PROC. ENTOMOL. SOC. WASH. 97(3), 1995, pp. 654-658 THE IDENTITY OF PELOCORIS BIIMPRESSUS MONTANDON AND SYNONYMY OF PELOCORIS SPECIES IN THE SOUTHWESTERN UNITED STATES (HETEROPTERA: NAUCORIDAE) John T. Polhemus and Robert W. Sites (JTP) University of Colorado Museum, 3 1 1 5 S. York St., Englewood, CO 80 1 1 0; (RWS) Wilbur R. Enns Entomology Museum, Department of Entomology, University of Mis-souri, Columbia, Missouri 6521 1. Abstract. —Pelocoris shoshone amargosus La Rivers 1 956 is synonymized with Pelocoris biimpressus Montandon 1898, NEW SYNONYMY; a lectotype is designated for the latter. Pelocoris femoratus (Palisot de Beauvois) 1820 is compared to P. biimpressus and dis-cussed, and a neotype is designated. Key Words: Insecta, Heteroptera, Naucoridae, synonymy A recent review (JTP in prep.) of the ge-nus Pelocoris StSl revealed that P. biim-pressus Montandon is the most common species in northern Mesoamerica with a range extending from Guatemala north-ward into Texas, Louisiana, Arizona, Ne-vada and California, and that Pelocoris shoshone amargosus La Rivers 1956 is a synonym. To characterize species of this difficult ge-nus, several morphological characters have been found to be useful in addition to those used by La Rivers (1948, 1956) and Nieser (1975) (e.g. shape of male ventral lateroter-gites VI and VII, shape of female ventral laterotergite VI, sculpturing of male tergite V, dentition of female ovipositor lobes, shape and setiferation of male parameres). The characters used by La Rivers (loc. cit.) to separate species include the morphology of the female sternum VII (subgenital plate), male aedeagus, male dorsal aedeagal plate, coloration of dorsum, and body size; Nieser added the coloration of the fore femora and hemelytra, and development of spines on the connexiva. Some, but not all, of these characters are used below in distinguishing North American species. This contribution is intended to clarify the status of the Pelocoris species of the cen-tral and southwestern United States, from Louisiana and Texas westward; therefore, the voluminous Mexican and Mesoameri-can material in the Polhemus Collection is not treated here, except for a few examples. The resolution of Pelocoris species-group problems in the southeastern United States (particularly Florida), and Mesoamerica plus northern South America are beyond the scope of this paper, and will be treated in future publications. Pelocoris biimpressus biimpressus Montandon Pelocoris biimpressus St^l in litt.; see Mon-tandon 1898: 285, and Champion 1901: 360. Manuscript name, unavailable. Pelocoris biimpressus Montandon 1898. Bull. Soc. Sci. Buc.-Roum. 7: 285. Lec-totype, male, here designated, Mexico, in Stockholm Museum.