Phylogeographical analysis on the Arisaema ovate group, a circum. Japan Sea element

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A monophyletic Glade including Arisaema ovate was detected through molecular phylogeny on the wide samples of Arisaema. Intensive geographical studies were carried out on the Glade (the Arisaema ovate group) using mass samples collected from various populations throughout the geographical range. In each samples, morphology, chromosome numbers and sequence variation in the chloroplast DNA (trnL-trnF, psbB-psbH, rpl20-rpsl2 regions) were examined. Some regions of nuclear DNA including phytochlome B region were also analyzed. A phylogeographical consideration was made based on the results as follows:1) The Arisaema ovale group is endemic to Japan. It includes neither A. sachalinense nor A. amurense.2) The A. ovale group shows a series of polyploidy with diploid (2n=26), triploid, tetraploid, pentaploid and hexaploid. The diploid plants are distributed in the pacific regions, while tetraploid plants are widely distributed in the Japan Sea side regions. Pentaploids are in Aomori prefecture as well as Hokkaido, and hexaploids are endemic to Hokkaido.3) Six haplotypes were distinguished in the cpDNA sequence. The major type, Type A, was found in all the levels of polyploidy. Local Types, B, C, E, F, were found only in the tetraploids. Type D was specific to A. inaense, a diploid species.4) Multiple origin was not suggested for the widely distributed tetraploids. For further analysis to reveal the origin of polyploids and gene flow in the A. ovale group Phytochrome B gene may be useful.5) A new species, A. nagiense was described