Little is yet known about Consalus Ponce de Leon. He is not the explorer Ponce de Leon who went looking for the fountain of youth, though he is probably of the same family. He was from Spain but probably was in Rome when he wrote his book. He was born around 1530. He was obviously well educated, and could read Greek well enough to translate into Latin. He was also well read, with access to a good library (possibly at the Vatican), as indicated by the wide range of authorities he references in his commentary on the Physiologus; several of the referenced texts were published by Plantin.
Ponce de Leon calls himself Cubicularius secretus to Pope Sixtus V. Cubicularius is defined as a valet-de-chambre, bed-chamber servant; chamberlain, head of chamber servants.
"There were various kinds of cubicularii, and they had many functions, which generally centered around personal service to the pope; see Hoffman, 1:160-61, especially n. 4. [W. von Hoffman, Forschungen zur Geschichte de kurian Behörden vom Schisma bis zur Reformation (Rome, 1914)] ... Hoffman distinguishes three different types of cubicularii. The third type took care of personal service to the pope in the papal chamber (1:160-61 n.4). According to Hoffman, it was only in during the reign of Pope Sixtus IV (1471-84) that this branch of the office was divided into two types. There were then the cubicularii extra cameram and the cubicularii secreti, the latter of whom took special care of the pope's personal needs (even the pope's barber, e.g., was among this number). But this did not mean that those who held these offices had unimportant positions; they were close to the pope and often had considerable influence (ibid.)." - Celenza, 1999, p. 181, note 44.
It appears that Ponce de Leon and Plantin had an association that went beyond the publication of the Sancti Epiphanii ad Physiologum. For two letters written to Ponce de Leon, see Plantin's correspondence.
If you have any information on Consalus Ponce de Leon, please contact the editor.
Saint Epiphanius