Niger
The West African Giraffe or Nigerian Giraffe Giraffa peralta (Wildlife Extra) was recently proposed as a distinct species (BioMed Central pdf file) and survives only in Niger.
A beaked snake Rhamphiophis maradiensis (Reptile Database) has been described from Maradi, but is apparently a misidentified specimen of the Hooded Malpolon (ARKive).
Invertebrates known definitely solely from Niger include a leafhopper Helionidia ahua (AMNH), a dung beetle Mesontoplatys rougoni (hExApOdA), a flower beetle Gnathocera sericinitens (Google Books), a longhorned beetle Eunidia breuningiae (Lamiaires
du Monde), a grasshopper Brachycrotaphus nigericus (OSF), a goblin spider Melchisedec birni (Goblin Spider PBI), a lynx spider Oxyopes fallax (World Spider Catalog), and a jumping spider Thyene chopardi (Salticidae of the World).
The few vascular plant species described from Niger and not known
elsewhere all appear to be synonyms of more widespread species.
These include Commiphora airica (JSTOR), Euphorbia tellieri (JSTOR), Vigna marchali (JSTOR), and Ipomoea aridissima (IPNI).