Allocasuarina hystricosa Wege is described as new. Known largely from the Ravensthorpe region, this dioecious species is characterised by erect branchlets with 10–12 leaf teeth per whorl, long articles (mostly 15–35 mm long), and three (more rarely two or up to five) spines per cone bracteole protuberance. Revised descriptions are provided for the phylogenetically related species A. scleroclada (L.A.S.Johnson) L.A.S.Johnson, A. corniculata (F.Muell.) L.A.S.Johnson, A. spinosissima (C.A.Gardner) L.A.S.Johnson, A. globosa L.A.S.Johnson and A. tortiramula E.M.Benn., and a lectotype chosen for A. tortiramula. A putative new taxon, A. spinosissima subsp. short spine (D.L. Serventy & A.R. Main s.n. 25/8/1960), is highlighted for further research. The recent acquisition by the Western Australian Herbarium of a significant number of Allocasuarina specimens of Western Australian origin is noted.