrow altitudinal band distribution than non-endemic dung beetle species. Although there was a trend of decreasing species body size with the increase in altitude, such a trend depended on the distribution pattern of the species group. This possible insular-mediated endemicity mechanism has generated baffling biodiversity levels, considered the highest worldwide per unit area. Costa Rica is an expanse represented by a geographic overlap of two or more temporally disjunct areas and is not part of a natural transition zone. The effect of the insular Miocene origin of Costa Rica still pervades today, reflected by different insular syndromes shown by the dung beetle fauna. The importance of geological origins in generating biodiversity seems to have been an underrated criterion for conservation biology practices and should be considered ex officio.
RESUMO
This note reports on placement of Ateuchus benitojuarezi Moctezuma, Sánchez-Huerta, Halffter, 2018 (Coleoptera: Scarabaeidae: Scarabaeinae: Ateuchini) as a junior synonym of Ateuchus guatemalensis (Bates, 1887) new synonymy. Ateuchus guatemalensis was originally described from Guatemala and is now known from Chiapas (Mexico), Honduras, and Nicaragua (Kohlmann Vaz-de-Mello 2018). With the new synonym discussion below, A. guatemalensis also occurs in the Chimalapas region in Oaxaca (Mexico), thus following a very typical biogeographic distribution pattern known from other dung beetles that encompasses the Pacific slope between the Isthmus of Tehuantepec to the Nicaraguan lakes (Solís Kohlmann 2012).
Assuntos
Besouros , Animais , Guatemala , Honduras , México , NicaráguaRESUMO
Two new endemic species of scarab beetles are described from Costa Rica, Onthophagus humboldti sp. nov. and Uroxys bonplandi sp. nov. Onthophagus humboldti sp. nov. is also the tenth brachypterous Onthophagus species to be described worldwide, representing also a case of extreme brachyptery in Onthophagini. Illustrations for both new species, as well as marking differences with closely related species are included. Maps showing the distribution of the new species, as well as the distribution of brachypterous and endemic scarab-beetle species for Costa Rica are presented and discussed. The Cordillera de Talamanca represents an area where Scarabaeinae (four genera) show very high known levels of brachypterism in Mesoamerica. A reconstruction of the montane environment in the Cordillera de Talamanca during the Last Glacial Maximum (~24 ka) is analyzed, in order to try to understand a possible historical biogeography model that might promote high levels of brachypterism in scarab-beetles. The present study supports previous proposals that brachyptery is correlated with stable environments associated with deeply incised valleys. Tropical mountain ranges are also identified as having more endemics than lowland rain forests, contradicting accepted wisdom. Lastly, a mitochondrial DNA analysis supports the existence of the Onthophagus dicranius and the O. clypeatus species-groups as two well-defined and closely related branches.
RESUMO
Abstract The first Ateuchus Weber (Scarabaeinae) species, A. tuza sp. nov., from a rodent burrow from North America is described. Diagnostic characters are presented; photographs of an adult male and illustrations of male genitalia are included. A key for all known Mexican Ateuchus Weber species is provided. Ateuchus hornai (Balthasar) is revalidated. New distribution records from Mexico and Central America are reported.
RESUMO
In this paper we describe Canthidium quercetorum new species (Coleoptera: Scarabaeidae: Scarabaeinae), a species that inhabits dry oak forest in the Mexican state of Oaxaca, between 2100 and 2300 m above sea level. Photographs and an illustration of the habitus and a distribution map are provided. The unusual distribution and ecology of this species are discussed. An updated key for the genus in Mexico and the United States of America is also presented.
Assuntos
Besouros , Animais , Ecologia , Florestas , MéxicoRESUMO
An analysis of vicariant speciation of Geotrupes and Phanaeus (Coleoptera, Geotrupidae, Scarabaeidae) from the mountains of Oaxaca, Mexico is undertaken. The new species of dung beetle (Coleoptera: Scarabaeidae) from Oaxaca, Mexico, Phanaeus dionysiussp. n. is described. Photos of the habitus and a distribution map are provided. Phanaeus malyi Arnaud is revalidated. An updated key for the Phanaeus endymion species group and new localities are also presented. An updated key for the Geotrupes of Oaxaca and new locality records are also submitted.
ResumenSe realiza un análisis de especiación vicariante de Geotrupes y Phanaeus (Coleoptera, Geotrupidae, Scarabaeidae) de las montañas de Oaxaca, México. La siguiente especie nueva de escarabajo estercolero (Coleoptera: Scarabaeidae) se describe de Oaxaca: Phanaeus dionysiussp. n. Se incluyen fotografías, así como el respectivo mapa de distribución. Se revalida a la especie Phanaeus malyi Arnaud. Se presenta una clave puesta al día del grupo de especies de Phanaeus endymion, así como nuevos registros de distribución. Se incluye también una clave puesta al día para los Geotrupes de Oaxaca.