A REDEFINITION OF STONEMYIA 
(DIPTERA: TABANIDAE) AND DESIGNATION 
OF A NEW GENUS, PEGASOMYIA, FROM 
WESTERN NORTH AMERICA' 
By John F. Burger 
Department of Entomology, 
Nesmith Hall, University of New Hampshire, Durham, NH 03824 
The genus Stonemyia was erected by Brennan (1935) to receive 
North American pangoniine species previously assigned primarily 
to non-Nearctic genera. Brennan placed species with bare eyes in 
Stonemyia s. str. For species with pilose eyes, at least in the male, he 
proposed the subgenus Pilimas. He did not, however, fix a type for 
Pilimas as required by the International Code of Zoological 
Nomenclature for genus-group names proposed after 1930. Pilimas, 
therefore, was unavailable. Pilimas was raised to the generic level by 
Philip (1941a) and Brennan subsequently (in Philip, 1941b) desig- 
nated Diatomineura californica Bigot as the generotype of Pilimas 
in a note at the end of Philip’s paper. 
Structurally, both genera are very similar. Authors treating them 
have used primarily the presence or absence of a spur at the fork of 
the R 4 and R 5 veins and whether the eyes are bare or pilose. Neither 
of these characters, however, will absolutely separate these genera. 
Differences in the male and female genitalia have been used less 
frequently, perhaps because it is difficult to interpret structural dif- 
ferences observed. 
Middlekauff and Lane (1980) summarized the morphological dif- 
ferences between Stonemyia and Pilimas, but did not mention geni- 
talic differences. In their key, only the presence of the spur vein in 
Pilimas and its absence in Stonemyia is used to separate them. 
However, in their discussion of generic differences, they state that 
5% of Pilimas californica (sic) lack the spur vein. They also mention 
that the eyes of Pilimas are “slightly” hairy and that those of Stone- 
myia are “practically bare.” 
'Scientific Contribution Number 1331 from the New Hampshire Agricultural Experi- 
ment Station. 
Manuscript received by the editor, November 27, 1984. 
119 
