Definition

Noun: - A taxonomic category (form genus) used in mycology to classify certain imperfect fungi (fungi for which a sexual reproductive stage is unknown or not observed). This grouping is primarily based on morphological characteristics observed in their asexual state. Some species historically placed in this form genus have since been reclassified into other genera (such as Pellicularia and Corticium) after their perfect (sexual) stages were discovered.

Usage Examples

• Noun:
  • The isolate was tentatively identified under the form genus Rhizoctinia due to its characteristic hyphal structure.
  • Advances in molecular phylogeny have led to the reclassification of many species originally described in the form genus Rhizoctinia.

Advanced Usage

• Taxonomic Context: The term is used almost exclusively in scientific, particularly mycological and phytopathological, literature. It signifies a provisional classification based on asexual morphology, acknowledging that the true phylogenetic relationships may be different.
  • The pathogen causing sheath blight was long referred to as a member of the form genus Rhizoctinia before its sexual stage, Thanatephorus cucumeris, was identified.

Variants and Related Words

• Rhizoctonia (n): A corresponding genus name often used for similar fungi, sometimes used interchangeably in non-technical contexts, though taxonomically distinct. is a major plant pathogen.
• Form genus (n): A taxonomic genus defined for a group of organisms (especially fungi) based on their asexual (imperfect or anamorphic) form, when the sexual (perfect or teleomorphic) form is unknown.

Synonyms

• Anamorph genus: A more technical synonym emphasizing the classification is based on the asexual (anamorphic) state of the fungi.

Notes on Different Meanings

• This term has a single, highly specialized meaning within scientific taxonomy and plant pathology. It does not have general English usage or idiomatic meanings.

Noun

1. form genus of imperfect fungi some species of which are now placed in genera Pellicularia and Corticium because their perfect stages have been found