Synonyms and other taxonomic changes
Argus Scopoli, 1777. Type species: Papilio eurydice Linnaeus [Invalid name; preoccupied by Argus Bohadsch, 1761)]
Lethe Hübner, 1819. Type species: Papilio europa Hübner
Enodia Hübner, 1819. Type species: Oreas andromacha Hübner (= Papilio portlandia Fabricius)
Satyrodes Scudder, 1875. Type species: Papilio eurydice Linnaeus
Also, about 20 additional synonyms described from Eurasia, and not directly relating to North American species.
Explanation of Names
This is a large, primarily Asian and Indonesian genus, with few representatives in North America. There are two different looking groups of species in North America that have been treated as distinct genera or subgenera by various authors. These are treated as subgenera of Lethe
in 'A Catalogue of the Butterflies of the United States and Canada'
, which is followed on BugGuide.
Enodia [including L. portlandia, L. anthedon, & L. creola]
Satyrodes [including L. eurydice & L. appalachia]
The often cited distinction of larvae of Old World Lethe species having only one head horn, as compared to two on American species is false. All have two horns, though their length varies from species to species and with the age of the caterpillar. The top of the head is produced forward, and horns on mature larvae are close together and often parallel. On many species they are very close together, or sometimes fused at the base, and could conceivably be mistaken as a single horn - if a person does not look closely.
The genus Lethe is the only American representative of the Old World subtribe Lethina.
Five species are recognized in North America. There are about 115 Eurasian/Indonesian species listed.
The subgenus Enodia is very similar to "typical" Eurasian subgenus Lethe and is of dubious distinction. It is easily distinguished from the next by the scalloped and angled outer margin of the hind wings and the produced apex of the front wings.
The Subgenus Satyrodes is more distinctive from the bulk of the genus Lethe, at least in general appearance, and is characterized by the more evenly rounded shape of the wings.
From other genera of Satyrinae, Lethe differs in having a combination of the following characterstics. The base of the main veins in the front wings are only slightly swollen; the eyes are hairy; the pattern below is "clean" with sharp markings consisting of distinct dark lines on a pale ground; ocelli are several along the outer margins of all four wings, prominent both above and below; the pattern above is usually paler around the ocelli, usually with a darker diagonal zone across the front wings and often a dark bent line across the hind wings.
Paramacera xicaque is similar, but not found in the same areas (in our area, only known from se. Arizona), and on the front wings has ocelli only near the apex. It has the base of main veins in the front wing prominently swollen. The coloring below is finely peppered with light and dark scales, making it less "smooth" looking.
Megisto includes smaller rounded-winged butterflies; has at least the middle two ocelli on all wings below tiny and often absent, fewer prominent ocelli above; the eyes of living adults are non-hairy and black (they are pale grayish with vertical stripes in Lethe (and in most Satyrinae).
Hermeuptychia are smaller, similar to Megisto below, and nearly plain above (almost no pattern, just brown coloring).
As a whole, Lethe ranges widely across Eurasia and Indonesia, with most species found in southeast Asia. In North America the genus is found only east of the Rockies, from southern Canada to the Gulf of Mexico. Rare west of the forested portions of eastern North America.
in general, subgenus Enodia favors wooded environments, while subgenus Satyrodes favors open moist meadows and marshes.
Randy Emmitt's Butterfly pages
have excellent discussions on identification.