Two new species of the subgenus Cacoxenus (Nankangomyia) from the Oriental Region (Diptera, Drosophilidae)

Two new species of the subgenus Cacoxenus (Nankangomyia) Máca and Lin, 1993 are described: C. (N.) gani sp. nov. from southwest China and C. (N.) unipaxillus sp. nov. from Myanmar. The diagnosis of Nankangomyia is revised.


Introduction
The Nankangomyia was originally established as a subgenus of the genus Leucophenga Mik by Máca and Lin (1993). Sidorenko (2002) revised the classification of the tribe Steganini and related taxa, and transferred the subgenus Nankangomyia to the genus Cacoxenus. Sidorenko's suggestion is strongly supported by two important characters (as diagnostic): first flagellomere with several internal organs (new examination; Figure 8); mesonotum with dark patches around setal sockets. On the other hand, Cacoxenus resembles the genus Amiota Loew in sharing a (plesiomorphic) character, the aedeagal apodeme lobe-shaped and horizontally flattened (Figures 4,5,10,11). In the genus Cacoxenus, Nankangomyia is easily distinguished from the other subgenera by the following characters: arista short, or long and plumose; at least one acrostichal setula between posterior dorsocentral and prescutellar setae thicker and longer than others; mid tarsus with a row of cuneiform setulae. However, Nankangomyia resembles the genus Phortica Schiner in sharing an important (plesiomorphic) character, palpus with a hollow sense organ, which is also present in Amiota humeralis Loew, 1862 (Grimaldi 1990).
The type specimens are deposited in the following institutions: Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China (KIZ); Department of Entomology, South China Agricultural University, Guangzhou, China (SCAU); and Systematic Entomology, the Hokkaido University Museum, Hokkaido University, Sapporo, Japan (SEHU).
The morphological terminology and the definition of indices follow Chen and Toda (2001).
Legs. Yellow. Apical and preapical setae present on all tibiae. Fore femur with one to two row(s) of setae on posterior surface. Hind tarsus without a row of minute cuneiform setulae ventrally.
Abdomen. All tergites brown with grey pollinosity, pale on median of first and second; third to six with narrow, silver-grey bands along posterior margins. Sternites yellow-grey.

Relationship
This species is very similar to Ca. (Na.) academicus in the arista short plumose and shape of paramere, but can be distinguished from the latter in surstylus and aedeagus (in academicus: surstylus neither distally elongated nor apically pointed; aedeagus neither basally expanded nor distally sclerotized).

Description
Some characters commonly seen in A. gani are not referred to in the following description.
Thorax. Obscure brown, with brown-black patches, grey pollinose pattern, and dark clouds around sockets of setae. Postpronotal lobe with a long humeral seta and seven or eight small setae.

Etymology
A combination of the Latin words: unus + spina, referring to the surstylus with a paxilluslike prensiseta.