New World dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) colonization of a recent Miocene insular territory: The case of Costa Rica.

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, and (Coleoptera: Scarabaeidae: Scarabaeinae), are here studied, in the first analysis of a volcanic paleo-archipelago, colonized from its emergence, and then later becoming .

A new Ateuchus guatemalensis (Bates, 1887) (Coleoptera: Scarabaeidae) synonym from Mexico.

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.

Description of and , two new scarab beetles (Coleoptera, Scarabaeidae, Scarabaeinae) from Costa Rica, with notes on tropical mountain brachyptery and endemicity.

Two new endemic species of scarab beetles are described from Costa Rica, . and is also the tenth brachypterous 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.

An unusual new species of Canthidium (Coleoptera: Scarabaeidae: Scarabaeinae) from Oaxaca, Mexico.

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.

Dung beetle vicariant speciation in the mountains of Oaxaca, Mexico, with a description of a new species of (Coleoptera, Geotrupidae, Scarabaeidae).

An analysis of vicariant speciation of and (Coleoptera, Geotrupidae, Scarabaeidae) from the mountains of Oaxaca, Mexico is undertaken. The new species of dung beetle (Coleoptera: Scarabaeidae) from Oaxaca, Mexico, is described. Photos of the habitus and a distribution map are provided.

THE EFFECT OF A PARTIAL BARRIER ON THE MOVEMENT OF A HYBRID ZONE.

Computer simulations of clines (Brues, 1972; Endler, 1977) as well as theoretical arguments (Nagylaki, 1975), have shown that steps in gene frequencies will be pulled to partial barriers (areas of reduced gene flow) if they form within approximately a cline width of the partial barrier. The behavior of a hybrid zone between two chromosomal taxa ("Moreton" and "Torresian") of the acridine grasshopper Caledia captiva in southeast Queensland has been analyzed and found to comform qualitatively with a model of altered gene flow patterns. Clines in four enzyme systems were analyzed for 1983 and 1986 along a transect across the hybrid zone.