First record of the critically endangered Hydrangea steyermarkii Standl. (Hydrangeaceae) in Mexico, and description of a new widespread Hydrangea species of Mesoamerica
Author
Samain, Marie-Stéphanie
Instituto de Ecología, A. C., Centro Regional del Bajío, Avenida Lázaro Cárdenas 253, 61600 Pátzcuaro, Michoacán, Mexico; e-mail: MarieStephanie. Samain @ gmail. com & Ghent University, Department of Biology, Research Group Spermatophytes, 9000 Gent, Belgium
Author
Najarro, Francisco Hernández
Herbario CHIP, Dirección de Botánica Dr. Faustino Miranda, Secretaria de Medio Ambiente e Historia Natural, Apartado Postal 6, 29000 Tuxtla Gutiérrez, Chiapas, Mexico
Author
Salas, Esteban Manuel Martínez
Herbario Nacional de México, Departamento de Botánica, Instituto de Biología, Universidad Nacional Autónoma de México, 04510 Mexico City, Distrito Federal, Mexico
text
Phytotaxa
2014
2014-03-17
162
4
181
197
http://dx.doi.org/10.11646/phytotaxa.162.4.1
journal article
10.11646/phytotaxa.162.4.1
1179-3163
5132092
Hydrangea steyermarkii
Standl.
, amended description
,
Figs. 2
,
3
,
5
TYPE
:
-
GUATEMALA
.
San Marcos
:
Along Quebrada Canjulá
,
between Sibinal and Canjulá, Volcán de Tacaná
,
2200–2500 m
,
18 February 1940
,
J
.
A
. Steyermark 36044
(
F
!,
GH
! (photo)) [functionally female, immature fruits].
Root-climbing liana of up to
30 m
high, functionally dioecious. Main stem clinging to the host tree with many large adventitious roots, up to
12 cm
diameter, bark dark brown to black, with reddish lenticels. Runner shoots (stolons) dark brown, fibrous, with adventitious roots and stellate hairs, with small leaves. Branches many-ribbed, with reddish pubescence and adventitious roots, cortex brownish-reddish, contracting, forming corchy patches (
Fig. 2C
), notorious line between petioles of opposite leaves. Petiole sulcate adaxially, terete abaxially, reddish pubescent, sparsely pubescent with short hairs in young stage, glabrous in mature stage,
1.5–3 cm
long, leaving a semicircular scar on the branch when leaves fall. Leaves decussate, lanceolate-obovate, base cuneate to slightly rounded, sometimes slightly asymmetric,
10–18 cm
long,
4.5–6 cm
broad, apex acute to acuminate, leaf margin crenate with marked glandular teeth, especially notorious in leaves of young branches and of stolons, venation brochidodromous, veins 8–9, adaxial leaf side with protruding tertiary veins forming areole, secondary veins end in the glandular teeth, abaxially with protruding primary and secondary veins in young leaves, sunken in mature leaves, tertiary veins well defined in young leaves, invisible in mature leaves, glabrous, abaxial leaf side sparsely whitish pubescent on midvein to pubescent allover the surface, with whitish stellate adnate hairs, shiny dark green, young leaves red-brown, but glands green, with whitish indument (
Fig. 2D
), all veins reddish-brownish, acarodomatia
form cavities
between midvein and primary veins, sometimes even in between primary and secondary veins. Inflorescence axis with reddish stellate hairs,
7 cm
long, with two small decussate leaf pairs below the inflorescence, petiole
1 cm
long, lamina
2–3.5 cm
long, apex of the floral axis not visible, inflorescence bracts rapidly deciduous, decussate, about 8, of different sizes, consecutively and rapidly caducous during inflorescence development, with whitish to reddish, adnate, stellate hairs, including margin, inflorescences lateral, opposite, two per flowering branch which continues growing vegetatively during inflorescence development, with up to four leaf pairs above the node where the inflorescences originate in the axil of a leaf pair with reduced petiole (
0.6–1.5 cm
) and without lamina, these ‘leaves’ caducous, only present at the base of inflorescence buds, leaving a scar at the base of mature inflorescences, corymbous,
5 cm
diameter,
2–3 cm
high, with 5–6 partial inflorescences (corymbs) which on their turn again consist of several corymbs, secondary and tertiary inflorescence axes with reddish stellate hairs. Flower pedicel
0.8–2 mm
long, receptacle campanulate in functionally male flowers, broadly semiglobose in functionally female flowers,
2 mm
long, ovary inferior, calyx lobes 4, triangular with rounded apex,
1 mm
long, petals 4, white, valvate, cucullate, coriaceous, smooth adaxially and abaxially,
1.2–2 mm
long, 1,2 mm broad, functionally male flowers (
Figs. 3 D, E, F
,
5 B
): hypanthium
2–2.5 mm
diameter, stamens (6–)8(–9), welldeveloped, filaments
1.5–2 mm
long, anthers
0.7–0.8 mm
long,
0.5 mm
broad, pistils 2, reduced,
1–1.2 mm
long, remnants of ovules present, functionally female flowers (
Fig. 5 C
): stamens in the only available female specimen shriveled as this specimen has only nearly mature fruits, pistils 2, not seen in fertile stage, enlarging up to
3–4 mm
in mature fruits, stigmas apically clavate and shortly penicellate, fruit a broadly semiglobose capsule, lateral ribs cannot be distinguished because of the shriveled state of the fruits, dark brown,
3–4 mm
high,
4–5 mm
broad above,
3–4 mm
diameter, opening between the two pistils to release seeds, seeds not seen.
Habitat:
―Very deep valleys in cloud forest (“selva mediana perennifolia” according to Miranda & Hernández X., 1963, “bosque mesófilo de montaña” according to
Rzedowski, 1978
) dominated by
Hedyosmum mexicanum
. This species gets easily established in primary forest on very steep slopes in ravines where there are recurrent disturbances as a consequence of very strong winds which cause treefall. This species occurs in conserved localities, as well as on disturbed places with very strong succession dynamics, protected from the humid winds from the south, on igneous rocks, with approximately
3000 mm
rainfall.
Distribution:
―South-facing slopes of the volcano Tacaná in México and
Guatemala
, between 2200 and
3000 m
.
Phenology:
―This species has been observed flowering in September and fruiting in February.
Observations:
―The population on the Mexican side of the volcano Tacaná near the village of Chiquihuite,
5– 6 km
in straight line from the
type
locality, is the first record of this species in
Mexico
. Interestingly, the
type
specimen belongs to a functionally female individual, whereas our collection is a male specimen. Despite extensive explorations on the Mexican side of the volcano Tacaná, it has not been possible to encounter a female specimen. In contrast to the description, which mentions as habit a climbing epiphytic shrub (‘
frutex scandens epiphyticus
’;
Standley 1940: 233
), this species is a root-climbing liana.
Standley (1940)
, in the description of
H. steyermarkii
, mentions a dense reddish pubescence for the branches (‘
quoque pilis stellatis brunnescentibus laxe tomentosis
’). Nevertheless, this reddish ‘indument’ is a mixture of young adventitious roots and penicellate, stellate hairs. In contrast, the indument on the lamina is whitish on the
type
specimen and all other studied collections.
The marginal vein is closer to the leaf margin than in
H. albostellata
. The apex of the leaves on the terminal branch of
M.S. Samain et al. 2012-009
and
M.S. Samain et al. 2012-010
) is acuminate.
The majority of the available herbarium specimens of
Guatemala
,
Honduras
,
El Salvador
and
Nicaragua
as well as a few collections of
Costa Rica
bear the identification of
H. steyermarkii
. However, only the specimens mentioned below coincide with the
type
of this species and nearly all other specimens belong to
H. albostellata
.
The number of stamens in the observed functionally female flowers is variable although the average number is 8 with 6 large stamens and 2 smaller stamens. When there are only 6 stamens, they are all of the same size.
FIGURE 5.
Hydrangea steyermarkii
. A. Habitus of branch with inflorescences. B. Functionally male flower with 8 fertile stamens and 2 reduced pistils. C. Maturing capsule, fertile stigmas still visible, seeds are released through the opening between the 2 pistils. D. Inflorescence branch with inflorescence bud, inflorescence bracts and leaf pair visible. E. Detail of inflorescence branch with stellate indument. Drawn by Ramiro Cruz Durán from the specimen
M.S. Samain et al. 2012-078
(MEXU; A, B, D, E), and from the holotype
J.A. Steyermark 36044
(F; C).
Additional specimens examined:
―
GUATEMALA
.
San Marcos
:
Río Vega
, near San Rafael and Guatemala-
Mexico boundary,
Volcán
de Tacaná
,
2500–3000 m
,
J
.
A
.
Steyermark
36250
(
F
) [sterile];
between Canjulá and La Unión Juárez
, near southeast portion of
Volcán
de Tacaná
,
2000–3000 m
, slopes of
Río Tonaná
,
J
.
A
.
Steyermark
36411
(
F
) [sterile];
El Progreso
: between
Finca Piamonte
and top of
Montaña
Piamonte
, along
Joya Pacayal
,
2500– 3000 m
,
J
.
A
.
Steyermark
43635
(US!);
Quezaltenango
: western slopes of
Volcán Zunil
, opposite
Santa María de Jesús
,
1500 m
,
21 January 1940
,
J
.
A
. Steyermark 35109
(
GH
! (photo of
F
specimen)); Huehuetenango, Cerro Huitz,
between Barillas and Mimanhuitz, Sierra
de los Cuchumatanes,
1600–2600 m
,
14 July 1942
,
J
.
A
. Steyermark 48536
(
US
!) [sterile]; wet cloud forest at
Cruz
de Limón
,
between San Mateo Ixtatán and Nucá, Sierra
de los Cuchumatanes;
2600–3000 m
,
31 July 1942
,
J
.
A
. Steyermark 49826
(US!) [sterile]
.
MEXICO
.
Chiapas
:
Cacahoatán
,
Volcan Tacaná
,
Chiquihuite
,
15°6'23.07"N
,
92°6'9.13"W
,
2362 m
,
3 September 2012
,
M
.
S
. Samain et al. 2012-078
(
CHIP
!,
GENT
!,
MEXU
!) [functionally male]; loc. cit.,
15°6'24.83"N
,
92°6'4.25"W
,
2476 m
,
4 January 2012
,
M
.
S
. Samain et al. 2012-008
(
GENT
!,
MEXU
!) [sterile]; loc. cit.,
15°6'25.1"N
,
92°6'4.11"W
,
2481 m
,
4 January 2012
,
M
.
S
. Samain et al. 2012-009
(
GENT
!,
MEXU
!) [sterile]; loc. cit.,
15°6'23.23"N
,
92°6'7.26"W
,
2426 m
,
4 January 2012
,
M
.
S
. Samain et al. 2012-010
(
GENT
!,
MEXU
!) [sterile]; loc. cit.,
15°6'22.28"N
,
92°6'11.11"W
,
2423 m
,
5 January 2012
,
M
.
S
. Samain et al. 2012-011
(
GENT
!,
MEXU
!) [sterile],
M
.
S
. Samain et al. 2012-012
(
GENT
!,
MEXU
!) [sterile]
.
Conservation:
―Critically Endangered; known from one population with adult flowering and juvenile runner shoots on the Volcano Tacaná on the border of
Mexico
and
Guatemala
, and five sterile, mostly juvenile collections by Julian Steyermark from
Guatemala
, none of them recent. Monitoring of remaining populations in
Guatemala
would be important for evaluation of the conservation status of
H. steyermarkii
in that country. On the Mexican side of the volcano ascending from the village of Chiquihuite, several flowering individuals have been observed, although only one functionally male individual could be sampled up to now, as a consequence of the quite inaccessible extremely steep slopes. There are many runner shoots on this locality, showing that this population most probably reproduces vegetatively. This area is located at approximately
5–6 km
in straight line from the
type
locality on the Guatemalan side which could not yet be visited. The Mexican (sub)population is suffering as a consequence of habitat destruction and land use change, such as floriculture of
Zantedeschia aethiopica
(‘alcatraz’) and
Hydrangea macrophylla
cultivars.