Trichophyton rubrum (Cast.) Sabouraud var. nigricans var. nova differs from the typical form by producing a dark brown pigment and an antibiotic effective against Cryptococcus. Cultures were obtained from diseased nails and skin. The fungus shows no significant microscopic differences from the typical form.
Frágner P. (1966): Trichophyton rubrum (Cast.) Sabouraud var. nigricans var. nova. – Česká Mykologie 20(1): 27–28.