Mexican fire knee is very distinctive, the red area of knee looks like fire, so it has this name. The Mexican Fire Knee looks thick and huge as a whole. The adult Mexican Fire Knee has a foot span of about 15-16cm and is covered with bright fluff.

Because its name is one word short of the Mexican red knee, the Mexican fire knee was once considered a regional variant or subspecies of the Mexican red knee. In fact, if you look closely, they are indeed very similar.