Molecular phylogeny and taxonomy of Hosta (Asparagaceae) on Shikoku Island, Japan, including five new species, one new subspecies, and two new status assignments.

Japan has 16 native species of the genus Hosta Tratt. (Asparagaceae). A recent study on Hosta based on field surveys and molecular phylogenetic analyses resulted in the discovery of six unknown taxa in Kochi Prefecture, Shikoku Island, southwestern Japan. We aimed to identify these unknown taxa. Therefore, we constructed a finely resolved phylogeny for 320 Hosta samples collected from the Honshu, Shikoku, and Kyushu Islands using multiplex inter-simple sequence repeat genotyping by sequencing (MIG-seq). Based on this phylogenetic analysis and related morphological observations, we describe five new species, H.longipedicellatasp. nov., H.minazukiflorasp. nov., H.polyneuronoidessp. nov., H.samukazemontanasp. nov., and H.takiminazukiflorasp. nov. and one new subspecies, H.takiminazukiflorasubsp.grandissubsp. nov. In addition, we propose two new status assignments, H.tardivasubsp.densinerviacomb. and stat. nov. and H.scabrinerviastat. nov. We also propose classifying H.kikutiivar.tosana as a species, H.tosana. Further studies that combine MIG-seq with careful morphological observations are needed for Hosta plants on all Japanese islands, which may result in the discovery of even more undescribed species.

Molecular phylogeny and taxonomy of the Hydrangeaserrata complex (Hydrangeaceae) in western Japan, including a new subspecies of H.acuminata from Yakushima.

According to the contemporary classification of Hydrangea native to Japan, H.serrata is a polymorphic species including six varieties. We discovered a plant identified as H.serrata, but morphologically distinct from previously known varieties, in Yakushima island where approximately 50 endemic species are known. To determine the relationship of this plant with previously known varieties, we examined morphology and constructed a highly resolved phylogeny of H.serrata and its relatives using three chloroplast genomic regions, rbcL, trnL intron, psbA-trnH, and two nuclear genomic regions, ITS1 and ITS2, and Multiplex ISSR genotyping by sequencing (MIG-seq). Based on these morphological and phylogenetic observations, we describe Hydrangeaacuminatasubsp.yakushimensissubsp. nov. as a newly discovered lineage in Yakushima, Japan and propose Hydrangeaminamitanii stat. nov. and Hydrangeaacuminatasubsp.australisstat. nov. which were previously treated as varieties of H.serrata.

Validation of Hostaalata (Asparagaceae) as a new species and its phylogenetic affinity.

Molecular phylogenetic studies of Hostapulchella (Asparagaceae) and its relatives, which are native to Japan, have been conducted and resulted in a highly resolved phylogeny. Specifically, the relationship of H.pulchella to H.alata Hatusima, nom. nud. is investigated. These data include genome-wide SNPs obtained through conducting multiplexed ISSR genotyping by sequencing (MIG-seq). Based on these phylogenetic results, morphological observations, distribution, and differences in flowering periods of H.alata collections sympatric with H.pulchella, we find the two species closely related, but distinct. As such, we formally describe Hostaalata sp. nov. from the Oita Prefecture of Kyushu island, southwestern Japan.

A new subspecies of Stellariaalsine (Caryophyllaceae) from Yakushima, Japan.

An unknown taxon of Stellaria was discovered in Yakushima, a Japanese island known to harbor several endemic species. To determine the identity of this taxon, this study employed MIG-seq for the reconstruction of a finely resolved phylogenetic tree of the newly discovered taxon, along with some related species of Stellaria. The results showed that the newly discovered taxon is a relative of S.alsine. Based on this result, Stellariaalsinesubsp.nanasubsp. nov. was published.