The Genera of Nearctic Therevidae

Abstract

During the course of preparing the Therevidae chapter for the soon-to-be published Manual of Nearctic Diptera (Canada Department of Agriculture 1981), we've found that the previously published descriptions of genera were totally inadequate to form a framework for the therevid species of North America. The genus Psilocephala Zett., for instance, was found to be polyphyletic, containing species from several diverse ancestors. An effort to describe the many new genera contained herein was begun because we realized the definitive nature of the forthcoming Manual of Nearctic Diptera and the importance of establishing a generic base for the Therevidae founded on synapomorphies. We have restrained ourselves from grouping the genera beyond the subfamilial level simply because we feel that better natural groupings can be formed once genera from other parts of the world are included in the scheme.

We have attempted to place the described species in the new generic concepts at the end of each diagnosis. All North American genera are diagnosed, and male terminalia are figured for all genera. In total, 29 genera and 143 currently valid species have been described for North America, excluding Apsilocephala Krober (1914) and its included species, longistyla Krober (1914), which we feel does not belong within the family Therevidae. We have not included Melanothereva MaWoch (1932:249) that occurs in Chile, Peru, and parts of Argentina and contains a single Nearctic species, nigra (Bellardi) [1861:92, (Psilocephala)] that, to our knowledge, has not been rediscovered since it was first described from Mexico.

The descriptions and keys follow morphological terminology developed by us. Male terminalia characters were originally defined and described by Lyneborg (1968a) and have since been modified slightly by Lyneborg (1972, 1976, and 1978) and by Irwin (1977a and 1977b). Female terminalia characters were defined and described by Irwin (1976) . Other morphological features are generally accepted in Diptera literature, and we refrain from detailing them here. The immature stages of Therevidae have not been used in developing this preliminary classification. Larval and pupal stadia are being gathered and associated with adults in the hope that eventually they will help to elucidate the proper phylogenetic placement of species within genera and genera within suprageneric taxa.