Length 10-49 mm. Head longer than third of whole animal in females (Streetsia challengeri 1), shorter than third in males. Rostrum with serrate ventral margin. ART 5 of P I slightly expanded distally, as broad as long, posterodistal corner dentate, with numerous setae (Streetsia challengeri 2). ART 2 of P II with triangular posterodistal process in adult females, weak in males and young females. ART 5 of P II as long as wide, palmar margin dentate, with extremely strong denticle on posterodistal corner. ART 2 of P VI slightly longer than distal ART combined, narrowing distally, anterior margin smooth, posterior margin convex, with rounded proximal lobe; pointed triangular distal lobe much longer than ART 3 (important character). Epimeral plates I-II in large specimens with sharp posteroventral corner, in small specimens with rounded corners. Epimeral plate III with straight ventral margin, produced sharp posteroventral corner. All epimeral plates with small, rounded, pit-like gland in centre. Fused (II+III) urosomite twice as long as wide. Telson as long as fused urosomite or longer, with produced sharp top.