Styx infernalis

's The Macrolepidoptera of the World Styx infernalis is a medium sized, translucent winged, brown veined, and gray-colored butterfly. The cloudy grayish white color of the wings darkens towards the outer edge. Its wings are narrow, with short antennae, and it has a stout black-colored body which resembles to a Geometrid or Lymantriid moth. Staudinger's original description of specimens he had obtained in Chanchamayo states that the butterfly had a wingspan of 46-49 millimeters. The male's forelegs lacked pretarsal claws and exhibits less than five tarsomeres. In the males, the foretarsus is severely reduced, being half the size of the pterothoracic legs. Additionally, they lacked the apophyses posteriores on the female genitalia. These morphological differences served as justification for the reclassification of S. infernalis into the Riodinidae. ==Life history==

Styx infernalis has a fairly little known life history. In an unpublished paper by Hall et al., the larvae lack spathulate setae, a feature that is present on larvae of the subfamily Euselasiinae. Akin to other Nemeobiines, the larvae feed on members of the family Primulaceae, in this case the plant genus Myrsine. Due to their severely reduced forelimbs, it is unlikely that adult males use them for movement, akin to Nymphalid butterflies. ==Taxonomic history==

Styx infernalis has had a fraught taxonomic history, being reclassified within four separate butterfly families; Pieridae, Lycaenidae, however, he had initially mistaken the butterfly for a moth. It was later moved to the family Erycinidae due to its morphological characteristics. In particular, its antennae, which had set it apart from other Pierids. Structural differences with regards to the thorax, legs, wing venation, and eggs warranted reclassification out of the family Pieridae. Harvey (1987) justified the genus Styx as belonging within the Erycinidae (now known as Riodinidae) citing morphological differences. Ehrlich had considered the Styginae at equal rank to the (at the time) tribe Riodininae. Harvey (1987) proposed that Styx belonged within the family Riodinidae. Robbins (1988) used a scanning electron microscope to highlight morphological differences with regards to the forelimbs to corroborate upon Harvey's proposed placement. It had been previously thought to be a "missing link" between the butterfly families Lycaenidae, Riodinidae, and Nymphalidae. ==Distribution==

Styx infernalis is native to central and southern Peru. It is distributed over a small area in a region with high species diversity. Habitat Styx infernalis inhabits elevations between 1000 and 1600 meters. S. infernalis inhabits the tropical montane cloud forests or the Peruvian Yungas of central and southern Peru. ==Conservation==

The butterfly is currently unranked by the IUCN. Brown (1993) lists the species as "Vulnerable". It is distributed over a very small area and is rarely seen. There have been little studies in relocating the butterfly for scientific purposes. Brown highlighted the importance of conservation of its native habitat by securing tracts of its native cloud forest habitat and stressed the importance of locating colonies. Threats The primary threat to Styx infernalis is habitat degradation by coffee plantations and other types of plantation developments in its native habitat. ==Etymology==

Otto Staudinger's original rationale for naming the genus Styx was because that the butterfly "[seemed] to have come from the underworld" rather than resembling the colorful tropical vegetation that had surrounded it. Thus he had named it after the River Styx, with the specific name infernalis meaning "infernal" or "nether". Staudinger wrote in his first description of the genus Styx published in Neue Lepidopteren des südamerikanischen Faunengebiets: "eher aus der Unterwelt zu stammen scheint als aus der prachtvollen Tropenvegetation". ==References==