Ulmites microphylla (NEWBERRY) Manchester, 2014

Manchester, Steven R., 2014, Revisions To Roland Brown’S North American Paleocene Flora, Acta Musei Nationalis Pragae Series B 70 (3 - 4), pp. 153-210 : 173-174

Ulmites microphylla (NEWBERRY) comb. nov.

Text-fig. 10

1868 Planera microphylla NEWBERRY, Lyceum Nat. Hist. New York Ann., 9, p. 55 [basionym]; 1898 Newberry U. S. Geol. Surv. Monogr., 35, p. 81, pl. 33, figs 3, 4.

1977 Chaetoptelea microphylla (NEWBERRY) HICKEY, Geol. Soc. Amer Mem. 150, p. 122, and synonymy therein.

Brown (1962) distinguished three species of ulmaceous foliage on the basis of shape (e.g., cordate base in Planera microphylla vs cuneate or rounded base in Zelkova planeroides ) and size (relatively large in Ulmus rhamnifolia ), but it seems likely that these represent variation within one species, given the range of morphology documented in leaves of modern individuals ( Denk and Dillhoff 2005). Kvaček et al. (1994) adopted the non-committal name Ulmites DAWSON for Paleogene leaf types that may not unequivocally belong to the genus Ulmus .

Hickey (1977) reassigned Planera microphylla NEWBERRY to Chaetoptelea , a segregate genus of Ulmus that was subsequently demoted to subgeneric status. A twig bearing several leaves of Ulmites microphylla from Black Buttes Coal Mine Pit 3, in southwestern Wyoming shows the distichous attachment of leaves to a twig as expected for Ulmaceae ( Text-fig. 10 ). No fossil fruits of Ulmus (including Chaetoptelea morphology) have been recovered from Paleocene strata, although they are relatively common in the Eocene of western North America ( Manchester 1989; Denk and Dillhoff 2005). I recommend that these leaves be placed in the genus Ulmites DAWSON and here above establish the new combination Ulmites microphylla (NEWBERRY) comb. nov. In addition to the species placed in synonymy by Hickey (under the name Chaetoptelea microphylla (NEWBERRY) HICKEY ), I consider the leaves of U. rhamnifolia and Zelkova planeroides sensu Brown (1962) to be representatives of this species.

In reviewing specimens from the Paleocene of Russia and China they attributed to U. furcinervis, Feng et al. (2003, p. 149) observed, “Fossils described here are comparable to C. microphylla in the frequently forked secondary veins, the percurrent tertiary and the convex to acuminate apical side and the convex basal side of marginal teeth. We suggest that these fossils are probably conspecific considering their close similarities. Further works should be done to get more evidence and to verify this idea.” If indeed conspecific, Newberry’s epithet, microphylla , will take priority.

Celtidaceae / Cannabaceae

Brown (1962) attributed two species to the genus Celtis , i.e., Celtis newberryi KNOWLTON et COCKERELL , and Celtis peracuminata R. W. BROWN. The first of these has not been disputed, although a more detailed study is warranted. Celtis peracuminata R. W. BROWN appears to be too symmetrical and regularly serrate to be reliably assigned to Celtis . This leaf, recorded only from a single Paleocene site, resembles Grewiopsis wyomingensis BERRY that became common in the middle Eocene.

Celtis aspera (NEWBERRY) MANCHESTER, AKHMETIEV et KODRUL

Manchester et al. (2002) reassigned leaves of Viburnum asperum NEWBERRY to Celtis aspera based on a suite of foliar features common to Cannabaceae / Celtidaceae such as blunt teeth with submedial vein insertion, abundant, regularly spaced agrophic veins, and noted a consistent association with diagnostic reticulately sculptured endocarps of Celtis at Paleocene sites both in North America and Asia. None of the extant species of Celtis has identical leaf architecture, but the presence of corresponding leaf architecture in one of the extant species of the related genus Aphananthe ( Manchester et al. 2002; Stockey et al. 2013), shows the potential for this leaf architectural pattern in the family and supports the conclusion that this foliage type was probably produced by the same plant as the Celtis endocarps. Endocarps of extant Aphananthe species differ from Celtis by having a smooth, rather than reticulate, outer surface. Stockey et al. (2014) disagree with the Celtis interpretation and refer the leaves to Aphananthe sp. , although Aphananthe -like fruits are absent and Celtis fruits are present at their localities as at other Paleocene sites in North America and Asia cited by Manchester et al. (2002).

Malvaceae s.l.

Figures

Text-fig. 10. Ulmaceae. Ulmites microphylla (NEWBERRY) comb. nov. Twig with distichously attached leaves, Black Buttes Mine pit 3, Wyoming, UF 15886-14248. Scale bar = 1 cm.