The Mexican fireleg resembles its better-known relative, the Mexican redknee tarantula (Brachypelma smithi), in its dramatic orange and black coloration, though the adults of the species range from 5 to 6 inches in size. This species of tarantula has a slower growth rate than many of the larger South American tarantula species. The black upper legs provide a dark dividing band between the rich orange color of the carapace and lower legs. Unlike the orange joints of Brachypelma smithi, the legs of this species are a bright, fiery red on the knees, fading gradually to a paler orange further down and tipped by black feet. Although not particularly defensive, this species of spider can have a nervous temperament, where the spider can flick hairs when it feels threatened.