The Description of a New Species of South American Hocicudo, or Long-Nose Mouse, Genus Oxymycterus (Sigmodontinae, Muroidea), with a Critical Review of the Generic Content Philip Hershkovitz Abstract The description of a new species of Oxymycterus entailed a review of the entire genus but without arriving at a definitive taxonomic revision. The many outstanding problems such as the complex dental morphology of the unworn molars, the function of the trumpet-shaped snout, the elongate front claws, and the origin, affinities, and biogeography of the genus, and of sigmodontines in general, could not be addressed within the limitations of current knowledge and available material. The size relationships of the 23 described forms are indicated in terms of size classes, from small to large. They are separated into two coordinate geographic groups, one Atlantic, the other Andean, both confined to between the south bank of the Rio Amazonas-Solimoes-Maranon system and the north bank of the Rio Parana system, with absence of hocicudos in the floodlands between. Each originally named taxon is listed with type data, including original measurements, putative geographic distribution, relevant taxonomic infor-mation, and some comparisons. What is known of habits and habitats is summarized. Notions of oxymycterine burrowing are dispelled, and generally accepted interpretations of supposed sigmodontine origins and dispersal are questioned. Introduction The following description of a new mouse of the genus Oxymycterus discovered in the lower basin of the Rio Amazonas in Brazil required a review of the genus and organization of the 23 forms de-scribed since the first by Felix Azara in 1801. Available material is inadequate for a definitive taxonomic revision, 18 of the 23 holotypes being in European museums, 1 1 of them known only from their types, and 2 without types. Neverthe-less, specimens at hand suffice for attainment of immediate objectives and organization of most of the accumulated data. Geographic boundaries of the genus (map, Fig. 1 ) are extrapolated from type localities (map, Fig. 2) and marginal localities. De-lineation of the range of each species, however, awaits taxonomic revisions based on direct com-parison of all holotypes or acceptable represen-tatives. For the present, published measurements of types and topotypes or near topotypes form the primary basis for arrangement of the material into size classes each with the appearance of a species or species-group. Recognized are three Atlantic Division size classes and three Andean Division size classes with no distinguishable intermediates. Abbreviations The following abbreviations are used for insti-tutions and terminology. fmnh = Field Museum of Natural History, Chicago mnr = Museu Nacional de Brasil, Rio de Ja-neiro mpeg = Museu Paraense Emilio Goeldi, Belem mvz = Museum of Vertebrate Zoology, Uni-versity of California, Berkeley F1ELDIANA: ZOOLOGY, N.S., NO. 79, OCTOBER 31, 1994, PP. 1-43
The description of a new species of South American hocicudo, or long-nose mouse, genus Oxymycterus (Sigmodontinae, Muroidea), with a critical review of the generic content
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