Acidogona Loew

Norrbom, Allen L., Sutton, Bruce D., Steck, Gary J. & Monzón, José, 2010, New genera, species and host plant records of Nearctic and Neotropical Tephritidae (Diptera) 2398, Zootaxa 2398, pp. 1-65 : 5

Acidogona Loew

Acidogona Loew 1873: 285 (type species Trypeta melanura Loew , by monotypy).

Xenochaeta Snow 1894: 166 (type species X. dichromata Snow , by monotypy). New synonymy.

Xenochaeta Snow is here considered a junior synonym of Acidogona Loew , and A. dichromata (Snow) , new combination, is transferred to the latter genus. The characters previously used to distinguish Xenochaeta and Acidogona , which are both monotypic, intergrade or are variously shared with A. stecki , a new species from Mesoamerica, so that the latter cannot be easily placed in either taxon.

The key of Foote et al. (1993, couplet 34) separates Acidogona from Xenochaeta (in which X. aurantiaca (Doane) , now considered a synonym of A. dichromata ( Goeden & Teerink 1997) , also was recognized), based on the size of the first flagellomere, which is indicated to be longer than 2/3 the eye height in Acidogona , but less than half as long as the eye height in Xenochaeta . There is a distinct difference in first flagellomere relative size between females of A. melanura and A. dichromata , but not between males. It is larger in females of all three species than in males, and in A. stecki females is intermediate in size between the former two species. Measured on the mesal side, the first flagellomere is 0.53–0.61 times as long as the eye height in females (n=4) and 0.33–0.35 in males (n=3) of A. melanura , 0.49–0.53 in females (n=4) and 0.37–0.39 in males (n=3) of A. stecki , and 0.38–0.43 (n=5) in females and 0.31–0.34 (n=3) in males of A. dichromata . Foote et al. (1993: 490) also distinguish these two genera by “the very different type of wing pattern”, and the much smaller size of Xenochaeta species. Although the wing pattern in A. melanura is not sexually dimorphic, it is dimorphic in A. stecki , as in A. dichromata , and the patterns of the males of the latter two species are similar. In females the wing pattern differs among the species but the homology of the elements of the patterns can be recognized. In A. dichromata the hyaline spots are smaller and more numerous, but are arranged similarly to both sexes of A. melanura , whereas in A. stecki many of the spots are fused to form a more banded pattern. In size, all three species broadly overlap. Korneyev (1999) indicated differences in the degree of acuteness of the first flagellomere and the color, size and orientation of the scutellar setulae between these two genera, but based on a broader range of examined material there are no significant differences in these characters. In all three species the apex of the first flagellomere varies similarly, and it is always distinctly acute. Specimens of A. dichromata from California have more of the scutal setulae brown and acuminate, but in northern specimens most of these setulae are white and lanceolate, similar to A. melanura . A better character that consistently separates both sexes of A. dichromata from the other two species is that in A. melanura and A. stecki the scutellum is lightly microtrichose, whereas it is bare and shiny in A. dichromata . Given the intergradation in other characters, however, the difference in this character alone does not justify the continued recognition of Xenochaeta as a separate genus.

All three species of Acidogona breed in flowers of Hieracium species ( Asteraceae : Cichorieae ) ( Foote et al. 1993, Goeden & Teerink 1997).