Phytotaxa 257 (3): 201–229 ISSN 1179-3155 (print edition) http://www.mapress.com/j/pt/ PHYTOTAXA Copyright © 2016 Magnolia Press Article ISSN 1179-3163 (online edition) http://dx.doi.org/10.11646/phytotaxa.257.3.1 STUDIES IN MESPILUS, CRATAEGUS, AND ×CRATAEMESPILUS (ROSACEAE), I. DIFFERENTIATION OF MESPILUS AND CRATAEGUS, EXPANSION OF ×CRATAEMESPILUS, WITH SUPPLEMENTARY OBSERVATIONS ON DIFFERENCES BETWEEN THE CRATAEGUS AND AMELANCHIER CLADES JAMES B. PHIPPS Department of Biology, The University of Western Ontario, London, Ontario N6A 5B7, Canada; email:
[email protected] Abstract The paper argues the position for retaining a monotypic Mespilus, i.e., in the sense of M. germanica, the medlar. Recent cladistic papers lend support for Mespilus being sister to Crataegus, and there is a clear morphological distinction from Cra- taegus, emphasized by adaptation to carnivore frugivory. Mespilus secured, the paper then treats each of the known hybrids between Mespilus and Crataegus, making the new combination Crataemespilus ×canescens (J.B. Phipps) J.B. Phipps. Keywords: Crataemespilus ×canescens (J.B. Phipps) J.B. Phipps comb. nov.; inflorescence position; medlar; Mespilus a folk-genus; Mespilus distinct from Crataegus; Rosaceae; taxonomic history of Mespilus Introduction The author has a long-standing interest in generic delimitation in the Maloid genera of the Rosaceae (Maleae Small, formerly Maloideae C. Weber, Pyrinae Dumort.), as shown particularly in a series of papers with K. Robertson, J. Rohrer, and P.G. Smith (Phipps et al. 1990, 1991; Robertson at al. 1991, 1992; Rohrer at al. 1991, 1994) which treated all 28 genera of Maleae as recognised by us. There is also a revisionary treatment of New World Heteromeles M.J.