Since the first report of an rbcL sequence of fossil Magnolia from the Clarkia fossil beds (17-20 MYBP), the validity of "fossil DNA" from this site has been questioned. However, an rbcL sequence from a fossil Taxodium was reported later, and here we report a partial ndhF sequence of a fossil Magnolia from this fossil site. Use of closely spaced primers, developed during a molecular phylogenetic study of Magnoliaceae, and a two step PCR method produced sufficient PCR product for sequencing from a very small amount of fragmented fossil template. With this approach 1504 base pairs of ndhF sequences were determined from a fossil leaf of M. latahensis. Parsimony analysis of this sequence and previously reported ndhF genes in Magnoliaceae placed M. latahensis at the base of the Theorhodon clade with zero branch length. The ndhF sequence of M. latahensis was identical to those of extant M. grandiflora, M. schediana, M. guatemalensis, and M. tamaulipana. This result is reasonable considering: 1) The morphology of M. latahensis is very similar to that of M. grandiflora although the other species placed with M. latahensis in the Theorhodon clade possess very different morphologies. 2) A recent molecular phylogenetic study of the family showed that the maximum sequence divergences of ndhF in extant Magnoliaceae is very low (1.05% in subfamily Magnolioideae) compared with other angiosperm families. 3) The possibility of contamination is extremely low because DNA of M. latahensis was extracted, amplified, and sequenced in the USA, and other Magnoliaceae were studied in Korea. We re-analyzed the previously reported rbcL sequence of M. latahensis with sequences for all major lineages of extant Magnoliaceae. The M. latahensis rbcL sequence is the sister group of the two subfamilies of Magnoliaceae in this analysis, rather than a close relative of M. grandiflora as predicted by morphology and the results of the ndhF analysis.

Key words: fossil DNA, Magnolia latahensis, Magnoliaceae, Miocene fossil, ndhF, rbcL