PROC. BIOL. SOC. WASH. 93(1), 1980, pp. 61-67 REVISION OF THE COLLARED GNATWREN, MICROBATES COLLARIS (AVES: PASSERIFORMES) Kenneth C. Parkes Abstract. — Microbates coUaris, a small passeriform bird of uncertain af-finities, has a highly disjunct range in northern South America. Three sub-species are recognized in current literature. Two more are described, from Colombia and the Guianas; a name for the latter is already available. The gnatwrens, of which two species {collaris, cinereivenths) are placed in the genus Microbates and one, the longer-billed, longer-tailed melannrus , in the genus Ramphocaenus, are of uncertain affinities within the Passeri-formes. The history of their classification was reviewed by Rand and Traylor (1953). Their relationships are currently thought to be with the Old World warblers, which are variously given their own family, Sylviidae, or consid-ered members of a large family Muscicapidae which includes all the so-called ''Old World insect-eaters." The only other sylviid-like birds in the Neotropics are the gnatcatchers, Polioptila, and the gnatwrens are now uniformly placed next to Polioptila. Paynter (1964) gave these three genera their own subfamily, Polioptilinae, within the enlarged Muscicapidae, thus giving them equal rank with the Old World warblers (Sylviinae). At the same time he admitted in a footnote (p. 443) that ''The three genera in this subfamily are presumably not closely related to one another, with the pos-sible exception of Microbates and Ramphocaenus. Their proper taxonomic placement awaits further study." This is a highly conservative statement, as many authors believe that Microbates and Ramphocaenus are barely separable as genera. The range of Microbates collaris appears to be composed of several dis-junct populations, and it is probable that this is not entirely an artifact of insufficient collecting (although the species is not abundantly represented in museums). Paynter (1964) recognized three subspecies in the "Peters" Check-Hst. The species has not been critically studied since the description of M. c. paraguensis by Phelps and Phelps (1946). Material in any one museum is so limited that a full appreciation of variation in this species can be attained only by assembling specimens from several sources. The present study is based on the combined collections of Carnegie Museum of Natural History (CM) and the American Museum of Natural History (AMNH), sup-plemented by key specimens borrowed from the Field Museum of Natural History (FMNH) and the Los Angeles County Museum (LACM). I am
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