Asemesthes lamberti is known only from the female. The carapace is medium brown with dark edges, lateral darkened mottling, and a faint broad median band of pronewhite hairs. The dorsal surface of the opisthosoma has a dark greyish median band extending halfway and followed by a series of arrow-shaped dark marks narrowing towards the spinnerets. The lateral and posterior borders of the upper surface are dark. The legs are slightly lighter than the carapace, with darkened and mottled femora on the upper surface. The total length is 7 mm.
The species was originally described by Richard William Ethelbert Tucker in 1923 from Lamberts Bay. It has not been revised since its original description.