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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. University of California Press and AmericanOrnithologists' Union are collaborating with JSTOR to digitize, preserve and extend access to Ornithological Monographs.Abstract. -The Slaty Antshrike is currently considered a single polytypic species (Thamnophilus punctatus) that ranges from Belize to southeastern Brazil. We present evidence that its distribution is highly patchy and that geographic representatives differ in vocalizations and external morphology. As a consequence, we recommend that six species be recognized within the complex and that the taxonomic position of two additional taxa, potentially warranting species status, be reevaluated when their vocalizations and behavior are better known. Recognition at the species level has important conservation implications because most members of the complex are concentrated in tropical dry-forest habitats that are rapidly disappearing in the Neotropics. Moreover, our results suggest that studies of taxa occupying dry forest can provide new insights into the evolution of Neotropical birds.Resumo. -A choca-bate-cabo {Thamnophilus punctatus) 6 correntemente considerada uma espe"cie politipica unica que se distribui de Belize ate o sudeste do Brasil. Apresentamos evidencia que sua distribuisao e bem espalhada e que seus representantes geograficos diferem em vocalizacoes e morfologia externa. Como consequencia, recomendamos que sejam reconhecidas seis especies dentro do complexo e que a posicao taxonomica de dois taxons adicionais, potencialmente merecedores do "status" de especie, sejam reavaliados quando suas vocalizacoes e comportamento estiverem melhor conhecidas. O reconhecimento ao nivel de especie tern importante implicac^o na conservacao porque a maioria dos membros do complexo estao concentrados em habitats tropicais de floresta seca que estao rapidamente desaparecendo nos Neotr6picos. Ale"m disso, nossos resultados sugerem que estudos de taxons que ocupam florestas secas podem fornecer novas perspectivas para entender a evolucao de aves neotropicais.Birds restricted to dry forest are among the most threatened in the Neotropics (Stotz et al. 1996). Neotropical dry forests are patchily distributed, and disjunct regions are often home to sister taxa. Such taxa typically have been considered "geographical representatives" and reduced to subspecies rank (Mayr 1982). Biogeographic and systematic studies of these allopatric populations are needed to identify isolated regions that contain strongly differentiated populations as a basis for setting conservation priorities.Additionally, most studies of patterns of avian speciation in the lowland Neotropics (e.g., Haffer 1987) focus on species inhabiting rain forest or savanna/grassland....