Citron
A source of confusion is that "citron" or similar words in French (and other languages), and English are false friends, as they refer to the lemon. Indeed, into the 16th century, the English name "citron" included the lemon and perhaps the lime as well.
Lumia (citrus)
The most known origin for the Lumia is from the Mediterranean basin. The Lumia is also classified as "Citrus limon var. lumia" by Swingle which places it under the taxonomy of lemon, and "Citrus medica L. var. lumia", that suggests it is similar to citron.