Rhobs el Arsa
The Rhobs al Arsa has long been viewed as a citron hybrid, though a different cultivars have been suggested for the parent, for example, Moroccan citron as a male parent and sour orange as the female parent, citron or lemon and a mandarin., or citron and the lime. Detailed genomic analysis has shown Rhobs al Arsa to be highly similar to several cultivars of "Citrus limetta", the limetta or Persian sweet lime, and likely shared a common origin with them, arising from a cross between citron ("Citrus medica") and sour orange ("Citrus" × "aurantium"). The common lemon arose from a distinct hybridization event involving the same two species.
Siracusa Lemon
The European Union has nine (PGI) denominations for lemons: six of these are from Italy, one from France, one from Spain, and one from Portugal. Other than the "Siracusa lemon", the Italian denominations are the "Limone di Sorrento", the "Limone Costa d'Amalfi", the "Interdonato di Messina", the "Femminello del Gargano", and the "Limone di Rocca Imperiale". The French denomination is the "Citron de Menton". The Spanish denomination is the "Citricos Valencianos", while in Portugal the "Citrinos do Algarve" is protected.