Rediscovery of the vesicles that characterized Rhizopogon vesiculosus.

Molecular distinction between Rhizopogon vinicolor and R. vesiculosus has been made recently, but the diagnostic "yellow-brown (fresh) inflated cells" of R. vesiculosus, originally described by AH Smith, were not observed. These distinctive hyphal cells (vesicles) have not been reported since the type description. In that description they were said to collapse upon drying and described as being difficult to find. Here we report the rediscovery of these vesicles and describe their specific location on sporocarps of R. vesiculosus. We also report an original discovery that coiled, dark-walled hyphae on the sporocarps and in the mycorrhizae of R. vinicolor are of taxonomic value. The coiled hyphae, combined with the presence or absence of the elusive vesicles, allow R. vesiculosus and R. vinicolor to be morphologically distinguished with increased accuracy.