Searching for the sister to sedges (Carex): resolving relationships in the Cariceae-Dulichieae-Scirpeae clade (Cyperaceae) ÉTIENNE LÉVEILLÉ-BOURRET 1,2 *, CLAIRE N. GILMOUR 1,2 , JULIAN R. STARR 1,2 , ROBERT F. C. NACZI 3 , DANIEL SPALINK 4 and KENNETH J. SYTSMA 4 1 Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5 Canada 2 Canadian Museum of Nature, Ottawa, ON, K1P 6P4 Canada 3 The New York Botanical Garden, Bronx, NY 10458-5126, USA 4 Department of Botany, University of Wisconsin-Madison, 430 Lincoln, Madison, WI 53706, USA Received 24 October 2013; revised 3 June 2014; accepted for publication 3 July 2014 With approximately 2000 species, tribe Cariceae (Cyperaceae) comprises a morphologically distinctive cosmopolitan clade, with holocentric chromosomes (N = 6 to 56), complex biogeographical patterns, and habitat diversity ranging from rainforests to deserts. Such a remarkable combination of characteristics should make Cariceae an ideal model for studying the evolution of biodiversity, although they also obscure their relationships in Cyperaceae, compli- cating attempts to identify the contributing factors to diversity of Cariceae. Recent molecular studies place Cariceae in a strongly supported clade consisting of tribes Dulichieae, Scirpeae s.s, and the enigmatic monotypic genus Khaosokia, although relationships in this clade are unresolved. Using the plastid genes matK and ndhF and a greatly improved taxonomic sampling covering 16 of 17 genera and 55% of the species outside Cariceae, our analyses firmly position Dulichieae and Khaosokia (79% and 85% bootstrap support) as successive sisters to a clade consisting of five major lineages (Calliscirpus, Trichophorum + Oreobolopsis + Cypringlea, Cariceae, Scirpus + Eriophorum, and Amphiscirpus + Phylloscirpus + Zameioscirpus), the first four of which receive good to strong support (> 80% bootstrap support). Cariceae are sister to the Trichophorum clade, although topological tests cannot exclude either Calliscirpus or a Scirpus clade + Zameioscirpus clade as sister to the tribe. Trichophorum appears to be paraphyletic and Eriophorum is firmly nested in Scirpus. There appears to be a trend in the increase of chromosome numbers in Scirpus and Eriophorum and a trend in the reduction and proliferation of the inflorescence throughout the major Cariceae-Dulichieae-Scirpeae clades. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 1–21. ADDITIONAL KEYWORDS: Calliscirpus – Eriophorum – Khaosokia – matK – ndhF – molecular phyloge- netics – Scirpus – Trichophorum. INTRODUCTION Cyperaceae (> 100 genera, approximately 5500 species) comprise the third largest family of mono- cotyledons and are found throughout the globe in habitats ranging from lowland marshes and alpine meadows to rainforests and deserts (Goetghebeur, 1998; Govaerts et al., 2007). Approximately 36% of the family is found in a single monophyletic tribe, Cariceae, that stands out not only for its amazing diversity (approximately 2000 species), but also for its diverse biogeography (e.g. amphiatlantic, bipolar, Gondwanan; Raymond, 1951; Croizat, 1952) and intriguing cytology (holocentric chromosomes: N =6 to 56; Davies, 1956). These characteristics should make Cariceae an ideal system for studying the evo- lution of biodiversity, and studies are increasingly focusing on biogeographical, ecological, and evolution- ary questions (Escudero et al., 2010, 2012a, b; Gehrke & Linder, 2011). However, characteristics such as their cosmopolitan distribution, high diversity, and, *Corresponding author. E-mail: eleveille-bourret@mus -nature.ca Botanical Journal of the Linnean Society, 2014, 176, 1–21. With 1 figure © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 1–21 1