R&D CENTER

Phylogenetic relationships among species of Pseudostellaria (Caryophyllaceae) in Korea: With special emphasis on the origin of Korean endemic P. longipedicellata

YongSung Kim, JongSun Park, Seon-Hee Kim, and Seung-Chul Kim
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Pseudostellaria Pax (Caryophyllaceae) is a small genus with between 16 and 21 species and is distributed in temperate regions, primarily extending from Central Asia and Afghanistan to Korea and Japan. A single species is also known from southeastern Europe, while three species occur exclusively in western North America. Of 16-17 species known in Asia, China (11 species; 4 endemics) and Korea (9 species; 4 endemics) harbor most number of species. The number of species in Pseudostellaria differs greatly in Korea, due in part to species delimitation problems in some species and highly variable morphological characters in P. heterophylla and P. palibiniana, ranging from as few as 5 to as many as 9 species. With the most recent and conservative taxonomic treatment of Pseudostellaria (6 spp.) and two recently described species, P. longipedicellata and P. baekdusanensis, a total of 8 species is currently recognized. A previous attempt to resolve species delimitation and overall phylogenetic relationships among species in Korea was not satisfactory. In this study, we carried out two stages of phylogenetic analyses. First, we evaluated the monophyly and phylogenetic position of Pseudostellaria based on broader phylogenetic analysis. The ITS phylogeny suggests that the eastern Asian species is monophyletic, while western North American species (P. jamesiana) is closely related to Stellaria, making Pseudostellaria not monophyletic. It also shows that eastern Asian Pseudostellaria is sister to subg. Solitaria (formerly known as Arenaria). Second, we assessed phylogenetic relationships among species mainly from Korea based on nuclear ITS and 7 chloroplast noncoding regions. Both ITS and cp phylogenies suggested that subseries Distantes is paraphyletic, while subseries Verticillatae is paraphyleic in ITS, but monophyletic in cp phylogeny. P. setulosa is monophyletic in ITS phylogeny, but its relationship to other species was unresolved. P. longipedicellata did not form monophyly, but it can be distinguished from P. palibiniana based on ITS tree. Cp phylogeny is highly unresolved and majority of species are not monophyletic. Phylogenetic incongruence between nuclear and cp phylogeny is apparent, requiring additional gene genealogies to dissect possible effect of incomplete lineage sorting and/or gene flow among species.