Tarache knowltoni (McDunnough)
Acontia knowltoni McDunnough, 1940, Canad. Ent., 72:199.
Diagnosis: The forewing of Tarache knowltoni
is heavily suffused with gray-brown. The male forewing usually has a darker
streak from the inner third of the costa to an indentation of the postmedial
line about midway down the postmedial line. The upper half of the basal
and median areas are dark gray brown, while the lower half is dull white
speckled with gray. There is an oval gray spot at the lower base of the
wing. The orbicular is a small, dark dot and the reniform is weak and
obscured by the dark brown postmedial band. A small, linear streak arises
from the costa near the apex of the wing. The male hindwing is geographically
variable. Specimens from Utah and Colorado have the hindwing above completely
suffused with dark brown. In contrast material from Oregon and Washington
have a distinctively contrasting white base to the wing. The underside
of the hindwing is variegated with white and dark areas. Females are similar
to males, but more heavily marked. The hindwing is always completely suffused
with dark brown. Forewing expanse from base to apex in one selected individual 10.5 mm.
Distribution: (Based on specimens in the USNM only). This species is known from western Colorado, Utah, Oregon, and Washington State. Geographical variation in hindwing color was discussed in the diagnosis.
Adults have been collection in June, August, and September.
Identification Quality: Good
Distribution map based on specimens in the USNM
Tarache abdominalis is most likely to be confused with knowltoni. The males of knowltoni have the basal area of the forewing completely suffused with gray-brown. The white streak near the apex of the costa is almost always smaller and narrower than in abdominalis. The basal area of the hindwing in knowltoni is either distinctively white contrasting with the dark outer third of the hindwing or completely suffused with dark brown. In contrast the male hindwing of abdominalis has a lighter brown inner portion. The vesica of the male genitalia of abdominalis has 4 major spines. The vesica has 5 to 6 major spines in knowltoni. The clasper of the male valve is larger and longer in abdominalis than it is in knowltoni. Females of abdominalis and knowltoni are similar in appearance. However the female forewing of abdominalis has a distinctive diagonal band from the costa joining the postmedial line. In contrast this diagonal band is absent in knowltoni and replaced by a consistently dark, triangular basal region.