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Haseltonia 17: 8286. 2012 82
With approximately 420 species and a distri-bution that includes
many regions of both the Oldand New World,Sedum L. ( ribe Sedeae,
subfamily
Sempervivoideae) is the largest and most widespreadgenus of
Crassulaceae (Tiede and Eggli 2007). Ge-neric delimitation and
relationships within the taxonhave been largely problematic, and at
present it iswidely acknowledged thatSedum, as
traditionallyrecognized, is highly paraphyletic, and nested
withinit are many genera such as Altamiranoa ,
Echeveria,Graptopetalum, Villadia, etc. (van Ham and t Hart1998;
Mort et al. 2001; Carrillo-Reyes et al. 2008,2009; Mort et al.
2010). Te lack of phylogeneticunderstanding for most of the
species, and poor reso-lution of hypothetical clades, has lead to
the accep-tance inherently pro tem of t Harts (1995)proposal to
maintainSedum as a paraphyletic as-semblage instead of proposing
drastic changes in itsclassication, as discussed by Tiede &
Eggli (2007).However, it is obvious that numerous
taxonomicmodications are needed in order to obtain a clas-sication
that is based on the recognition of mono-phyletic groups. Tere are
two basic problems associ-ated with the failure to get a better
classication ofthe Crassulaceae: (1) Te general lack of
resolutionof DNA-based phylogenies and (2) the lack of
mor-phological diagnostic characters for many of thosegroups
identied as monophyletic (Tiede & Eggli2008; Carrillo-Reyes et
al. 2009; Mort et al. 2010).During the course of a oristic
inventory in El
riunfo Biosphere Reserve (Martnez-Melndez etal. 2008), and the
examination of herbarium ma-terial for phylogenetic analyses
(Carrillo-Reyes etal., 2009), we encountered a taxon of the
Crassu-laceae with white tubular owers and cymose ino-
rescences that has been collected in many localitiesfrom
southern Mexico and adjacent Guatemala. It ismorphologically
similar toSedum goldmanii (Rose)
Moran, with which it is often confused. After com-paring the
morphological characteristics with thoseof other species
ofSedumwith tubular corollas (for-merly placed in Altamiranoa
Rose), and with thoseof the closely relatedVilladia Rose, we
conclude thatthe material concerned is an undescribed species,
asfollows:
Sedum mesoamericanum P. Carrillo & Prez-Farrera SP . NOV
.Planta succulenta glabra. Caulibus erectis vel postratisad 2530 cm
longi rubelli. Foliis sessilia, cocleatimdispositis. Foliorum
margines papilatae, primum visumdenticulatae. Flores in cymis
dispositi, corolla 78 mmlonga, alba, tubum basalem 2.53.0 mm longum
fe-rens.
Type : MEXICO. Oaxaca, Mun. San Mateo RoHondo, ca. 0.5 km al NO
de San Jos del Pacco,16 10 23N, 96 30 10 W, 2520 m, 20 Jul
2009(pressed on 2 Dec 2009).P. Carrillo-Reyes & D. Ca-brera-
oledo 5562 (holotype IEB, isotypes HEM,MEXU, MO) (Figs. 1, 2).
Paratypes: MEXICO.Oaxaca : Cerro de San Fe-lipe, 2400 m, 6 Dec
1962,R. Moran 10135 (SD);Mun. Oaxaca, Cerro Microondas Corral de
Piedra,al N de la ciudad de Oaxaca, 3200 m, 3 Nov 1994,
M. Chzaro& B.L. Mostul 7485 (IBUG); Ibd. M.Chzaro & B.L.
Mostul 7495 (IBUG); Mun. VillaDaz Ordaz, 2 km al E de Benito Jurez,
2960 m, 16Nov 1984,R. Lpez et al., 253(IEB, ENCB, MEXU,
Abstract: Sedum mesoamericanum is described as a new species,
and illustrated based on collections from the Mexi-can states of
Oaxaca and Chiapas, as well as Guatemala. It is distinguished by
the possession of subclasping lewith denticulate margins. Previous
phylogenetic analyses placed this species in a clade ofVilladia
species from theSierra Madre del Sur, with which it is compared.
Additionally, the morphological similarities ofSedum
mesoameri-canum toS. goldmaniiandS. porphyranthes are
discussed.
Keywords: Acre clade, Altamiranoa , Mesoamerica, Sedeae,
Sempervivoideae,Sedum, Villadia.
SEDUM MESOAMERICANUM CRASSULACEAE , A NEW SPECIES FROMMEXICO AND
GUATEMALA
PABLO CARRILLO REYESCentro de Investigaciones en Ecosistemas,
Universidad Nacional Autnoma de Mxic
Antigua carretera a Ptzcuaro 8701. Col. San Jos de la Huerta,
58190 Morelia,Michoacn, Mexico;
email: [email protected] A. PREZ-FARRERA
Escuela de Biologa, Universidad de Ciencias y Artes de
Chiapas,Libramiento Norte Poniente 1150, CP 29039,
uxtla Gutirrez,Chiapas, Mxico
.
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HASEL ONIA VOL. 17. 2012 83
OAX); Mun. Mixistln de la Reforma, Mixistln,2200 m, 27 Jan 1986,
J. Rivera Reyes& G.J. Martin71 (MEXU); Mixistln, 15 Sep 1992,
J. Martnez-Nicolasa 15 (MEXU); Mun. Santiago Zacatepec, 2.6km al SE
de la desviacin a otontepec sobre la car-retera Mitla-Zacatepec, 17
08 23 N, 96 01 58
W, 2576 m, 13 Jun 2008,E. Ruiz-Snchez& V. Sosa 215 (IEB);
Mun. otontepec Villa de Morelos, o-tontepec, 1900 m, 2 Nov 1986, J.
Rivera Reyes 489 (MEXU, MO); Mun. San Andrs Paxtln, 2 milessouth of
Portillo San Andrs, 2500 m, 23 Nov 1959,R. Moran & M. Kimnach
7757 (SD); Mun. San
Juan Mixtepec, Ladera del Cerro Quieshovee, 3500m, 4 Feb 1992,S.
Salas 285(OAX).Chiapas : Mun.La Concordia, Cima del Cerro Ceb, 2236
m, 16Dec 2004, J. Martnez-Melndez 705 (HEM, IEB,MEXU); Mun.
Mototzintla de Mendoza, Cerro Mo-
zotal, 3000 m, 30 Dec 1972,D.E. Breedlove& R.F.Torne 31167
(ENCB, MEXU, MO); Mun. Mo-totzintla de Mendoza, Cerro Mozotal, 3000
m, 22Nov 1976,D.E. Breedlove 41728 (MEXU, MO);Mun. Unin Jurez,
Volcn acan, above alquin,3500 m, 11 Nov 1972,D.E. Breedlove 29393
(ENCB, MEXU, MO); GUA EMALA.San Marcos,Volcn acan, 3500 m, 5 Feb
1987,E. Martnez etal. 19525 (MEXU); Entre aldea onin y Plan de
Ar-dillas, 2700-3200 m, 8 May 1987,E . Martnez et al.
20827 (MEXU).Succulent glabrous perennial herb, branchingfrom
the base and less often from the old stems.Stems erect or
prostrate, to 25 (30) cm long, 0.5cm diameter at the base, reddish,
glossy, with paleyellow leaf scars to ca. 0.4 mm wide. Leaves
dense-ly arranged, the sterile shoots (0.5) 13 (3.5) cm
Figure 1. Sedum mesoamericanum from the type collection
(Carrillo-Reyes & Cabrera- oledo 5562) near San Jos
Pacco,Oaxaca. A. Habit; B. Detail of the rosette showing the
papillose margin of the leaves; C. Detail of the stem showing the
cling base of the leaves; D. Flower. Photos: P. Carrillo-Reyes.
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84 CARRILLO REYES & PREZ FARRERA.SEDUM MESOAMERICANUM
long, to 1 cm wide, with (25) 4090 leaves each.Leaves succulent,
ascending, imbricate, the upperone slightly incurved, oblong,
5.58.0 mm long,1.52.5 mm wide, green or becoming reddish at
age,
obtuse at the apex, margins with prominent papillae,giving it a
denticulate appearance, the base with twolateral clasping
projections ca. 0.4 mm long. Inores-cence cymose to 20 cm high,
including the peduncle,the cymes 2.03.5 cm high, 2.04.0 cm wide,
with510 (15) owers. Bracts similar in shape and sizeto the leaves.
Pedicels to 2.5 mm long or usuallyabsent. Sepals ascending,
unequal, free, oblong-lan-ceolate 4.56.0 mm long, 0.73.0 mm wide,
acuteor obtuse and sometimes purple-reddish through-out or just at
the apex, the base with a small spurto 0.5 mm long. Corolla 78 mm
long, white, thepetals 5, united at the base into a tube 2.53.0
mmlong, lobes spreading, triangular 4.05.5 mm long,(2.2) 2.53.5 mm
wide, acute at the apex, canalicu-late above, keeled below. Stamens
10; the episepalous4.55.0 mm long, the epipetalous 5.06.5 mm long.
Anthers orbicular to obovate, 0.81.4 mm long, ca.0.71.0 mm wide.
Nectar scale slightly cuneate, ca.1 mm long and wide. Gynoecium
with 5 carpels,5.56.0 mm long. Follicles erect at anthesis,
stellatespreading and widely opened along the suture at ma-turity,
67 mm long, ca. 1.3 mm wide, color brown.Seeds ca. 1 mm long,
reddish-brown, with reticulatesurface.
Phenology : Flowering from October to January.Fruiting from
December to May.
Common name : Te only common name recordedby collectors is Kix
zooy (Mixe language, Martnez-Nicolasa 15 ).
Chromosome number : n = 20 (Uhl & Moran, 1999,cited asSedum
sp.)
Distribution . Sedum mesoamericanum is endem-
ic to the Sierra Madre del Sur and Sierra Madre deChiapas (known
as the Cordillera Central in Guate-mala) (Fig. 2). Following the
characterization of veg-etation presented by Breedlove (1981), it
occurs onigneous or metamorphic outcrops in pine-oak andevergreen
cloud forests, as well as in evergreen cloudscrubs (Fig. 3), at
elevations from 2200 to 3500 m.Te presence of this species in El
riunfo BiosphereReserve (Martnez-Melndez et al. 2008, cited
asVil-ladia sp.) promotes its conservation.
DiscussionPhylogenetic analyses in the Acre clade of Crassu-
laceae placed the new species in a clade with somespecies
ofVilladia from the Sierra Madre del Sur(Carrillo-Reyes et al.
2009;Sedum mesoamericanum was included asSedum sp.). However, in
their anal-ysis the genusVilladia was also demonstrated to
beparaphyletic, and relationships are not yet satisfac-torily
resolved.Villadia , together with Altamiranoa ,were segregated
fromSedum on the basis of hav-ing owers with united petals;Villadia
was furthercharacterized by possessing racemose or
spiciformthyrses, these in contrast to the broad cymose
ino-rescences that occur in Altamiranoa and many speciesof Sedum
(Britton and Rose 1903). Both the fusionof the corolla and the type
of inorescence havebeen used as diagnostic features in many groups
ofthe Crassulaceae; however, in light of phylogeneticstudies these
characters have proven to be unreliable.Indeed, the status and
relationships betweenSedum,
Figure 2. Geographic distribution ofSedum mesoamericanum ( ), S.
porphyranthes ( ), andS. goldmanii ( ) .
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HASEL ONIA VOL. 17. 2012 85
Altamiranoa and Villadia , have long been controver-sial
(Frderstrm 1935; Baehni 1937; Walther 1938;Tiede; 2003). Moran
(1996), however, maintainedVilladia , but included Altamiranoa in
Sedum, arguingthat Altamiranoa and Sedum intergrade
morphologi-cally and that the phylogeny of t Hart (1995) sug-gests
a close relationship of the only Altamiranoa species included in
this analysis and some MexicanSedum species. However it should be
noted that tHarts sampling was very limited and no species
ofVilladia (sensu stricto) was included.
Until an analysis aimed to clarify the delimitationof Villadia
is published, we have decided to followprovisionally Morans (1996)
proposal and assign thepresent novelty toSedum for the following
reasons:(1) S. mesoamericanumpossesses cymose inorescenc-es, a
feature that is otherwise unknown inVilladia but is common inSedum.
(2) Te group ofVilladia species with whichS . mesoamericanum is
associatedis in itself not closely related to the group ofVilla-dia
that containsV. misera (Lindl.) R. . Clausen, thetype of the genus
(see Carrillo-Reyes et al. 2009).Sedum mesoamericanum is
distinguished by aunique combination of characters including
cymoseinorescenses, reddish stems, white owers, andleaves with
papillose margins. Closely related spe-cies suggested by the only
phylogenetic analysis inwhich this taxon has been included
(Carrillo-Reyes
et al. 2009), areVilladia diffusaRose, V. imbricataRose,V.
nelsoniiRose, and V. recurvaMoran, Kimn-ach & Uhl.(combinations
inSedum unavailable). Allof these species occur in southern Mexico,
mostly inthe Sierra Madre del Sur, and share vegetative
char-acters, as well as white owers with petals fused intoa tube at
the base. However, they are easily distin-guished fromS.
mesoamericanum by their spicate orthyrsoid inorescences. Although
phylogenetic anal-ysis did not suggest a close relationship
withSedum
goldmanii (Rose) Moran (= Altamiranoa mexicana (Schltdl.) Rose),
these two are morphologically alikeand share a similar habit,
reddish stems, cymose in-orescences and white owers with the petals
unitedat the base. In fact, some collections of the new spe-cies
have been found in herbaria determined asS.
goldmanii(or as one of its many synonyms). Te newtaxon can be
distinguished fromS. goldmanii by hav-ing leaves with papillose
margins, and clasping lateralprojections at the base (Figs. 1B, 1C)
(vs. leaves withentire margins and decurrent projections at the
base).In addition, the follicles of the new species are veryoften
stellate spreading and widely opened along thesuture at fruiting
time (vs. divergent and slightlyopened), and the foliage is never
glaucous (vs. foli-age glaucous in youngS. goldmanii ). So far as
isknown,Sedum goldmanii has a haploid chromosomenumber of 25, while
that ofS. mesoamericanum has
Figure 3. Habitat in evergreen cloud scrub withWerauhia
gladioliora (H. Wendl.) J.R. Grant, granitic stonecrop at El
riunfoBiosphere Reserve. Photo: J. Martnez-Melndez.
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86 CARRILLO REYES & PREZ FARRERA.SEDUM MESOAMERICANUM
been reported as 20 (Uhl & Moran, 1999). Further-more, both
taxa are geographically separated:S. gold-manii is distributed
along the rans-Mexican Volca-nic Belt (Clausen 1959; Prez-Calix
2008), whereasS. mesoamericanum occurs in the Sierra Madre delSur
and Sierra Madre de Chiapas (Fig. 2). Te near-est collection points
between them are separated byapproximately 200 km. Te citation of
Altamiranoamexicana (Schltdl.) Rose for the state of Oaxaca
byPrez-Calix (2008), is very likely based onS. meso-americanum.
Sedum porphyranthes J. Reyes, Brachet& O. Gonzlez, from the
Sierra Norte de Oaxaca,vegetatively resembles bothS. mesoamericanum
andS. goldmanii ; however, it is clearly separated by itspurple
owers (Reyes et al. 2008).
Acknowledgements
We thank Victor W. Steinmann and Urs Eggli fortheir valuable
comments on the manuscript. AarnRodrguez, Francisco Lorea, Victoria
Sosa, and JerzyRzedowski also gave us comments on a previous
ver-sion; the latter also kindly helped us with the Latindiagnosis.
We are indebted to Billie L. urner, whoencouraged us to describe
the new species, whichwas previously and independently identied by
himas a novelty. Alejandro Abundis-Santamara, DnaeCabrera- oledo,
Jorge Martnez-Melndez, and Fer-nando Z. Vaz-de-Mello kindly helped
us during theeldwork. We thank the curators of the herbaria
ENCB, HEM, IBUG, IEB, MEXU, MO, OAX, SDand XAL, for permitting
us to consult their collec-tions. PCR acknowledges support from
CONACy(179254). MAPF acknowledges Christopher David-son and Sharon
Christoph for nancial support ofthe project Inventario Florstico de
la Reserva de laBisfera El riunfo, Chiapas, Mxico.
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