Ringworm, also known as tinea, is a superficial fungal infection of the skin caused primarily by dermatophyte fungi. Among these, Trichophyton species are the most common causative agents, invading keratinized tissues such as the skin, hair, and nails. These fungi produce characteristic ring-shaped, scaly, and itchy lesions, which is the hallmark clinical presentation of ringworm. Effective diagnosis and treatment depend on identifying Trichophyton as the pathogen, as other fungi like Candida or Aspergillus typically cause different clinical manifestations. Therefore, Trichophyton is the definitive fungus responsible for ringworm infections.

Reference: Andrews' Diseases of the Skin, James, William D., 13th Edition.