July 2017. A message from a member (country unstated), who was sent a Phalaenopsis hybrid, probably of Dutch origin. Could it be a Tospovirus or at least a virus?
Stephan Winter, DSMZ, wrote: we have received over the past years several times Phalaenopsis plants with this type of symptoms, but all attempts at isolating or identifying something like a virus failed. It also appears that this is the ONLY hybrid that has this type of symptoms AND that the symptom is transient, visible on a few leaves before it disappears, although it may appear again later. Indeed there are several tospos on Phalaenopsis reported from Thailand and elsewhere. The symptom you show, however, is not that typical since tospo ringspots are different. From my side, after spending a long time on this, I decided to move on as all we did was inconclusive.
Another member also did not think the symptoms typical of virus infection: the first photo shows only one leaf affected, and the youngest not affected, which is somewhat atypical of virus infection. So the symptom is most likely physiological, due to an insect that has punctured the leaf, or perhaps an aedema.