Swartzia mexicana (Fabaceae, Swartzieae), a New Species from
Oaxaca, Mexico
Mario Sousa S.
Departalnento de Botanica, Institut dte Biologia, Universidad Nacional Aut6noma de
Mexico. Apdo. Postal 70-367, 04510 Mexico, D.F. Mexico. sousa@servidor.unam.mx
Rosaura Grether
Departamnento de Biologia. Divisi6n de Ciencias Biol6gicas y de la Salud, Universidad
Aut6noma Metropolitana-lztapalapa, Apdo. Postal 55-535, 09340 Mexico, D.F. Mexico.
rogg@xanum.uam.mx
A STI \t :T. Swartzia mexicana, a new legume
species from the State of Oaxaca. Mexico,. is de-
scribed and illustrated. It is presently known only
from the districts of Ixtlhn and Tuxtepec. The new
species belongs to section Suartzin. subsection
Swartzia, and is assigned to series Tbunatene. With-
in that series, it is closely related to S. sumorum
by the leaflets not prominently reticulate, the style
uncinate. and the stigma truncate, as well as by the
legume elliptic in shape. A key to distinguish the
new species fromn S. sumorum and S. wuirdackii is
provided.
RIE:S Ml:N. Se describe e ilustra Swatrtzi mexi-
canat. uiia especie de leguminosas nueva para la
ciencia. del estado de Oaxaca. Mexico. Hasta ahora
se conoee sl6o de los distritos de lxtlan y Tuxtepec.
La especie nueva corresponde a la sect. Swartzia,
subsect. Swartzia v se incluve en la serie Touna-
teae. Dentro de esa serie, se relaciona estrecha-
mente con S. sumorum por los foliolos sin nervacion
reticulata prominente, el estilo uncitnado y el es-
tigma truncado, asi como por la legulmbre de forma
elfptica. Se presenta una clave para distinguir a la
especie nueva de S. sumorum v de S. wurdackii.
Key words: Fabaceae, Mesoamerica. Mexico,
Oaxaca. series Tounateae, Swartzia.
Swarlzia is a neotropical genus of about 155 spe-
cies. most of them found in South America. Only
two species are known to occur elsewhere, in trop-
ical Africa. according to Cowan (1981). Species of
the genus vary from small trees or shrubs (1.5-)3-
18 m high. such as S. in/renusnta arneby and S.
alato-sericea Barneby, to large trees up to 35-40 mi
high, such as S. gigantea R. S. Cowan and S. po-
lyphylt I)DC. Some slender trees, such as S. pal-
ustris Barneby. have occasionally sarmentose
branches. but the only species with a clambering
habit is S. froesii K. S. Cowan. The genus is a com-
mon component of lowland forests. especially along
rivers and in swampy forests. but in the Andean
area it can be found from sea level up to 2100 m
elevation, as S. amplifodia Harms var. colombiana
R. S. Cowan (Cowan, 1968: rarneby. 1991. 1996).
In Mexico. Swartzia is found from Nayarit to
Chiapas along the Pacific slope, and it extends
eastward to Veracruz, Tabasco. and the Yucaadn
Peninsula. Swartzia habitats include tropical rain-
forests, semideciduous and deciduous forests, as
well as cloud forests. Besides Swartzia nexiucna.
three other species of the genus are known to occur
in Mexico: S. cubensis (Britton & V ilson) P. (.
Standlev (Chiapas. Tabasco. Campeche. Yucatan.
and Quintana Roo). S. myrtifolia J. E. Smith (\e-
racruz, Oaxaca. Chiapas. Tabasco). and S. simplex
(Swartz) Sprengel (Nayarit. Jalisco. Michoacan.
Guerrero, Veracruz, Oaxaca. and Chiapas). In the
State of Oaxaca, the latter two are allopatric to the
new species; they are found along the Pacific slope
in the districts of Jamiltepec, Pochutla, and Juchi-
tan, growing mainly in lowland forests. 200 to 78(
m.s.m., although S. simplex has been collected up
to 1660 m elevation in the District of Pochutla.
Swurtzia cubensis also belongs to series i7ouna-
tae; it is distinguished from S. mexicana by its mar-
ginate to winged leaf rachis, shorter inflorescences.
and yellow to orange, long stipitate, subglobose or
ovate, rostrate fruits. Swarizia myrtifolia and S. sim-
plex are members of series Possir. T'heyI are dis-
tinguished from the new species by their petalif-
erous flowers, by the narrowly margined or winged
petiole and leaf rachis, and by the subglobose or
oblong fruits, very similar to those of S. cubensis.
Mesoamerica is a more diverse region: alout 9
to 12 species of Suartzia have been found fromn
northern Oaxaea and the Isthmus of Tehuantepec.
NoVON 12: 115-119. 2002.


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Fiigunr 1. 'icnarlzii mr.\icanal M. Sousa & I1. (;Grther. -A. Branch with leaves andl infloiresc'nes. -B. (lose-up of
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116
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Volume 12, Number 1
2002
117
Sousa & Grether
Swartzia mexicana from Mexico
and in Tabasco. Chiapas, and the Yucattin Penin-
sula in Mexico. to Panama. The new species is de-
scribed from the northwestern phytogeographic lim-
it of the Mesoamerican region, as part of the
ongoing Flora Mesoamericana project coordinated
hb the Missouri Botanical (arden. the Instituto de
Biologia. Universitlad Nacional Autonoma de Mex-
ico, and The Natural History Museum (London)
(Davidse et al., 1994).
Swartzia mexicana M. Sousa & R. (rether. sp.
nov. TYPE: Mexico. Oaxaea: 1)istrito tde Ixtlan.
Municipio de Ixtlan de Juarez, 12 km NE d(I
Vista Hermosa. carretera de Ixtlan a Valle Na-
tional. 17 Apr. 1982. R. Cedillo-Trigos 12341
& R. borres-Colhn (holotype. MEXU: isotypes.
BM. MEXU. MO, UAMIZ). Figures 1-3.
Arbor 20-14) m alia; stitpulac 1-2.5 mmi lIngac. ().1-I
nin latae. axis foliaris (petiolus ci eii rachis) 8-18(-2() (111
Itl gus; foliola (5-)7, lanceolato-oblonga. ramr ellipti'a.
utrinque glabra, apice acuininiaa: racemni caltliflori (7-1)-
16(-20) cm longi. bracteae 0.6-()0.9 min lInia: ,pc lic( li
3-7 mm longi, alabastra ad 6 x 5 rnr: Icgumin obi liilqi
ellipticum, base atenuata, verrucosurl , brtlr iinnurin, senltiic
uno. elliptico.
Trees 20-40 m high, the bark striate to rugose.
grayish brown, with prominent lenlitcels: branchlets
strigulose, rufous, glabrescent. Iedaf budls strigose,
rufous; young leaves purple, strigulose: mlature
leaves green. glabrous: stipules 1-2.5 X 0.4-1 rmii,
subulate to deltoid. strigose to strigulose. tecidu-
ous: petioles (1-)2.5-5 m long. terete to flattened
or slightly sulcate on the upper surface, glabrous:
rachis (3.5-)5.5-13(-15) cm long. flattened to sul-
cate on the upper surface. very sparsely strigulose
to glabrous, not stipellate: leaflets (5 to)7. the pet-
iolules 3-5 mm. sulcate, glabrous, the blades of the
lowermost pair (3.5-)4.5-10 X (2-)2.5-4.5(-5.5)
cm. the other pairs (6-)7-14.5(-16) X (2.5-)3-5(-
5.5) cm. lanceolate-oblong, rarely elliptic, glabrous
on both surfaces. venation tenuoius. the mlain vein
prominent on the lower surface. very sparsely stri-
gulose at the base, glabrescenl, the base cuneate,
the margins entire, thickenedl sometimes very
slightly revolute. the apex acuminate. Inflorescenc-
es racemose. (7-)9-16(-20) cm long. strigose, ru-
fous, cauliflorous. the young racemes growing on
very compressed brachyblasts, and disposed in
groups of (3 to)6 to 9(to 12). rarely axillary, and
solitary; peduncle (0.3-)0.5-1.5(-2) cm long, the
peduncle and the floriferous axis strigulose, rufous;
bracts 0.6-0.9 X 0.4-0.6 mm, deltoid, strigose. ru-
fous. caducous: bracteoles lacking: pedicels 3-7
nrn long, strigose, rufous: floral buds 3.5-6 X 3-
5 mm, almost globose, strigulose. rufous, the apex
shortly apiculate. Flowers apetalous. calyx 5-5.5
umm long. strigulose. with 4(or 5) irregular lobes,
free or shortly fused at the base. green. persistent:
corolla lacking; stamens numerous (29 or 30). the
longer filaments 6.5-8 mm, free to base. the smaller
ones 4-5 mm. white, exceptionally fused in groups
of 2 or 3 at the base (Fig. IF), glabrous, anthers
1.5-2 X 0.8-1.2 mnm, oblong to elliptic. nearly bas-
ifixed: gynoecium glabrous. ovary stilitate. 4-6 nmm
long, including the gynophore, the latter 2 mm long.
sparsely strigulose at the base, with 4 or 5 cam-
pilotropous ovules, obliquely disposed. style 1.5-2
Irm. arcuate, glabrous, stigma truncate to obliquely
truncate. Legume 4.5-5 X 2-2.3 cm. obliquely el-
liptic, the base attenuate, the valves 2-5 nmm thick.
ligneous, verrucose, dark brown, 1-seeded, the
apex obliquely obtuse. Seed 3.2 X 1.7 X 1.4 cm.
elliptic, the testa chartaceous, rugose, brown, bril-
liant, the aril probably red, thin.
Common names. "Jarrito silvestre." "palo de
jarrito de monte."
Distribution and habitat. As far as we know.
the new species is endemic to northern (axaca. It
occurs in cloud forest with Lauraceae and Rheedia.
premontane wet forest. and montane tropical rain-
forest. at elevations of 725-1300 m.
Phlieology. It has been collected in flower dur-
ing March and April, ant the fruits have been
found in May.
The new species belongs to section Siwarizia.
subsection Swartzia. and is assigned to series 7Ton-
ateae, which is characterized by the floral buds
usually 5 mm or less in diameter, as well as byi the
lack of a petal and bracteoles.
Swartzia mexicana is closely related to S. so-
morum A. R. Molina. Both species share the leaf-
lets not prominently reticulate, the style uncinate.
and the stigma truncate. as well as the legume el-
liptic in shape. It is distinguished from S. sumorum
by the narrower leaflets, the larger stipules and flo-
ral buds, the larger number of leaflets, as well as
the longer racemes and pedicels (see key). The new
species is also related to S. wurdackii R. S. Cowan
by the leaf rachis lacking wings or stipels, and the
gynoecium glabrous; the latter can be distinguished
by the longer stipules. the leaflets with prominent
with campylotropous ovules. --1. Legume. -1. Seed. (A
Herndndez 142).
;. Cedillo-Trigos 1234 & R. Torres-Colin: H . P. I(s hrio-


118
Novon
5 mm
Figure 2. Suwarlzia mnexictan M. Sousa & I. Grether.
fromn R. (Cdillo-Trigos 1234 & R. bTrre.s-Colrn).
reticulate venation, and the shorter racemes (see
key).
Series Tounalteae comprises 22 species, includ-
ing Swartzia rnexicana. Other species of this group
with leaf rachis lacking wings or stipels lut having
a densely pubescent gynoecinni are Swa~urzi amna-l
zonica Moore occurring in Brazil, S. lannia Sand-
with known fron Suriname and (Guyana, and S . car-
ihaeua Grisebach from the West Indies.
The new species can be distinguished by addting
it to Cowan's key to species of series iToateae
(lose-up of racemes. floral budis. and flowers (photoligralphed
(19>8: 23-24) in his treatment fotr Flora \eotropi-
(n. at couplet II (p. 23). in the following way:
I . (Gynioeciun glabrous or sparsely strigose basallh.
12. Stipules 5 imm long: alealets with prominiinl
retieulatie tenation: racemei's 4- .5 cull long:
V\enezueila ................ .S. .. orlanh kii
12. Stipules (.1-2.5 nun long: eafllets wilt one
promininrDt vein ant lenuous. pintnate \tena-
tion on the lower surface: racemes (7-)8-
16(-20() (ri long.
13. Stipules 0.1-0(.5 mu1 long: leaflets (3
ID):: racemes 8-10 cin long: floral buds


Volume 12, Number 1
2002
Sousa & Grether
Swartzia mexicana from Mexico
5 mm
Figure 3. Suwartzial mexicana M. Sousa & H. (;rether. (:lose-up o'f iopn fruit adl seed (photographed from P. Osorio-
Hernundez 1,12).
3 X 3 nun; pedicels 1-1.5 ion long; 2,
rarely 1, globose seeds. 1-1.5 cm diam.:
Nicaragua . ........... . . *. sniornil
13. Stipules 1-2.5 min long; leaflets 7(less
often. to 5); racemes (7-)9-16(-20) cm
long: floral buds 3.5-6 X 3-5 nmn: ped-
icels 3-7 nm long; 1 elliptic seed. 3.2
X 1.7 X 1.4 cm: Mexico . . S. . mcxiracna
Paratrpes. MEXICO. Oaxaca: l)istrito de Ixtliin.
Mun. (omaltepec alongr trail that descends from Hwy. 175
at 1280 in elevation (Puerto Antonio) to settlement of Cua-
je. 2-6 Dec. 199)l B. BHole & S. Icosta 3960 (MEXU,
MO. A(), H. H oyle & S. Acostal 4011 (MEX[. MO);
Puerto 
tonio. 25 Mar. 198). R. Isipe:-Luna 0438
(MEX[): )istrito de Tuxtepec. Munl. San Felipe Usila.
Monte Pan. 3.1 km en Ifnea recta al SE (135�) de Santa
Cruz 'Tpeitoutla . II Apr. 991, P Osorio-Herndndez 37
(MEXU). 7 May 1991. . O.sorio-'ermiidez 142 (MEXU),
P Osorio-Herndnde': 152 (MEXU): 5.1 km en linea recta
al SE (154�) dle Santa Cruz Telpetotutla. 29 Mar. 1995, A.
Rinledn-Gutidrrez 607. C. (allardo & E. Perez-Garcia
(MEXU).
Acknowledgneinis. We express our gratitude to
Fernando Chiang. Instituito de Biologia, UNAM, for
the Latin translation of the diagnosis, to Lawrence
M. Kelly. Instituto de Biologia. UNAM, for his re-
view of the English version of the manuscript, to
(loria Alnrade, Instituto de Biologia, UNAM, and
to Elvia I'sparza, Institutl de Biologia, UNAM, for
tie excellent illustration. Special thanks are given
to Victoria C. Hollowell, Missouri Botanical (Gar-
den. and I)avid A. Neill. Missouri Botanical Gar-
den. Herhario Nacional de Ecuador, for critical
comment improving the manuscript.
Literature Cited
Barnebv. R. C. 1991. Notes on Swartzia (Ieguminoisae:
Swartzieae) preliiinary to the Flora of the Venezuelan
Guavana. Ann. Missouri Hot. Card. 78: 177-183.
. 1996. Neotropical Fahales at NY: Asides and
oversights. Brittonia 18: 171-187.
Cowan, 1. S196. 98. w0n'rtziti (Ieguminosae, Caesalpinioi-
deae, Swarlzieae). Flora Neotropica, Monogr. 1: 1-228.
- 1981. Swartzieae. Pp. 209-212 in R. M. Polhill
& P. H. Raven (editors). Advances in Legume Systein-
atics, Part 1. HKyal Botanic (;ardens, Kew.
Davidse, (., M. Sousa & A. 0. Chaler (editors). 1994.
Flora Mesoanericaina 6: XIII-XIV: Mapa del area de la
Flora Mesoamericana. Universidad Nacional Aut6noma
de Mexico, Mexico, I).F; Missouri Botanical (;arden,
St. Louis; The Natural History Museum. London.
119