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381
Salariato & al. • New genus RupichloaTAXON 58 (2) • May 2009: 381–391
INTRODUCTION
Urochloa P. Beauv. and Brachiaria (Trin.) Griseb.,
together with other genera of Paniceae such as Mega-
thyrsus (Pilg.) B.K. Simon & S.W.L. Jacobs, Eriochloa
Kunth, Melinis P. Beauv. and Tricholaena Schrad. ex
Schult. & Schult. f., share a C4-PCK photosynthetic path-
way in which the C4 compounds are decarboxylated in the
cytosol of the Kranz cells by the phosphoenol pyruvate
carboxykinase enzyme (PEP-ck) (Gutiérrez & al., 1976;
Brown, 1977; Hattersley, 1987). These genera also pres-
ent a similar foliar anatomy, characterized by a double
bundle sheath with specialized centrifugal chloroplasts,
located toward the outer cell wall in the external paren-
chymatic Kranz sheath (PS or XyMS+) (Ellis, 1977, 1988;
Hattersley, 1987). All these genera are part of a monophy-
letic clade (PCK) based on nucleotide synapomorphies
(Gómez-Martínez & Culham, 2000; Giussani & al., 2001;
Duvall & al., 2001; Aliscioni & al., 2003).
Urochloa and Brachiaria share several morphologi-
cal, anatomical and physiological characters. As a con-
sequence, their delimitation has always been contentious
(Clayton & Renvoize, 1986; Webster, 1987; Morrone &
Zuloaga, 1992; Veldkamp, 1996b).
Urochloa was based on a single species, U. panicoides
P. Beauv. (Palisot de Beauvois, 1812), while Brachiaria was
initially established as a section of Panicum L. (Trinius,
1826) and later raised to the generic level (Grisebach, 1853),
including a single species, B. eruciformis (Sm.) Griseb.
Subsequent authors transferred numerous species, mainly
from Panicum, to the latter genus (Chase, 1911, 1920; Stapf,
1917–1934; Hitchcock, 1950), and circumscribed Brachi-
aria by the adaxial orientation of the spikelet and inflores-
cences with racemose primary branches. Although Bra-
chiaria and Urochloa were distinguished basically by the
spikelet orientation (Stapf, 1917–1934; Clayton & Renvoize,
1982, 1986), this character is difficult to ascertain when
spikelets are paired (Morrone & Zuloaga, 1992). For this
reason, Webster (1987), Morrone & Zuloaga (1992, 1993),
Ashalatha & Nair (1993) and Veldkamp (1996a) restricted
Brachiaria to species with disarticulation at the base of the
upper anthecium and by having a smooth and shiny, muti-
cous upper anthecium. As a result, in most recent treatments
Brachiaria was restricted to just three species (B. eruci-
formis, B. malacodes (Mez & K. Schum.) H. Scholz, and
B. schoenfelderi C.E. Hubb. & Schweick.); the remaining
species were transferred to Urochloa, drastically increasing
the number of species in the latter genus. Later, Veldkamp
(1996b, 2004) indicated that the name Brachiaria is a syn-
onym of Urochloa and transferred the species of Brachiaria
to the new genus Moorochloa Veld kamp.
Nowadays, Urochloa comprises nearly 110 species
distributed in tropical and subtropical regions of the World.
About 20% of the species are native to America, 11% from
Oceania and the rest are widely distributed in Africa and
Asia (Stapf, 1917–1934; Clayton, 1972; Clayton & Ren-
voize, 1982; Webster, 1987; Morrone & Zuloaga, 1992,
1993). Morphologically, Urochloa has been defined by the
transversely rugose upper anthecium with a mucronate,
crestate or aristulate apex, and by the disarticulation of
the diaspore (the spikelet) below the lower glume (Webster,
1987, 1988; Morrone & Zuloaga, 1992; Veldkamp, 1996a).
Based on recent phylogenetic studies (Giussani & al.,
2001), the taxonomic position of some species of Uro-
chloa has been questioned. Among these are U. maxima
(Jacq.) R.D. Webster, now treated as the type species
of the genus Megathyrsus (Simon & Jacobs, 2003), and
U. acuminata (Renvoize) Morrone & Zuloaga, which
appeared as the most basal taxa within the PCK clade
(Giussani & al., 2001; Aliscioni & al., 2003). The latter
species was first described by Renvoize (1984) as Strep-
tostachys acuminata and later transferred to Urochloa
Rupichloa, a new genus segregated from Urochloa (Poaceae) based on
morphological and molecular data
Diego L. Salariato, Liliana M. Giussani, Osvaldo Morrone & Fernando O. Zuloaga
Instituto de Botánica Darwinion, Labardén 200, Casilla de Correo 22, B1642HYD, San Isidro, Buenos
Aires, Argentina. dsalariato@darwin.edu.ar (author for correspondence)
Rupichloa, a new genus of Paniceae restricted to Bahia and Minas Gerais, Brazil, and including two spe-
cies, R. acuminata and R. decidua, is here described on the basis of morphological and molecular characters.
Analyses of DNA sequence data from plastid rpl16 and ndhF indicate that the two included species do not
belong to Urochloa, in which they were previously placed. The affinities of the new genus with other genera
of Paniceae are discussed.
KEYWORDS: Paniceae, Panicoideae, phylogeny, Poaceae, Rupichloa, taxonomy, Urochloa
382
TAXON 58 (2) • May 2009: 381–391Salariato & al. • New genus Rupichloa
based on its PS anatomy, PCK photosynthetic subtype
and rugose upper anthecium (Morrone & Zuloaga, 1991).
Thereafter, Morrone & Zuloaga (1996) described a new
species, Urochloa decidua, and pointed out its similarity
with U. acuminata. Both species have particular features
that distinguish them from the other taxa Urochloa. The
aim of this paper is to evaluate the taxonomic position of
Urochloa acuminata and U. decidua and their relation-
ships with other genera of the tribe Paniceae, based on
molecular and morphological characters.
MATERIALS AND METHODS
Morphological analyses. —
Morphological data
were based on field and herbarium collections, and pub-
lished accounts. Because the ornamentation and the type
of the apex of the upper floret are the most relevant char-
acters in Urochloa, the upper anthecia were removed from
herbarium specimens and studied under scanning electron
microscope. Samples were cleaned with xylene and sub-
jected to sonication for 5 min, then dried at room tempera-
ture for 12 hrs. They were mounted on aluminium stubs,
coated with gold-palladium 40%–60%, and examined
in a Philips XL serie 30 scanning electron microscope,
operating at 10–15 kV, at the Museum of Natural Sciences
“Bernardino Rivadavia”.
Taxon sampling and
DNA
sequencing. —
Two
specimens each of Urochloa acuminata and U. decidua,
together with 17 species of Urochloa, Moorochloa eru-
ciformis (Sm.) Veldkamp, M. malacodes (Mez & K.
Schum.) Veldkamp, Melinis minutiflora P. Beauv, M. re-
pens (Willd.) Zizka, Tricholaena monachne (Trin.) Stapf
& C.E. Hubb., Megathyrsus maximus (Jacq.) B.K. Simon
& S.W.L. Jacobs, and Eriochloa punctata (L.) Desv. ex
Ham., were included as ingroup taxa to represent the
morphological variation in the PCK clade (Appendix 1).
Three species were used as outgroups: Digitaria ciliaris
(Retz.) Koeler, Panicum repens L., and Setaria sulcata
Raddi, which represent the closest relatives from the x = 9
Paniceae clade (Giussani & al., 2001).
Total DNA was isolated from fresh leaves or silica
gel dried leaves using modified CTAB protocols (Murray
& Thompson, 1980; Saghai-Maroof & al., 1984; Doyle
& Doyle, 1987). DNA from herbarium material was ex-
tracted using the DNeasy Plant Mini kit (Qiagen, Hilden,
Germany).
Two chloroplast markers were sequenced: rpl16 region
and ndhF gene. The rpl16 region corresponds to the intron
and partial sequence of the gene encoding the ribosomal
protein L16; it has been widely used in grass phylogenetic
studies (Kelchner & Clark, 1997; Zhang, 2000; Cialdella &
al., 2007). It was amplified in one fragment using primers
F71 of Jordan & al. (1996) and R1661 of Kelchner & Clark
(1997), or partitioned in two fragments using the internal
primers F584 (5′-TTCATTGGGTGGGATGGCGGAA-3′)
and R584 (5′-TTCCGCCATCCCACCCAATGAA-3′).
When amplification failed, primers R270 (Zhang, 2000),
and F80 (5′-C/TTATTGCTTCGTATTGTCG-3′) were
used. The ndhF is a chloroplast gene encoding a subunit
of the NADH dehydrogenase. This gene was amplified in
two fragments using two pairs of primers (5F/972R and
972F/2110R (Olm stead & Sweere, 1994). Additional prim-
ers: 536R, 536F, 1318R, and 1318F), were used when the
others failed.
Polymerase chain reactions (PCRs) were performed
in 25 or 50 ml containing 20–40 ng/ml of DNA template,
and a final concentration of 1× PCR Buffer minus Mg,
5 mM MgCl
2
, 0.025 mM dNTP each, 0.2 mM each primer,
and 1.25–3 units Taq Polymerase, from Invitrogen life
technologies (São Paulo, Brazil). PCR amplifications were
set at the following conditions for most of the species:
rpl16: 1 cycle of 94°C for 4 min, 34 cycles of 94°C for 1
min, 55°C for 1 min, and 72°C for 2 min 30 s, and a final
extension cycle of 72°C for 7 min; ndhF : 1 cycle of 96°C
for 4 min, 39 cycles of 94°C for 1 min 30 s, 55°C for 1
min, and 72°C for 1 min 30 s, and a final extension cycle
of 72°C for 7 min. For the species that failed to amplify,
variations in the annealing temperature (1°C–8°C), and
number of cycles were followed. In addition, a variety
of PCR additives and enhancing agents (bovine serum
albumin, dimethyl sulfoxide, formamide) were used to
increase the yield, specificity and consistency of PCR
reactions. Cleaning of PCR products and automated se-
quencing were performed by Macrogen, Inc. Sequences
were assembled and edited using the program Chromas
Pro version 1.34 (Technelysium Pty, Ltd, Tewantin, Aus-
tralia). All sequences were submitted to GenBank (http://
www.ncbi.nlm.nih.gov); voucher information and Gen-
Bank accession numbers are provided in the Appendix.
Alignment and phylogenetic analyses. —
Align-
ment of sequences of each independent dataset were ini-
tially performed using ClustalX 1.81 (Thompson & al.,
1997) with the default pairwise and multiple alignment
parameters. The alignment was adjusted manually using
the program BioEdit version 7.0.9 (Hall, 1999) and follow-
ing the recommendation of Kelchner (2000) when aligning
non-coding chloroplast DNA sequences.
Gaps of the rpl16 alignment were coded as presence
or absence using the “simple indel coding” method of Sim-
mons & Ochoterena (2000). Ambiguous gaps as derived
from the mononucleotide repeat units (poly-N’s) were not
scored (Kelchner, 2000). The aligned matrices were sub-
mitted to TreeBase (http://www.treebase.org/treebase/;
submission name “Diego Leonel Salariato”, reviewer’s
P.I.N. code 6297).
A combined matrix with both datasets was gener-
ated in order to perform a simultaneous analysis (Nixon
383
Salariato & al. • New genus RupichloaTAXON 58 (2) • May 2009: 381–391
& Carpenter, 1996). Parsimony and Bayesian inference
were used to estimate phylogenies for each separate re-
gion and cpDNA partitions combined. In the parsimony
analyses, both substitution and gap characters were used,
while in the Bayesian inference methods, only the nu-
cleotide substitution data was included in the analyses.
Parsimony trees were generated by the program TNT
version 1.1 (Goloboff & al., 2003) with equal weighted
and non-additive characters. Heuristic searches involved
1,000 replicates, using random addition sequences, tree-
bisection-and-reconnection (TBR) branch swapping, and
holding ten trees per replicate; trees were then submitted
to a new round of TBR branch swapping. Support values
for nodes were estimated by Jackknife analysis (Farris &
al., 1996; JK) with 1,000 pseudoreplicates of 10 random
addition sequences, holding four trees per replicate and us-
ing the default removal probability (0.36). Bremer support
(Bremer 1994; hereafter referred to as BS) was calculated
as the length difference between the optimal trees with
and without a given clade (Baker & al., 1998).
Bayesian analysis was conducted using MrBayes ver-
sion 3.1.2 (Huelsenbeck, 2000; Huelsenbeck & Ronquist,
2001). The evolutionary model was select by the Akaike
Information Criterion (AIC) using Modeltest version
3.7 (Posada & Crandall, 1998). Models for separate and
combined dat a were: K81uf + I + G (rpl16), T VM + I + G
(ndhF) a nd GTR + I + G (rpl16 / ndhF). The models were
set in MrBayes as nst = 6, Rates = invgamma and the pri-
ors on state frequencies, rates and shape of the gamma
distribution were estimated automatically from the data
assuming no prior knowledge about their values (Dirichlet
default option). Two simultaneous analyses, starting from
different random trees and with four simultaneous Markov
Monte Carlo chains, were run for 4 million generations
and sampled every 100 generations. The first 10,000 trees
(25% of total trees) were discarded as burn-in (determined
by plotting the likelihood values to determinate conver-
gence), and a 50% majority rule consensus was calculated
for the remaining trees.
RESULT S
Morphology of the upper anthecium. —
Or-
namentation. – The surface of the upper anthecium of
Urochloa decidua and U. acuminata presents verrucose
papillae associated with the transverse anticlinal cell
walls (Fig. 1A, C). The papillae (20–30 μm diam.) have
2–5(–7) “verrucose” protuberances (3–8 μm diam.). The
distribution of the papillae along the anthecium, together
Fig. 1. Scanning electron micro-
graphs of the upper anthecium
of Rupichloa decidua. A, upper
anthecium, dorsal view; B, apex of
the upper lemma with prickles and
flat microhairs; C, surface of the
upper lemma showing the orna-
mentation with verrucose papillae
(from Zuloaga & al. 9037). Scale: A
= 500 m, B =100 m, C = 80 m.
384
TAXON 58 (2) • May 2009: 381–391Salariato & al. • New genus Rupichloa
with the slightly evident longitudinal periclinal cell walls
(rib-like), outline a particular longitudinal striate pattern.
This epidermical pattern agrees with the Eriochloa type
of ornamentation previously reported by Thompson &
Estes (1986) and Salariato & al. (2008), and here observed
in Eriochloa montevidensis (Fig. 2K), while is absent in
all remaining species of Urochloa (Salariato & al., 2008).
Regarding the species included in this phylogenetic
analyses, Urochloa paucispicata (Morong) Morrone &
Zuloaga, U. plantaginea (Link.) R.D. Webster, U. arrecta
(Hack. ex T. Durand & Schinz) Morrone & Zuloaga and
U. panicoides (Fig. 2C–E, L, respectively) together with
U. deflexa (Schumach.) H. Scholz, U. distachya (L.) T.Q.
Nguyen, U. lata (Schumach.) C.E. Hubb., U. lorentziana
(Mez) Morrone & Zuloaga, U. oblita (Swallen) Morrone
& Zuloaga and U. texana (Buckley) R.D. Webster present
Fig. 2. Scanning electron micrographs of the upper lemma surface. A, Moorochloa eruciformis (Saénz & Morrone 260);
B, Melinis minutiflora (Beck 423); C, Urochloa paucispicata (Morrone & al. 2755); D, Urochloa plantaginea (Morrone & al.
5078); E, Urochloa arrecta (Morrone & al. 4695); F, Urochloa jubata (Bucklock & Shabani s.n.); G, Megathyrsus maximus
(Zuloaga & al. 843); H, Urochloa humidicola (Morrone & Pensiero 369); I, Urochloa brizantha (Zuloaga & Morrone 7348);
J, Urochloa mosambicensis (Sulekic & Cano 3819); K, Eriochloa montevidensis (Burkart & Troncoso 11432); L, Urochloa
panicoides (Morrone & al. 4340). Scale: A = 250 m, B = 20 m, C–L = 100 m.
385
Salariato & al. • New genus RupichloaTAXON 58 (2) • May 2009: 381–391
conspicuous transversal ridges with simple or verrucose
papillae. Urochloa jubata. (Fig. & De Not.) Sosef, U. bo-
vonei (Chiov.) A.M. Torres & C.M. Morton, U. humidicola
(Rendle) Morrone & Zuloaga and U. dictyoneura (Fig.
& De Not.) Veldkamp have less prominent transversal
ridges, and papillae are absent (Fig. 2F, H, respectively).
Urochloa mosambicensis (Hack.) Dandy (Fig. 2J) pres-
ents slight transversal ridges and conspicuous longitudinal
ridges, with verrucose papillae in the transversal anticlinal
cell walls, and numerous small papillae in the remain-
ing walls. Urochloa brizantha (Hochst. ex A. Rich.) R.D.
Webster (Fig. 2I) and U. decumbens (Stapf) R.D. Webster
have a reticulate aspect, by the presence of slight trans-
versal and longitudinal ridges. Megathyrsus maximus is
characterized by its manifest transversal ridges (Fig. 2G),
while the surface of the upper anthecium has not any kind
of ornamentation in Moorochloa, Melinis and Tricholaena
(Fig. 2A, B). For an extensive study of ornamentation in
the genus Urochloa and the existence of additional pat-
terns see Salariato & al. (2008).
Apex. – The upper margins of the lemma in U. acu-
minata and U. decidua are fused forming a crest (0.10–
0.20 mm long) (Fig. 1B). The apical portion of lemma
and palea present prickles and flat macrohairs of 0.15–
0.25 mm long.
Molecular phylogeny. —
rpl16. – A total of 31 se-
quences were obtained for the rpl16 region. A partial se-
quence of rpl16 was obtained only for Urochloa texana.
The longest sequences correspond to Urochloa oblita (in-
group taxa) with 1,160 bp, and Panicum repens (outgroup
taxa) with 1,257 bp. The aligned data consist of 1,366 bp,
of which 43 characters are parsimony informative. Twenty
seven gaps were added while aligning, of which ten were
parsimony informative, whereas seventeen were excluded
because they were uninformative (14) or were placed in
ambiguous hypervariable regions (3).
Parsimony analysis resulted in 54 most parsimonious
trees (length, L = 77 steps; consistency index, CI = 0.78;
retention index, RI = 0.83). The strict consensus tree re-
covered the PCK clade (BS = 4, JK = 89), although the
resolution was low (not shown). In this analysis, Urochloa
decidua–U. acuminata were not recovered as a monophy-
letic group.
ndhF. – The dataset has 31 sequences and 2,137 nucle-
otide positions, of which 123 characters were parsimony
informative. Three gaps were introduced in the alignment:
a gap of 18 bp long at positions 1,518–1,535 pertains to
Digitaria ciliaris (outgroup), and two gaps of 15 bp long at
positions 1,693–1,707 and 1,699–1,713, present in Urochloa
deflexa and U. oblita (ingroup), respectively. Parsimony
analysis generated 18 equally
parsimonious
trees (L = 215
steps, CI = 0.64, RI = 0.81). The strict consensus tree (not
shown) recovered the PCK clade (BS = 8, JK = 98), and
a highly supported basal clade (BS = 4, JK = 98) that
includes U. decidua and U. acuminata. The sister clade
of U. decidua–U. acuminata, although weakly supported
(BS = 1, JK = 51), is composed by two major clades: the
first containing Moorochloa, Melinis and Tricholaena, and
a second clade with Eriochloa and Megathyrsus, and the
rest of the species of Urochloa (not show n).
rpl16 + ndhF. – Topologies of the two regions, ana-
lyzed with parsimony and Bayesian analyses, were highly
congruent and therefore combined in a simultaneous analy-
sis. Parsimony analysis of the combined matrix resulted in
10 optimal trees (L = 295 steps, CI = 0.67, RI = 0.81), and
their topologies were highly congruent with the tree ob-
tained from the Bayesian analysis. Urochloa decidua and
U. acuminata were recovered in a clade (Fig. 3) (BS = 4,
JK = 97, PP = 1.00) that is sister to the remaining PCK
species (BS = 2, JK = 73, PP = 0.98). Moorochloa, Melinis,
and Tricholaena formed a highly supported monophyletic
clade: Group I (BS = 8, JK = 99, PP = 1.00). This clade
was sister to all other Urochloa species, Megathyrsus and
Eriochloa, and this relationship received moderate support
(BS = 2, JK = 78, PP = 0.98). Within this clade, American
species of Urochloa form a monophyletic group: Group II
(BS = 5, JK = 98, PP = 1.00), which is sister to a clade that
includes the Old-World Urochloa species plus Megathyrsus
and Eriochloa (Group III) (BS = 5, JK = 98, PP = 1.00).
DISCUSSION
All genera of Paniceae with C
4
PCK photosynthetic
subtype (Gutiérrez & al. 1976; Hattersley, 1987), here ana-
lyzed, are grouped in a well supported clade, the PCK clade,
in concordance with previous results published by Gómez
& Culham (2000), Duvall & al. (2001); Giussani & al.
(2001) and Aliscioni & al. (2003). The foliar anatomy (PS,
XyMS+) and the photosynthetic subtype are synapomor-
phies of the PCK clade, hence these characters are shared by
Chaetium Nees, Eriochloa, Megathyrsus, Melinis, Mooro-
chloa, Tricholaena and Urochloa. The inclusion of other
genera in the PCK clade, such as Oryzidium C.E. Hubb. &
Schweick., Scutachne Hitchc. & Chase, Thuarea Pers. and
Yvesia A. Camus, should be further corroborated.
Within the PCK clade, Urochloa acuminata and U. de-
cidua are grouped together in a highly supported clade,
sister to that one that included the rest of PCK genera
sampled, and segregated from the remaining species of
Urochloa. The latter species, including the type of the ge-
nus, U. panicoides, are grouped in a clade with Eriochloa
and Megathyrsus. Urochloa decidua and U. acuminata
were originally classified within Urochloa mainly by the
type of apex and the ornamentation of the upper surface
in the upper anthecium (Morrone & Zuloaga, 1991, 1992).
However, and even though the apex is crestate in both
U. decidua and U. acuminata, there are differences in the
386
TAXON 58 (2) • May 2009: 381–391Salariato & al. • New genus Rupichloa
ornamentation and presence of hairs in the upper anthe-
cium of both species. The upper anthecium of Urochloa
acuminata and U. decidua is longitudinally striate, with
verrucose papillae associated with the transverse anticli-
nal cell walls (Fig. 1C). This pattern of ornamentation,
previously cited by Thompson & Estes (1986) is absent in
all species of Urochloa (Salariato & al., 2008) (Fig. 2). A
similar ornamentation pattern, to the one present in U. de-
cidua and U. acuminata, is also found in species of Erio-
chloa (Fig. 2K), but this genus is clearly differentiated by
a globular bead-like callus at the base of the spikelet. Also,
U. acuminata and U. decidua are unique, within Urochloa,
by the presence of flat macrohairs at the apex of the upper
anthecium, a character absent in all the remaining spe-
cies of the genus and also in related genera. Furthermore,
both species share a combination of characters that also
differentiate them from Urochloa, such as inflorescences
pyramidal and lax, with second order branches present,
and stipitate spikelets (Morrone & Zuloaga, 1992, 1996).
Additionally, Morrone & al. (1995) reported a chromo-
some count of n = 13 for U. acuminata and n = 14 for U.
decidua with an x = 7 basic chromosome number while the
Fig. 3. Strict consensus tree
of 10 most parsimonious trees
obtained in a parsimony analy-
sis of the combined dataset
(rpl16 and ndhF). The cladogram
shows the phylogenetic relation-
ships of Rupichloa acuminata
and R. decidua with related taxa.
Bremer support/jackknife sup-
port are given above branches.
Posterior probability for the 50%
majority rule consensus tree ob-
tained in the bayesian analysis
is given below the branches.
387
Salariato & al. • New genus RupichloaTAXON 58 (2) • May 2009: 381–391
most common basic chromosome number for Urochloa is
x = 9 (Gould, 1958; Gould & Soderstrom, 1967; Davidse
& Pohl, 1972; Basappa & al. 1987; Penteado & al., 2000);
only a similar chromosome basic number was also reported
for U. mosambicensis (Spies & al., 1991) and U. reptans
(L.) Stapf (Basappa & al. 1987). Finally, both species are
restricted to “campos rupestres”, which are humid, high
elevation outcrops formed in part from the pre-Cambrian
Brazilian shield, of Bahia and Minas Gerais.
Urochloa acuminata and U. decidua are distinguished
from Moorochloa by having lax and not unilateral inflo-
rescences (vs. racemose and unilateral inflorescences in
Moorochloa), spikelet as a diaspore, disarticulating below
the lower glume (vs. upper anthecium as a diaspore, dis-
articulating below the upper lemma), upper anthecium
longitudinally striate, crestate, and with flat macrohairs
in the apex (vs. upper anthecium smooth, shiny, muticous,
and glabrous; Fig. 2A). Also, the lower glume is 1/2 to 3/4
the length of the spikelet (vs. lower glume reduced, less
or equal to 1/5 the length of the spikelet).
Eriochloa is widely distributed in tropical and sub-
tropical regions of both the New and Old World. This ge-
nus is easily distinguished from U. acuminata and U. de-
cidua by the presence of a cup-like structure at the base
of the spikelet, a structure unique within the Paniceae.
Megathyrsus is an African genus, now introduced
and widespread in tropical and subtropical regions of the
world. This genus includes two species with transversely
rugose anthecia (Fig. 2G) and lower glume reduced, less
or equal to 1/3 the length of the spikelet, upper anthecium
glabrous and the basic chromosome number is x = 8, 9. In
U. acuminata and U. decidua the upper anthecium is, as
previously mentioned, pilose and longitudinally striate,
and the glume is longer.
Melinis is a native genus from Africa with two spe-
cies introduced in tropical regions throughout the world.
Melinis differs from Urochloa acuminata and U. decidua
by having a non stipitate spikelet, with the lower glume
nerveless and not embracing the spikelet, 1/5 or less the
length of the spikelet, the upper glume usually dorsally
awned, the lower lemma with a delicate dorsal awn, and
the upper anthecium cartilagineous, glabrous, smooth and
shiny (Fig. 2B).
Thricholaena is an African genus with only four spe-
cies. The genus has a reduced nerveless or 1-nerved lower
glume, less or equal to 1/5 the length of the spikelet, and
upper anthecium, cartilagineous, smooth and shiny.
According to the phylogenetic studies conducted here,
two different paths are possible for classification purposes:
the first one would render Urochloa paraphyletic, while
the second one segregates Urochloa acuminata and U. de-
cidua, resulting in a strongly monophyletic clade. We
consider the second choice to be the better for the sys-
tematics of grasses, since there are unique morphological
characters, aside from the molecular ones, that allow one
to distinguish both taxa in a new genus; this also more
precisely delimits Urochloa, a genus in need of additional
studies in order to define its real boundaries. It should be
pointed out that between the Urochloa decidua–U. acu-
minata clade and the core of the genus Urochloa, there is
a clade made of Moorochloa, Tricholaena and Melinis, all
genera clearly differentiated from Urochloa s.l. (Clayton &
Renvoize, 1986; Webster, 1987; Morrone & Zuloaga, 1992).
As a consequence, U. acuminata and U. decidua are
here transferred to the new genus Rupichloa. Morpho-
logical characteristics that distinguish Rupichloa from
related taxa are given in Table 1 and a key is provided to
distinguish all genera here discussed.
KEY TO THE GENUS RUPICHLOA
AND RELATED GENERA
1 Upper anthecium smooth, shiny, coriaceous to mem-
branous or hyaline; apex of the upper anthecium mu-
ticous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1’ Upper anthecium longitudinal or transversely rugose,
with simple or verrucose papillae all over its surface,
coriaceous to crustaceous; apex of the upper anthe-
cium mucronate, crestate, or awned . . . . . . . . . . . . 4
2 Upper anthecium early deciduous, without the bracts
of the spikelet, dorsiventrally compressed . . . . . . . 3
2’ Upper anthecium falling with glumes and lower an-
thecium, not early deciduous, laterally compressed .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Melinis
3 Inflorescences lax, pyramidal, with spikelets not se-
cund on long, capilliform pedicels . . . . Tricholaena
3’ Inflorescence racemose, not pyramidal, with spikelets
secund, pedicels short . . . . . . . . . . . . . . Moorochloa
4 Spikelets with a globular bead-like callus at its base
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Eriochloa
4’ Spikelets without a globular bead-like callus at its
base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5 Upper anthecium transversely rugose to slightly or
strongly reticulate, without flat macrohairs at the
apex; inflorescences with racemose branches (except
in Megathyrsus, the latter with lower glume 1/3 to 1/4
the length of the spikelet, 3-nerved, upper glume and
lower lemma 5-nerved, and upper anthecium trans-
versely rugose with manifest simple papillae over the
wrinkles) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5’ Upper anthecium longitudinally rugose, with flat
macrohairs at the apex; inflorescences lax, without
racemose branches . . . . . . . . . . . . . . . . . Rupichloa
6 Inflorescences lax, pyramidal, with third order
branches present . . . . . . . . . . . . . . . . . Megathyrsus
6’ Inflorescences racemose or lax, but only with first
and second order branches . . . . . . . . . . . . Urochloa
388
TAXON 58 (2) • May 2009: 381–391Salariato & al. • New genus Rupichloa
TAXONOMIC TREATMENT
Rupichloa Salariato & Morrone, gen. nov. – Type: Strep-
tostachys acuminata Renvoize in Kew Bull. 39(1):
182. 1984 ≡ Urochloa acuminata (Renvoize) Mor-
rone & Zuloaga in Ann. Missouri Bot. Gard. 78(2):
372. 1991.
Plantae perennes, caespitosae, rhizomatosae. Ligu-
lae membranaceae et ciliatae. Laminae lanceolatae usque
lineares et lanceolatae. Inflorescentiae laxae, pedicelli
ad apicem pilosi, cum pilis flexuosis albidis. Spiculae
ellipsoideae, bi-convexae, ad basim stipitatae. Gluma infe-
rior 1/2–3/4 spiculam aequans, circum basin glumae supe-
rioris amplectens, 5–7 nervia, ad apicem ciliata. Gluma su-
perior anthoecium superum brevior, 7–9 nervia, ad apicem
ciliata. Anthoecium inferum masculum. Lemma glumae
superiori simile, spiculae aequans, 5–7 nervia. Anthoecium
superum ellipsoideum, plano-convexum, durum, cum pa-
pillis verrucosis et macropilis complanatus versus apex.
Rhizomatous or caespitose perennial, rooting at the
lower nodes. Ligules membranous–ciliate. Blades lanceo-
late to linear lanceolate. Inflorescences lax, radiate, the
Table 1. Comparison of Rupichloa with related taxa.
Character Rupichloa Urochloa Eriochloa Megathyrsus Moorochloa Melinis
Trichloaena
Cycle of life Perennial Annual or
perennial
Annual or
perennial
Perennial Annual Perennial Annual or
perennial
Inflorescence
branches
Radiate Bilateral or
radiate
Bilateral or
radiate
Radiate Unilateral Radiate Radiate
Spikelet
articulation
Below the
lower glume
Below the
lower glume
Below the
lower glume
Below the
lower glume
Below the up-
per anthecium
Below the up-
per anthecium
Below the
lower glume
Spikelet base Stipitate Stipitate or
non stipitate
Cup-like, non
stipitate
Non stipitate Non stipitate Non stipitate Non stipi-
tate
Spikelet Dorsally
compressed
Dorsally
compressed
Dorsally
compressed
Dorsally
compressed
Dorsally
compressed
Laterally
compressed
Laterally
compressed
Lower glume
length
1/2–3/4 1/6 to 1/1 – 1/3–1/4 ≤ 1/5 ≤ 1/5 ≤ 1/5
Lower glume
nervation
5–7-nerved (0–1)–3–5–7–
9–11-nerved
– (1–)3-nerved 1-nerved Nerveless 0–1-nerved
Lower glume
embracing the
spikelet
Yes Variable – Yes No No No
Upper anthe-
cium apex
Crestate with
long flattened
macrohairs
Mucronate,
crestate or
aristulate;
macrohairs
cylindric
when present
Mucronate
or aristulate;
macrohairs
cylindric
when present
Mucronate
and glabrous
Muticous
and glabrous
Muticous
and glabrous
Muticus
and gla-
brous
Upper anthe-
cium surface
Longitudi-
nally striate
with verrucose
papillae
Transversely
rugose,
reticulate or
longitudinally
striate with
simple or/
and verrucose
papillae
Longitudi-
nally striate
with verrucose
papillae
Transversely
rugose
Smooth, with-
out ornamen-
tation
Smooth, with-
out ornamen-
tation
Smooth,
without
ornamenta-
tion
Upper anthecium
consistency
Crustaceous Crustaceous Crustaceous Crustaceous Cartilaginous Cartilaginous
to herbaceus
Cartilagi-
nous
Basic chromo-
some number
7 9 (7–8) 9 8–9 9 9 9
Distribution Bahia and
Minas Gerais,
Brazil
Tropics and
subtropics of
the World
Tropics and
subtropics of
the World
Africa,
introduced in
tropics and
subtropics of
the World
Africa
and Asia,
introduced in
tropics and
subtropics of
the World
South Africa,
Madagacar,
introduced in
tropics and
subtropics of
the World
African,
Madagas-
car, Medi-
terranean
389
Salariato & al. • New genus RupichloaTAXON 58 (2) • May 2009: 381–391
pedicels pilose toward the apex with flexuous, whitish
hairs. Spikelets ellipsoid, biconvex, stipitate at the base.
Lower glume 1/2–3/4 the length of the spikelet, embracing
the upper glume at its base, 5–7-nerved, ciliolate at the apex.
Upper glume not covering the apex of the upper anthecium,
7–9-nerved, ciliolate at the apex. Lower lemma glumiform,
as long as the spikelet, 5–7-nerved. Lower floret male, sta-
mens 3. Upper anthecium ellipsoid, plano-convex, indurate,
with verrucose papillae and flattened macrohairs toward
the apex. Foliar anatomy: C4 Kranz subtype PS ( XyMS+).
Biochemical photosynthetic pathway: subtype PEP-ck.
Etymology. – The name of the new genus refers to the
environment, “campos rupestres”, where the two constitu-
ant species occur.
Distribution. – The genus is endemic to the states of
Bahia and Minas Gerais, Brazil (Fig. 4).
Key to species
1 Culms with extravaginal innovations, nodes, sheaths
and blades pubescent. Blades lanceolate 20–40 cm
long. Spikelets (5.6–)6–6.8 mm long . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . Rupichloa acuminata
1’ Culms with intravaginal innovations, nodes, sheaths
and blades glabrous. Blades linear-lanceolate 7–10
(–12) cm long. Spikelets 4.4–4.8 long. . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . Rupichloa decidua
Rupichloa acuminata (Renvoize) Salariato & Morrone,
comb. nov. ≡ Streptostachys acuminata Renvoize in
Kew Bull. (39)1: 182. 1984 ≡ Urochloa acuminata
(Renvoize) Morrone & Zuloaga in Ann. Missouri Bot.
Gard. 78(2): 372. 1991 – Type: Brazil. Bahia: estrada
de Lençois, BR-242, 5 km ao N de Lençois, A.M. da
Carvalho, G.P. Lewis & J.L. Hage 1007 bis (Holo-
type: CEPEC! photo SI!; isotypes: K!, SI! fragm. ex
CEPEC).
= Brachiaria tatianae Zuloaga & Soderstrom in Smith-
sonian Contr. Bot. 59: 7, figs. 3–4. 1985 [Panicum
megastachyum Nees, in Martius Fl. Bras. Enum. Pl.
2(1): 154. 1829. Not Panicum megastachyum Nees
ex Trin., Gram. Panic: 205. 1826]. – Lectotype (des-
ignated [as holotype] by Zuloaga & Soderstrom in
Smithsonian Contr. Bot. 59: 7. 1985): Brazil. Minas
Gerais: Habitat in marginibus sylvarum Districtus
Adamantum ad Tejuco etc. provinciae Minarum gen-
eralium, Martius s.n. (lectotype M!; isolectotype: US-
974752! fragm. & photo ex M).
Phenology. – Flowering between January and July.
Chromosome number. – n = 13 (Morrone & al., 1995,
under Urochloa acuminata).
Distribution and habitat. – Rupichloa acuminata is
found in Brazil, in the states of Bahia and Minas Gerais,
growing in margins of woods over sandy or limestone
soils.
Rupichloa decidua (Morrone & Zuloaga) Salariato & Mor-
rone, comb. nov. ≡ Urochloa decidua Morrone & Zu-
loaga in Novon 6(3): 315, f. 3, 4, 5A–C. 1996 – Type:
Brazil. Bahia: Palmeiras, Pai Inácio, BR-242, 12°27′ S
41°28′ W, 1,000–1,060 m, 19 Nov 1983, erva em toucei-
ras de 1 m de altura, frequente em campo rupestre, L.R.
Noblick & A. Pinto 2792 (holotype: CEPEC-49111!;
isotypes: CEPEC-35263!, MO-3304058! photo SI!, SI!).
Phenology. – Flowering between January and No-
vember.
Chromosome number. – n = ca. 14 (Morrone & al.,
1995, under Urochloa sp.).
Distribution and habitat. – R. decidua is restricted to
Bahia, Brazil, growing in “campos rupestres”, between
1,000 and 1,070 m elevation, on outcropping rocks.
For additional specimens examined see Appendix 2.
ACKNOWLEDGEMENTS
Funding of this research was provided by ANPCyT (Agen-
cia Nacional de Promoción Científica y Técnica, Argentina),
grants 11739, 13374 and 32640 and CONICET, grant 5453. Col-
lections were supported by the National Geographic Society
through grant 7792-05. We thank Juliana de Castro Souza for
assistance and help during the field trip to Brazil. We are also
grateful to Silvana Sede and Raúl Pozner for their assistance
with the Latin description and to the anonymous reviewers
whose comments greatly strengthened the manuscript.
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Appendix 1. Voucher information and GenBank accession numbers of the sampled taxa. Sequences generated in this study are marked
with *. Species, geographic location, voucher information, and GenBank accession number (rpl16, ndhF).
Digitaria ciliaris (Retz). Koeler, Argentina, Misiones: Zuloaga & Morrone 6753 (SI), FJ486541*, AY029630; Eriochloa punctata (L.) Desv. ex Ham.,
Argentina, Misiones: Zuloaga & Morrone 6838 (SI), FJ486555*, FJ486528*; Megathyrsus maximus (Jacq.) B.K. Simons & S.W.L. Jacobs, Argentina,
Salta: Morrone & al. 3343 (SI), FJ486550*, AY029649; Melinis minutiflora P.Beauv., Argentina, Misiones: sin colector s.n. (SI), FJ486551*, FJ486524*;
Melinis repens (Willd.) Zizka, Argentina, Misiones: Zuloaga & Morrone 6764 (SI), FJ486559*, FJ486532*; Moroochloa eruciformis (Sm.) Veldkamp,
Argenti na, Entre Ríos: Zuloaga & Morrone 7045 (SI), FJ486552*, FJ486525*; Moorochloa malacodes (Mez. & K.Schum.) Veldkamp, South Africa: O.H.
Vol k 510 (US), FJ486564*, FJ486536*; Panicum re pens L., Uruguay, Colonia: Morrone 5229 , EU920053*, AY029651; Rupichloa acuminata (Renvoize)
Salariato & Morrone, (a) Brazil, Bahía: Zuloaga s.n. (SI), FJ486560*, AY029692; (b) Brazil, Bahía: Zuloaga & al. 9029 (SI); FJ486568*, FJ486540*;
Rupichloa decidua (Morrone & Zuloaga) Salariato & Morrone, (a) Brazil, Bahía: Zuloaga & Morrone 6942 (SI), FJ486553*, FJ486526*; (b) Brazil,
Bahía: Mun. Palmeiras, Morro de Pai Inacio; Zuloaga & al. 9037 (SI), FJ486567*, FJ486539*; Setaria sulcata Raddi, Argentina, Salta: Morrone et al.
4548 (SI), EU920054*, AF499147; Tricholaena monachne ( Trin.) Stapf & C.E.Hubb., Pretoria , Traansval : Gog frey & Meeuse SH-1596 (US), FJ486563*,
FJ486535*; Urochloa arrecta (Hack. ex T. Durand & Schinz) Morrone & Zuloaga, Mexico, Oaxaca: Zuloaga 7413 & al. (SI), FJ486544*, FJ486517*;
Urochloa bovonei (Chiov.) A.M.Torres & C.M.Morton, Zimbabwe, Goromonzi: CIAT 16847 (SI), FJ486557*, FJ486530*; Urochloa brizantha (Hochst.
ex A.Rich.) R.D.Webster, Ecuador, Napo : Quintana & Laeggard 305 (SI), FJ486546*, FJ486520*; Urochloa decumbens (Stapf) R.D.Webster, Argen-
tina, Corrientes: Zuloaga & Morrone 7119 (SI), FJ486556*, FJ486529*; Urochloa deflexa (Schumach.) H.Scholz, Zimbabwe, Kariba: CIAT 16856 (SI),
FJ486562*, FJ486534*; Urochloa distachya (L.) T.Q.Nguyen, Mexico, Oaxaca: Zuloaga & al. 7415 (SI), FJ486545*, FJ486518*; Urochloa dictyoneura
(Fig. & De Not.) Veldkamp, Paraguay, Amambay: Zuloaga & Morrone 7288 (SI), FJ486549*, FJ486523*; Urochloa humidicola (Rendle) Morrone &
Zuloaga, Venezuela, Portuguesa: Morrone & al. 4696 (SI), FJ486547*, FJ486521*; Urochloa jubata (Fig. & De Not.) Sosef, Kenya, CIAT 16516 (SI),
FJ486558*, FJ486531*; Urochloa lata (Schumach.) C.E. Hubb., CIAT 26886 (SI), FJ486561*, FJ486533*; Urochloa lorentziana (Mez) Morrone & Zuloaga,
Argentina, Salta: Cialdella & al. 562 (SI), FJ486548*, FJ486522*; Urochloa mosambicensis (Hack.) Dandy, Argentina, Sgo. Del Estero: Sulekic & al.
3819 (SI), FJ4865 42*, FJ486516*; Urochloa oblita (Swallen) Morrone & Zuloaga , Ecuador, Azu ay: Holm-Nielsen & al. 4926 (MO), FJ486566*, FJ486538*;
Urochloa panicoides P.Beauv., Mexico, Mexico: Zuloaga & al. 7358 (SI), EU920055*, FJ486519*; Urochloa paucispicata (Morong.) Morrone & Zuloaga ,
Argentina, Jujuy: Morrone & al. 3675 (SI), FJ486554*, FJ486527*; Urochloa plantaginea (Link.) R.D.Webster, Argentina: Sulekic s.n. (SI), FJ486543*,
AY029693; Urochloa texana (Buckley) R.D.Webster, U.S.A., Mississippi: Bryson & Morris 6906 (MO), FJ486565*, FJ486537*.
Appendix 2. Representative specimens examined: COUNTRY, STATE, location, collector, voucher number and herbarium acronym.
Rupichloa acuminata. BRAZIL. BAHIA: Lençois, Rodovia de Lençois, 4 km de Remanso, Zuloaga & al. 4766 (MO, SI); Mun. Rio de Contas, subida
a Pico das Almas Zuloaga & al. 4843 (MO, SI); Entrada a Lençois por la BR-242, Km. 8, en salida de tierra; Zuloaga & al. 9029 (MO, SI); Zuloaga s.n.
(SI). Rupichloa decidua. BRAZIL. BAHIA: Mun. Palmeiras, Pai Inácio, Morro do Pai Inácio, Zuloaga & al. 4787 (IBGE, MO, SI, US), Zuloaga &
Morrone 6942 (SI); Morro de Pai Inácio, entre Lençois y Palmeiras, Zuloaga & al. 9037 (ESA, MO, SI).
