Jaera forsmani Bocquet, 1950

Jaera are small, ubiquitous intertidal marine isopods which can be identified to species by the examination of male reproductive structures (specifically the preoperculum) and pereopods. Preopercula can be examined using a binocular dissecting microscope, but examination of pereopods is best done using a compound microscope at low power.

Jaera forsmani is one of the 'albifrons' group of species (along with Jaera albifrons, Jaera ischiosetosa and Jaera praehirsuta), all of which have a T-shaped male preoperculum. It can be distinguished from the other species by the presence of a prominent distal carpal spine on the male 6th pereopod and by sparse curved setae on the propodus, carpus and merus of male pereopods 1-4. Males up to 3.4mm, females up to 6.0mm. See further the Identifying Jaera page.