Abstract
To understand the relationships among species of Carex sect. Rarae in Japan, we conducted molecular phylogenetic analyses based on a combined dataset of DNA sequences of plastid (atpB–rbcL, rpl16– rpl16–rps3, rps16, trnT–trnL, trnL–trnL–trnF) and nuclear (ITS) regions. All species and varieties of C. sect. Rarae in Japan were included. The resulting phylogenetic tree consisted of two major clades: Clade I with distinctly veined perigynia, and Clade II with indistinctly veined perigynia. Clade I further consisted of two subclades A and B. Subclade A comprised C. biwensis and C. capillacea, while subclade B included the Japanese endemics C. fulta, C. koyaensis, C. noguchii, and C. ruralis. Clade II comprised C. hakonensis, C. onoei, C. semihyalofructa, and C. uda. Clade II and subclade A corresponded to Carex subsect. Capitellatae (excluding C. fulta) and Carex subsect. Rarae circumscribed by Egorova, respectively. We propose a new subsection, Fultae, for subclade B, which is characterized by distinctly veined perigynia that lack rusty dots. We suggest that Carex koyaensis var. yakushimensis be treated as C. yakushimensis. Carex inagawaensis is described as a new species from Hyogo Prefecture. A diagnostic key to subsections and species of Carex sect. Rarae in Japan is presented.
