A new species of the genus Periscelis Loew (P. stuckenbergi, Diptera: Periscelididae: Periscelidinae), the first from the Afrotropical Region, is described. Brief diagnoses of the family, subfamily, genus, subgenus and species are provided to facilitate identification of members of this uncommon family. A key to the subfamilies of the family and subgenera of Periscelis and habitus photographs and detailed illustrations of structures of the male terminalia are also included.
Specimens of Periscelididae Oldenberg, 1914 are generally uncommon in collections, although numerous specimens, especially of the subfamily Periscelidinae, are sometimes common at preferred habitats, such as fluxes on deciduous trees. Thus it was of considerable interest to discover an undescribed species of the genus Periscelis Loew, 1858 from Ethiopia. The purpose of this paper is to document this species, which is the first of the subfamily Periscelidinae from the Afrotropical Region. Previously only species of Cyamops Melander, 1913 and Stenomicra Coquillett, 1900, both of the subfamily Stenomicrinae Papp, 1984, were known from the Afrotropics (Mathis & Rung 2011).
Because specimens are uncommon, we have included brief diagnoses of the family, subfamily and genus to facilitate their recognition and identification. To provide perspective and potential references for the Afrotropical fauna of Periscelidinae, we have included a few principal references about the Palaearctic fauna in the synonymy of the respective taxa.
MATERIAL AND METHODS
The descriptive terminology, with the exceptions noted in Baptista and Mathis (1994, 2000), is that published in the Manual of Nearctic Diptera (McAlpine 1981). The format for the species description adheres to Baptista and Mathis (1994, 2000). As specimens are small, less than 3 mm in length, study and illustration of the male terminalia requires use of a compound microscope. For most of the structures of the male terminalia we follow the terminology adopted previously (Baptista & Mathis 1994, 2000; Sueyoshi & Mathis 2004).
Three proportions in the wing used in the descriptions of new species are based on the largest, smallest, and one other specimen, and are defined as follows: (1) Wing proportion: straight-line distance between wing base and apex/greatest straight-line distance from anterior margin to posterior margin; (2) 1st costal proportion: straight-line distance between apices of R2+3 and R4+5 (costal section III)/distance between apices of R1 and R2+3 (costal section II); (3) 2nd costal proportion: straight-line distance between apices of R2+3 and R4+5 (costal section III)/distance between apices of R4+5 and M(costal section IV).
All specimens examined as part of this study were collected by Amnon Freidberg and colleagues and are deposited in Tel Aviv University (TAU) and the Smithsonian Institution (USNM).