Butterflies of
the Amazon and Andes
Arnaca Blue Ringlet
Chloreuptychia
arnaca
FABRICIUS,
1776
Family -
NYMPHALIDAE
subfamily -
SATYRINAE
Tribe - SATYRINI
subtribe -
EUPTYCHIINA
Chloreuptychia arnaca Trinidad
© Keith Grant
Introduction
There are 1100 known species of Satyrinae in the neotropical region. About 400
of these are placed in the Euptychiina. Butterflies within this tribe include
the "ringlet" genera Euptychia,
Magneuptychia,
Harjesia,
Cissia,
Caeruleuptychia,
Magneuptychia, Harjesia etc; together with
Oressinoma and the various "wood nymph" genera i.e.
Parataygetis, Posttaygetis
and Taygetis. Most are inhabitants of the forest
understorey and tend to fly close to the ground. They generally avoid sunlight
and prefer to fly at dawn or on cloudy days when light levels and temperatures
are low.
Until
fairly recently almost all of the "ringlets" were placed in the genus
Euptychia,
but revisions by Forster and Lamas divide this
"convenience" genus into a number of smaller genera, on the basis of
anatomical differences and larval foodplants. There
are 42 species of "blue ringlets", now variously allocated to the genera
Caeruleuptychia,
Cepheuptychia
and
Chloreuptychia.
The 12
Chloreuptychia
species
are characterised by having ovoid forewings, a subtle blue sheen on the underside, and a pair of elongated silvery ocelli within the series of
eyespots on the underside hindwings.
Chloreuptychia arnaca is
distributed from Costa Rica to Bolivia.
Habitats
This species is found in rainforest habitats at altitudes
between 0-900m.
Lifecycle
The egg is globular, shining white in colour, and laid singly on
grasses. Chloreuptychia arnaca lays
on
Eleusine,
Oplismenus
and
Ichnanthus
( Poaceae )
where it grows around the base of trees.
The larva is
mottled in shades of brown, and has a row
of diamond-shaped marks along the back. It's head is black with a
pair of short horns that bear auxiliary spines. The tip of the abdomen bears a pair of
caudal prongs. In common with almost all other Satyrines, the
larvae feed nocturnally. The
pupa of arnaca is mottled in shades
of brown. Chloreuptychia pupae
are typically wedge-shaped, and are formed attached by
the cremaster to a stem, projecting horizontally.
Adult behaviour
The butterflies inhabit the understorey, and are usually only seen
along the darker and narrower trails.
They don't visit
flowers but feed instead at decomposing fungi
and bird droppings. Most of the time they sit
motionless on leaves in the shade, and if disturbed they generally fly a distance of no more than
3 or 4 metres, and then re-settle. Unlike most blue ringlets,
arnaca commonly basks in dappled sunlight with
it's wings fully
outspread.
It is likely that the wings
reflect high levels of ultra-violet, enabling the butterflies to locate
potential mates visually in the dark environment where they breed.
The
vertical
lines on the underside are an example of disruptive colouration.
They help break up the outline of the wings into separate
shapes, making it more difficult for a bird to detect the
butterfly.
If however a bird
succeeds in discovering where it has settled, the butterfly has a
secondary defence in the form of the ocelli on the underside
hindwings. These function to divert attacks away from the
butterfly's vulnerable body, allowing it to escape with nothing worse than a
pecked
wing.
Chloreuptychia arnaca Ecuador
© Tony Hoare
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