Tapena thwaitesi, commonly known as the Black Angle, is a monotypic

Monotypic

In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of butterfly

Butterfly

A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...

 belonging to the family Hesperiidae. The species name is after G. H. K. Thwaites, the Director of the Botanical Garden at Peradeniya

Peradeniya

Peradeniya is a town of about 50,000 inhabitants on the outskirts of Kandy in Sri Lanka. It is situated on the A1 main road connecting Kandy and Colombo, just a few kilometres west of Kandy....

, Sri Lanka

Sri Lanka

Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...

between 1849 and 1880.

Description

Male has the upperside dark purple-brown, with blackish outer margins and indistinct discal transverse band of spots; forewing with two small translucent white spots on the costa near the apex. Underside dark purple-brown.

Female has the upper and underside greyish purple-brown, transverse band of spots and outer border dark purple-brown; forewing with three small semi-diaphanous white subapical spots, the lowest transversely narrow, two spots also at end of the cell, the upper one very slender, and two spots on the disc, each series being bordered by the dark band; hindwing with a semi-diaphanous spot at end of the cell.