Thallic Conidia

  • Develop by SEPTATION and FRAGMENTATION of a hypha.
  • May develop at the TIP OF A HYPHA or in an INTERCALARY (central) POSITION.
  • In both cases, ALL LAYERS of the hyphal wall are involved in spore formation.
Arthrospores:
Diagram illustrating arthrospore formation.
  • Formed by septation and fragmentation of an existing hypha.
  • Elements of the hypha (incl. all wall layers) become converted into conidia.
  • Each fragment is rounded off and liberated in succession.
  • Separation of the conidia from one another is due to breakdown of the middle region of each septum.
Chlamydospores:
Diagram illustrating chlamydospore formation.
  • A type of resting (survival) spore.
  • Found in several groups of fungi (e.g. Zygomycota and mitosporic fungi).
  • An intercalary (see diagram) or apical hyphal cell or compartment enlarges, rounds up and develops a thickened, often pigmented wall.
  • Contain dense cytoplasm and nutrient storage compounds.
  • All wall layers are involved in their formation.
  • Become isolated from adjacent hyphal compartment(s) by the sealing of septal pores (if present).
  • Usually develop under conditions of stress that are unfavourable for normal somatic growth.

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