Editing Kumquat (section)

== Species ==
[[Citrus taxonomy]] is complicated and controversial. Different systems place various types of kumquats in different species or unite them into as few as two species. Botanically, many of the varieties of kumquats are classified as their own species, rather than a cultivar.{{citation needed|date=February 2023}} Historically they were viewed as falling within the genus ''Citrus'', but the [[Citrus taxonomy#Citrus naming systems|Swingle system]] of citrus taxonomy elevated them to their own genus, ''Fortunella''. Recent phylogenetic analysis suggests they do fall within ''Citrus''. Swingle divided the kumquats into two subgenera, the ''Protocitrus'', containing the primitive Hong Kong kumquat, and ''Eufortunella'', comprising the round, oval kumquat, Meiwa kumquats,<ref name="Swingle">{{cite journal|last=Swingle| first=Walter T.| title=A new genus, Fortunella, comprising four species of kumquat oranges| journal=Journal of the Washington Academy of Sciences| volume=5| issue=5| pages=165–176| year=1915| jstor=24520657}}</ref> to which Tanaka added two others, the Malayan kumquat and the Jiangsu kumquat. Chromosomal analysis suggested that Swingle's ''Eufortunella'' represent a single 'true' species, while Tanaka's additional species were revealed to be likely hybrids of ''Fortunella'' with other ''Citrus'', so-called x''[[Citrofortunella]]''.<ref name="Yasada">{{cite journal| last1=Yasuda| first1=Kiichi| last2=Yahata |first2=Masaki |last3=Kunitake| first3=Hisato| title=Phylogeny and Classification of Kumquats (''Fortunella'' spp.) Inferred from CMA Karyotype Composition| journal=The Horticultural Journal|volume=85| number=2| pages=115–121| year=2015| doi=10.2503/hortj.MI-078| doi-access=free}}</ref>

One recent genomic analysis concluded there was only one true species of kumquat, but the analysis did not include the Hong Kong variety seen as a distinct species in all earlier analyses.<ref>{{cite journal|title=Genomics of the origin and evolution of ''Citrus'' | last1=Wu | first1=Guohong Albert | last2=Terol | first2=Javier | last3=Ibanez | first3=Victoria | last4=López-García | first4=Antonio | last5=Pérez-Román | first5=Estela | last6=Borredá | first6=Carles | last7=Domingo | first7=Concha | last8=Tadeo | first8=Francisco R | last9=Carbonell-Caballero | first9=Jose | last10=Alonso | first10=Roberto | last11=Curk | first11=Franck | last12=Du | first12=Dongliang | last13=Ollitrault | first13=Patrick | last14=Roose | first14=Mikeal L. Roose | last15=Dopazo | first15=Joaquin | last16=Gmitter Jr | first16=Frederick G. | last17=Rokhsar | first17=Daniel | last18=Talon | first18=Manuel | journal=Nature | year = 2018 | volume=554 | issue=7692 | pages=311–316 | doi=10.1038/nature25447| pmid=29414943 | bibcode=2018Natur.554..311W | doi-access=free | hdl=20.500.11939/5741 | hdl-access=free }}</ref> A 2020 review concluded that genomic data were insufficient to reach a definitive conclusion on which kumquat cultivars represented distinct species.<ref name="citrus taxonomy">{{cite book |chapter=''Citrus'' taxonomy |last1=Ollitrault |first1=Patrick |last2=Curk |first2=Franck |last3=Krueger |first3=Robert |title=The Citrus Genus |editor-last1=Talon | editor-first1=Manuel | editor-last2=Caruso |editor-first2=Marco | editor-last3=Gmitter |editor-first3=Fred G Jr. |publisher=Elsevier |year=2020 |pages=57–81 |isbn=9780128121634 |chapter-url=https://books.google.com/books?id=2wo4swEACAAJ&pg=PA57 |doi=10.1016/B978-0-12-812163-4.00004-8|s2cid=242819146 }}</ref> In 2022, a genome-level analysis of cultivated and wild varieties drew several conclusions. The authors found support for the division of kumquats into subgenera: ''Protocitrus'', for the wild Hong Kong variety, and ''Eufortunella'' for the cultivated varieties, with a divergence predating the end of the [[Quaternary glaciation]], perhaps between two ancestral populations isolated south and north, respectively, of the [[Nanling Mountains|Nanling mountain range]]. Within the latter group, the oval, round and Meiwa kumquat each showed a level of divergence greater than between other recognized citrus species, such as between pomelo and citron, and hence each merits species-level classification. Though Swingle had speculated that the Meiwa kumquat was a hybrid of oval and round kumquats, the genomic analysis suggested instead that the round kumquat was an oval/Meiwa hybrid.<ref name="FASE">{{cite journal |last1=Zhu |first1=Chenqiao |display-authors=etal |title=New insights into the phylogeny and speciation of kumquat (''Fortunella'' ssp.) based on chloroplast SNP, nuclear SSR and whole-genome sequencing |journal=Frontiers of Agricultural Science and Engineering |year=2022 |volume=9 |issue=4 |page=627 |doi=10.15302/J-FASE-2021436|s2cid=247640336 |doi-access=free }}</ref>

{| class="wikitable"
|+Kumquat species
!'''Image'''
!'''Scientific name'''
!'''Common name'''
!'''Distribution'''
|-
|[[File:Fort-hindsii.jpg|120px]]
|''[[Citrus hindsii]]''
|[[Hong Kong]] kumquat
|China
|-
|[[File:Starr-121108-0788-Fortunella_x_crassifolia-fruit-Pali_o_Waipio-Maui_(25103025561).jpg|120px]]
|''[[Citrus crassifolia]]''
|Meiwa kumquat
|China, Japan
|-
|[[File:Fortunella.jpg|120px]]
|''[[Citrus margarita]]''
|oval kumquat, Nagami kumquat
|Japan
|-
|[[File:Citrus_japonica.jpg|120px]]
|''[[Citrus japonica]]''
|round kumquat, Marumi kumquat, Morgani kumquat
|China, Japan
|-
|[[File:Fortunella_obovata_Fukushu_0zz.jpg|120px]]
|''[[Citrus obovata]]''
|Jiangsu kumquat, Fukushu kumquat
|China, Japan
|-
|[[File:Fortpolyandra.jpg|120px]]
|''[[Citrus swinglei]]''
|Malayan kumquat
|[[Malay Peninsula]]
|}

=== Hybrids ===
{{Main|Citrofortunella}}

[[citrus hybrids|Hybrid]] forms of the kumquat include the following:
* [[Calamansi]]: [[mandarin orange]] x kumquat<ref>{{GRIN|×''Citrofortunella microcarpa''|313479|access-date=1 June 2014}}</ref>
* [[Citrangequat]]: [[citrange]] x kumquat
* [[Limequat]]: [[key lime]] x kumquat
* [[Orangequat]]: [[Satsuma mandarin]] x kumquat
* [[Procimequat]]: [[limequat]] x kumquat
* [[Sunquat]]: [[Meyer lemon]] (?) x kumquat
* [[Yuzuquat]]: [[yuzu]] x kumquat