Macrocneme durcata Dietz, 1994

Dietz, R. E. IV (1994). Systematics and biology of the genus Macrocneme Hübner
(Lepidoptera: Ctenuchidae). University of California Publications in
Entomology 113: pp. 81-82 (Figs. 58-61, 156-157, 222; Map 20).

Macrocneme durcata Dietz, new species

The bright blue iridescence broadly suffused over the wings makes this one of
the most beautiful species in the genus. It is common in collections, but has
been misidentified as coerulescens Dognin or cyanea Butler. In males the
double-pronged juxta is unique. In females the prominent ventral pockets from
the encircling pleura of segment VII are diagnostic. Similar pockets are found
elsewhere only in females of aurifera Hampson. M. coerulescens, although
sympatric with durcata in northern South America, is smaller and seldom as
extensively blue on the wings. M. cyanea is restricted to southern Brazil.

MALE. Head: brownish black; labial palpi reaching base of antennae. Thorax:
brownish black with iridescence green to blue-green; white points on patagia
small, iridescent spots large and covering outer half of sclerite; tegulae
with iridescent streak along anterior margin and partially mesad, white scales
present on underside of tegulae but not along fringe; pectus without
iridescence except for scattered scales in metacoxal grooves; brownish black
hair-like scales overlie prominent white spots on meso- and metapleuron; legs
brownish black; all tibiae with thin iridescent streaks; coxae and femoral
grooves of mid and hind legs white; distal three segments of metatarsi white.
Forewing: strikingly iridescent blue, brownish black at apex and termen; black
streak from basal angle to distal third of anal fold; scattered black scales
above streak and into cell; underside similarly iridescent blue, but less
extensive than above, basal half iridescent, outer half brownish black;
diffuse white spots basally; inner margin at wing overlap tan. Hindwing:
bright iridescent blue; costal margin at wing overlap tan; anal area with
brownish black hair-like scales overlying metallic scales; underside
iridescent blue, apex brownish black. Abdomen: brownish black; iridescent
scales restricted to faint mid-dorsal stria on tergum from posterior margin of
A1 to A3; slightly broader striae along lateral margins of tergum and venter;
basal sternite entirely white; small, mesal spots on succeeding 4 segments;
white spot absent from pleurite II. Genitalia: as in Figs. 58-61 (drawn from
paratype, RED prep. 39190, USNM; 4n); dorsal processes (claspers) of valvae
symmetrical; ventral processes incurved at tips and extending beyond claspers;
mesal sclerite between processes of valvae with prominent protuberance; dorsum
of uncus with lateral margins appearing as auriculate flanges; juxta short,
double-pronged, with points barely reaching base of ventral processes; dorsum
of aedeagus strongly curved to right, with single horizontal spine on upper
margin; vesica with three bursae, the smallest lying ventrad (not seen in
illustration).

FEMALE. Similar to male, except general appearance darker due to reduction in
white scaling. Thorax: white from underside of tegulae visible along fringe of
mesal margin; pectus comparatively darker than in male, with white on meso-
and metapleura and coxae reduced to scattered scales or absent; white absent
from femoral grooves of mid and hind legs and reduced to distal two segments
on metatarsi. Forewing: distal two-thirds of wing bright iridescent blue, with
color reaching termen and extending closer to apex than in male; base of wing
more extensively black than in male, with black scales as irregular streak
from basal angle to costa; proximal edge of streak interrupted at three points
by metallic blue-green scales. Abdomen: white spots of basal tergite smaller
and ground color darker than male; venter with white restricted to three
points on basal sternite and a medial row of small spots on next 5 sternites.
Genitalia: as in Figs. 156-157 (drawn from RED prep. 39263, USNM; 3n);
sternite VII triangular, two oblique carinae at center, sides subequal, apex
continuing as small intersegmental sclerite in shape of right triangle, caudal
margin with prominent medial emargination; encircling portion of pleura VII
with two sclerotized pockets (see Fig. 156) from anterior margin; inner margin
of lamella antevaginalis smooth, unmodified at ostium; ovate sclerite of
lamella postvaginalis narrowed and decurved at ostial opening; ductus bursae
short; corpus bursae and base of accessory bursa with concentric plicae;
opposing, spinose, scallop-shaped signa at middle of corpus bursae; anterior
apophyses as triangulate pockets on lateral edges of sternite VIII.

VARIATION. Length of forewing: male, 19.0-20.0 mm; female, 18.5-21.3 mm.
Populations of M. durcata from Venezuela and Colombia have more extensively
blue wing iridescence than those from the upper Amazon. In general, specimens
from Peru (Sto. Domingo; Carabaya), Bolivia (Rio Yapacani; Rio Chiripiri), and
Brazil (Cuyaba) have more green in the iridescence than the same species from
Venezuela. Occasional Venezuelan specimens (Aroa) have green on the inner
margin of the forewing or a green to blue-green spot at the forewing base (El
Guacharo). Rarely, a specimen is bright, shiny golden-green (one male, Km 125,
El Dorado-Sta. Elena, Venezuela). M. cupreipennis Walker was named from a
similarly golden-green female. Except for a slight difference in the
iridescent hue, the cupreipennis holotype is remarkably like the green variant
of durcata. Both specimens are atypical of the species they represent.

TYPE DATA. Holotype male: Aroa, Venezuela, (Schaus); USNM Type 73263, USNM.
Allotype: 3 km N. El Guacharo, Monagas, Venezuela, 28/29-VIII-1975 (Dietz),
USNM.