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Molecular phylogenetic analysis of Arenaria(Caryophyllaceae: tribe Arenarieae) and its alliesinferred from nuclear DNA internal transcribed spacerand plastid DNA rps16 sequences
SOMAYEH SADEGHIAN1*, SHAHIN ZARRE2*, RICHARD K. RABELER3 andGÜNTHER HEUBL4,5
1Department of Biology, Faculty of Science, University of Bu-Ali Sina, Hamedan, Iran2Center of Excellence in Phylogeny of Living Organisms and Department of Plant Science, School ofBiology, College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran3University of Michigan Herbarium – EEB, 3600 Varsity Drive, Ann Arbor, MI 48108-2228, USA4Systematic Botany and Mycology, Department Biology I, Ludwig-Maximilians-Universität München,Menzinger Str. 67, D-80638, München, Germany5GeoBio-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 morphologicaldata has resulted in contradictory taxonomic concepts in the past due to their homoplastic nature. We present aphylogenetic analysis based on internal transcribed spacer (ITS) and rps16 sequence data of 140 (132 taxa) and131 (120 taxa) accessions, respectively. Maximum parsimony and Bayesian analyses of each marker producednearly congruent trees. Monophyly of Arenaria s.s. and Eremogone is confirmed here. Our results corroborateearlier results indicating that Arenaria subgenus Odontostemma is monophyletic, but outside the core group ofArenaria. Arenaria subgenus Solitaria is sister to Odontostemma and also not closely related to the latter; both ofthese subgenera are excluded from Arenaria and treated as distinct genera. The molecular data indicate thatthe ‘Arenaria s.s. clade’ consists of a few well-supported subgroups and that the current subgeneric classificationof the genus does not reflect evolutionary history. Arenaria subgenus Leiosperma is clearly monophyletic, but wereduce it to sectional level. Our molecular data show that the monotypic Arenaria subgenera Porphyrantha andArenariastrum 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 than300 species, depending on the author and differentgeneric 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 arcticregions (Zhengyi et al., 2001). The highest number ofspecies and subgenera inhabit areas in the Mediter-ranean and west-central Asia reaching eastward tothe Qinghai–Tibetan Plateau in China (Zhou, 1996).Arenaria species show a variety of life forms (Figs 1,2) consisting of small annuals, densely caespitose topulvinate, spiny suffruticose perennials, succulent
*Corresponding authors. E-mail: [email protected],[email protected]
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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, 648–669648
Figure 1. See caption on next page.
MOLECULAR PHYLOGENETICS OF ARENARIA 649
© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669
maritime herbs, xerophytes adapted to Mediterra-nean and steppe climates, and lax broadleaved meso-phytes (McNeill, 1962). In the widely used taxonomicclassification of Caryophyllaceae (Bittrich, 1993), Are-naria is included in subfamily Alsinoideae with 27additional genera. According to most authors, Are-naria is a member of tribe Alsineae, consisting of 23additional genera, and is closely related to Moehrin-gia L. (McNeill, 1962; Bittrich, 1993; Fior & Karis,2007), but the most recent classification system ofCaryophyllaceae assigned it to tribe Arenarieae(Harbaugh et al., 2010).
In the most comprehensive taxonomic treatment ofAlsinoideae, McNeill (1962) divided Alsineae intothree groups: the Arenaria group comprising Are-naria, Brachystemma D.Don, Bufonia L., GooringiaWilliams, Honckenya Ehrh., Lepyrodiclis Fenzl,Reicheella Pax, Minuartia L., Moehringia, ThuryaBoiss. & Balansa, Thylacospermum Fenzl and Wil-helmsia Rchb. (= Merckia Fisch.); the Stellaria–Cerastium group including Cerastium L., MyosotonMoench, Holosteum L., Moenchia Ehrh., Pseudostel-laria Pax and Stellaria L.; and the Sagina groupconsisting of Sagina L. and Colobanthus Bartl. Pre-vious molecular phylogenetic data (Harbaugh et al.,2010; Greenberg & Donoghue, 2011) have revealedthat Alsineae (sensu Pax & Hoffmann, 1934; McNeill,1962; Bittrich, 1993) and their subgroups are clearlypolyphyletic except for the Sagina group, which isnow best treated as a small unit called tribe Sagineae.
The taxonomic history of Arenaria is complex andhas, during the course of time, been intertwined withseveral other genera (Table 1). One of the major ques-tions in subfamily Alsinoideae relates to the genericboundaries around Arenaria (Pax & Hoffmann, 1934;Maguire, 1951; McNeill, 1962) and whether it shouldbe broadly or more narrowly circumscribed. If oneaccepts a narrow concept of Arenaria, the ‘Arenariacomplex’ includes three large genera, Arenaria, Minu-artia and Moehringia, and several smaller ones includ-ing Brachystemma, Cherleria L., Gouffeia Robill. &Castagne ex DC., Greniera J.Gay, Honckenya, Lepy-
rodiclis, Moehringella H.Neumayer, Queria L., Rhod-alsine J.Gay, Triplateia Bartl. (= Hymenella Ses. &Moc. ex DC.) and Wilhelmsia (McNeill, 1962). Someauthors even split Minuartia into additional genera(Löve & Löve, 1975), a notion recently confirmed by amolecular survey of Minuartia (Dillenberger &Kadereit, 2014). A broad concept of Arenaria comprisesall of the above-mentioned genera as synonyms(Fernald, 1919; Maguire, 1951) of Arenaria.
The infrageneric classification of Arenaria s.s. hasalso been problematic and included such groups asEremogone, Dolophragma and Odontostemma, one ormore of which have been treated either as genera(Fenzl, 1840, 1842; Ikonnikov, 1973; Rabeler &Hartman, 2005) or as subgenera by others (McNeill,1962; Bittrich, 1993) (Table 1). Additionally, somespecies were described more than once under differentnames, reflecting the widespread occurrence of thegenus worldwide.
In one of the oldest and most comprehensive treat-ments on Arenaria, Fenzl (1840, 1842) placed 11genera referable to the ‘Arenaria complex’ into threetribes (Table 1) mainly based on the type of capsuledehiscence and the number of its valves proportionalto the styles. Bentham & Hooker (1862) preservedonly three genera, Arenaria, Brachystemma andQueria, and transferred the other genera intounranked subgeneric taxa under Arenaria. Boissier(1867) mainly followed Fenzl’s (1840) system andarranged 39 Arenaria species known to him in thearea of the Flora Orientalis into three unrankedgroups (indicated by ‘§’), Eremogoneae, Sclerophyllaeand Euthaliae. In the first comprehensive revision ofArenaria, Williams (1898) classified 168 Arenariaspecies into seven subgenera, again following Fenzl’ssystem. Maguire (1951), in his synopsis of the NorthAmerican members of Arenaria, treated Honckenya,Minuartia, Moehringia and Wilhelmsia as sectionsof Arenaria. McNeill (1962) split Arenaria into tensubgenera, which in turn were further divided into24 sections and several series. The morphologicalfeatures characterizing subgenera recognized in
Figure 1. Habit and morphological variation in Arenaria and Eremogone. A, Arenaria densissima (subgenus Dolo-phragma), photo by David E. Boufford; B–C, A. polytrichoides (subgenus Dolophragma), photo by Harry Jans; D,A. przewalskii (subgenus Dolophragma), photo by David E. Boufford; E–F, Eremogone pumicola (subgenus Eremogone),photo by Kier Morse; G, E. congesta (subgenus Eremogone), photo by Sheri Hagwood; H, E. insignis (subgenusEremogone), photo by Harald Pauli; I, E. persica (subgenus Eremogone), photo by M. Tehranian; J, E. macradenia(subgenus Eremogone), photo by Neal Kramer; K–L, E. procera (subgenus Eremogone), photo by Jan Thomas Johansson;M, E. biebersteinii (subgenus Eremogone), photo by Jan Thomas Johansson; N, E. hookeri (subgenus Eremogoneastrum),photo by Ernie Marx; O, A. bryophylla (subgenus Eremogoneastrum), photo by Harry Jans; P, E. kansuensis (subgenusEremogoneastrum), photo by Harry Jans. Homepages: A, D: http://hengduan.huh.harvard.edu/fieldnotes/specimens; B–C,O, P: http://www.jansalpines.com; E–F, J: http://calphotos.berkeley.edu; G: http://www.wildflowersearch.com; H: http://www.gloria.ac.at; K–M: http://angio.bergianska.se; N: http://www.easterncoloradowildflowers.com.
◀
650 S. SADEGHIAN ET AL.
© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669
Figure 2. See caption on next page.
MOLECULAR PHYLOGENETICS OF ARENARIA 651
© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669
Arenaria by McNeill (1962) are summarized inTable 2. Since then, most authors have followedMcNeill and treated this complex as a set ofseveral different genera. Several authors haveamended McNeill’s concept by segregating the genusEremogone Fenzl (Ikonnikov, 1973; Löve & Löve,1975; Rabeler & Hartman, 2005).
Despite considerable efforts to clarify the delimita-tion of Arenaria and closely related genera, problemsin determining useful morphological characters havehindered producing definitive treatments; comparableto many other genera in the family (Kurtto, 2001;Oxelman et al., 2001), the limits of Arenaria in rela-tion to its closely related genera are somewhat uncer-tain. There have been several recent transfers ofspecies between Arenaria and Eremogone, Minuartiaand Moehringia (e.g. McNeill, 1980; Fior & Karis,2007; Dillenberger & Kadereit, 2014) as these fea-tures have been reinterpreted.
Although Caryophyllaceae as a whole are welldefined by apomorphic characters, infrafamilial clas-sification is still in a state of flux. Bittrich (1993)suggested that the relationships between subfamiliesand tribes are highly blurred, owing to the apparentconvergent evolution of morphological characters.Thus, the high level of homoplasy in morphologicalcharacters and problems in determining morphologi-cal synapomorphies indicate the importance ofmolecular data in understanding the relationships inthe family (Smissen et al., 2002; Fior et al., 2006;Harbaugh et al., 2010; Greenberg & Donoghue, 2011).In subfamily Caryophylloideae (shown to be non-monophyletic; see Harbaugh et al., 2010), molecularphylogenetic studies of tribe Sileneae (Oxelman &Liden, 1995; Oxelman, Lidén & Berglund, 1997) haverevealed the inadequacy of current classificationsand the problematic process in distinguishing well-supported monophyletic lineages.
In recent years, the use of DNA sequence data hasproved useful in inferring phylogenetic relationshipsin Caryophyllaceae (Nepokroeff et al., 2001; Smissenet al., 2002; Fior et al., 2006; Harbaugh et al., 2010;
Greenberg & Donoghue, 2011), including relation-ships in and among the few genera of Alsinoideae(Minuartieae) (Smissen, Garnock-Jones & Chambers,2003; Scheen et al., 2004; Fior & Karis, 2007;Dillenberger & Kadereit, 2014). Molecular phyloge-netic studies have confirmed the close relationshipbetween Moehringia and Arenaria and provided someinsights into the phylogeny of both genera (Fior et al.,2006; Fior & Karis, 2007; Harbaugh et al., 2010;Greenberg & Donoghue, 2011). In the systems ofHarbaugh et al. (2010) and Greenberg & Donoghue(2011), a new tribal classification in Caryophyllaceaewas proposed, including at least 11 tribes represent-ing well-supported monophyletic clades. Thesestudies showed that Arenaria is polyphyletic andthree of its subgenera, Odontostemma (Benth. exG.Don) Williams, Eremogone (Fenzl) Fenzl andEremogoneastrum F.N.Williams, should be excludedand treated as two genera. They placed Arenarias.s. [Arenaria subgenus Arenaria, A. subgenus Leio-sperma McNeill and A. subgenus Porphyrantha(Fenzl) McNeill] and Moehringia into tribe Arenar-ieae Kitt. and described tribe Eremogoneae, includinggenera Eremogone (Arenaria subgenera Eremogoneand Eremogoneastrum), Thylacospermum and Minu-artia subgenus Spergella (Fenzl) McNeill. In a paral-lel molecular analysis of Caryophyllaceae as awhole, Greenberg & Donoghue (2011) described theclade ‘Plurcaryophyllaceae’ including the traditionalAlsinoideae and Caryophylloideae (tribes Alsineae,Arenarieae, Caryophylleae, Eremogoneae, Sagineae,Sclerantheae and Sileneae) plus Sperguleae (sensuHarbaugh et al., 2010) characterized by the synapo-morphies of presence of petals, ten stamens and cap-sular fruit.
The only investigation focusing specifically on phy-logenetic relationships within Arenaria to date is thatof Valcárcel, Vargas & Feliner (2006) and covers onlysection Plinthine (Reichenb.) McNeill. That study con-firmed that a combination of morphological, molecu-lar and ecological data provides useful information forresolving taxonomic controversies within this group.
Figure 2. Habit and morphological variation in Arenaria and Eremogone. A, A. roseiflora (subgenus Odontostemma),photo by Harry Jans; B, A. barbata var hirsutissima (subgenus Odontostemma), photo by Jan Thomas Johansson; C,A. pogonantha (subgenus Odontostemma), photo by David E. Boufford; D, A. forrestii (subgenus Solitaria), photo by DavidE. Boufford; E, A. glanduligera (subgenus Solitaria), photo by Harry Jans; F, A. lanuginose (subgenus Leiosperma), photoby Brad Boyle; G, A. tetraquetra (subgenus Arenaria), photo by Andrés Ivorra; H, A. arcuatociliata (subgenus Arenaria),photo by Andrés Ivorra; I, A. pungens (subgenus Eremogone), photo by Andrés Ivorra; J, A. fontqueri (section Pseudomoe-hringia), photo by Andrés Ivorra; K, A. suffruticosa (section Pseudomoehringia), photo by Andrés Ivorra; L, A. serpyllifolia(subgenus Arenaria), photo by Patrick J. Alexander; M, A. purpurascens (subgenus Arenaria), photo by Harald Pauli; N,A. norvegica (subgenus Arenaria), photo by Jan Thomas Johansson. Homepages: A, E: http://www.jansalpines.com; B:http://angio.bergianska.se; C, D: http://hengduan.huh.harvard.edu/fieldnotes/specimens; F: http://tcf.bh.cornell.edu; G–K:http://www.almerinatura.com; L: http://plants.usda.gov/java; M: http://www.gloria.ac.at; N: http://angio.bergianska.se.
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652 S. SADEGHIAN ET AL.
© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669
Tab
le1.
Cla
ssifi
cati
onh
isto
ryof
the
Are
nar
iaco
mpl
exan
dov
ervi
ewof
prev
iou
sin
frag
ener
iccl
assi
fica
tion
sof
Are
nar
ia
Lin
nae
us
(175
3)F
enzl
(184
0,18
42)
Ben
tham
&H
ooke
r(1
862)
Wil
liam
s(1
895)
McN
eill
(196
2)R
abel
er&
Har
tman
(200
5)H
arba
ugh
etal
.(2
010)
Trib
e(u
pper
row
,bo
ld)
and
gen
era
(low
erro
w,
non
-bol
d)S
tell
ari
nea
eA
lsin
eae
Ste
lla
rin
eae
Als
inea
e*A
lsin
oid
eae
Are
na
riea
eO
don
tost
emm
aC
her
leri
aQ
uer
iaE
rem
ogon
eQ
uer
iaH
onck
enya
Hon
cken
yaL
epyr
odic
lis
Lep
yrod
icli
sW
ilh
elm
sia
Wil
hel
msi
aB
rach
yste
mm
aB
rach
yste
mm
aB
rach
yste
mm
aM
inu
arti
aM
inu
arti
aM
inu
arti
aM
oeh
rin
gia
Moe
hri
ngi
aM
oeh
rin
gia
Moe
hri
ngi
aM
oeh
rin
gia
Moe
hri
ngi
aA
ren
aria
Are
nar
iaA
ren
aria
Are
nar
iaA
ren
aria
Are
nar
iaA
ren
aria
s.s.
Mer
ckie
ae
Ere
mog
onea
eD
olop
hra
gma
Th
ylac
ospe
rmu
mM
erck
iaE
rem
ogon
eS
abu
lin
eae
Als
inea
eL
epyr
odic
lis
Lep
yrod
icli
sA
lsin
eP
seu
dos
tell
aria
Bu
ffon
iaH
onck
enya
Qu
eria
Su
bgen
era
ofA
ren
aria
Eu
thal
iaM
oeh
rin
gia
Eu
aren
aria
Are
nar
iaA
ren
aria
Are
nar
iaG
offe
iaR
hod
alsi
ne
Pen
tad
enar
iaL
eios
perm
aL
eios
perm
aL
eios
perm
aD
icra
nil
laA
lsin
eM
acro
gyn
Por
phyr
anth
aP
orph
yran
tha
Por
phyr
anth
aP
orph
yran
tha
Min
uar
tia
Dic
ran
illa
Dol
oph
ragm
aD
olop
hra
gma
Ere
mog
one
Ch
erle
ria
Are
nar
iast
rum
Sol
itar
iaS
olit
aria
Hym
enel
laO
don
tost
emm
aD
icra
nil
laD
icra
nil
laG
offe
iaE
rem
ogon
east
rum
Are
nar
iast
rum
Are
nar
iast
rum
Lep
yrod
icli
sO
don
tost
emm
aO
don
tost
emm
aA
mm
oden
iaE
rem
ogon
east
rum
Mer
ckia
Ere
mog
one
*On
lyth
ose
gen
era
are
list
edth
atar
ere
late
dto
Are
nar
iaco
mpl
ex.
MOLECULAR PHYLOGENETICS OF ARENARIA 653
© 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 648–669
Tab
le2.
Dia
gnos
tic
mor
phol
ogic
alch
arac
teri
stic
sof
the
ten
subg
ener
aof
gen
us
Are
nar
iase
nsu
McN
eill
(196
2)
Are
nar
iaA
ren
aria
stru
mD
icra
nil
laD
olop
hra
gma
Ere
mog
one
Ere
mog
onea
stru
mL
eios
perm
aO
don
tost
emm
aP
orph
yran
tha
Sol
itar
ia
Typ
eA
.ser
pyll
ifol
iaA
.mas
sili
ensi
sA
.dic
ran
oid
esA
.glo
bifl
ora
A.g
ram
inif
olia
A.f
estu
coid
esA
.mu
scif
orm
isA
.bli
nkw
orth
iiA
.pu
rpu
rasc
ens
A.c
ilio
lata
No.
ofsp
ecie
sca
.10
6*1
ca.
12ca
.7*
ca.
70*
ca.
20*
ca.
32ca
.65
*1
ca.
6*
Hab
itan
nu
alor
pere
nn
ial
her
b,so
met
imes
den
sely
caes
pito
se
ann
ual
orbi
enn
ial
her
b,sl
ende
r
pere
nn
ial,
den
sely
pulv
inat
e
pere
nn
ial,
den
sely
pulv
inat
e(s
omet
imes
caes
pito
se)
pere
nn
ial,
pulv
inat
epe
ren
nia
l,de
nse
lyca
espi
tose
tode
nse
lypu
lvin
ate
pere
nn
ial
her
ban
nu
al,
bien
nia
lor
pere
nn
ial
her
b,di
ffu
se
pere
nn
ial,
ceas
pito
sepe
ren
nia
l,ce
aspi
tose
(som
etim
esde
nse
ly)
Lea
ves
lan
ceol
ate
toov
ate
lin
ear
tosu
bula
tesu
bula
teto
ovat
e,im
bric
ate
atba
se
lin
ear
tosu
bula
teor
lin
ear-
lan
ceol
ate
lin
ear
tosu
bula
te,
gram
inoi
d
subu
late
toli
nea
r;n
ever
seti
form
orgr
amin
oid
lin
ear-
lan
ceol
ate
lin
ear
toov
ate,
rare
lysu
bula
te
ovat
eto
lan
ceol
ate
ovat
e,of
ten
over
lapp
ing
Infl
ores
cen
cety
pe/p
osit
ion
term
inal
orax
illa
rycy
me,
rare
lyre
duce
dto
1–3
flow
ers
cym
eso
lita
ryte
rmin
al,
1–3-
flow
ered
term
inal
cym
eor
pan
icle
ofcy
mes
,ra
rely
hea
dor
soli
tary
soli
tary
orte
rmin
alcl
ust
er
axil
lary
cym
eva
riou
ste
rmin
alcy
me,
1-to
few
-flow
ered
soli
tary
Sep
alla
nce
olat
eto
broa
dly
ovat
ela
nce
olat
eov
ate-
lan
ceol
ate
tola
nce
olat
eov
ate
toov
ate-
lan
ceol
ate
orel
lipt
ic
lin
ear-
lan
ceol
ate
toov
ate
lan
ceol
ate
toov
ate-
lan
ceol
ate
lan
ceol
ate
toov
ate
excu
rved
lan
ceol
ate
elli
ptic
orla
nce
olat
eto
orbi
cula
r
Sep
alap
exob
tuse
orac
ute
toac
um
inat
eac
ute
toac
um
inat
ein
flex
edat
the
apex
obtu
seob
tuse
toac
ute
,ac
um
inat
e,or
spin
ose
lon
g acu
min
ate-
acu
teac
ute
toac
um
inat
etr
un
cate
acu
teac
ute
Pet
alen
tire
orsl
igh
tly
emar
gin
ate
enti
reen
tire
enti
reor
slig
htl
yem
argi
nat
een
tire
orsl
igh
tly
emar
gin
ate
enti
reen
tire
retu
se,
emar
gin
ate
orfi
mbr
iate
enti
reen
tire
som
etim
estr
un
cate
orem
argi
nat
e
Pet
alsi
zeof
ten
shor
ter
than
sepa
lspa
rtly
lon
ger
than
sepa
lssh
orte
rth
anse
pals
usu
ally
lon
ger
than
sepa
lsva
riou
ssh
orte
rth
anor
aslo
ng
asse
pals
,ra
rely
lon
ger
than
them
lon
ger
than
sepa
lsu
sual
lylo
nge
rth
anse
pals
½ti
mes
aslo
ng
asse
pals
twic
eas
lon
gas
sepa
ls
Sty
le3
22
(3)
33
33
2(3
)3
3
Spe
cial
feat
ure
s–
inde
his
cen
ceca
psu
lese
eds
usu
ally
smoo
than
dsh
iny
leaf
mar
gin
slig
htl
ysw
olle
n
sepa
lm
arke
dly
har
den
edat
the
base
;co
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654 S. SADEGHIAN ET AL.
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To investigate the phylogenetic relationships ofArenaria and its allied genera and to evaluate thephylogenetic importance of morphological charactersused for subgeneric classification of Arenaria, nuclear(internal transcribed spacer region, ITS) and plastid(rps16) DNA sequences are used in the present study.We selected species representing all patterns of mor-phological divergence and covering the geographicalrange in an attempt to generate reliable phylogenetictrees. The aims of this study are briefly: (1) a detailedmolecular phylogenetic investigation based on abroad taxon sampling on Arenaria and the generaaround it; (2) re-circumscription of Arenaria andallied genera based on the results obtained; and (3)evaluation of the subgeneric classification of Arenariaand other related genera.
MATERIAL AND METHODSTAXON SAMPLING
Sequence data in the present study were generatedfrom specimens held at Botanische StaatssammlungMünchen (M), München Systematische Botanik(MSB) and Central Herbarium of the University ofTehran (TUH). The sampling strategy was to includeall generic names allied or attributed once to Are-naria, all recognized subgenera of Arenaria (sensuMcNeill, 1962) except subgenus Dicranella (Fenzl)Williams for which no material was available, and afew species representing Moehringia and Lepyrodiclisknown to be related or among the species of Arenariain previous investigations (e.g. Harbaugh et al., 2010;Greenberg & Donoghue, 2011). We generated 201DNA sequences, of which 118 represent 56 taxa ofArenaria (57 ITS and 61 rps16 sequences), 80 repre-sent 38 taxa of Eremogone (40 ITS and 40 rps16sequences) and three sequences represent two speciesof Lepyrodiclis (one ITS and two rps16 sequences). Tocover the taxonomic diversity known in Arenaria andits allies, several additional sequences were down-loaded from GenBank. Furthermore, the GenBanksequences of tribes Polycarpaeae and Paronychieaewere used as outgroups according to former molecularphylogenetic studies of Caryophyllaceae (e.g.Greenberg & Donoghue, 2011). All taxa and summa-rized sources, voucher information and GenBankaccession numbers of the sequences of all specimensused in this investigation are given in Appendix S1.
DNA EXTRACTION, AMPLIFICATION AND SEQUENCING
The phylogenetic study was conducted based onsequence data of the ITS (comprising ITS1, 5.8S rDNA,ITS2) of nuclear ribosomal (nr) DNA and the plastidrps16 intron. DNA extractions were performed usingdried leaf material. Whole genomic DNA was extracted
using a NucleoSpin Plant DNA Extraction kit(Macherey-Nagel) according to the manufacturer’s pro-tocol. The ITS region was amplified using primer pairsITS1/ITS4 (Popp & Oxelman, 2001; Kool, Perrigo &Thulin, 2012). For amplification of the complete intronof the plastid rps16 gene we used primer pairs rpsF/rpsR2R (Oxelman et al., 1997; Petri & Oxelman, 2011;Kool et al., 2012) or rpsF/rpsR3R. PCR reactions wereperformed according to Salmaki et al. (2012).
SEQUENCE EDITING AND PHYLOGENETIC
RECONSTRUCTION
All sequences were first aligned using default param-eters in Mafft v.7 (Katoh & Standley, 2013) and thenalignment errors were identified and manuallycorrected in Mesquite v.1.12 (Maddison & Maddison,2006). This method was especially effective forimproving the ITS alignment. The beginning and endof the alignments where the majority of taxa did notprovide complete data were excluded. When a minor-ity of taxa lack some positions we treated them asmissing (see Appendix S2, S3). The polymorphic sitesin the ITS dataset were minor and were treated asmissing when present. Ambiguously aligned regionswere minor in both data matrices and have a negli-gible effect on the tree topology in the form of dimin-ishing the resolution in few terminal branches andconsequently they were kept in the data matrix.Bayesian phylogenetic inference (BI) and maximumparsimony (MP) approaches were used for phyloge-netic reconstruction. An alignment for each ITS andrps16 sequence was analysed without indels coded.
Bayesian analyses of the individual matrices wereconducted using the Markov chain Monte-Carlo(MCMC) algorithm of MrBayes v.3.1.2 (Huelsenbeck& Ronquist, 2001). The best nucleotide substitutionmodel was selected using the Akaike information cri-terion (AIC) in jModelTest v.0.1.1 (Posada, 2008). Thegeneral time reversible model of nucleotide substitu-tion with gamma-shaped rate variation and a propor-tion of invariable sites (GTR+I+G) was the estimatedbest-fit model for ITS and a simpler model, GTR+G,was chosen for rps16. Trees were sampled every1000th generation with the default of three ‘heated’and one ‘cold’ chain for 12 million MCMC generationsfor ITS and 3 million generations for rps16 as theconvergence of runs had been reached earlier and thestandard deviation of split frequencies fell signifi-cantly below 0.01. Burnin was set to 3000 and 750,respectively. Bayesian search results were summa-rized by the 50% majority rule consensus tree, andposterior probability (PP) values (‘clade credibility’)are indicated at the branches.
MP of the individual genes was performed usingPAUP* v.4.0b10 (Swofford, 2003). Searches were
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performed separately on each data set, as the taxoncomposition of plastid DNA and nrDNA matrices wasnot the same and as the two genomes are different inevolutionary history. MP bootstrapping was done usingthe following settings: hsearch addseq = random,nchuck = 10, chuckscore = 1, nreps = 10, bootstrapnreps = 1000. The bootstrap results are summarized ina 50% majority-rule consensus cladogram. TreeGraph2.0.54–364 beta (Stöver & Müller, 2010) was used fortree presentation. The alignments used in this studyare available in Appendices S2 and S3.
RESULTSSEQUENCE CHARACTERISTICS AND ALIGNMENT
The data sets included a total of 271 sequences; 201produced by this study and 70 obtained fromGenBank (Appendix S1). For the following taxa, wewere not able to produce any ITS sequences: Arenariaconimbricensis Brot. subsp. viridis Font Quer,A. grandiflora L., A. merckioides Maxim., A. serpylli-folia L., A. speluncarum McNeill, Eremogone zargari-ana (Parsa) Holub and Lepyrodiclis holosteoidesFenzl ex Fisch. & C.A.Mey. For E. saxatilis (L.)Ikonn., the amplification of rps16 was not successful.Ultimately, the final dataset of ITS included 140accessions, and the final rps16 matrix contained 131sequences. Detailed information about alignmentcharacteristics and statistics of MP analyses is givenin Table 3.
PHYLOGENETIC RELATIONSHIPS
Phylogenetic trees generated using parsimony werecongruent with those produced by Bayesian analysis.
Therefore, only the BI cladograms are presented anddiscussed in detail here (Figs 3–5). Some informationfrom MP analyses, including tree length, number ofpotentially informative characters, and consistencyand retention indices, are summarized in Table 3. Thetrees gained from both ITS and rps16 markers revealthat Arenaria s.l. (as defined by McNeill, 1962) isdivided into three major clades: (1) the ‘Odon-tostemma clade’ (Figs 3, 4, with PP = 0.926, BS = 66%and PP = 1.00, BS = 91%, respectively) including A.subgenus Odontostemma and A. subgenus SolitariaMcNeill plus representatives of the genera Lepyrodi-clis and Pseudostellaria; (2) the so-called ‘Arenarias.s. clade’ (Figs 3, 4, with PP = 1.00, BS = 86% andPP = 0.995, BS = 88%, respectively) embracing thevast majority of the species attributed to A. subgenusArenaria, A. subgenus Arenariastrum Williams, A.subgenus Porphyrantha, A. subgenus Leiosperma, A.section Pseudomoehringia McNeill and the monotypicA. section Pungentes McNeill; and (3) the ‘Eremogoneclade’ (Figs 3, 4, with PP = 1.00, BS = 100% andPP = 1.00, BS = 100%, respectively) representing thegenus Eremogone and the former A. subgenusEremogoneastrum. More details of the branchingpattern are discussed below (see Discussion).
The monophyletic crown groups recognized inITS (Figs 3, 5) and rps16 (Figs 4, 5) topologies werehighly congruent, but the rps16 tree (Fig. 4) is moreresolved. Most cases of incongruence involved theposition of a few terminal branches in the two topolo-gies; some of these differences are outlined below.
‘Eremogone clade’In the ITS cladogram it is sister to the members of‘Arenaria s.s.’ and ‘odontostemma’ clade (with lowsupport: BS = 0.52%; Fig. 3), whereas in the rps16tree it is sister to A. densissima ex Edgew. & Hook.f.,which is in turn sister to the members of Caryophyl-leae (Fig. 4).
Arenaria densissimaIn the ITS topology this species is sister to themembers of Sileneae and Caryophylleae (with weaksupport: PP = 0.676; Fig. 3), whereas in the rps16 treeit is sister to the ‘Eremogone clade’ (Fig. 4, PP = 0.914,BS = 67%).
The placement of Arenaria antitaurica McNeill andA. gracilis Waldst. & Kit.These taxa form a clade in the ITS tree (Fig. 3,PP = 1.00, BS = 94%), whereas they are nested in twoseparate clades in rps16 tree (Fig. 4).
Moehringia lateriflora FenzlIn the rps16 phylogenetic tree this species is nestedwithin the ‘Arenaria s.s.’ clade (with moderate
Table 3. Sequence characteristics and statistics ofmaximum parsimony analysis for ITS and rps16
ITS rps16
No. of accessions 140 131BIC model choice GTR+I+G GTR+GSequence length (bp) 626 810Aligned length (bp) 651 1174Invariable sites (bp) 239 559Variable sites (bp) 412 615Variable sites (%) 63.29 52.38Potentially parsimony-
informative characters (bp)340 422
Potentially parsimony-informative characters (%)
52.23 35.94
Consistency index, excludinguninformative characters
0.3167 0.5494
Retention index 0.7994 0.9024Tree length 2362 1508
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Figure 3. Majority-rule consensus tree inferred from Bayesian analysis of ITS data. Posterior probability values areindicated above branches, MP bootstrap values below. Values below 50% are not shown.
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support: PP = 0.647; Fig. 4), whereas in the ITS topol-ogy it is sister to the same clade (Fig. 3).
DISCUSSION
Our data, with a rather different taxon sampling andusing one plastid DNA marker (rps16) and nrDNAITS sequences, corroborate the findings of formermolecular phylogenetic studies on Caryophyllaceaeand reject the application of tribe Alsineae in theirolder circumscription (Harbaugh et al., 2010;Greenberg & Donoghue, 2011). Our analyses recoverthe three tribes recognized by Harbaugh et al. (2010):Eremogoneae, Alsineae and Arenarieae. The speciesattributed to Arenaria in earlier treatments are scat-tered through these three clades. The composition ofeach of these main clades is explained in detail below.
TRIBE EREMOGONEAE
The earlier molecular phylogenetic studies usingseveral plastid DNA markers and the nrDNA ITSsequences provided new insights into the delimitationof Eremogone (Nepokroeff et al., 2001; Harbaughet al., 2010; Greenberg & Donoghue, 2011) andresulted in the creation of tribe Eremogoneae. In allour phylogenetic analyses, the former Arenaria sub-genera Eremogone and Eremogoneastrum are unitedin a strongly supported single clade representingtribe Eremogoneae (Figs 3, 4, with PP = 1.00,BS = 100% and PP = 1.00, BS = 100%, respectively),which is characterized by narrow, grass-like leaves(Fig. 1E–M). Whereas the ITS phylogenetic treessupport Sileneae as sister to this clade (Fig. 4), theplastid trees do not exactly address the placement ofEremogoneae.
Figure 3. Continued.
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Figure 4. Majority-rule consensus tree inferred from Bayesian analysis of rps16 data. Posterior probability values areindicated above branches, MP bootstrap values below. Values below 50% are not shown.
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First used in recent treatments by Ikonnikov (1973)and especially in North American floras by Weber,Johnston & Wittmann (1981), Dorn (2001) and morerecently by Rabeler & Hartman (2005), Eremogone isa taxonomic segregate from the polyphyletic Arenarias.l. Eremogone is a morphologically distinctive groupcharacterized by several synapomorphies (e.g. accum-bent cotyledons and chromosome number x = 11;Table 2). Several investigations have attempted toprovide an infrageneric classification of the genus(Maguire, 1947, 1951; McNeill, 1962; Hickman, 1971),but due to its heterogeneous morphology noneseems to be appropriate (Rabeler & Hartman, 2005).McNeill (1962) recognized eight sections in his Are-naria subgenus Eremogone. Thirty-seven representa-
tives of all sections of Eremogone (except themonotypic section Monogone Maxim.) were includedin our ITS and rps16 analysis (see Figs 3–5). Both ITSdata (with higher resolution) and rps16 show thathardly any of the sections recognized by McNeill(1962) could be considered as monophyletic withcertainty. In the case of section Pungentes, thistaxon should be removed from Eremogone and placedin Arenaria (see further discussion under tribeAlsineae). A few clades matching certain sections(such as section Eremogone) could be recovered byboth markers (when ignoring E. graminea C.A.Mey.ex Fisch. & Mey.) (Fig. 5, compare box H). Arenariasection Capillares McNeill with about nine specieswas described by McNeill (1962) to encompass those
Figure 4. Continued.
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dense caespitose species having long linear or seta-ceous leaves and acute to acuminate sepals. Accordingto McNeill (1962), members of this section appear tobe closely related to species of A. section Sclerophyllae(Boiss.) McNeill, so close that it is sometimes difficultto distinguish the sections (Fig. 5, box J). However,due to low support values and incomplete sampling, itis premature to propose a new infrageneric classifi-cation for Eremogone. Therefore, we highlight hereonly one example indicating the need for additionalmolecular phylogenetic study in Eremogone.
A densely caespitose to densely pulvinate habit alsocharacterizes members of subgenus Eremogoneastrum(Fig. 1N–P). However, these taxa have scarious leafmargins and acuminate sepals, separating them fromDolophragma (Fig. 1A–C). In the topology acquiredfrom the ITS sequence analysis, the species of subge-nus Eremogoneastrum form a moderately supportedmonophyletic group, but this group is not completelyrecovered by the rps16 trees (Fig. 5, box I). Our dataindicate that members of subgenus Eremogoneastrumshould clearly be included in Eremogone. Therefore, wetransfer the species of subgenus Eremogoneastrum inour analysis to Eremogone.
Greenberg & Donoghue (2011) reported that A. lan-cangensis L.H.Zhou and A. roborowskii Maxim.,included in Arenaria subgenus Eremogoneastum byZhengyi, Zhou & Wagner (2001), were found in aclade containing more than 20 Cerastium species. Wedid not include these species in our analysis, butbelieve that their result should be verified. We foundthe same results as Dillenberger & Kadereit (2014)regarding placement of Eremogone picta (Sibth. &Sm.) Dillenb. & Kadereit, confirming the inclusion ofMinuartia subgenus Spergella in Eremogone.
PLACEMENT OF ARENARIA SUBGENUS DOLOPHRAGMA
The single species of A. subgenus Dolophragmaincluded in the present study (Arenaria densissima)shows a sister relationship to Eremogoneae in therps16 tree and falls in the same clade as tribesSileneae and Caryophylleae in the ITS tree (but withdistinctly lower support; Figs 3–5). Another species(A. przewalskii Maxim.; Fig. 1D) assigned to this sub-genus by McNeill (1962) was nested in the ‘Odon-tostemma clade’ (Greenberg & Donoghue, 2011),making it likely that this subgenus is polyphyletic. Atleast in the case of A. densissima, it probably shouldnot be maintained and should instead be Dolo-phragma juniperinum (D.Don) Fenzl. As material ofthe type species of A. subgenus Dolophragma [Dolo-phragma globiflorum Fenzl ≡ A. globiflora (Fenzl)Wall. ex Edgew. & Hook.f.] was not available, wecannot completely confirm this usage. However, dueto the close morphological resemblance of A. densis-
sima, A. polytrichoides Edgew. and A. globiflora char-acterized by dense pulvinate habit, swollen coriaceousleaf margin and short obtuse sepals (Fig. 1A–C),it seems likely that the genus Dolophragma shouldbe reinstated and recircumscribed to exclude otherspecies with dense cushion-forming but caespitosehabit having linear leaves (Fig. 1D), such as A. prze-walskii, which are probably related to the members ofthe ‘Odontostemma clade’. The dense cushion habithas most probably arisen independently in this groupof species.
TRIBE ALSINEAE
Among the genera once attributed to this tribe, Odon-tostemma was treated as a subgenus of Arenaria byMcNeill (1962). However, two recent molecular phy-logenetic studies both suggested that this genus hasto be resurrected (Harbaugh et al., 2010; Greenberg &Donoghue, 2011). In the present study and basedon both analyses, Odontostemma, Lepyrodiclis andPseudostellaria and members of Arenaria subgenusSolitaria are assigned to the ‘Odontostemma clade’(Figs 3–5). These genera are clearly apart from Are-naria s.s. in both trees obtained. The genera formingthis clade are morphologically well defined (Fig. 2A–E). Most genera in this clade show an East Asian(Sino-Himalayan) distribution and are characterizedby petals mostly conspicuous overtopping the sepalsand entire or emarginate at the apex (only rarelyabsent in some Pseudostellaria), leaves relativelylarge, linear to ovate and capsules dehiscing by twiceas many valves as styles (except for Lepyrodiclis).Due to the ± sharp boundaries between these genera,uniting them into one genus would make the groupheterogeneous. Furthermore, such a treatment maycause the disappearance of several generic namesthat are currently in common use. Whereas the rps16data (Fig. 4) show Pseudostellaria to be nested inOdontostemma, both consensus trees (Fig. 5) showa segregation of the genera similar to the resultsobtained by Harbaugh et al. (2010). Greenberg &Donoghue’s (2011) figure 3 suggested that Pseudostel-laria may be paraphyletic. Our sampling of Pseudos-tellaria was not sufficient to confirm or refute thispossibility, providing another reason for retainingcurrent usage until additional studies can be made. Amore plausible taxonomic treatment with the fewestnomenclatural changes would be the resurrection ofOdontostemma as a genus (type species: O. glandu-losa Benth. ex G.Don) and treating A. subgenus Soli-taria as a new genus (genus Solitaria, type species:A. ciliolata Edgew.; see below). A new taxonomicsystem involving the members of the ‘Odontostemma’clade along with a key to the accepted genera in thisclade is presented at the end of the Discussion.
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TRIBE ARENARIEAE
The members of the tribe have mostly conspicuousentire petals, capsules dehiscing by twice as manyvalves as styles and often ± broad leaves ovate tolanceolate in shape (Fig. 2F–L). In all trees weobtained, a core group of Arenaria, the so-calledArenaria s.s., is recovered with Moehringia s.s. assister (Figs 3, 4; PP = 1.00, BS = 95% and PP = 1.00,BS = 93%, respectively). This finding is in agreementwith previous studies (Fior & Karis, 2007; Harbaughet al., 2010; Greenberg & Donoghue, 2011). However,contrary to those studies, Moehringia is paraphyleticin our analyses (see results, Figs 3–5). This fact couldbe caused by the lack of enough informative signalsand/or the low sampling. The greater number ofmarkers used in the previous studies and the greaternumber of taxa sampled (Harbaugh et al., 2010;Greenberg & Donoghue, 2011) probably resulted indifferent topologies obtained in those studies versusour results.
There are few clades in Arenaria s.s. with adequatesupport from both markers that would allow recogni-tion as natural taxonomic groups. Most of the extantsubgenera and sections are not monophyletic. Givenour results, we consider the rank of subgenus inArenaria is not justified, but there is enough supportfor several sections, as smaller natural groups, withinArenaria. The main supported monophyletic cladesinside Arenaria which are in accordance with alreadyrecognized subgeneric taxa in the genus are asfollows.
1. Arenaria subgenus Leiosperma (Fig. 5, box C).Both morphological and molecular data stronglysupport this clade as a distinct group. Further-more, with about 32 species, it is distributed in theNew World with centre of diversity in the Andes.The members of this subgenus are homogeneous invegetative and floral traits and are also character-ized by smooth and shiny seeds (Sadeghian, Zarre& Heubl, 2014). Although several features supportthe monophyly of this group, questions regardingits proper taxonomic rank could not be addresseduntil now. Based on the trees obtained from ITSand rps16 sequence data, it seems that acceptingLeiosperma as a subgenus would make other sub-genera and sections in Arenaria paraphyletic.Based on our results, treating Leiosperma as asection (section Leiosperma F.N.Williams) is moreappropriate.
2. Arenaria section Rotundifoliae McNeill (Fig. 5, boxD). The members of this section are convenientlyrecognizable by rounded leaves and creeping habit.Our analyses imply that section Rotundifoliaemay possibly be monophyletic, if A. orbicularis Visand A. balearica L. are excluded. The latter species
differ from other species of the section by havingsolitary flowers with obtuse sepals on long pedi-cels. Arenaria orbicularis was placed by McNeill(1962) in section Rotundifoliae but has subse-quently been transferred to section OrientalesMcNeill by Jalas & Suominen (1988). Our resultsalso show a possible relationship between thisspecies and some members of section Orientales.
3. Arenaria section Plinthine (Fig. 5, box E). In ourstudy, the monophyly of section Plinthine is sup-ported in the ITS and plastid DNA phylogenetictrees, confirming the results of previous molecularphylogenetic studies (Valcárcel et al., 2006;Greenberg & Donoghue, 2011). There are alsoseveral morphological synapomorphies supportingthe monophyly of section Plinthine (Valcárcelet al., 2006). This natural group is geographicallyrestricted to the western Mediterranean and themorphology of these species is distinctive com-pared with the rest of Arenaria (Valcárcel et al.,2006; Fig. 2G, H). Our results suggest that themembers of section Plinthine are related to agroup of other Mediterranean species such asA. retusa Boiss. and A. arundana Gallego.
4. Arenaria section Arenaria (Fig. 5, box F). This is adistinct and natural group of annual plants. In theITS and rps16 trees, two short-lived perennialspecies, A. teddii Turrill and A. graeca (Boiss.)Halácsy (previously considered as members of A.section Orientales), are nested in the same cladewith the species of section Arenaria. As it appearsthat the annual habit seems to be derived severaltimes in Arenaria, the circumscription of thissection could be extended to also encompass someperennial species. However, due to the low numberof taxa sampled in the present study (five of 15species recognized), it is premature to suggestany formal treatment of this section and itsmembers.
5. Section Pseudomoehringia (Fig. 5, box G). Themembers of this section were originally placed inMoehringia due to the papillo-strophiolate seeds.In accordance with Fior & Karis (2007), our ITSand rps16 phylogenetic trees indicate that theseIberian taxa should be transferred to Arenaria.From a morphological point of view, the seeds ofthe members of this section resemble Moehringia,but the seed surface is rather tuberculate insteadof being smooth (McNeill, 1962; Fior & Karis,2007). Our results indicate high support for thissection. Furthermore, the species assigned to thissection are homogeneous morphologically. There-fore, this group should be considered as a well-supported monophyletic group within Arenariaand, by the new combination made below, we treatit as a formal section under Arenaria. The plants
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are mostly annual with sepals obscurely veinedand show a western Mediterranean distributionpattern (centred in Spain and North Africa)
Most other subgenera (sensu McNeill, 1962) are notmonophyletic according to the results of our molecu-lar phylogenetic analyses. These groups are explainedbelow.
1. A. subgenus Arenaria. In McNeill’s (1962) classifi-cation system on Alsinoideae, the species-rich A.subgenus Arenaria, with at least 100 species, wasdivided into 11 sections. These sections shareseveral morphological characters, such as ± entirepetals, three carpellate capsules, six capsule teethand incumbent cotyledons. Our results from ITSand rps16 sequence analyses indicate that thislarge subgenus is paraphyletic with several othersubgenera (such as A. subgenera Leiospermaand Arenariastrum) nested in it. Therefore, theabove-mentioned shared characters are probablysymplesiomorphies. As mentioned above under A.subgenus Leiosperma, the application of the rankof subgenus in Arenaria is not helpful; sectionswould provide a better interpretation of thenatural groups present in the genus. The singlespecies of A. subgenus Arenariastrum (A. provin-cialis Chater & G.Halliday) is closely related tosome members of A. section Orientales, A. sectionOccidentales McNeill and A. section Rariflorae (A.subgenus Arenaria sensu McNeill, 1962) in ouranalyses and its separation from these sections, orat least part of them, is not supported. The affinityof this species with members of Arenaria was alsopreviously determined by detailed morphologicaland biogeographical analyses as well as moleculardata (Youssef et al., 2011).
2. The monotypic A. subgenus Porphyrantha,restricted to the Pyrenees and the CantabrianMountains, appears to share a similar fate. Ourmolecular data clearly place the type species ofthis subgenus (A. purpurascens Ramond ex DC.) inArenaria s.s., although the species seems to beunique in Arenaria by its odd morphological char-acters (e.g. elongated capsule and smooth seedshaving a tuft of white hairs at the hilum).
3. Although with low support, the rps16 sequenceanalysis places Eremogone pungens (Clemente exLag.) Fenzl (the type of McNeill’s monotypic A.section Pungentes) close to A. purpurascens andmembers of A. section Africanae McNeill. There-fore, Eremogone pungens is not related to otherspecies of Eremogone and should instead be treatedas a species of Arenaria, i.e. A. pungens Clementeex Lag. This is consistent with Ikonnikov (1973),who excluded E. pungens from his review ofEremogone.
4. Arenaria sections Orientales, Occidentales andRariflorae F.N.Williams. The species once assignedto sections Orientales and Occidentales are scat-tered among various groups of Arenaria s.s. Asoutlined by McNeill (1962), the 11 species recog-nized in A. section Occidentales are mainly distrib-uted in the western Mediterranean. Presence oflinear to subulate leaves is the most importantmorphological characteristic separating the speciesof this section from the members of the alliedA. section Orientales, which encompasses about20 species with somewhat ovate leaves and aneastern Mediterranean distribution. The closerelationship between these sections has beenexpressed by several authors (e.g. López Gonzáles,1990). The phylogenetic trees depicted here showthat the species of both sections are mixed witheach other and the members of several other sec-tions such as A. section Rariflorae. In general, ourresults suggest that the subgeneric classification ofArenaria s.s. needs to be revised substantially andthat the available system, which is mainly accord-ing to McNeill (1962), does not present a naturalclassification. For this purpose, it is necessary toconduct a detailed morphological study along withan inclusive molecular analysis using severalmarkers and denser sampling.
TAXONOMIC CONCLUSION
Although our study does not provide a complete phy-logenetic basis for a revised taxonomy for Arenaria, itindicates that some infrageneric taxa may be natural,whereas others are paraphyletic or polyphyletic. Inaddition, our results highlight several taxonomicambiguities that may be corrected by transferringsome taxa to other genera. The present study shedslight on the borders between Arenaria and alliedgenera. In general, the results of our molecular phy-logenetic investigation demonstrate the need for asubstantial revision of Arenaria to include the major-ity of its species. Our phylogenetic analyses of ITSand rps16 were unable to resolve fully relationshipsamong species of Arenaria and Eremogone. The appli-cation of additional plastid and nuclear markers couldhelp to resolve some of the polytomies detected here.The following taxonomic treatments could be pro-posed based on our results.
• Section Pseudomoehringia should be transferredfrom Moehringia to Arenaria:
Arenaria section Pseudomoehringia (McNeill)Rabeler & Zarre, comb. nov. = Moehringia sectionPseudomoehringia McNeill, Notes Roy. Bot. Gard.Edinburgh 24: 131. 1962. Type: Arenaria suffruticosa
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Fior & P.O.Karis = Moehringia intricata Willk., nonA. intricata (Ser.) Rivas Mart. & M.J.Costa.
Some species of Arenaria subgenus Eremogoneas-trum are transferred to the genus Eremogone:
1. Eremogone brevipetala (Y.W.Tsui & L.H.Zhou)Sadeghian & Zarre, comb. nov. = Arenaria brevi-petala Y.W.Tsui & L.H.Zhou, Acta Phytotaxon. Sin.18:360. 1980 – Type: China, Sichuan, Kangding,Yingguanzhai, 3650 m, Dept. of Agriculture,Sichuan Agriculture College (58)100 (holotype,KUN).
2. Eremogone bryophylla (Fernald) Sadeghian &Zarre, comb. nov. ≡ Arenaria bryophylla Fernald,Rhodora 21:5. 1919, nom. nov. ≡ Arenaria musci-formis Wall. ex Edgew. & Hook.f. Fl. Brit. India1(2): 237. 1874, not Triana & Planch., 1862 –Syntypes: Alpine Eastern and Western Tibet,16–18000 ft, Webb & Jacquemont s.n.; Balch pass,R. Strachey. & J.E. Winterbottom, s.n.; Karakoramand Parang passes, T. Thomson s.n.; TibetanSikkim, 15–16000 ft, J.D. Hooker s.n. (K?).
3. Eremogone edgeworthiana (Majumdar) Sad-eghian & Zarre, comb. nov. ≡ Arenaria edgewor-thiana Majumdar, J. Indian Bot. Soc. 44:141.1965 ≡ A. monticola Edgew. – Type: India,Himalya, Sikkim Lama Krupa, J.D Hooker,Hooker & Thomson, Herb. Ind. Orient. 4 (holotype:K, K000723993 [photo!]).
The genus Odontostemma Benth. ex G.Don shouldbe reinstated to include the members of Arenariasubgenus Odontostemma:
Odontostemma Benth, ex G.Don, Gen. Syst. 1:449. 1831 ≡ Arenaria subgenus Odontostemma(Benth. ex G.Don) F.N.Williams, Bull. Herb. Boissier3:603. 1895 – Type: O. glandulosum Benth. ex G.Don
= Gooringia F.N.Williams, Bull. Herb. Boissier 5:530, 1897 – Type: G. littledalei (Hemsley) F.N.Wil-liams (≡ Arenaria littledalei Hemsley).
As a major conclusion of our study, the genus isdescribed in detail below:
Herbs annual, biennial, or perennial, denselybranched. Leaves linear to ovate, rarely subulate andnever setaceous. Inflorescences various, but oftenwith vegetative branches arising within them. Sepalscurved, often saccate, veins inconspicuous, marginbroadly membranous, apex truncate. Petals usuallylonger than sepals (but sometimes smaller) cleistoga-mous flowers sometimes present, apex emarginate orfimbriate. Styles usually two, rarely three. Seedsoften inflated, winged, rough on surface. About 65species, with a Sino-Himalayan distribution.
Accepted species:
1. Odontostemma glandulosum Benth. ex G.Don,Gen. Syst. 1: 449. 1831 ≡ Arenaria blinkworthii
McNeill, Notes Roy. Bot. Gard. Edinburgh 24: 128.1962 ≡ Arenaria glandulosa (Benth. ex G.Don)F.N.Williams, Bull. Herb. Boissier 5: 603. 1895,not Jacquin (1798) ≡ Arenaria benthamii Edgew.,Fl. Brit. India. 1: 242. 1874, not Fenzl ex Torrey &A. Gray (1840) – Type: India: Kamoun, R.Blinkworth s.n., Wallich Cat. 645 (holotype: K,K000742186 [photo!]; isotype: E, E00317569[photo!]).= Arenaria debilis Hook.f., Fl. Brit. India. 1: 242.1874 – Type: India, Sikkim, Kankok, 15000 ft, 27Aug 1849, J.D. Hooker, Hooker & Thomson, Herb.Ind. Orient. s.n. (lectotype, designated here; K,K000742183, right-hand plant on sheet [photo!];isolectotypes; K, K000742185, excl. plants imme-diately above label [photo!]; GH, GH00353888[photo!]).
2. Odontostemma barbata (Franch.) Sadeghian &Zarre, comb. nov. ≡ Arenaria barbata Franch.,Bull. Soc. Bot. France. 33: 430. 1886 – Type:China, Yunnan, in lapidosis calcareis, ad pedemmontis Yang-in-chan, supra Lankong, 2500 m, 14Sep 1885. Delavay 1901 (P?).
3. Odontostemma fridericae (Hand.-Mazz.) Sad-eghian & Zarre, comb. nov. ≡ Arenaria fridericaeHand.-Mazz., Anz. Akad. Wiss. Wien. 57: 142.1920. – Type: China, Yünnan bor.occid.: in laterisoccid. montis Piepun ad austro-orient. pagi Dsc-hungdien (‘Chungtien’) regione alpina, in glareamobile, 4300–4650 m, 11 Aug 1914, H.R.E.von Handel-Mazzetti 4684 (holotype; (WU,WU0043547 [photo!]).
4. Odontostemma ionandra (Diels) Sadeghian &Zarre, comb. nov. = Arenaria ionandra Diels,Notes Roy. Bot. Gard. Edinburgh. 5: 182. 1912. –Type: China, Lichiang Range, 11–12000 ft, lat.27°20′N, Sep 1906. G. Forrest 2902A (holotype; E,E00313709 [photo!]).
5. Odontostemma pogonantha (W.W.Smith) Sad-eghian & Zarre, comb. nov. ≡ Arenaria pogonan-tha W.W.Smith, Notes Roy. Bot. Gard. Edinburgh.11: 198. 1920. – Type: China, Yunnan, westernflank of Shweli Salween Divide, 10000 ft, lat25°20′ N, Aug. 1912, G. Forrest 8935 (holotype; E,E00117574 [photo!]).
6. Odontostemma roseiflora (Sprague) Sadeghian& Zarre, comb. nov. ≡ Arenaria roseifloraSprague, Bull. Misc. Inform. Kew: 33. 1916 ≡ Moe-hringella roseiflora (Sprague) H.Neumayer, Verh.Zool.-Bot. Ges. Wien, 73: 14. 1923 – Type: China:Forrest 13225, described from cultivated plant atK (holotype; K, K000723896 [photo!]).= Arenaria atuntziensis var. stenopetala Y.W.Cui exL.H.Zhou, Acta Biol. Plateau Sin. 6: 27. 1987.Type: China: Yunnan: Dequin, 2700 m, C.W. Wang70086 (holotype, KUN).
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7. Odontostemma trichophora (Franch.) Sad-eghian & Zarre, comb. nov. ≡ Arenaria trichophoraFranch., Bull. Soc. Bot. France, 33: 431. 1886 ≡ Are-naria yunnanensis var. trichophora (Franch.)F.N.Williams – Type: China, Yunnan, in monteHee-chan-men, supra Lankong, 11 Jul 1883,Delavay 110 (P?).
Arenaria subgenus Solitaria should be elevated togeneric rank:
Solitaria (McNeill) Sadeghian & Zarre, comb.nov. ≡ Arenaria subgenus Solitaria McNeill, NotesRoy. Bot. Gard. Edinburgh. 24: 128, 1962. ≡ Arenariasection Sikkimenses F.N.Williams, Bull. Herb. Bois-sier 3, 600, 1895. – Type: S. ciliolata (Edgew.) Sad-eghian & Zarre
As another major conclusion of our study, the genusis described in detail below:
Herbs perennial, caespitose, sometimes denselybranching, but never pulvinate. Stems clustered,short. Leaves relatively large (> 5 mm long), leaf bladeremote or sometimes approximate (covering eachother), but never imbricate in four rows, lanceolateto ovate-orbicular, base narrowed, margin usuallyslightly hard. Flowers solitary, rarely paired, terminal,large and showy. Sepals elliptic or lanceolate to nar-rowly orbicular, margin membranous, usually carti-laginous, apex acute, about twice as long as sepals.Petals white, pink or violet, obovate to obovate-elliptic.Styles three. About six species, with a Sino-Himalayandistribution.
Accepted species:
1. Solitaria ciliolata (Edgew.) Sadeghian & Zarre,comb. nov. ≡ Arenaria ciliolata Edgew., Fl. Brit.India. 1: 240. 1874. – Type: India, Sikkim LamaKengna, 15000 ft, 24 Jul 1849, J.D.Hooker, Hooker& Thomson, Herb. Ind. Orient. 11 (K, lectotype,designated here, K000742194 [photo!]; isolecto-type; GH, GH00353887 [photo!]).
2. Solitaria glanduligera (Edgew.) Sadeghian &Zarre, comb. nov. ≡ Arenaria glanduligeraEdgew., Fl. Brit. India. 1: 240. 1874. – Syntypes:Kashmir, H. Falconer s.n. (K, K000742189[photo!]; India, Kumaon, Barji Kang pass, 14 500ft, R. Strachey & J.E. Winterbottom (K?); India,Sikkim, 12–16000 ft, J.D.Hooker, Hooker &Thomson, Herb. Ind. Orient. 12 (E, E00317564[photo!]; GH, GH00353890 [photo!]; K?).
3. Solitaria stracheyi (Edgew.) Sadeghian & Zarre,comb. nov. ≡ Arenaria stracheyi Edgew., Fl. Brit.India. 1: 240. 1874. – Type: China, Tibet nearRakas Tal., R. Strachey & J.E. Winterbottom 3(lectotype, designated here, K, K000723873[photo!]).
ACKNOWLEDGEMENTS
We are grateful to the Research Council, University ofHamedan, for a grant to S.S. as well as the ‘Alexandervon-Humboldt-Stiftung’ for a grant to S.Z. We thankthe curators at M, MSB and TUH for permission tosample from herbarium specimens used in this study.Kind assistance from Tanja Ernst (Munich) in Heubl’splant molecular systematic laboratory and fromYasaman Salmaki in alignment and analysis areappreciated. We are grateful also to Patrick J. Alex-ander, David E. Boufford, Brad Boyle, Sheri Hagwood,Harry Jans, Andrés Ivorra, Thomas Johansson, NealKramer, Ernie Marx, Kier Morse, Harald Pauli andM. Tehranian for providing high-resolution photo-graphs used in this paper.
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KEY TO THE GENERA OF THE ‘CLADE ODONTOSTEMMA’1a. Flowers of two types: chasmogamous at stem apex, with five large, entire or rarely bifid petals and an ovary of
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SUPPORTING INFORMATION
Additional Supporting Information may be found in the online version of this article at the publisher’s web-site:
Appendix S1. Voucher information and GenBank accession numbers for the sequences analysed in this study.For the accessions obtained from GenBank, the collection data were not available.Appendix S2. Aligned data matrix of ITS sequences of Arenaria and allied genera used in the phylogeneticstudy in nexus format.Appendix S3. Aligned data matrix of rps16 sequences of Arenaria and allied genera used in the phylogeneticstudy in nexus format.
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