Pythium insidiosum complex hides a cryptic novel species: Pythium periculosum

Area of Science:

• Mycology
• Veterinary Medicine
• Molecular Biology

Background:

• Pythium insidiosum is the causative agent of pythiosis in mammals.
• Previous phylogenetic studies indicated a complex structure with multiple clusters.
• Recent analyses suggested evolving phylogenetic patterns within P. insidiosum.

Purpose of the Study:

• To re-evaluate the phylogenetic and genetic diversity of Pythium insidiosum isolates.
• To clarify the taxonomic status of previously identified clusters within the P. insidiosum complex.
• To identify novel species within the complex that may impact pythiosis epidemiology.

Main Methods:

• Phylogenetic analysis of available P. insidiosum isolates.
• Population genetic analysis.
• Protein MALDI-TOF mass spectrometry analysis.

Main Results:

• Phylogenetic and genetic analyses revealed distinct differences between proposed clusters III and IV compared to clusters I and II.
• A novel group, comprising two sub-clusters (USA and global), was identified.
• The original P. insidiosum cluster III was confirmed as a distinct cryptic species, identified as Pythium periculosum.

Conclusions:

• The P. insidiosum complex is more complex than previously understood, containing at least two distinct phylogenetic groups.
• The identification of Pythium periculosum as a novel species has significant implications for the diagnosis and treatment of pythiosis.
• Further research into the epidemiology and pathogenicity of these distinct species is warranted.