Endemic families of Madagascar. XII. Resurrection and taxonomic revision of the genera Mediusella (Cavaco) Hutchinson and Xerochlamys Baker (Sarcolaenaceae)
Author
Hong-Wa, Cynthia
text
Adansonia
2009
3
2009-12-31
31
2
311
339
http://www.bioone.org/doi/abs/10.5252/a2009n2a7
journal article
10.5252/a2009n2a7
1639-4798
5190688
10.
Xerochlamys villosa
F.Gérard
Comptes rendus de l’Association française pour l’Avancement des Sciences
1914 (sess.43): 408 (1915). —
Type
:
Madagascar
, Prov.
Toliara
, massifs gréseux du mont
Vohibasia
, dans le bassin
du Mangoky
, dans le sud-ouest de l’île,
500 m
, [
21°41’S
,
45°20’E
],
VIII.1910
, fr.,
Perrier de la Bâthie
3011
(holo-,
P
! [
P00389140
]; iso-,
P
! [
P00389141
])
.
Xerochlamys luteola
H.Perrier
,
Bulletin de la Société
botanique de
France
128: 57 (1931)
. —
Type
:
Madagascar
, Prov.
Fianarantsoa
,
Isalo
, près
de Ranohira
, grès, [
22°11’S
,
45°10’E
],
800 m
,
X.1924
, fr.,
Perrier de la Bâthie
16694
(holo-, P! [
P00389142
]; iso-, MO!, P! [2 sheets:
P00389143-44
]).
ADDITIONAL MATERIAL EXAMINED. —
Madagascar
.
Prov.
Fianarantsoa
, between
Tametsoa
and
Sahanafo
, [
22°18’S
,
45°22’E
],
700-1100 m
,
30.
I
.1955
,
Cours
5045
(
K
,
MO
,
P
)
. —
Parc
national
d’Isalo
, [
22°33’S
,
45°25’E
],
II.1963
,
Bosser
17245
(
MO
,
P
,
TAN
)
. —
Idem
, rebords est
de l’Isalo
à l’ouest
de Ranohira
, [
22°36’S
,
45°23’E
],
31.XII.1962
,
Chauvet
393
(
K
,
MO
,
P
,
TEF
)
. —
Idem
,
800 m
,
29.
I
.1955
,
Cours
5041
(
K
,
MO
,
P
)
. —
Idem
,
10 km
west of
Ranohira
, [
23°16’S
,
45°11’E
],
810 m
,
3.II.1975
,
Croat
30570
(
MO
,
TAN
)
. —
Idem
,
10 km
southwest of
Ranohira
, [
22°30’S
,
45°15’E
],
800-900 m
,
27.III.1985
,
Dorr
et al
.
4182
(
K
,
MO
,
P
)
. —
Idem
, northwest of
Ranohira
, [
22°33’S
,
45°19’E
],
800 m
,
14.II.1990
,
Du Puy
et al
.
MB659
(
P
,
TAN
)
;
Homolle
1341
(
P
)
;
Homolle
s
.
n.
(
P
)
. —
Parc
national de
l’Isalo
forêt
d’Ampandrabe
,
22°36’51”S
,
45°20’45”E
,
905 m
,
19.XII.2001
,
Hong-Wa &
Ludovic
38
(
MO
,
P
,
TAN
,
TEF
)
. —
Idem
, ouest de
Ranohira
, [
22°11’S
,
45°10’E
],
800-1250 m
,
29.I-10.IV.1955
,
Humbert
28698
(
P
)
. —
30.VII.1928
,
Humbert
&
Swingle
4992
(
MO
,
P
)
. —
Idem
, falaise au nord
de Sakamalio
, [
22°26’S
,
45°17’E
],
21.IV.1967
,
Jacquemin
334
(
P
)
. —
Idem
,
Ranohira-Sakaraha
, [
22°39’S
,
45°21’E
],
900 m
,
8.VIII.1995
,
Leeuwenberg
&
Rapanarivo
14620
(
K
,
MO
,
P
,
TAN
)
. —
Idem
,
15 km
southwest of
Ranohira
, [
22°41’S
,
45°16’E
],
800 m
,
1.II.1990
,
Phillipson
3408
(
K
,
MO
,
P
,
TAN
)
. —
Idem
,
34 km
west of
Ranohira
along the
Sahanafa
trail,
1200-1500 m
,
6.VII.1992
,
A
.
Randrianasolo
239
(
MO
)
. —
Idem
, à l’ouest de
Ranohira
, [
22°11’S
,
45°10’E
],
514-1268 m
,
24.
I
.1955
,
Service Forestier
11672
(
K
,
MO
,
P
,
TEF
)
. —
17-18.
VI
.1958
,
Service Forestier
18574
(
K
,
MO
,
P
,
TEF
)
. —
Ranohira
,
22°37’04”S
,
45°21’45”E
,
871 m
,
27.
VI
.2005
,
Hong-Wa et al
.
380
(
MO
,
P
,
TAN
)
. —
[
22°33’S
,
45°25’E
],
800 m
,
13.VII.1954
,
Service Forestier
14325
(
P
,
TEF
)
.
DESCRIPTION
Trees
4-8 m
tall, trunk to
20 cm
dbh; young twigs yellow-tomentose, older twigs glabrous. Leaf blades glossy bright green above, dull green beneath, broadly ovate or sometimes elliptic, 4-8 ×
2-4 cm
, chartaceous, with scattered trichomes on the abaxial midvein only when young, glabrous at maturity, base cordate to rounded, margin plane, apex rounded to emarginate, midrib yellow, slightly raised above, distinctly raised beneath, secondary veins prominent, 6-14 per side,
5-6 mm
apart, looping
1-4 mm
from the margin; petiole
4.5- 11 mm
long, glabrous. Flowers solitary, axillary, or rarely inflorescences axillary or terminal, with 2 flowers; peduncle
1-3 mm
long, glabrous, pedicel absent to
1 mm
long, glabrous. Involucre light brown, urceolate, 3-10 × 4-10, yellow tomentose with scattered white trichomes, teeth 12-20,
0.5- 2.8 mm
long; flowers
20-37 mm
long at anthesis from apex of pedicel to apex of petals; sepals obovate, 5-12.5 ×
4-9 mm
, deeply emarginate, exserted
3-5 mm
beyond the involucre; petals white, obovate, 17-27 ×
8-15 mm
, exceeding the involucre by
14-17 mm
; disc
2-3.5 mm
tall; stamens 24-47, 8-
18 mm
long; ovary ovoid,
3-4 mm
high, style
7-17 mm
long, basally pubescent, stigma
2-3 mm
wide. Fruits ovoid to subglobose, 7-11 ×
5.5-12 mm
, exceeding the accrescent involucre by
2-7 mm
; seeds black, ovoid,
2-4 mm
long, 3-6 per fruit.
PHENOLOGY
Flowering and fruiting from December to July.
VERNACULAR NAME
Foto.
HABITAT
On sandstone in evergreen sclerophyllous
Uapaca bojeri
(tapia) woodland from
800-1200 m
in subhumid and subarid bioclimatic zones.
DISTRIBUTION
From Mt. Vohibasia to Isalo National Park in SW
Madagascar
(
Fig. 4
).
REMARKS
This species can be distinguished by its large (>
4 cm
long) and broadly ovate, glabrous leaf blades that are glossy bright green above and dull green beneath, its distinct leaf venation, and its large white flowers subtended by a yellow-tomentose, urceolate involucre. Both
Xerochlamys villosa
and
X
.
undulata
are found around the Isalo massif, but field observations indicate that the former is abundant on rocky substrates whereas the latter grows in sandy areas. The two species clearly differ from each other by the length (≥
4 cm
long in
X
.
villosa
vs. <
4 cm
long in
X
.
undulata
) and the shape (ovate vs. elliptic) of their leaf blades, the absence (vs. presence) of trichomes, the colour of the petals (white vs. pale yellow to white) and of the indumentum on the involucre (yellow vs. red).
Perrier de la Bâthie (1931)
described
Xerochlamys luteola
, failing to recognize that it represented the same entity as
X
.
villosa
, which he erroneously placed in synonymy under
L
.
bojeriana
. Indeed, the
type
of
X
.
villosa
(
Perrier 3011
, the only material available to him at the time) differs from
X
.
bojeriana
in several notable ways, including leaf blade shape and size, petiole length, and the shape and size of the involucre. Although no additional material of
X
.
villosa
s.s.
has been collected since the
type
was made,
X
.
luteola
is clearly the same taxon.
CONSERVATION STATUS
Xerochlamys villosa
has only been recorded in less than five locations within and around the Isalo and Vohibasia National Parks. With an extent of occurrence of
938 km
2, an area of occupancy of
90 km
2, this species is provisionally considered Endangered [EN B1ab(i,ii,iii,iv)+2ab(i,ii,iii,iv)].
UNPLACED MATERIAL
Madagascar
.
Prov.
Fianarantsoa
:
Ambatofinandrahana
,
20°30’43”S
,
46°46’31”E
,
1475 m
,
31.VII.2001
,
Andriamihajarivo
et al
.
11
(
MO
,
P
,
TAN
,
TEF
). — [
20°33’S
,
46°48’E
]
,
1600-1800 m
,
9.II.1938
,
Decary 13081
(
MO
,
P
). —
Andranofimoritra
, bassin supérieur
de l’Onilahy
, [
23°53’S
,
46°31’E
],
1000-1200 m
,
19.XII.1928
,
Humbert
7047
(
P
). — Itremo, eastern margin of the Itremo Massif,
c.
19 km
west of
Ambatofinandrahana
,
20°34’21”S
,
46°34’54”E
,
1580-1700 m
,
10.III.2000
,
Schatz et al
.
3963
(
MO
)
.
REMARKS
The
four specimens
listed above could not be placed in any of the species recognized here because of their unusual morphology.The material represented by
Andriamihajarivo et al
.
11
may be a hybrid between
Xerochlamys diospyroidea
and
X
.
bojeriana
, and likewise
Humbert 7047
may be the result of hybridization involving
X
.
diospyroidea
and
X
.
coriacea
, or they may be completely distinct entities that could be recognizable with additional collections. By contrast, material of
Decary 13081
appears to be related to
X
.
elliptica
, but cannot be accommodated therein because the leaf blades are broadly elliptic, deeply emarginate and lack the whitish coloration beneath, the secondary veins are not prominent and the specimen is described to be a small bush with pink flowers, whereas
X
.
elliptica
is a small tree generally with white flowers. The fourth specimen (
Schatz et al
.
3963
) seems to represent nothing more than a variant of
X
.
bojeriana
as it has the same pubescent and elliptic (albeit almost cuneiform) leaf blade, which is also larger than usual; but these odd features, as well as the absence of reproductive organs on this specimen, preclude the confident assignment of a name.