抄録
熱帯アメリカに自生するキワタ科3属3種について,根端分裂細胞を用いて調べた体細胞染色体数を報告する。調べた3属3種の染色体数はすべて初めての報告である。染色体数は以下の通りである。Gyranthera caribensis(キワタ亜科分岐群)は2n=96,Quararibea aurantiocalyx(アオイ亜科分岐群)は2n=88,"Spirotheca" rosea(キワ夕亜科分岐群)は2n=88の染色体数をもつことが明らかとなった。また,今回の染色体の観察から,従来の分類システムのキワタ科の染色体数は一般的に2n=86から2n=92の範囲にあるとするBaum and Oginuma(1994)の提唱を基本的に支持できた。
Somatic chromosome numbers for representatives of three genera of neotropical Bombacaceae were investigated using meristematic cells of root tips. Two of the three genera were investigated for the first time cytologically, and for the third genus, the chromosome count reported here is the first for the species studied. The chromosome numbers were 2n=96 in Gyranthera caribensis, 2n=88 in Quararibea aurantiocalyx, and 2n=88 in Spirotheca rosea. In view of these results, the range of chromosome numbers for the traditional Bombacaceae, from 2n=86 to 2n=92, proposed by Baum and Oginuma (1994), should be extended to 2n=86 to 2n=96. For the entire Bombacoideae clade, which appears to include the genera Chiranthodendron and Fremontodendron, the reported numbers range from 2n=40 to 2n=98, pending new counts from these two genera.
