IPOMOEA TEHUANTEPECENSIS (CONVOLVULACEAE): A NEW SPECIES FROM THE ISTHMUS OF TEHUANTEPEC, MEXICO

2008·3.3 MB·English

by  Leticia Torres-Colín

IPOMOEA TEHUANTEPECENSIS (CONVOLVULACEAE):
NEW
FROM THE ISTHMUS OF TEHUANTEPEC, MEXICO
A
SPECIES
Torres-Colin, Rafael Torres-Colin,
Leticia
Andrew McDonald
Anda
and Miriam Ramirez de
J.
P.
de The University of Texas Pan American
Biologfa
Instituto
Department of Biology
Un
Departamento de Botdnica 120 West
1
7854
Apartado Postal 70-367, Del. Coyoacdn Edinburg, Texas -2999, i
1
MEXICO,
14510 Mexico,
D.F.
Recent investigations in the Tehuantepec District of Oaxaca, Mexico, have uncovered ten species of
floristic
Ipomoea (Torres-Colin 1989; Torres et 1997), one of which is new to science. The new species belongs to
al.
accommodated
and comose and
Ipomoea subg. Eriospermum Verde, on the basis of lignescent stems seeds is
= complex'
comfortably within Ipomoea Mirandinae D.F. Austin (Austin 1977, 1979; 'microsticta
ser. s. str. I.
&
Huaman
on account deciduous
sensu McPherson 1979 or Eriospermum Austin 1996) of its
ser. s. lat.,
I.
mm
leaves and relatively small (4.0-4.5 long), subequal sepals. These and a combination of ornithophilous
features, including red, hypocrateriform corollas, and exserted reproductive structures suggest close
floral
between which
with Ipomoea concolora (Matuda) D.F. Austin and conzattii Greenm., distinctions
relations
I.
presented herewith.
are
&
McDonald,
Ipomoea tehuantepecensis Torres-Colin, R. Torres-Colin, M.P. Ramirez J.A. sp. nov. (Figs.
L.
W
Rancho Limon,
1A-G). MEXICO. Oaxaca: Distrito Tehuantepec, Mpio. Tehuantepec, road to Arroyo de Las Minas, to the of
Type:
mm
bark yellow-brown, glabrous, rarely squa-
Twining lianas; Stems cylindrical, to 5 in diameter, striate,
5-11.0
mose, abundant. Leaves deciduous before anthesis; blades ovate to broadly ovate, (3. 8-)5.
lenticels
Hani
n Campos 41 3831). B. Compound
of mature seed. G. Persistent septum of dehisced capsule (based on Rafael Torres 4892).
cm cm
long, (2.5-)3. 5-8.5 wide, upper surface dark green, lower surface light green,
on both apex margin
surfaces, acute, base obtuse or rarely subcordate, entire; petiole
1
mm
cm
distally terete, striate, (2.0-)3.0-8.7 long, 1-2 wide, glabrous. Inflorescence a pleiocasium 4.0-6.0
mm mm
cm
4-6
long, flowers 15-45, primary peduncle 1-3 long, glabrous, secondary peduncles long,
mm
4-6
bracteoles deciduous; pedicels long, erect, glabrous, sparingly dilated at the apex, striate; sepals
new
Torres-Colin et A species of Ipomoea from Mexico 795
al.,
mm mm
2-3
imbricate, reddish, ovate to broadly ovate, 4.0-4.5 long, wide, chartaceous, glabrous, the
cm
margins entire, apex obtuse, rarely acute, mucronate; corolla hypo crater iform, red, 2.5-3.0 long, tube
mm
mm
cm
5-6 3-6
2.5-2.8 long, in diameter, limb irregularly 5-lobate; segments long; stamens sub-
5,
cm
equal, exserted, filaments basally pubescent, anthers yellow; style exserted, glabrous, ca. 3 long, stigma
mm mm
9-13 6-7
capitate. Fruit a capsule, ellipsoid, long, wide, 4-valvate, brown, chartaceous, dehiscent,
mm mm
glabrous; seeds 4, brown, ellipsoid, three angled, 7 long, ca. 4.6 wide, the lateral margins comose,
—
Habitat. Ipomoea tehuantepecensis thrives in short tropical deciduous forest on dry gradients between
200-750
meters. The vines prefer steep slopes with thin soil mantles and often grow in association with
&
Bursera schlechtendalii Engl., Gossypium aridum (Rose Standi.) Skovst., and Juliania adstringens Schltdl.
—
Distribution. As presently known, tehuantepecensis a narrow endemic of Oaxaca, Mexico, known
is
I.
only from the District of Tehuantepec in the Municipalities of Santiago Laollaga and Santo Domingo Tehu-
antepec
(Fig.
2).
—
Phenology. Ipomoea tehuantepecensis flowers and fruits following the rainy season, from November to
March.
—
Etymology. The species epithet refers to the Isthmus of Tehuantepec, in which the new taxon ap-
is
parently
restricted.
Dormido, al S de Laollaga, Alvaro Campos 4116 (MEXU,
V.
de Tehuantepec, Alvaro Campos 3831 y Cipriano Martir
V.
km NE
11 al de Tehuantepec, Abisai Garcia M. 2802, L.
1
N
C. y C. Martinez R. (MEXU, PAUH); ruinas del Cerro Guiengola, de
al
y Cipriano Martinez R. (MEXU, PAUH); ladera S del Cerro Guiengola, po
y Cipriano Martinez R. (MEXU, PAUH); Cerro Guiengola at the ruins, P.]. Stafford 8y R.J.
DISCUSSION
Ipomoea tehuantepecencis and its close relatives, concolora and I.conzattii, belong to an assemblage of deciduous
I.
lianas that extends from southern Mexico to northern South America, with a secondary center of diversity in
the Caribbean (Austin 1977). Ipomoea tehuantepecencis distinguished by glabrous laminas with an obtuse
is
or subcordate leaf base, while the blades of conzattii are strigose and elliptical with obtuse bases. Laminas
I.
of concolora are tomentose on the undersurface and basally cordate. Whereas tehuantepecensis produces
I.
I.
mm
compound cymes with secondary peduncles from 4-6 and
long, concolora exhibit simple
conzattii
J. I.
mm
cymes with secondary peduncles that range from 2-4(-5) long. Glabrous pedicels of tehuantepecencis
J.
mm
4-6
ranging from with and which
are relatively short, long, contrasting those of conzattii concolora,
I. J.
mm mm
pubescent and 10-15 7-12
are or long
(respectively).
many
Like other Ipomoea species, tehuantepecencis readily diagnosed by distinctive sepals, these
is
J.
mm mm
being reddish, glabrous, and relatively small (4-4.5 long, 2.3 wide). In contrast, sepals of
conzattii
I.
mm mm
5-7 4-6
and and
are greenish, sericeous, long, wide, those of concolora are reddish, sericeous,
I.
mm mm
7-8 and 3.5-4 The
long, wide. brightly colored, glabrous corollas of tehuantepecensis are 2.5-3.0
I.
mm mm
cm
long, the tube less than 2.8 in diameter at base and 5.0-6.0 from the middle to the throat,
while corollas of conzattii and concolora are pilose and sericeous (respectively), measuring from 3.0-4.5
I. I.
cm
These and summarized
long. other less discrete distinctions are in Table
1.
ACKNOWLEDGMENTS
Journal of the Botanical Research Institute of Texas 2(2)
/pomoea
concolora,
Comparative morphology of
Table 1. I.
Ovate to broadly ovate, base
Blades
both surfaces strigose upper surface glabrous, lower obtuse to subcordate, glabrous
on both surfaces
secondary
Monochasium, secondary Pleiocasium,
:e
mm
2-4
peduncles long,
mm
mm mm
4-6
Pedicels 10-15 long, tomentose 7-12 long, sericeous long, glabrous
mm mm mm mm mm mm
2-3
Sepals 5.0-7.0 long, 4-6 wide, 7.0-8.0 long, 3.5-4.0 4.0-4.5 long,
apex
greenish, sericeous, apex acute wide,reddish, sericeous, apex wide, reddish, glabrous,
to roundish, not mucronate acute, not mucronate obtuse, mucronate
cm
cm tube
2.5-3.0 long, glabrous,
Corolla 3.0-4.5 long, scarcely pilose,
cm cm cm cm cm
tube 2.5-3.5 long, 3.0-3.6 long, 0.5-0.6 2.5-2.8 long, 0.5-0.6
0.5-0.7 cm wide, limb segments wide, limb segments wide, limb segments 0.3-0.6
cm
0.3-0.4 long
.
REFERENCES
Austin, D.F. 1977. Realignment of the species placed in Exogonium (Convolvulaceae). Ann. Missouri Bot. Gard.
64:330-339.
An
979. infrageneric Ipomoea (Convolvlulaceae).Taxon 28:359-361
Austin, D.F. classification for
1
A
Austin, D.F. and Z. HuAman. 996. synopsis of Ipomoea (Convolvulaceae) in the Americas. Taxon 45:3-38.
1
genus Ipomoea
McPherson, G.D. 1979. Studies the (Convolvulaceae). Ph.D. Dissertation, University of Michi-
in
CM!.
Torres, 989. Estudio florfstico y descripcion de vegetacion del Cerro Guiengola en Istmo deTehuan-
la el
1
de de
tepec, Oaxaca.Tesis Licenciatura, Escuela Nacional Estudios Profesionales Universidad Nacional
Iztacaia,
Autonoma
de Mexico. Mexico
D.F.
Torres, C.R., Torres, Davila, and Villasenor. 997. Listados floristicos de Mexico. XVI. Flora del Distrito de
L. P. J.L. 1
Autonoma
Tehuantepec, Oaxaca. de Universidad Nacional de Mexico.
Institute Biologia.