Crataegus ×ninae-celottiae and C. ×cogswellii (Rosaceae, Maleae), two spontaneously formed intersectional nothospecies.
Crataegus monogyna Jacq. is naturalized in North America, where it has hybridized with native diploid hawthorns at least twice. We provide names for the two nothospecies (as well as for the corresponding nothosections and nothoseries), referring to existing documentation in the literature for nothosp. nov. Crataegus ×ninae-celottiae K.I. Chr. & T.A. Dickinson (C. monogyna × C. punctata Jacq.). New data are provided to further document nothosp. nov. Crataegus ×cogswellii K.I. Chr. & T.A. Dickinson (C. monogyna × C. suksdorfii (Sarg.) Kruschke). In both cases, the striking differences in leaf shape between most New World hawthorns and Old World section Crataegus, and the intermediacy of the hybrids, account for the relative ease with which these hybrids can be recognized. Finally, new sequence data from ITS2 and chloroplast DNA barcoding loci confirm the genetic relationships between the two nothospecies and their respective parents.
Assoc. Prof. M.Sc. Ph.D. Knud Ib Christensen (born 13 October 1955, deceased 16 January 2012), formerly at the Botanical Garden, Natural History Museum of Denmark, University of Copenhagen.
Knud Ib
KI
Christensen
The Centre for Applied Genomics (TCAG), The Hospital for Sick Children, Peter Gilgan Centre for Research and Learning, Rm. 139715, 686 Bay St., Toronto, Ontario, M5G 0A4.
Mehdi
M
Zarrei
Department of Botany, MRC-166 National Museum of Natural History Smithsonian Institution Rm W106 Washington, DC 20013-7012 USA.
Maria
M
Kuzmina
Green Plant Herbarium (TRT), Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario Canada M5S 2C6.
Nadia
N
Talent
Green Plant Herbarium (TRT), Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario Canada M5S 2C6 ; School of Education, University of Stirling, Scotland UK FK9 4LA.
Charlotte
C
Lin
Green Plant Herbarium (TRT), Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario Canada M5S 2C6 ; Department of Ecology & Evolutionary Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada M5S 3B2.
Timothy A
TA
Dickinson
DNA barcodes; ITS2; North America; diploid; hawthorn; hybridization; leaf shape