A 28-year-old woman from Mumbai presents with a 6-week history of itchy, scaly patches on her groin and inner thighs. She reports the lesions started after a holiday in Goa during the monsoon season. On examination, she has well-demarcated erythematous plaques with a raised, active border and central clearing. The lesions are bilateral and symmetric. KOH mount of scale shows branching septate hyphae. She has no systemic symptoms. What is the most likely causative organism?