Larta magus
Larta magi are non-Gifted members of House Jerbiton. They were introduced during the Fourth Edition in the sourcebook Houses of Hermes sourcebook, and were further discussed in the Sanctuary of Ice:The Greater Alpine Tribunal book, but are notably missing from the Jerbiton treatment in Fifth Edition's Houses of Hermes: Societates.
They nevertheless are still canonical under Fifth Edition. Guardians of the Forests mentions Larta magi as unGifted Jerbiton magi on page 121. It also contains an obscure reference to unGifted members of House Jerbiton on page 111, that probably also refers to them.
Houses of Hermes: True Lineages says that Larta magi are usually raised in House Mercere and join House Jerbiton only after taking their Oath (page 93).