Styx infernalis

File:Styx infernalis.JPG'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 wing coloration has been described as resembling isinglass.{{cite book |last1=Pyle |first1=Robert Michael |title=Mariposa Road: The First Butterfly Big Year |date=27 September 2010 |publisher=Houghton Mifflin Harcourt |isbn=978-0-547-52785-7 |url=https://books.google.com/books?id=XqT7a3boztkC&dq=%22styx+infernalis%22&pg=PT295 |language=en |access-date=20 November 2021 |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065017/https://www.google.ca/books/edition/Mariposa_Road/XqT7a3boztkC?hl=en&gbpv=1&dq=%22styx+infernalis%22&pg=PT295&printsec=frontcover |url-status=live }} Its wings are narrow, with short antennae, and it has a stout black-colored body which resembles to a Geometrid or Lymantriid moth. The butterflies have been noted to resemble smaller versions of Parnassius butterflies. Patterning akin to Styx have been observed in the butterfly genera Parnassius, Aporia, and Davidina.{{cite journal |last1=Lukhtanov |first1=Vladimir A. |last2=Dubatolov |first2=Vladimir V. |title=Phylogenetic position and taxonomic rearrangement of Davidina (Lepidoptera, Nymphalidae), an enigmatic butterfly genus new for Europe and America |date=2020 |doi=10.1093/zoolinnean/zlaa104 |journal=Zoological Journal of the Linnean Society |volume=190 |issue=3 |pages=1036–1053 |biorxiv=10.1101/2020.06.25.171256 |s2cid=220253066 |url=https://www.researchgate.net/publication/342492435 |access-date=20 November 2021 |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065019/https://www.researchgate.net/publication/342492435_Phylogenetic_position_and_taxonomic_rearrangement_of_Davidina_Lepidoptera_Nymphalidae_an_enigmatic_butterfly_genus_new_for_Europe_and_America |url-status=live }}

Staudinger's original description of specimens he had obtained in Chanchamayo states that the butterfly had a wingspan of 46-49 millimeters.{{cite journal |last1=Staudinger |first1=Otto |title=Neue Lepidopteren des südamerikanischen Faunengebiets |journal=Verhandlungen der Kaiserlich-Königlichen Zoologisch-Botanischen Gesellschaft in Wien |date=1876 |volume=25 |pages=89–124 |url=https://www.biodiversitylibrary.org/part/57933 |access-date=2021-11-20 |archive-date=2021-11-20 |archive-url=https://web.archive.org/web/20211120220148/https://www.biodiversitylibrary.org/part/57933 |url-status=live }}

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. The females have centrally clustered trichoid sensillae on the foretarsus, a feature shared with the Old World butterfly genus Laxita.{{cite journal |last1=Robbins |first1=Robert K. |title=Male Foretarsal Variation in Lycaenidae and Riodinidae, and the Systematic Placement of Styx infernalis (Lepidoptera) |journal=Proceedings of the Entomological Society of Washington |volume=90 |pages=356–368 |date=1988 |hdl=10088/7715 |url=https://repository.si.edu/handle/10088/7715 |access-date=20 November 2021 |archive-date=20 November 2021 |archive-url=https://web.archive.org/web/20211120212136/https://repository.si.edu/handle/10088/7715 |url-status=live }} 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.{{cite book |last1=Kitching |first1=Roger Laurence |title=Biology of Australian Butterflies |date=1999 |publisher=CSIRO Publishing |location=Collingwood, VIC, Australia |isbn=978-0-643-05027-3 |page=29 |url=https://books.google.com/books?id=cTFychx78QIC&dq=%22styx+infernalis%22&pg=PA29 |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065018/https://www.google.ca/books/edition/Biology_of_Australian_Butterflies/cTFychx78QIC?hl=en&gbpv=1&dq=%22styx+infernalis%22&pg=PA29&printsec=frontcover |url-status=live }}

Styx infernalis has a fairly little known life history.{{cite book |last1=Boggs |first1=Carol L. |last2=Watt |first2=Ward B. |last3=Ehrlich |first3=Paul R. |title=Butterflies: Ecology and Evolution Taking Flight |date=15 June 2019 |publisher=University of Chicago Press |isbn=978-0-226-06319-5 |page=500 |url=https://books.google.com/books?id=eoSYDwAAQBAJ&dq=styx+infernalis&pg=PA500 |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065018/https://www.google.ca/books/edition/Butterflies/eoSYDwAAQBAJ?hl=en&gbpv=1&dq=styx+infernalis&pg=PA500&printsec=frontcover |url-status=live }} 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.

Adults are active during the midday near sunny patches, they often engage in mud-puddling near streams. The adult's flight is weak, and appear like they are gliding in the air. There have been reports by Purser (2007) that it is possibly nocturnal.{{cite book |last1=Purser |first1=Bruce |title=Jungle Bugs in the Night: Scientific Adventure in the Tropical Forests of the World |date=2007 |publisher=Pensoft Publishers |isbn=978-954-642-282-8 |url=https://books.google.com/books?id=OANNAAAAYAAJ&q=%22styx+infernalis%22 |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065018/https://www.google.ca/books/edition/Jungle_Bugs_in_the_Night/OANNAAAAYAAJ?hl=en&gbpv=1&bsq=%22styx+infernalis%22&dq=%22styx+infernalis%22&printsec=frontcover |url-status=live }} Due to their severely reduced forelimbs, it is unlikely that adult males use them for movement, akin to Nymphalid butterflies.

Styx infernalis has had a fraught taxonomic history, being reclassified within four separate butterfly families; Pieridae, Erycinidae,{{cite book |title=The Zoological Record, Volume 46, Issue 13 |date=1911 |publisher=Zoological Society of London. |url=https://books.google.com/books?id=_xpFAQAAMAAJ&dq=styx+infernalis+erycinidae&pg=PA309 |access-date=22 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065019/https://books.google.com/books?id=_xpFAQAAMAAJ&dq=styx+infernalis+erycinidae&pg=PA309 |url-status=live }} Lycaenidae, and Riodinidae, following its initial description by Staudinger in 1875. Erycinidae as a family was later split in two, with the Riodinids, including Styx, being placed within the family Lycaenidae.

In Staudinger's original description of the butterfly, he classified Styx as a member of the family Pieridae;{{cite book |title=Newman's Entomologist |date=1909 |publisher=Simpkin, Marshall & Company |page=162 |url=https://books.google.com/books?id=kcZQAQAAMAAJ |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065019/https://www.google.ca/books/edition/Newman_s_Entomologist/kcZQAQAAMAAJ?hl=en&gbpv=0 |url-status=live }} however, he had initially mistaken the butterfly for a moth.{{cite journal |last1=Espeland |first1=Marianne |last2=Hall |first2=Jason P.W. |last3=DeVries |first3=Philip J. |last4=Lees |first4=David C. |last5=Cornwall |first5=Mark |last6=Hsu |first6=Yu-Feng |last7=Wu |first7=Li-Wei |last8=Campbell |first8=Dana L. |last9=Talavera |first9=Gerard |last10=Vila |first10=Roger |last11=Salzman |first11=Shayla |last12=Ruehr |first12=Sophie |last13=Lohman |first13=David J. |last14=Pierce |first14=Naomi E. |title=Ancient Neotropical origin and recent recolonisation: Phylogeny, biogeography and diversification of the Riodinidae (Lepidoptera: Papilionoidea) |journal=Molecular Phylogenetics and Evolution |date=December 2015 |volume=93 |pages=296–306 |doi=10.1016/j.ympev.2015.08.006 |pmid=26265256 |bibcode=2015MolPE..93..296E |url=http://manuscript.elsevier.com/S1055790315002377/pdf/S1055790315002377.pdf |access-date=20 November 2021 |archive-date=20 November 2021 |archive-url=https://web.archive.org/web/20211120224452/http://manuscript.elsevier.com/S1055790315002377/pdf/S1055790315002377.pdf |url-status=live }} 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.{{cite book |title=Novitates Zoologicae: A Journal of Zoology |date=1898 |publisher=order of the Trustees, British museum (Natural history) |page=376 |url=https://books.google.com/books?id=o2RBAQAAIAAJ |language=en |access-date=2021-11-20 |archive-date=2022-04-18 |archive-url=https://web.archive.org/web/20220418065020/https://www.google.ca/books/edition/Novitates_Zoologicae/o2RBAQAAIAAJ?hl=en&gbpv=0 |url-status=live }} Structural differences with regards to the thorax, legs, wing venation, and eggs warranted reclassification out of the family Pieridae.{{cite book |title=The Entomologist's Monthly Magazine |date=1909 |publisher=Entomologist's Monthly Magazine Limited |page=112 |url=https://books.google.com/books?id=NQ2eNRaWmTwC&dq=%22styx+infernalis%22&pg=PR13 |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065020/https://www.google.ca/books/edition/The_Entomologist_s_Monthly_Magazine/NQ2eNRaWmTwC?hl=en&gbpv=1&dq=%22styx+infernalis%22&pg=PR13&printsec=frontcover |url-status=live }}

Harvey (1987) justified the genus Styx as belonging within the Erycinidae (now known as Riodinidae) citing morphological differences. It was formerly considered as part of the subfamily Styginae, within the Lycaenidae, with the genus Styx its sole member by Ehrlich (1958) and Scott (1985).{{cite book |last1=Kudrna |first1=Otakar |title=Butterflies of Europe: Introduction to Lepidopterology |date=1985 |publisher=AULA-Verlag |isbn=978-3-89104-033-1 |url=https://books.google.com/books?id=rDogAQAAMAAJ&q=%22styx+infernalis%22 |access-date=20 November 2021 |language=en |archive-date=18 April 2022 |archive-url=https://web.archive.org/web/20220418065020/https://www.google.ca/books/edition/Butterflies_of_Europe_Introduction_to_Le/rDogAQAAMAAJ?hl=en&gbpv=1&bsq=%22styx+infernalis%22&dq=%22styx+infernalis%22&printsec=frontcover |url-status=live }} Ehrlich had considered the Styginae at equal rank to the (at the time) tribe Riodininae. When the family was classified as subfamily Riodininae within the Lycaenidae, it occupied the tribe Stygini. It had also been classified as its own separate family in its own right, the Stygidae (Eliot, 1973).{{cite thesis |last1=Mathew |first1=John |title=Aphytophagy in the Miletinae (Lycaenidae): Phylogeny, Ecology, and Conservation |year=2003 |publisher=Old Dominion University Libraries |doi=10.25777/v7rh-mb21 |url=https://www.proquest.com/docview/305261901 |access-date=20 November 2021 |id={{ProQuest|305261901}} |language=en |archive-date=20 November 2021 |archive-url=https://web.archive.org/web/20211120222215/https://www.proquest.com/docview/305261901 |url-status=live }}

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. Wahlberg et al. (2005) used DNA evidence to further solidify its proposed placement within the family Riodinidae.

Within the family, Styx was initially classified within the subfamily Euselasiinae, tribe Corrachiini due to biogeographical reasons rather than morphological means. This classification eventually fell through in favor of placement within the subfamily Nemeobiinae, a primarily Old World subfamily, despite the New World distribution Styx exhibits. Styx was surmised to be derived taxa from the Nemeobiine subfamily, where most other Nemeobiines had crossed the Bering Strait land bridge. Styx was most closely related to the genus Corrachia, another monotypic Riodinid from Costa Rica. Their inclusion within the subfamily Nemeobiinae thus made the subfamily monophyletic, and were sister taxa to the Old World genus Zemeros. Genetic studies by Wahlberg (2005), Heikkila (2012), and Saunders (2010) consistently placed Styx as being closely placed with Hamearis in studies with sparse Riodinid sampling.

Brown (1993) considers Styx infernalis as one of the most primitive Riodinids. Vane-Wright corroborates upon this idea, describing the butterfly as a "living fossil" akin to the Papilionid Baronia brevicornis of Mexico.{{cite book |last1=Dennis |first1=Roger L. H. |title=Butterfly biology systems connections and interactions in life history and behaviour |date=2020 |publisher=CABI |location=Oxfordshire, UK |isbn=9781789243574 |page=52}} It had been previously thought to be a "missing link" between the butterfly families Lycaenidae, Riodinidae, and Nymphalidae.{{cite web |title=Styx infernalis |url=http://tolweb.org/Styx_infernalis/103507 |website=Tree of Life Web Project |access-date=20 November 2021 |archive-date=20 November 2021 |archive-url=https://web.archive.org/web/20211120214932/http://tolweb.org/Styx_infernalis/103507 |url-status=live }}

Styx infernalis is native to central and southern Peru. It is distributed over a small area in a region with high species diversity.{{cite book |last1=New |first1=T. R |title=Conservation biology of Lycaenidae (butterflies) |date=1993 |publisher=IUCN |location=Gland, Switzerland |isbn=9782831701592 |page=146 |url=https://books.google.com/books?id=wMy0ocU7iuwC&dq=%22styx+infernalis%22&pg=PA146 |access-date=20 November 2021}}

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.

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.

The primary threat to Styx infernalis is habitat degradation by coffee plantations and other types of plantation developments in its native habitat.

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".

{{Reflist}}

{{Taxonbar|from1=Q2362492|from2=Q1763939}}

Category:Nemeobiinae

Category:Lepidoptera of Peru

Category:Riodinidae of South America

Category:Endemic fauna of Peru

Category:Taxa named by Otto Staudinger

Category:Butterflies described in 1875