BERRIOCHLOA GABELI AND BERRIOCHLOA HULETTI (GRAMINEAE: STIPEAE), TWO NEW GRASS SPECIES FROM THE LATE MIOCENE ASH HOLLOW FORMATION OF NEBRASKA AND KANSAS

Journal of Paleontology, Jan 2005 by Thomasson, Joseph R

As Elias (1942) concluded, and as I have discussed in detail elsewhere (Thomasson, 1976, 1979a), species of Berriochloa are clearly ancestral to members of the living Stipeae [recently included in the Pooideae (Grass Phylogeny Working Group, 2001)], including especially Hesperostipa (Elias) Barkworth and Everett, 1987 and Piptochaetium. Features of the lemma epidermis, such as long fundamental cells with sinuous side walls and the absence of short cells (i.e., silica and suberin cells) and the inflated to tube-shaped form and other macromorphological features of the anthoecia, support this proposed relationship. Nevertheless, the exact relationships of the fossil and living forms remains elusive as no Pliocene-Quaternary stipoid fossils have been found that provide the intermediate features needed to make additional interpretations.

ACKNOWLEDGMENTS

Portions of the research work were supported by grants from the National Science Foundation (DEB-7809150) and National Geographic Society (1833) and funds from the Elam Bartholomew Herbarium endowment fund. The scanning electron microscopy facilities of Black Hills State University and Fort Hays State University, supported by the Department of Biology and the Department of Biological Sciences, respectively, were used in the preparation of specimens for this report. Some of the research was completed during a sabbatical leave granted by Fort Hays State University. For assistance in the field I thank A. and N. Bailey, J. Buck, C. Hillgren, C. Longpine, S. Moses, R. Packauskas, L. Rice, B. Ross, J. Swinton, R., H., and S. Thomasson, J. Meis, S. Vopat, and R. J. Zakrzewski. I thank M. R. Voorhies and R. J. Zakrzewski for their assistance in identifications of vertebrates and age determinations, but any errors in interpretation if they occur are mine. Thanks to M. Gabel, M. R. Voorhies, R. J. Zakrzewski, and two anonymous persons for reviewing the manuscript and providing valuable comments and suggestions that have improved it, and R. Channell for assistance with statistical aspects of the study. Special thanks to M. Grace of Lewellen, Nebraska, and his family and friends for their support of my studies on their land. Their enthusiastic and complete cooperation has resulted in the discovery of numerous new fossil plants and animals that have significantly expanded our understanding of the late Tertiary landscape of Nebraska. Finally, I thank my wife, Nadine, for her assistance, support, and encouragement during all portions of this study.

REFERENCES

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BARKWORTH, M. E. 1990. Nassella (Gramineae, Stipeae): revised interpretation and nomenclatorial changes. Taxon, 39:597-614.

BARKWORTH, M. E. 1993. North American Stipeae (Gramineae): taxonomic changes and other comments. Phytologia, 74:1-25.