Systematic mycology: Which organism listed is NOT a member of the division Ascomycota (sac fungi)?

Introduction / Context:
Ascomycota (sac fungi) include many clinically and industrially important genera that form ascospores within asci. Distinguishing them from other divisions, particularly Mucorales (formerly Zygomycota), is central to both taxonomy and clinical practice.

Given Data / Assumptions:

• Aspergillus, Penicillium, Claviceps, and Candida are commonly associated with Ascomycota.
• Rhizopus belongs to Mucorales, not Ascomycota.
• We consider broad, widely accepted placements used in teaching.

Concept / Approach:
Aspergillus and Penicillium produce abundant asexual conidia and are placed within Ascomycota; sexual states (teleomorphs) belong to related ascomycete genera. Claviceps (ergot fungi) is an ascomycete. Candida yeasts are also within Ascomycota (e.g., Candida albicans in Saccharomycetales). Rhizopus, however, is a mucoralean mold forming sporangiospores in sporangia and zygospores sexually, placing it outside Ascomycota.

Step-by-Step Solution:
List genera and recall their higher-level taxonomy. Identify Rhizopus as a Mucorales member (non-ascomycete). Confirm the others are ascomycetous lineages. Select “Rhizopus.”

Verification / Alternative check:
Clinical mycology distinguishes mucormycosis agents (Rhizopus, Mucor, Lichtheimia) from ascomycete molds like Aspergillus due to differing hyphal morphology and antifungal susceptibility patterns.

Why Other Options Are Wrong:

• Aspergillus/Penicillium/Claviceps/Candida: All fall within Ascomycota.

Common Pitfalls:
Equating sporangiospore production with ascomycetes; sporangia are typical of mucoralean molds, not of Ascomycota.

Final Answer:
Rhizopus.