JAMES CHESTER BRADLEY 199 



CONTRIBUTIONS TOWARD A MONOGRAPH OF THE 



MUTILLIDAE AND THEIR ALLIES OF AMERICA 



NORTH OF MEXICO 



BY JAMES CHESTER BRADLEY 



II. A REVISION OF TIAIULLA ASHMEAD, A SUBGENUS 

 OF MUTILLA EQUIVALENT TO THE SPECIES 

 GROUP HEXAGON A OF FOX 



Failure to apprehend certain excellent structural character- 

 istics which in reality differentiate the males of our eastern species 

 of this group, and consequent attempts to separate them bj' their 

 color, has led to complete confusion. Five abundantly char- 

 acterized, distinct species have been included under the names 

 hcxagona, promethea and floridensis. The character by which 

 separation has heretofore been sought, especially of the two 

 former, has been largely the degree of redness. Erythrization, 

 the replacing of black with red, is a phenomenon commonly met 

 with in Hymenoptera as we proceed from north to south in the 

 eastern United States. Consequently, when the species are 

 correctl}' separated, it is no surprise to find each of them var^-ing 

 to a greater or less extent from red to black. In the species 

 rufa, as here defined, we find the majority of the northern speci- 

 mens with black head and thorax, all of the southern ones, except 

 one from northern Georgia, and some northern ones with head 

 and thorax partially red ; of briaxus I have specimens from Virginia 

 and northward, all with black thorax, and one from Florida with 

 red dorsum; of hexagona my series is smaller, but the only two 

 entirely black ones come from Virginia; promethea is entirely 

 confined to the far south, and all the specimens have the top of 

 the head and the dorsum red; Jloridensis is confined to south 

 Georgia and Florida, and has not only the dorsum but also the 

 sides of the thorax red, except in one specimen from Georgia. 



It would seem, from the evidence at hand, that the red forms 

 are to be looked for not only in the distinctly Lower Austral Zone, 

 but also in its northern coastal extension, while the black forms 

 occur inland and perhaps far southward in the Carolinian Zone. 



TRANS. AM. EXT. .SOC, XLII. 



