Urbanua viterboana (Ehrmann), 1907
Figures 7 (♂), 8 (♀), 34 (♂ genitalia), 49 (♀ genitalia)
Thymele viterboana Ehrmann, 1907: 321. Type locality Colombia: Socorro, type in CM.
The ♂ forewing has a costal fold. In both sexes, the forewing bears the usual
complement of hyaline spots, those in the ♀ generally larger than in the ♂. Either sex
may have a subapical spot in M2-M3 but seldom in M1-M2. The subapical spots are not
present in the holotype. The upper surface basal hair scale clothing is bright blue,
occasionally with a green tint. On the hindwing this basal clothing is sharply defined
distally. The under surface ground color varies from a medium brown (holotype) to a
dark purple gray. The under hindwing central band is entire; the subcostal spots may
be conjoined resulting in a widening of the band at the costa, or separate, making the
band bifurcate. A few individuals exhibit nearly complete separation of these spots not
only from each other but also from the rest of the band. The postdiscal band is entire;
the pale distal edging to the subtornal spot of this band and to the cell spot of the
central band is very faint.
The hindwing fringe is white to pale brown and checkered dark brown at the vein
ends; forewing fringe is only slightly paler than the ground color and faintly checkered,
usually to the apex. The antennal club beneath is prominently darkened centrally.
A random sample of 15 ♂ and 13 ♀ specimens gave the following wing
measurements: ♂ forewing averaged 23.4 mm from base to apex and 13.1 mm from
costa to tornus, varying from 22 x 12 to 25 x 14 (holotype 25 x 13.5); average hindwing
tail length 9 mm, varying from 7 to 10 (holotype 10 mm); ♀ forewing averaged 25.8 x
14.5, varying from 23 x 13 to 28 x 16; average hindwing tail length 12 mm, varying from
10 to 14.
In the ♂ genitalia, viewed ventrally, the uncus arms are narrowly separated, deeply
divided and nearly parallel, diverging slightly towards the tips; the gnathos is slender,
bluntly pointed. The valvae are symmetrical, long and relatively slender, the ampulla
with a rounded shoulder caudally where it meets the cucullus, its dorsal margin
sinuous. The cucullus has a moderately dentate dorsal area which may be dorsally more
or less pointed, but usually rounded, just caudad of the ampulla and seldom projecting
dorsad beyond the dorsal edge of the ampulla. The cucullus is very variable, more or
less an isosceles triangle, sharply to bluntly pointed caudally and often with the dorsal
edge more or less concave.
In the ♀ genitalia the terminal margins of the papillae anales are nearly straight; the
anterior margin of the sterigma slightly concave centrally; the lamella postvaginalis
has a deep central indentation caudally; the lamella antevaginalis is weakly sclerotized,
its caudal margin with a broad shallow central concavity; the ductus bursae is short,
tapered; corpus bursae long, bent to banana shape.
129 specimens were examined from the following countries: Mexico 35 ♂, 18 ♀;
Guatemala 1 ♂, 2 ♀; El Salvador 10 ♂, 17 ♀; Costa Rica 6 ♂, 4 ♀; Panama 4 ♂, 3 ♀;
Colombia 16 ♂, 6 ♂; Ecuador 7 ♂. 34 ♂ and 6 ♀ genitalia preparations were made and
studied in addition to that of the holotype.
This is perhaps the most variable species in the proteus group. It and its close
relatives, belli, dubius and pronta are clearly distinct entities, yet some individuals can
be very difficult to place, suggesting that there may be considerable hybridizing
between them. There is less chance of confusing viterboana with pronta than with belli
and dubius because of the prominent division of the under hindwing band into separate
spots. It can be distinguished from belli by the upper surface color being blue in
viterboana and green in belli. The shape of the valvae is individually quite variable in
both species, making separation of the males on the basis of genitalia alone rather
difficult. However, when confronted with a blue-green individual, it usually can be
determined with little doubt on the basis of the valvae; in viterboana the dorsal dentate
area of the cucullus seldom projects dorsad beyond the dorsal edge of the ampulla,
whereas in belli it usually does project dorsad. Females can be separated genitalically
by the shape of the corpus bursae which is hooked like a letter "J" in belli and bent to a
banana shape in viterboana. From dubius it can be distinguished superficially by the
under hindwing distal pale edging to the cell and subtornal spots which are very faint in
viterboana and prominent in dubius, and by the continuation of the postdiscal band to
the costa in dubius but only to vein Rs in viterboana. Genitalically the males are
difficult to separate, but the females can be distinguished, usually without dissection,
by the shape of the caudal edge of the lamella postvaginalis which is a smooth, almost
uninterrupted curve in dubius, but deeply indented centrally in viterboana.