A molecular phylogeny of the subtribe Sporobolinae and a classication of the subfamily Chloridoideae (Poaceae) P M. P1, 5, K R1, 2, Y H A3, J M. S4 1Smithsonian Institution, Department of Botany, National Museum of Natu ral History, Washington, DC 20013-7012, U.S.A.; email: peterson@si . edu 2M . G. Kholodny Institute of Botany, National Acad emy of Sciences, Kiev 01601, Ukraine; email: kromaschenko@gmail . com 3Instituto Politécnico Nacional, CIIDIR Unidad Durango- COFAA, Durango, C.P. 34220, Mexico; email: yolah54@gmail . com 4Canadian Museum of Nature, Research and Collections, Ottawa, Ontario K1P 6P4, Canada; email: [email protected] 5Author for correspondence; email: peterson@si . edu Abstract . The classication of the subtribe Sporobolinae containing the following six genera is poorly understood: Calamovilfa (ve species endemic to North Amer i ca), Crypsis (11 species en- demic to Asia and Africa), Psilolemma (one species endemic to Africa), Spartina (17 species cen- tered in North Amer i ca), Sporobolus (186 species distributed worldwide), and Thellungia (one species from Africa and Asia). The goal of this study was to reconstruct the evolutionary history of the Sporobolinae using molecular data with increased species sampling. Most species in this sub- tribe have spikelets with a single oret, one- veined (occasionally three- veined) lemmas, a ciliate membrane or line of hairs for a ligule, and fruits with free pericarps (modied caryopses). A phyloge ne tic analy sis was conducted on 161 species (250 samples), of which 134 species were in the Sporobolinae, using nuclear rITS (ribosomal internal transcribed spacer region) 1 and 2 sequences to infer evolutionary relationships. The maximum likelihood phylogram provides moderate support for a paraphyletic Sporobolus that includes Calamovilfa, Crypsis, Spartina, and Thellungia. The subtribe Zoysiinae (Urochondra and Zoysia) is sister to a highly supported Sporobolinae where the Psilolemma jaegeri−Sporobolus somalensis clade is sister to the remaining species of Sporobolus s.l. Within Sporobolus s.l. there are 15 major clades, of which 12 are strongly supported, two are moderately supported, and one is unsupported. A complete generic classication of the subfamily Chloridoideae is given. Keywords: Calamovilfa, classication, Crypsis, ITS, phylogeny, Psilolemma, Spartina, Spo- robolus, Thellungia (11 species endemic to Asia and Africa); Spartina I Schreb. (17 species centered in North Amer i ca); and In the most recent classication of the grass Sporobolus (186 species worldwide) (Mobberley, subfamily Chloridoideae, the tribe Zoysieae Benth. 1956; Lorch, 1962; Napper, 1963; Thieret, 1966, includes the incertae sedis genus Urochondra C.E. 2003; Tan, 1985; Peterson et al., 2003, 2004, 2007, Hubb. and two subtribes, Zoysiinae Benth. and Spo- 2010a; Nightingale et al., 2005; Clayton et al., 2006; robolinae Benth. (Peterson et al., 2007, 2010a). Zoy- Kern, 2012; Saarela, 2012). Pogononeura Napper, a siinae includes a single genus, Zoysia Willd., with 11 monotypic, morphologically distinct genus with two- species native to Australasia (Nightingale et al., 2005; or three- owered spikelets with short- awned lemmas Clayton et al., 2006). They are primarily mat- forming (Clayton & Renvoize, 1986) has also previously been perennials with cylindrical racemes, spikelets that attributed to the Sporobolinae (Peterson et al., 2010a), usually disarticulate below the glumes, lower glumes but recent analyses place it in the Cynodonteae (Pe- absent or much reduced, upper glumes laterally com- terson et al., 2014a). The Sporobolinae share most of pressed and coriaceous, and one- to three- nerved hy- the same character trends as for the Zoysieae, such as, aline lemmas with entire or mucronate apices. The spikelets with a single oret, spiciform in orescences subtribe Sporobolinae Benth. consists of four genera: of numerous deciduous racemes disposed along a Calamovilfa (A. Gray) Hack. ex Scribn. & Southw. (5 central axis, lemmas usually rounded and rarely with species endemic to North Amer i ca); Crypsis Aiton apical awns, and glumes often modied and oddly http://dx.doi.org/10.21135/893275341.003 ©2017 by The New York Botanical Garden Bronx, NY 10458-5126 U.S.A. 128 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 118 shaped but differ by having modied caryopses with though the number of species sampled for molecular free pericarps (pericarps free, reluctantly so in Spar- studies has been rather small. In the rst molecu- tina), spikelets oriented abaxially along the axis lar study of the genus, based on nuclear ribosomal (lemma is facing the rachis), lemmas that are similar DNA ITS sequences, Ortiz- Diaz and Culham in texture to the glumes, and paleas that are relatively (2000) presented 42 species of Sporobolus. Several long and about the same length as the lemma (Bran- DNA- based phylogenies pres ent Sporobolus as para- denberg, 2003; Peterson et al., 2004, 2007). Zoysia phyletic with Calamovilfa, Crypsis, and Spartina have a true caryopsis (fused pericarps), spikelets ori- embedded within (Ortiz- Diaz & Culham, 2000; ented adaxially along the axis (lemma facing away Hilu & Alice, 2001; Columbus et al., 2007; from the rachis), lemmas less rm than the glumes, Bouchenak- Khelladi et al., 2008; Peterson et al., and paleas relatively short or very reduced when 2010a). Peterson et al. (2010a) recommended future compared with the lemma (Peterson et al., 2007). expansion of Sporobolus to include all of these Urochondra was shown to have similar characteris- genera, recognizing that only 42 Sporobolus species tics as Zoysia, and additionally, has beaked caryop- (ca. one fth of the species in the genus) have been ses formed from thickened style bases and caryopses included in a single phyloge ne tic study (Ortiz- Diaz with free pericarps (Clayton & Renvoize, 1986; Clay- & Culham, 2000). Peterson et al. (2010a), in their ton et al., 2006; Peterson et al., 2010a). study investigating 246 species of Chloridoideae using Sporobolus is characterized by having single- seven molecular markers, analyzed 15 species of owered spikelets, one- nerved (rarely three- nerved) Sporobolinae. lemmas, fruits with free pericarps or modied cary- Here we pres ent a new phyloge ne tic analy sis of opses, and ligules a ciliate membrane or line of hairs 58% of the species in Sporobolus based on analy sis (Peterson et al., 1995, 1997). Species of Sporobolus of the nuclear internal transcribed spacer regions generally inhabit dry or stony soils, to saline or alka- (ITS1 and ITS2) and we discuss morphological and line sandy soils, to clay loam soils in prairies, savan- anatomical characters supporting relationships. We nahs, and along disturbed roadsides (Clayton & also include an updated classication of the Chlori- Renvoize, 1986; Peterson et al., 1997). Numerous doideae. infrageneric classications of Sporobolus have been proposed over the last century, based primarily on M M morphology and anatomy. Stapf (1898) rst divided the genus into two sections: Chaetorhachia Stapf and Eus- T porobolus Stapf. Pilger (1956) divided the latter section The taxon sampling consists of 250 samples rep- into six groups based on life form and characteristics of resenting 161 species of grasses, of which 157 spe- the glumes and panicles. Based on caryopsis morphol- cies are included in subfamily Chloridoideae; these ogy, Bor (1960) divided Sporobolus into ve groups are represented in the following ve tribes (Soreng (Baaijens & Veldkamp, 1991) and Clayton (1965) et al., 2014): Centropodieae (one species), Triraph- treated the Sporobolus indicus (L.) R.Br. complex in ideae (two species), Eragrostideae (11 species), Cyn- the tropics and subtropics. Working on the Malesian odonteae (nine species), and Zoysieae (147 species). species, Baaijens and Veldkamp (1991) divided Spo- Our sampling was principally focused on genera robolus into ve sections based on a leaf anatomical that are morphologically similar to Sporobolus, in- survey and overall morphology. More recently, Weak- cluding a large sample of 134 species within the sub- ley and Peterson (1998) recognized the Sporobolus tribe Sporobolinae (Peterson et al., 2010a). The data oridanus complex to include ve species in the south- set for Sporobolus includes 108 of the 186 species eastern United States and Shrestha et al. (2003) recog- currently placed in the genus (Clayton et al., 2006). nized seven clades within the genus, while Denham A complete list of taxa, voucher information, and and Aliscioni (2010) recognized the S. aeneus (Trin.) GenBank numbers is given in the Appendix. Two Kunth complex to include ve species. Recent major species of Danthonioideae (Danthonia compressa revisions of Sporobolus include Boechat and Wagner Austin and Rytidosperma penicellatum (Labill.) Con- (1995) for Brazil, Simon and Jacobs (1999) and Simon nor & Edgar), one species from Aristidoideae (Aristida (2005) for Australia, Peterson et al. (2003, 2009) for gypsophila Beetle), and one species of Panicoideae the United States and Canada, and Giraldo- Cañas and (Chasmanthium latifolium (Michx.) H.O. Yates, Peterson (2009) for Peru, Ec ua dor, and Colombia. phyloge ne tic root) were chosen as outgroups (Peter- Molecular studies have provided new insights son et al., 2010a, 2011, 2012, 2014a, 2014b, 2014c; into the evolutionary history of Sporobolus, even 2015, 2016). 2017] PETERSON ET AL.: SPOROBOLINAE, CHLORIDOIDEAE (POACEAE) 129 DNA , , quences dropped below 0.01 and the potential scale reduction factor was