The Stygian ringlet (''Erebia styx'') is a

butterfly Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...

belonging to the subfamily

Satyrinae The Satyrinae, the satyrines or satyrids, commonly known as the browns, are a subfamily of the Nymphalidae (brush-footed butterflies). They were formerly considered a distinct family, Satyridae. This group contains nearly half of the known divers ...

, the "browns", within the family

Nymphalidae The Nymphalidae are the largest family of butterflies, with more than 6,000 species distributed throughout most of the world. Belonging to the superfamily Papilionoidea, they are usually medium-sized to large butterflies. Most species ha ...

. It is found locally in the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

on dry

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

slopes. It is very similar to the Styrian ringlet (''E. stirius'') and has sometimes been included in that species.

Description

It has a wingspan of 46–56 mm.Whalley, Paul (1993) ''The Mitchell Beazley Guide to Butterflies'', Mitchell Beazley, London. The upperwings of both sexes are mostly brown with reddish bands near the edge (postdiscal bands). The bands vary in size and may be dusted with brown in the males.Chinery, Michael (1998) ''Butterflies of Britain and Europe'', HarperCollins, London. Within the bands are a variable number of eyespots (ocelli); these are black with white centres. The forewing has a large eyespot near the tip, often with two white centres. The hindwing has three or four spots. The underside of the male's forewing is largely orange with brown dusting in the basal half and a brown border. Unlike in the Styrian ringlet, the brown border does not taper towards the rear of the wing and has a dark "tooth" projecting into the orangeTolman, Tom & Richard Lewington (2008) ''Collins Butterfly Guide'', HarperCollins, London. The tooth is less conspicuous in the females. The underside of the hindwing is mostly brownish, darker in the basal half. The

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

''E. s. triglites'' of the

Bergamo Alps The Bergamasque Alps or Bergamo Alps (; sometimes translated into English as Orobic Alps) are a mountain range in the Italian Alps. They are located in northern Lombardy and named after the city Bergamo, south of the mountains. Within the Easter ...

and

Monte Generoso Monte Generoso (also known as ''Calvagione'') is a mountain of the Lugano Prealps, located on the border between Switzerland and Italy and between Lake Lugano and Lake Como. The western and southern flanks of the mountain lie in the Swiss cant ...

is more strongly marked than the nominate subspecies ''E. s. styx''. It has a larger postdiscal band and larger eyespots on the upper forewing while the underside of the hindwing sometimes lacks eyespots. The subspecies ''E. s. trentae'' of the

Julian Alps The Julian Alps (, , , , ) are a mountain range of the Southern Limestone Alps that stretches from northeastern Italy to Slovenia, where they rise to 2,864 m at Mount Triglav, the highest peak in Slovenia. A large part of the Julian Alps is inclu ...

is even more strongly marked. It has large eyespots with bright white centres.

Distribution and habitat

It occurs in the Alps at altitudes of 600–2,200 metres. It is found in northern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

from near Monte Generoso to the

Dolomites The Dolomites ( ), also known as the Dolomite Mountains, Dolomite Alps or Dolomitic Alps, are a mountain range in northeastern Italy. They form part of the Southern Limestone Alps and extend from the River Adige in the west to the Piave Va ...

, in

Ticino Ticino ( ), sometimes Tessin (), officially the Republic and Canton of Ticino or less formally the Canton of Ticino, is one of the Canton of Switzerland, 26 cantons forming the Switzerland, Swiss Confederation. It is composed of eight districts ...

canton in south-east

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

, in the

Allgäu Alps The Allgäu Alps () are a mountain range in the Northern Limestone Alps, located on the Austria–Germany border, which covers parts of the Germany, German states of Bavaria and Baden-Württemberg and the Austrian states of Tyrol (state), Tyrol an ...

in south-east

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, in parts of

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

and in the Julian Alps in

Slovenia Slovenia, officially the Republic of Slovenia, is a country in Central Europe. It borders Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the south and southeast, and a short (46.6 km) coastline within the Adriati ...

. It inhabits steep limestone slopes with scattered trees and bushes. It favours warm, dry, rocky areas.

Life cycle

The barrel-shaped eggs are grey-brown with brown spots and prominent ribs. The

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder ...

s are grey-brown with lighter and darker stripes and can reach 20–25 mm in length. They feed on

grasses Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivated in ...

, particularly '' Sesleria varia''. They take up to two years to mature, hibernating during the first and penultimate

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

s. The butterfly

pupa A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...

tes among stones and grass in a green and brown chrysalis. The adults fly from early July until early September. A single brood is produced each year.

Etymology

Named in the

Classical tradition The Western classical tradition is the reception of classical Greco-Roman antiquity by later cultures, especially the post-classical West, involving texts, imagery, objects, ideas, institutions, monuments, architecture, cultural artifacts, ritu ...

.Styx was the name of an Oceanid nymph, one of the three thousand daughters of the Titans Oceanus and his sister-wife Tethys, and the goddess of the River Styx. Others make her one of the progenies of the primordial gods, Nyx (Night) and Erebus (Darkness)

References

{{Taxonbar, from=Q2140846 Erebia Butterflies of Europe Butterflies described in 1834