F. antimena is endemic to the South-Western spiny desert of Madagascar. It is not currently known to occur in any protected areas. The best known locality for this species is the spiny forests surrounding the village of Belalanda near Tulear. It is also known from a number of other localities in the general region of Tulear. Common within it's range, it occurs together with Furcifer labordi at Ranobe, north of Ifaty, Tulear (Raxworthy pers.comm.).

Males reach a maximum total length of 12-13 inches (33 cms). Females only grow to about 7 inches (18 cms). Scalation is heterogeneous with a longitudinal row of enlarged scales. Males exhibit a prominent, vertically compressed nasal projection that is present but less developed in females. The "nose" is thin and fragile. Males have a high casque which is much less elevated in females. Males also have a gular crest of a few pointed tubercles while females have a gular crest of numerous very small pointed tubercles. Males are green or yellowish green with a dark brown or black-colored, irregular net pattern on the sides and tail. Lower parts of the flanks are off-white. The central parts of the flanks are usually more yellowish. Labials are green or yellow green. The casque and dorsal crest are bone colored. Males have a strongly developed doral crest formed of +/- 30 saw-like spines. Females have an incomplete dorsal crest of a maximum of 8 small pointed tubercles at the anterior part of the back. Females in non-breeding condition are gray with irregular black markings, often with a faint bluish flush. Gravid females are green with the upper parts of the flanks colored in purple with numerous cobalt blue scales mixed within. These cobalt blue spots are very prominent on the cheeks. Labials of gravid females are white.

Similar species: F. antimena can only be confused with Furcifer rhinoceratus and Furcifer labordi, two closely related species. Male F. antimena differ from male Furcifer rhinoceratus by the complete dorsal crest and from male Furcifer labordi by the lack of a white midventral line. Female Furcifer antimena differ from female F.rhinoceratus and F.labordi by their heterogenous scalation (homogenous in F. rhinoceratus and F. labordi) .