WHERE ARE ALL THE UNDESCRIBED FUNGI

The hypothesis that there are 1.5 million fungal species on Earth, of which only about 70,000 are described, implies that 1.43 million remai n undescribed. The recognition that many new species have yet to be fo und is of fundamental importance to plant pathologists, agronomists, a nd plant regulatory officials, among others, who continue to encounter diseases caused by previously unknown or understudied fungi. Unexplor ed habitats with their arsenal of unknown fungi are also of interest t o those searching for novel organisms for use in biological control or for their pharmaceutical attributes. This paper presents data on the expected numbers of fungi in some relatively unexplored habitats, such as tropical forests, and those obligately associated with plants, lic hens, and insects. In addition to undiscovered species, many have been collected but remain lost or hidden as named species and ignored for lack of modern characterization; others have been collected and recogn ized as new species but remain undescribed. Some fungal species are un recognized within erroneously circumscribed species, often based on pr esumed host specificity, while others exist as biological species but remain buried within those broadly defined species for lack of gross m orphological characterization. From these data, one must conclude that enormous numbers of unrecognized fungi can be found almost everywhere , including one's own backyard.