Stenaelurillus nigricaudus, synonyms Aelurillus sahariensis and Stenaelurillus nigritarsis, is the type species of the genus Stenaelurillus. It is a jumping spider that lives in Algeria, Burkina Faso, Gambia, Mali, Niger and Senegal. The male was first described by Eugène Simon in 1886 and the female initially in 1936 by Ludovico di Caporiacco and more thoroughly by Nikolaj Scharff and Tamás Szűts in 2005. It is a medium-sized spider with a cephalothorax between 2.4 and 2.7 mm and an abdomen that is between 2 and 3.7 in long. The carapace is reddish-brown and has two white or yellow stripes. The female abdomen has a pattern of stripes and spots, with some examples having brown spots inside yellow spots. The male abdomen has either a single dark stripe or two white and one brown stripes. While the female pedipalps are yellow, the male has either dark or brown pedipalps. The female has distinctive flanges at its copulatory openings. The male is distinguished by the shape of its palpal bulb and, particularly, of its hook-shaped embolus.

Stenaelurillus is a genus of jumping spiders that was first described by Eugène Louis Simon in 1886. Most species live in Africa, with some species found in Asia, including China. All species have two white longitudinal stripes on the carapace, and both sexes show strong bristles around the eyes. The name is a combination of the Greek sten- "narrow" and the salticid genus Aelurillus.