Scopulariopsis
Also known as Scopulariopsis brevicaulis, Scopulariopsis candida
A filamentous surface mould, not a yeast, a sporadic and salt-and-drought-tolerant member of the natural mycobiota of dry-cured hams and sausages.
Scopulariopsis is a mould rather than a yeast, and it appears, sporadically but regularly, among the natural surface fungi of long-aged dry-cured hams and sausages, alongside the dominant Penicillium. It is ubiquitous in the environment and turns up across fermented foods, so its presence on a curing surface is unsurprising.
What sets it apart is a marked tolerance of dryness. Being more xerotolerant than the noble Penicillium nalgiovense, it tends to colonise late in ripening, once the water activity has fallen far enough that the noble mould's protective cover thins and its barrier effect weakens. It is generally treated as part of the traditional mycobiota rather than a deliberate culture.
The surface fungi are, however, exactly where toxin risk can hide, and the sound course does not depend on identifying every organism by eye. A known noble culture, established early and maintained, and a controlled surface leave the least room for whatever else, Scopulariopsis included, might otherwise take hold as the ham dries.