A Karyomorphological Study of Diploid Races of Aucuba japonica Thunb. (Cornaceae) in Southern Japan, to Confirm the Presence of Sex Chromosomes

Abstract

A new species, Codium tenuifolium Shimada, Tadano & J. Tanaka, is described from the Pacific coast of Japan. It is characterized in having thin blades, clavate utricles with tumid head and vegetative reproductive structures. In phylogenetic analysis of the sequences of the chloroplast encoded rbcL gene, C. tenuifolium formed a monophyletic clade with C. latum Suringar (with 69 % bootstrap support). The pairwise distance between them is 17 bp (2.6 %). Codium tenuifolium is morphologically distinguished from C. latum by almost simple and thinner thallus, shorter and broader clavate utricles.