The Dark Pierrot is a small butterfly found in India that belongs to the Lycaenids or Blues

Lycaenidae

The Lycaenidae are the second-largest family of butterflies, with about 6000 species worldwide, whose members are also called gossamer-winged butterflies...

 family. It was formerly placed in the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Castalius

Castalius

Castalius is a butterfly genus in the family Lycaenidae. They are commonly known as pierrots. This name is also often used for the very closely related genus Tarucus....

, and with the delimitation of Castalius versus Tarucus

Tarucus

Tarucus is a butterfly genus in the family Lycaenidae. They are commonly known as blue pierrots or simply "pierrots". But the latter name is often used for the very closely related genus Castalius. In fact, the delimitation of Castalius versus Tarucus is not yet fully resolved, with some species,...

being not fully resolved this may well be correct.

Distribution

Peninsular and South India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

; Sikkim

Sikkim

Sikkim is a landlocked Indian state nestled in the Himalayan mountains...

, Assam

Assam

Assam , also, rarely, Assam Valley and formerly the Assam Province , is a northeastern state of India and is one of the most culturally and geographically distinct regions of the country...

 and Khasi Hills

Khasi Hills

The Khasi Hills are part of the Garo-Khasi range in the Indian state of Meghalaya, and is part of the Patkai range and of the Meghalaya subtropical forests ecoregion...

 onto Myanmar

Myanmar

Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

 and Dawnas; Orissa

Orissa

Orissa , officially Odisha since Nov 2011, is a state of India, located on the east coast of India, by the Bay of Bengal. It is the modern name of the ancient nation of Kalinga, which was invaded by the Maurya Emperor Ashoka in 261 BC. The modern state of Orissa was established on 1 April...

. In Southern India the butterfly occurs in Kanara

Kanara

The Kanara or Canara region comprises three coastal districts of Karnataka, namely Dakshina Kannada, Udupi and Uttara Kannada and Kasaragod district of Kerala in southwestern India. Kanara forms the southern part of the Konkan coast...

, Nilgiris

Nilgiris (mountains)

The Nilgiri , often referred to as the Nilgiri Hills, are a range of mountains with at least 24 peaks above , in the westernmost part of Tamil Nadu state at the junction of Karnataka and Kerala states in Southern India...

 and Anaimalai Hills

Anaimalai Hills

The Anaimalai Hills is a range of mountains in the Western Ghats in Tamil Nadu and Kerala states of South India. The name "Anaimalai" derives from the Tamil word 'Ana' meaning elephant and 'Mala' meaning hill, thus Elephant Hill. The highest peak of the Anaimalai Hills is Anamudi, , located in the...

. Possibly Thailand

Thailand

Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

.

Description

For a key to the terms used see Lepidopteran glossary

Glossary of Lepidopteran terms

This glossary describes the terms used in the formal descriptions of insect species, jargon used mostly by professionals or entomologist....

Male

Upperside: dark purple, sometimes fuliginous, sometimes bright and shining. Fore and hind wings: terminal margins edged with fuscous brownish-black and an anticiliary jet-black line; cilia brown ; tail black tipped with white. Underside: more or less dingy white. Fore wing: a broad oblique brownish-black band from base to just before the middle of the eosta; from the latter a dark brownish-black bar proceeds vertically down to middle of interspace 3, on the inner side of this and touching it in the middle is a large brownish-black irregular spot that extends posteriorly to vein 1 ; beyond this a broad discal trausverse brownish-black band twice interrupted, the posterior portion slightly narrowed below is shifted obliquely inwards and ends on vein 1 ; this is followed by a postdiscal transverse series of brownish-black spots that anteriorly nearly coalesces with the discal band, a transverse subterminal line of similar but smaller spots and a well-marked anticiliary black line. Hind wing: a basal short, brownish-black, anteriorly attenuate bar placed obliquely, a transverse subbasal band of four large coalescent black spots, a transverse curved discal band twice broken as on the fore wing and similar postdiscal subterminal and terminal markings. Antennae black, shafts ringed with white, head, thorax and abdomen dark brownish-black; beneath : the palpi black, thorax and abdomen down the middle white.

Female

Upperside : fuscous black. Fore and hind wings: in most specimens the markings of the underside show (sometimes very conspicuously) through. Underside: as in the male. Antenna, head, thorax and abdomen similar to those of the male.

Larva

"Like that of Castalius ananda feeds only on the parenchyma of the leaf .... It is of the usual woodlouse form, slightly flattened head concealed in the second segment; surface more or less rough; a fringe of long white bristles all round with an erected ridge of similar bristles along the back from the second segment; those on the 3rd and 7th segments and the last two much longer than the others; those on the 2nd segment very few, short and black. It has a conspicuous gland on the 12th segment, and is attended by small species of ants of the genus Crematogaster. Its colour is pale green, the dorsal portion of the 2nd, 4th, 5th, 6th and last two segments being dark brown, while the centre segments are almost yellow with a darker dorsal line. We found it feeding on Zizyphus xylopyrus and also on Loranthus, where it was attended by Crematogaster ants."

Pupa

"Of the usual Castalius form but narrow and slightly flattened. It is intensely glossy as if covered with gum. It varies in colour, being sometimes black, at others green with inconstant black markings." (Davidson, Bell & Aitken)