PSYCHE. 



•211 



DIPTERA FROM THE MESILLA VALLEY OF THE RIO GRANDE 

 IN NEW MEXICO. — II. 



BY C. H. TYLER TOWNSEND, L.\S CRLfCES, X. .MEXICO. 



The present section of this paper is to 

 record what appears to be the growing 

 occurrence in the Mesilla Valley, in 

 southern New Me.xico, of species belong- 

 ing to the tachinid subfamilies Phasiidae, 

 Gymnosomatidae, and Ocypteridae. As 

 pointed out in section I, Gymnosoma 

 was not known in New Mexico previous 

 to 1 89 4, the only 'representatives of the 

 above groups known before then being 

 several hyalomyiid forms (belonging in 

 the Phasiidae). Since 1894, Gymno- 

 soma has turned up more commonly; 

 and in 1897 both Ocyptera and, what is 

 more remarkable, Trichopoda have been 

 discovered for the first time in New 

 Mexico. These occurrences are very 

 interesting from a biogeographical point 

 of view, and indicate the probable future 

 occurrence and discovery in the Mesilla 

 Valley not only of Cistogaster (which is 

 allied to Gymnosoma) , but also of Xan- 

 thomelanodes, a member of the Phanii- 

 dae, which is the remaining one of the 

 four small primordial groups of Tachini- 

 dae. The flies of these groups aje, as a 

 rule (excepting the hyalomyiid flies), 

 inhabitants of low moist regions in tem- 

 perate and tropical latitudes. Their 

 occurrence in the Mesilla Valley points 

 to a spread of these forms from lower 

 moister regions up the valley of the Rio 

 Grande into New Mexico. 



PHA.SIIUAE. 



13. Trichopoda histiio var. indivisa 

 Towns. One male, Sept. 3, and two 

 females, August 25 and Sept. 2, on 

 flowers of Solidago canadensis, on the 

 acequia banks within the town of Las 

 Cruces, all collected by myself in 1897. 

 These are the first and only specimens 

 of Trichopoda known from within the 

 boundaries of New Mexico, and their 

 discovery calls for an amendment of my 

 statement on page 279 of the Annals 

 and Magazine of Natural History (Lon- 

 don), series 6, vol. xx, Sept. 1897. 



The female difters from the male, 

 aside from the claw and frontal char- 

 acters, in the second segment being 

 without golden pollen, while the third is 

 golden pollinose except the wide anterior 

 and posterior margins. The male has 

 the third to sixth segments wholly golden 

 pollinose ; while the second segment is 

 yellowish except narrow anterior and 

 posterior margins, but not distinctly 

 pollinose. The coloring of the wings is 

 quite the same in both sexes. The male 

 front at vertex is hardly twice as wide as 

 the distance between the two posterior 

 ocelli ; while that of female is twice or 

 two and one-half times as wide as this 

 distance. The third and fourth seg- 

 ments of male, and fourth segment of 



