Microsporum gallinae (originally identified as Epidermophyton gallinae) is a type of fungi known as dermatophyte, which have the ability to utilise keratin as a nutrient source, i.e. they have a unique enzymatic capacity [keratinase]. It is responsible for causing dermatophytosis (tinea or favus aka ringworm) in chickens.
M. gallinae is found worldwide, however is more abundant in tropical and subtropical regions. It's optimal temperature for growth is between 26 to 28 °C (78 to 82 °F). M. gallinae seeks keratin-rich nutrients found on chicken's skin and nails.