Species recognition and cryptic species in the Tuber indicum complex

Area of Science:

• Mycology
• Plant Taxonomy
• Molecular Phylogenetics

Background:

• Morphological delimitation of Asian black truffles (Tuber spp.) is challenging.
• Previous phylogenetic analyses have yielded controversial results regarding species boundaries.
• Accurate identification is essential for understanding and conserving truffle diversity.

Purpose of the Study:

• To resolve taxonomic ambiguities among several Asian black truffle species.
• To clarify the species status of Tuber himalayense, T. indicum, T. sinense, T. pseudohimalayense, T. formosanum, and T. pseudoexcavatum.
• To reveal the phylogenetic diversity within the Tuber indicum complex.

Main Methods:

• Conducted five years of field investigations in China.
• Performed detailed morphological studies on 131 Tuber specimens.
• Utilized DNA sequence analyses of ITS, LSU, and β-tubulin gene regions.

Main Results:

• Tuber pseudohimalayense and Tuber pseudoexcavatum were confirmed as a single species.
• Tuber formosanum was identified as a distinct species based on host plants, distribution, and minor morphological differences from T. indicum.
• Tuber sinense is proposed as a synonym of Tuber indicum.
• The current Tuber indicum species encompasses at least two distinct phylogenetic species.

Conclusions:

• This research clarifies the taxonomy of several problematic Asian black truffle species.
• It highlights the existence of cryptic phylogenetic diversity within morphologically defined species.
• The findings are vital for accurate truffle taxonomy and the conservation of truffle biodiversity.