Molecular phylogenetic analysis of Arenaria (Caryophyllaceae: tribe Arenarieae) and its allies inferred from nuclear DNA internal transcribed spacer and plastid DNA rps16 sequences SOMAYEH SADEGHIAN 1 *, SHAHIN ZARRE 2 *, RICHARD K. RABELER 3 and GÜNTHER HEUBL 4,5 1 Department of Biology, Faculty of Science, University of Bu-Ali Sina, Hamedan, Iran 2 Center of Excellence in Phylogeny of Living Organisms and Department of Plant Science, School of Biology, College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran 3 University of Michigan Herbarium – EEB, 3600 Varsity Drive, Ann Arbor, MI 48108-2228, USA 4 Systematic Botany and Mycology, Department Biology I, Ludwig-Maximilians-Universität München, Menzinger Str. 67, D-80638, München, Germany 5 GeoBio-Center LMU, München, Germany Received 4 October 2014; revised 4 March 2015; accepted for publication 23 April 2015 The systematics and phylogeny of the genus Arenaria and allied genera are unresolved. The use of morphological data has resulted in contradictory taxonomic concepts in the past due to their homoplastic nature. We present a phylogenetic analysis based on internal transcribed spacer (ITS) and rps16 sequence data of 140 (132 taxa) and 131 (120 taxa) accessions, respectively. Maximum parsimony and Bayesian analyses of each marker produced nearly congruent trees. Monophyly of Arenaria s.s. and Eremogone is confirmed here. Our results corroborate earlier results indicating that Arenaria subgenus Odontostemma is monophyletic, but outside the core group of Arenaria. Arenaria subgenus Solitaria is sister to Odontostemma and also not closely related to the latter; both of these subgenera are excluded from Arenaria and treated as distinct genera. The molecular data indicate that the ‘Arenaria s.s. clade’ consists of a few well-supported subgroups and that the current subgeneric classification of the genus does not reflect evolutionary history. Arenaria subgenus Leiosperma is clearly monophyletic, but we reduce it to sectional level. Our molecular data show that the monotypic Arenaria subgenera Porphyrantha and Arenariastrum are nested in A. subgenus Arenaria, whereas subgenus Eremogoneastrum is included in Eremogone. None of the species-rich sections in subgenus Arenaria is monophyletic. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669. ADDITIONAL KEYWORDS: biogeography – Caryophyllales – determination key – Eremogone – Moehringia – Odontostemma – Solitaria – subgeneric classification – taxonomy – tribe Sileneae. INTRODUCTION Arenaria L. comprises between 150 and more than 300 species, depending on the author and different generic concepts applied (McNeill, 1962; Bittrich, 1993; Charter & Halliday, 1993; Zhou, 1996; Zhengyi, Zhou & Wagner, 2001; Rabeler & Hartman, 2005). They occur mainly in northern temperate to arctic regions (Zhengyi et al., 2001). The highest number of species and subgenera inhabit areas in the Mediter- ranean and west-central Asia reaching eastward to the Qinghai–Tibetan Plateau in China (Zhou, 1996). Arenaria species show a variety of life forms (Figs 1, 2) consisting of small annuals, densely caespitose to pulvinate, spiny suffruticose perennials, succulent *Corresponding authors. E-mail: s.hajisadeghian@basu.ac.ir, zarre@khayam.ut.ac.ir Botanical Journal of the Linnean Society, 2015, 178, 648–669. With 5 figures © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669 648 Downloaded from https://academic.oup.com/botlinnean/article-abstract/178/4/648/2416480 by guest on 02 June 2020