Calamansi was formerly identified as "Citrus mitis" Blanco, "C. microcarpa" Bunge or "C. madurensis" Lour., all those referred to it as a citrus. Swingle's system of citrus classification would put kumquats into a separate genus, "Fortunella", making the calamansi an intergeneric hybrid, and in 1975 it was given the hybrid name × "Citrofortunella mitis" by John Ingram & Harold E. Moore based on Blanco's species name, but in 1984, D. Onno Wijnands pointed out that Bunge's species name, "C. microcarpa" (1832), predated Blanco's "Citrus mitis" (1837), making × "Citrofortunella microcarpa" the proper name. Phylogenetic analysis now places the kumquat within the same genus as other citrus, meaning that its hybrids, including those formerly named as × "Citrofortunella", likewise belong in "Citrus".