Blacktailed Icius Jumping Spider

Icius nigricaudus is a small slender spider. The male has a carapace that is between 1.3 and 1.4 mm (0.05 and 0.06 in) long and 0.9 and 1.0 mm (0.04 and 0.04 in) wide. It is oval, low with a back that is particularly sloped. It is generally brown with a black line running along its edges and a pattern of four small patches of white hairs on the sides, the whole covered in delicate translucent hairs. The eye field is black with small scales near the eyes themselves. The underside of the spider opposite the carapace, the sternum, is light brown. The spider's face, or clypeus, is very low. The chelicerae are brown and unidentate. The other mouthparts include the labium, which is fawn-brown. The abdomen is between 1.2 and 1.3 mm (0.05 and 0.05 in) long and between 0.6 and 0.8 mm (0.02 and 0.03 in) wide. It is an elongated oval, the frontal two-thirds olive-yellow and the rearmost third black, marked with five patches formed of white scales. The underside is similar in colour to the topside. The spinnerets are black. The front legs are larger than the others, and black rather than brown. All the legs have fine brown hairs. The pedipalps are dark with a scattering of white hairs. The tegulum has a low posterior node, the embolus is straight and the tibial apophysis, or appendage, is hooked. The female is similar in size and shape to the male. …

Icius nigricaudus is endemic to South Africa. The holotype was discovered in 2005 in the Ndumo Game Reserve. The species is rare and lives on grasses found near to rivers and other wetlands and in the bark of Vachellia xanthophloea. It has been declared to be an Endangered species in 2019.