Thelebolus microsporus mycelial mats in the trachea of wild brown skua (Catharacta antarctica lonnbergi) and South Polar skua (C. maccormicki) carcasses.

Sixteen brown skuas (Catharacta antarctica lonnbergi) and seven South Polar skuas (C. maccormicki) were found dead near Boekella Lake, Hope Bay, Antarctica, in February 1997. Postmortem examination revealed conspicuous caseous, deep yellow fungal/mycelial mats or cores in the trachea of nine of 19 carcasses that were examined. These mycelial cores, highly suggestive of aspergillomas, completely occluded the tracheal lumen in four of these nine carcasses. Thelebolus microsporus, a psychrophilic ascomycetous fungus commonly isolated from skua dung and skua nesting material, was isolated in pure culture from these tracheal plugs. Awareness of pseudolesions resulting from Thelebolus microsporus profuse postmortem growth in the trachea of dead skuas will minimize potential confusion with aspergillosis when investigating causes of epornithics in Antarctica.