A 35-year-old woman from rural Maharashtra presents with a 2-month history of progressive hair loss from the scalp. Examination reveals a well-demarcated patch of alopecia with scaling, erythema, and broken hairs (not pulled out at the root). Some hairs appear black and dotted (black dot ringworm). Fungal culture on Sabouraud medium shows a slow-growing, buff-coloured colony with a red pigment on the reverse side. What is the most likely diagnosis and organism?