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- Ogdoconta Butler, 1891: 462.
Placodes cinereola Guenée, by original designation.
Ogdoconta is a moderately-sized (approximately 15 species) New World genus with its largest concentration of species in the southwestern United States, Mexico, and Central America. The North American species of Ogdoconta are small to moderate in size (forewing length 9.5–16.0 mm), and their appearance is not particularly distinctive, because there are no external characters that uniquely characterize this genus. There are, however, characters in both the male and female genitalia unique to Ogdoconta. The most distinctive feature is the divided valve in the male genitalia. The saccular and cucullar regions are separate, although joined at the base. In the female genitalia the junction of the ductus bursae, corpus bursae, and appendix bursae are proximate.
Head: Male and female antennae scaled above, naked below; occiput with dentate scales projecting slightly between antennal bases; a rough, poorly-developed line of scales just below antennal bases; front smoothly scaled, without frontal process, raised ring, or other modifications; eye normal, rounded, without hair; ocelli present; no lashes from either base of antenna or rear margin of eye; palpus unmodified, upturned, reaching about midpoint of front; third segment about one-third length of second; both second and third palpal segments smoothly scaled, first segment with a ventral tuft of scales; haustellum normal. Thorax: Wing venation normal for trifid noctuids; dorsum of thorax covered with elongate scales. Frenulum in female occasionally with a single bristle. Prothoracic leg: femur closely covered with flat scales except for a few rough scales projecting along ventral margin; tibia about one-half as long as femur, smoothly scaled, except for a few rough scales along outer margins; tibial claws and spines absent; first tarsal segment almost as long as tibia; first three tarsal segments scaled both dorsally and ventrally, fourth and fifth tarsal segments may have reduced scaling, fifth tarsal segment mostly naked ventrally; tarsal segments with three rows of spines ventrally. Mesothoracic and metathoracic legs: femur about four times longer than wide, smoothly scaled, except for fringe of long hairs along ventral margin; tibia scaling rougher than on femur; usual one mesotibial and two metatibial pairs of spurs; tarsal segments as in prothoracic leg. External tympanal region with alula strong; tympanic membrane circular, not elongate. Male abdomen: Weak tufts of scales present or absent on dorsum of segments one and two; sternite 1+2 without basal hair pencils or Stobe’s glands; sclerotized margin of eighth sternite appears U-shaped; eighth sternite with two separate strong lines of hairs, not clearly separated into two hair pencils; sclerotized region of eighth tergite Y-shaped. Male genitalia: Uncus straight, narrow, often hairy; scaphium variously sclerotized; subscaphium variously sclerotized; anal tube variously sclerotized; tegumen simple, with or without slight projecting lobe near articulation with vinculum; tegumen hairy; vinculum and tegumen articulating directly, neither extensions, processes, nor separate pleurites present; juxta variously triangular, drawn out posteriorly; valve with saccular and cucullar regions separated giving valve a bifid appearance; cucullar region rectangular, ovate, or elongate; mesial surface of distal part of cucullar region simple and densely hairy, projections from costal margin present or absent; type species with a clasper located near junction of cucullar and saccular parts of valve, clasper-like structure present or absent in other species; saccular part of valve long, shorter than cucullar part, narrow, mesially densely covered with hairs; shaft of aedeagus narrow, with slight apical process variable; vesica long, from one half loop to two full loops, with or without diverticula or spines. Female genitalia: Ovipositor lobes unmodified, setae present; anterior apophyses and posterior apophyses, short, approximately equal in length; ostium in membrane between seventh and eighth abdominal segments, closer to eighth segment, with varying amounts of sclerotization; ductus bursae generally narrow, sclerotized or membranous, of variable length; appendix bursae wide, membranous; corpus bursae globular, slightly narrowed at junction with ductus bursae and appendix bursae; signa present or absent.
In North America north of Mexico, the species of Ogdoconta are placed in three groups. The first group (here called the cinereola species group) contains five species; Ogdoconta cinereola, Ogdoconta moreno, Ogdoconta sexta, Ogdoconta altura, and Ogdoconta satana. This group has a simple divided valve without projections on the outer margin. The vesica of the aedeagus is elongate with a single large loop. In the female genitalia the ostium is sclerotized, partially sclerotized or membranous. The ductus bursae is variable in length, narrow or funnel shaped, straight or bent, and membranous or partially sclerotized. A single junction joins the ductus bursae, corpus bursae, and appendix bursae. The corpus bursae is globular, usually with a single concave signum. The appendix bursae is large and fully or partially coiled. The junction between the appendix bursae and ductus seminalis may not be distinct.
Ogdoconta cinereola differs from all other species in the group in that Ogdoconta cinereola has a small clasper at the juncture of the cucullar and saccular regions of the valve. Ogdoconta altura, Ogdoconta sexta, Ogdoconta moreno, and Ogdoconta satana have no clasper. The distribution of Ogdoconta cinereola generally falls outside that of the other four species in the cinereola group.
The second group contains two species Ogdoconta tacna and Ogdoconta fergusoni. The outer margin of the cucullar part of the valve is less curved than the cinereola group, and the outer margin of the cucullar part has one or more projections. The vesica of the aedeagus has two rows of short, stubby spines. The female genitalia of the two species in the tacna group are dissimilar from each other, and they are dissimilar from the other species groups.
The third group contains the single species Ogdoconta rufipenna that is characterized by the cucullar part of the valve, which is noticeably more narrow than the other species groups. The outer margin of the cucullar part of the valve has a conspicuous thumb-like projection. In the female genitalia the ostium is strongly sclerotized and the scler-otization continues down the ductus bursae. The ductus bursae, supported by the terminus of the sclerotization, is bent.