A subspecies is an alternate form of a monster. These monsters usually feature an alternate color palette and often boast different anatomical features and abilities from the common species. Subspecies can inhabit similar environments as the common species, but they can also sometimes be found in completely different locales, depending on the species of monster.
Subspecies are typically faster, stronger, and possess more health and defense than their common counterparts. Certain Subspecies may also be considered a "Rare" species; this is the case for Gold Rathian, Silver Rathalos, Abyssal Lagiacrus, Lucent Nargacuga and Molten Tigrex. These monsters are normally far more powerful than their original counterparts and other subspecies, but far rarer.
Golden Rajang is not actually a subspecies. It is an ordinary Rajang that looks almost golden while calm, and shows its Electric Aura in Rage mode. This is the same for the 3rd generation's Savage Deviljho, which G-rank version always has its shoulder muscles red and has its face covered in Dragon, while the normal Deviljho only huffs this element during its rage.