Basiothia laticornis is a moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

 of the Sphingidae

Sphingidae

Sphingidae is a family of moths , commonly known as hawk moths, sphinx moths and hornworms, that includes about 1,200 species . It is best represented in the tropics but there are species in every region . They are moderate to large in size and are distinguished among moths for their rapid,...

 family. It is only known from Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

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It is similar to Basiothia medea

Basiothia medea

The Small Verdant Hawk is a moth of the Sphingidae family. It is common in open habitats throughout the Ethiopian Region, including Madagascar. It is however probably absent from the equatorial forest belt, except as a vagrant. The species is an active migrant.The length of the forewings is 22-25...

, but immediately distinguishable by the generally brown forewing and hindwing uppersides. The antennae are strongly clubbed in both sexes, but noticeably longer and thicker in the male. The forewing upperside is purplish-brown. There are three antemedian lines present. There is a darker brown patch distal to the apex of the discal cell.