How Many Species are there in the Holomycotrophic Genus Didymoplexis Griff. (Orchidaceae) in Madagascar?

Abstract

Cribb, P., L. Gautier & L. Nusbaumer (2013). How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? Candollea 68: 41–49. In English, English and French abstract. The holomycotrophic genus Didymoplexis Griff. (Orchidaceae) is revisited for Madagascar. Two species, Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut. and Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut. are newly described based on recently collected flowering specimens. The relationship between these two species, the recently observed Didymoplexis verrucosa J. Stewart & Hennessy and the cryptic Didymoplexis madagascariensis (H. Perrier) Summerh., only known from two fruiting specimens, is discussed. A key to species in the genus in Madagascar and Africa based on flowering material is provided.

Full text

How many species are there in the holomycotrophic genus
Didymoplexis Griff. (Orchidaceae) in Madagascar?
Phillip Cribb, Laurent Gautier & Louis Nusbaumer
ISSN: 0373-2967 – Online ISSN: 2235-3658 – Candollea 68(1): 41-49 (2013) © CONSERVATOIRE ET JARDIN BOTANIQUES DE GENÈVE 2013
Abstract
CRIBB, P., L. GAUTIER & L. NUSBAUMER (2013). How many species
are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae)
in Madagascar? Candollea 68: 41-49. In English, English and French
abstract.
The holomycotrophic genus Didymoplexis Griff. (Orchidaceae)
is revisited for Madagascar. Two species, Didymoplexis
avaratraensis P. J. Cribb, Nusb. & L. Gaut. and Didymoplexis
recurvata P. J. Cribb, Nusb. & L. Gaut. are newly described
based on recently collected flowering specimens. The
relationship between these two species, the recently observed
Didymoplexis verrucosa J. Stewart & Hennessy and the
cryptic Didymoplexis madagascariensis (H. Perrier) Summerh.,
only known from two fruiting specimens, is discussed. A key
to species in the genus in Madagascar and Africa based on
flowering material is provided.
Key-words
ORCHIDACEAE – Didymoplexis – Madagascar – Taxonomy –
Mycotrophy – Conservation
Résumé
CRIBB, P., L. GAUTIER & L. NUSBAUMER (2013). Combien d’espèces
y a-t-il dans le genre holomycotrophique Didymoplexis Griff. (Orchida-
ceae) à Madagascar? Candollea 68: 41-49. En anglais, résumé anglais et
français.
Le genre holomycotrophique Didymoplexis Griff. (Orchida-
ceae) est révisé pour Madagascar. Deux espèces nouvelles,
Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut.
et Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut.
sont décrites sur la base de spécimens en fleur récemment
collectés. Elles sont comparées à Didymoplexis verrucosa
J. Stewart & Hennessy une espèce récemment observée à
Madagascar et à l’espèce cryptique, Didymoplexis madagasca-
riensis (H. Perrier) Summerh., connue seulement de deux spé-
cimens en fruit. Une clef des espèces du genre pour Mada-
gascar et l’Afrique basée sur les caractères floraux est proposée.
Addresses of the authors: PC: The Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, United Kingdom. E-mail: p.cribb@kew.org.uk
LN, LG: Conservatoire et Jardin botaniques de la Ville de Genève and Université de Genève, Laboratoire universitaire de Systématique végétale et Biodiversité, CP 60,
1292 Chambésy, Switzerland.
Submitted on November 1, 2012. Accepted on January 10, 2013. Edited by P. Bungener

The holomycotrophic genus Didymoplexis Griff. (Orchi-
daceae) is represented by about 20 species in the Old World,
mainly in Asia (Southeast Asia, India, Pacific Islands, North
Australia, Ryukyu Islands and Taiwan; see HS
U
& CH
UNG
,
2007), but also including the Afro-Madagascan region with
three known species (HERMANS & al., 2007; AFRICAN PLANTS
DA
TABASE
, 2012).
The species of Didymoplexis are whitish to brownish,
achlorophylous, terrestrial and leafless herbs reaching up to
40 cm and with the capsule borne on an erect stalk often elon-
gating during fruit maturation (PRIDGEON & al., 2006).
Published phylogenetic studies focus on species of the neigh-
bouring holomycotrophic genus Gastrodia R. Br., particularly
those used in traditional Chinese medicine and cuisine (WANG
& al., 2012), but we have not found any phylogenetic study
that includes Didymoplexis.
The three species occurring in the Afro-Madagascan region
are D. africana Summerh. from continental tropical Africa,
D. verrucosa J. Stewart & Hennessy, known from Southern
Africa (N KwaZulu-Natal) but recently found also in
Madagascar (CRIBB & al., 2011) and D. madagascariensis
(H. Perrier) Summerh., endemic to Madagascar based upon
our current knowledge of the genus.
The first herbarium specimen of Didymoplexis for Mada-
gascar was a fruiting specimen collected by H. Perrier de la
Bâthie in September 1912 at Fandrarazana on the mainland
coast of north-east Madagascar opposite the island of Sainte-
Marie. It was initially described as Gastrodia madagascariensis
H. Perrier. SUMMERHAYES (1953) transferred it to Didymoplexis
as D. madagascariensis (H. Perrier) Summerh. However, it is
extremely difficult to distinguish these two genera when the
plants are in fruit since both are mycotrophic orchids with a
similar habit and many species of both genera produce erect
ellipsoidal capsules borne on elongated stalks (PRIDGEON &
al., 2006).
A second known herbarium specimen of Didymoplexis was
collected 83 years later by F. Rasoavimbahoaka in June 1995
at Belaoko Lokoho on the Ambatosoratra Mountain in the Inte-
gral Natural Reserve of Marojejy close to Andapa (Rasoav-
imbahoaka 748 [TAN, MO, P and three more unlocalized
duplicates]). This was also a fruiting specimen and it was iden-
tified by J. Bosser in November 2001 as D. madagascarien-
sis, the only known species of this genus in Madagascar at this
time.
A number of field photographs of flowering and fruiting
specimens of Didymoplexis have subsequently been made:
1. One fruiting population on 26.X.2005, in Marojejy National
Park, at 471 m elevation (photographied by Jean-Michel
Hervouet).
2. Two flowering populations on 18.XI.2006, also in
Marojejy National Park, between entrance, Mantella
camp and Humbert View Waterfall, at 437 to 500 m
elevation (photographied by Mark Clements & Anne
Mackenzie).
3. One fruiting population on 19.XI.2006, near the “Maro-
jejy camp 2” of the Marojejy National Park, at 760 m
elevation (photographed by Mark Clements and Anne
Mackenzie, see photographs in C
RIBB & HERMANS,
2009).
4. Four to five flowering individuals on 8.XII.2007, in
the Verezanantsoro circuit in the National Park of
Northern Mananara, at 231 m elevation (photogra phied
by Jean-Michel Hervouet, see BOSSER & LECOUFLE,
2011).
5. One flowering individual on 17.VII.2010, along Man-
ambolo river near Bekopaka in the National Park of
Bemaraha, at 150 m elevation (photographied by Jean-
Philippe Castillon).
The specimen photographed by Castillon (5) has been
recently identified as D. verrucosa J. Stewart & Hennessy,
hitherto known from N KwaZulu-Natal in Southern Africa
(CRIBB & al., 2011). The two other above mentioned flower-
ing population’s photographs (2 and 4) have been associated
with D. madagascariensis by CRIBB & HERMANS (2009) and
BOSSER & LECOUFLE (2011) also based on the assumption that
it was the only species found on the island. Unfortunately, no
herbarium specimens were collected of any of the plants from
these populations.
Two recent flowering herbarium collections (Nusbaumer
& Ranirison 1763, Nusbaumer & Ranirison 1763bis) have
been made in December 2005 at 818 and 985 m in the Loky-
Manambato region (Daraina) in northern Madagascar and were
accompanied by high quality photographs. The specimens of
these two collections were originally collected under the same
number but were later separated since they proved to represent
two different taxa. These recent herbarium collections and pho-
tographs bring new elements that allow a revision of the delim-
itation of the species of Didymoplexis in Madagascar.
For most tropical orchids, fruiting specimens are difficult to
identify at species level. Identification is even more problem-
atic in holomycotrophic genera where leaves are lacking. A
screening of 30 articles dealing with the genus Didymoplexis
revealed that fruiting characters have never been used to distin-
guish species (SMITH, 1905; HOLTTUM, 1953; BACKER &
BAKHUIZEN VAN DEN BRINK, 1968; COMBER, 1990; for a review,
see PRIDGEON & al., 2006). Fruiting collections are thus impos-
sible to identify to species level based on morphology. As the
type of D. madagascariensis is a fruiting collection, its relation
with any other species will remain cryptic as it could potentially
be conspecific with any flowering specimen in the genus.
42 – Candollea 68, 2013

Among the specimens observed or collected with flow-
ers, the distinction is however very clear. The main criteria
u
sed for identification are the absence or presence of the arms
at the apex of the column and their shape when present; the
lateral sepals adnated to a third or to half their length;
the division of the apex of the callus, located at the base of
the lip, into two or three lobes; the presence or absence
of two lines of verrucose warts along lip length; and the petal
and sepal colour and length.
The morphological differences and taxonomic affiliation
of the known photographs and herbarium collections of
Didymoplexis are presented in Table 1. Comparison of the
flowering specimens of Didymoplexis photographed or
collected in Madagascar brings to at least three the number
of Didymoplexis species found in Madagascar among which
two are new to science and described below. If D. madagas-
cariensis proves to be distinct from these three, the number
would increase to four. Although a flowering collection from
the type locality would be an interesting find, only molecular
data from the type and other specimens collected in Mada-
gascar could possibly disentangle the application of this taxon.
Until then, the name D. madagascariensis should be restricted
to the type specimen.
Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut.,
spec. nova (Fig. 1-3).
Typus: M
ADAGASCAR. Prov. Diego-Suarez/Antsiranana:
sous-préfecture de Vohemar, commune rurale de Daraina,
forêt de Binara, 13°15’S 49°37’E, 818 m, fl., 12.XII.2005,
Nusbaumer & Ranirison 1763 (holo-: G [G00090146]!;
iso-: P, TAN!, research herbarium of Daraina).
Ab aliis speciebus Africanis Madagascariensibusque
sepalis lateralibus ad medium connatis, petalis ac sepalo
dorsali in parte infernus 1/5 adnatis, columna brachia
apicalia brevia recurvata ad apicem acuta ferenti, labello
sine seriebus verrucarum et callo ad apicem bilobato
distinguendo.
Holomycotrophic herb up to 15 cm tall, stem beige,
brown to blackish when old, growing from a subterranean
elongated brownish tuberous rhizome. Leaves scale like, very
small. Inflorescence erect, racemose, laxly few-flowered, the
flowers opening one at a time and successively; peduncle
slender, erect, bearing a small ovate bract below inflo-
rescence, white or pale buff-coloured; rachis terete, slender;
pedicel with longitudinal ridges 1.5-2 cm during flowering
period; bracts ovate, acuminate, 1-1.5 mm long. Flowers with
pink or white sepals and petals, flushed with red-brown in
the centre, the lip pink or white with reddish brown sides, the
callus spotted with yellow. Dorsal sepal strongly curved for-
ward, lanceolate, rounded, 15
 3.-3.5 mm; lateral sepals
somewhat recurved, fused in basal half, more or less paral-
lel and slightly falcate, ovate, rounded, 13
 4 mm. Petals
elliptic-lanceolate, acute, 13  4.5 mm, decurved at tip,
adnate in basal fifth with sepals. Lip narrowly clawed at
base, obovate-spatulate, truncate, 5-6  7-8 mm, the sides
upcurved, bearing three patches on the apical lip lamina; cal-
lus at base shortly erect and bilobed at tip. Column 5-6 mm
long, slender at base, with short recurved apical arms, trian-
gular, broader than long and acute at the tips, 0.7 mm long.
Capsule unknown.
Etymology. – The specific epithet refers to the North
(“Avaratra” in Malagasy) because the species occurs in the
northern part of Madagascar.
Distribution. – The species is known from Toamasina and
Antsiranana provinces in North-East Madagascar. Four popu-
lations each of between (4)-15-20 individuals were observed,
with a total of about 65-75 individuals observed in all sites.
Habitat and ecology. – Didymoplexis avaratraensis was
recorded in evergreen forest on metamorphic rock; up to
820 m. This terrestrial herb occurs in forests with dense
canopies reaching 10 to 15 m, with emergent trees reaching 18
to 20 m, with two woody strata in the canopy at 4 to 5 m and
at 1 to 1.5 m high, and with an absent, sparse or very sparse
ground flora, the soil densely covered with dry fallen leaves.
The most frequent species recorded together with D. avara-
traensis (considering the Loky-Manambato population) in veg-
etation surveys include, in decreasing abundance: Croton sp.,
Dypsis nodifera Mart., Ravenea sambiranensis Jum. & H. Perrier,
Dypsis aff. madagascariensis (Becc.) Beentje & J. Dransf. and
Noronhia sp.
Flowering time. – November to December.
Conservation Status. – With an extent of occurrence (EOO)
of 2,022 km
2
and area of occupancy (AOO) of 300 km
2
, and
only one subpopulation collected and three subpopulations
observed, all four in protected areas (Station Forestière à Usage
Multiple de Loky-Manambato, Marojejy National Park and
Mananara Nord National Park) , Didymoplexis avaratraensis
is assigned a preliminary status of “Vulnerable” (VU D2) fol-
lowing the IUCN Red List Categories and Criteria (IUCN,
2012; calculation following C
ALLMANDER & al. (2007) and
performed with MOAT (2012) tools.
Notes. – Didymoplexis avaratraensis is clearly distin-
guished from the other African and Malagasy species of Didy-
moplexis known with flowers (C
RIBB, 1984; CRIBB & al., 2011)
by its 2 lateral sepals fused to the mid-point while the remain-
ing two petals and sepal are adnate together in the basal fifth,
as well as by its column which has short recurved apical
arms that are acute at the tips, and by its lip lacking rows of
warts but with a bilobed callus at the apex. One observation
of predation of flowering plants by some kind of invertebrate
in one population is also interesting to note (Mark Clements,
pers. comm.).
How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? – 43

Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut., spec.
nova (Fig. 1, 4).
Typus: MADAGASCAR. Prov. Diego-Suarez/Antsiranana:
sous-préfecture de Vohemar, commune rurale de Daraina,
forêt de Binara, 13°15’S 49°37’E, fl., 985 m, 12.XII.2005,
Nusbaumer & Ranirison 1763 bis (holo-: G [G00181978]!;
iso-: TAN!, research herbarium of Daraina).
Affinis Didymoplexis avaratraensis sed floribius albis vel
roseis, sepalis petalisque latioribus, sepalis lateralibus
tertiobasali adnatis, labello late obovato emarginato, callo
elongato ad apicem trilobato et brachiis dolabriformibus
pendentibus ad apicem columnae satis distinguenda.
Holomycotrophic herb up to 10 cm tall, growing from a
subterranean elongated blackish tuberous rhizome. Leaves scale
like, very small. Inflorescence erect, racemose, laxly up to 6-
flowered, the flowers opening one at a time and successively;
peduncle slender, erect, bearing a small ovate bract below inflo-
rescence, white; rachis terete, slender; pedicel with longitudi-
nal ridges; bracts ovate, acute, 1.5-2 mm long. Flowers with
white sepals and petals and a white to rose-pink lip with a yel-
low callus, the column buff flushed. Dorsal sepal erect, lance-
olate, subacute, 7-8
 4-5 mm; lateral sepals adnate in basal
third, ovate, rounded to subacute, 7-8
 4-5 mm. Petals
oblanceolate, acute, 7-8  5-7.5 mm, adnate in basal third to
the sepals. Lip shortly narrowly clawed at base, very broadly
obovate-spatulate, emarginate, 3.5-4  5-6 mm, slightly
decurved at apex; callus on claw erect, dilated and 3-lobed at
tip. Column 3.5-5 mm long, slender at base, strongly winged
at apex, the wings dependent, recurved, rounded at tip, 1 mm
long. Fruit unknown.
Etymology. – The specific epithet refers to the column with
recurved apical arms bilobed at the tips.
Distribution. – The species is only known from the
Binara forests in the Loky-Manambato (Daraina) region, in
Antsiranana Province in North-East Madagascar. Only 15-
20 individuals were observed in one population in the Loky-
Manambato region among the 54,000 plant occurrences
recorded during the Loky-Manambato vegetation study
(NUSBAUMER, 2011).
Habitat and ecology. – Didymoplexis recurvata was recorded
in evergreen montane forest on metamorphic rock; at 985 m.
This terrestrial herb occurs in forests with canopies reaching 11
to 15 m, emergent trees reaching 21 to 24 m and with a second
aborescent stratum at 8 to 10 m, with two woody strata at 5 to
7 m and at 1 to 2 m high, and with a no herbaceous strata, the
soil densely covered with dry leaves of trees.
44 – Candollea 68, 2013
Table 1. – Known Didymoplexis Griff. herbarium collections (D. avaratraensis P. J. Cribb, Nusb. & L. Gaut., D. madagascariensis (H. Perrier) Summerh., D. recurvata
Characters used for «Perrier 11349» «Rasoavimbahoaka Hervouet’s fruiting Clement’s and Mackenzie’s Hervouet’s flowering
discrimination 748» photograph fruiting photographs photograph
(in decreasing order (26.X.2005) (19.XI.2006) (8.XII.2007)
of importance)
Arms at the apex unknown unknown unknown unknown present, triangular, acute
of the column at the tips, pink
Lateral sepal unknown unknown unknown unknown fused to the mid point
Lip unknown unknown unknown unknown lacking rows of warts,
strongly upcurved sides
Lip basal callus unknown unknown unknown unknown bilobed
Plant size [cm] ca. 10 up to 5 ca. 10
Petal and sepal color unknown unknown unknown unknown pale pink to pink
Petal and sepal unknown unknown unknown unknown unknown (a posteriori
length estimation of length of ca. 8 mm)
Capsule stalk elongated, up to elongated, up to a posteriori estimation elongated, up to 30-35 cm unknown
40 cm 32 cm of about 15 cm
Final identification D. madagascariensis D. sp. D. sp. D. sp. D. avaratraensis
Type of D. madagascariensis –– – – – – D

The most frequent species recorded together with D. recur-
vata in Loky-Manambato vegetation surveys include, in
decreasing abundance: Marojejya insignis Humbert, Ravenea
sambiranensis Jum. & H. Perrier, Dypsis nodifera Mart., Wein-
mannia decora Tul., Syzygium condensatum (Baker) Labat &
G. E. Schatz, Plagioscyphus aff. louvelii Danguy & Choux and
Blechnum attenuatum (Sw.) Mett. var. attenuatum.
Flowering time. – December.
Conservation Status. – With only one small subpopulation,
included in the Loky-Manambato protected area, Didymoplexis
recurvata is assigned a preliminary status of “Critically Endan-
gered” (CR D) following the IUCN Red List Categories and
Criteria (IUCN, 2012).
Notes. – Didymoplexis recurvata is clearly distinguished
from the other African and Malagasy species of Didymoplexis
known in flower by its column which has short recurved api-
cal arms that are bilobed at the tips, as well as by its lip which
lacks rows of warts but has at the base a tall apically trilobed
entire callus and by its sepals and petals that are adnate in the
basal third.
Conservation implications
These two new species add to numerous other botanical
and zoological taxa discovered in the Loky-Manambato area.
Based on these discoveries, the NGO Fanamby succeeded in
the establishment of a protected area (“station forestière à
usages multiples”, SFUM) for eight important forest blocks of
the Loky-Manambato region (RABOTOARISON, 2005), includ-
ing the forests where the two new Didymoplexis species have
been collected. Monitoring the populations is the next critical
step for the conservation of these species but it is a difficult
task since these plants do not conserve vegetative organs
aboveground, making them impossible to observe except dur-
ing the flowering time.
How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? – 45
P. J. Cribb, Nusb. & L. Gaut.) with observations (photographs), with the states of the main characters used for discrimination.
Clement’s and Mackenzie’s Castillon’s photograph «Nusbaumer & «Nusbaumer &
flowering photographs (17.VII.2010) Ranirison 1763» Ranirison 1763bis»
(18.XI.2006)
present, triangular, acute absent present, triangular, acute present, bilobed at the
at the tips, white at the tips, white tips, brown and white
fused to the mid point free almost to the base fused to the mid point adnate in the basal third
lacking rows of warts, presence of two lines of lacking rows of warts, lacking rows of warts,
strongly upcurved sides verrucose warts along strongly upcurved sides slightly emarginate, broadly
length, transversally triangular, obovate-spatulate, with
3-lobed at the tip sides only slightly upcurved
bilobed callus of two lines of small warts bilobed erect entire, trilobed at the tip
from base to tip with a fleshy
yellow ligule on the claw
10-15 unknown up to 15 up to 10
white with brown in the white white with brown in the white
centre centre
unknown (the whole flower unknown up to 15 mm 5-8 mm
was ca. 12-15 mm wide)
unknown unknown unknown unknown
D. avaratraensis D. verrucosa D. avaratraensis D. recurvata
–– D. avaratraensis D. recurvata

46 – Candollea 68, 2013
Fig. 1. – Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut. A. Habit; B, C. Flower, side view; D. Dorsal sepal abaxial view; E. Lateral sepals, front view; F. Lip (labellum),
flattened, front view; G. Labellum and column details, front view; H. Flower, front view. Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut. I. Flower, front view; J. Lip
(labellum), flattened, front view.
[A-H: Nusbaumer & Ranirison1763, G; I-J: Nusbaumer & Ranirison 1763bis, G] [Drawing: Juliet Beentje]
A
J
5
mm
5 mm
5 mm
10 mm
20 mm
20 mm
5 mm
5 mm
5 mm
I
H
B
E
D
F
C
G

How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? – 47
Fig. 2. – Didymoplexis avaratraensis P. J. Cribb, Nusb. & L. Gaut. A. Flower, front view; B. Labellum and column details, front view; C. Flower and pedicel, side view; D. Habit;
E. Tuberous rhizome.
[Nusbaumer & Ranirison 1763] [Photo: L. Nusbaumer, 12.XII.2005]

Key to flowering Didymoplexis in Africa and Madagascar
1. Two or more sepals or petals fused to the mid-point or
more, petals and sepals 11-15 mm.................................. 2
1a Sepals or petals adnate in the basal third or less but none
of them fused to the mid-point, petals and sepals 5-8 mm
long ................................................................................. 3
2. Lateral sepals fused to the mid-point, other sepal and petals
free to the base or fused to a fifth of their length; column
with short recurved triangular apical arms, broader than
long and acute at the tips; sepals and petals white up to
15 mm long; lip with a low basal bilobed callus and
strongly upcurved sides ......................... D. avaratraensis
2a All sepals and petals fused to the mid-point; column lack-
ing apical arms; sepals and petals white, up to 12 mm long;
lip flabellate, orbicular, distinctly clawed, apex of claw bear-
ing a reflexed or retrorsely placed ligule-like callus ............
........................................................................... D. africana
3 Column lacking apical arms; lip 3-lobed at the tip, with
two lines of verrucose warts along length; sepals and petals
white ............................................................ D. verrucosa
3a Column with recurved apical arms that are bilobed at the
tips; lip broadly obovate-spatulate, lacking rows of warts,
with sides only slightly upcurved, and a tall apically
trilobed callus at the base; sepals and petals white, pink or
brown ........................................................... D. recurvata
Acknowledgements
We would like to thank Juliet Beentje for the fine illustrations;
Melanie Thomas and Katherine Challis for commenting on the
Latin diagnoses; Jean-Philippe Castillon, Jean-Michel Hervouet,
Anne Mackenzie and Mark Clements for sharing with us the pre-
cious informations about their photographs. We thank Patrick
Ranirison for providing herbarium specimens, Rodolphe Spichiger
and Pierre-André Loizeau for giving us a strong support to carry
out the study in Loky-Manambato. We thank Martin Callmander
for assistance in evaluation of the IUCN Red List conservation
assessment. The research in Daraina (Loky-Manambato) was
funded by several institutions: the Conservatoire et Jardin
botaniques de la Ville de Genève, the University of Geneva,
Conservation International (CBC fund), the Malagasy NGO
“Fanamby” and “Fondation Jean-Marcel Aubert”. We would like
to thank these institutions as well as the Vontobel Stiftung for
financing the continuation of research, capacity building and col-
laborations in Madagascar. We also thank the Direction Générale
des Eaux et Forêts de Madagascar and the Département de Bio -
logie et Ecologie Végétale de l’Université d’Antananarivo for
supporting our project in Daraina (Loky-Manambato). Comments
by Jean-Michel Hervouet, Mark Clements, by anonymous review-
ers and by Candollea’s reviewers helped to clarify some ideas of
the text presented here.
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[Photos: A-B: Mark Clements and Anne Mackenzie, 18.XI.2006; C-D: Jean-Michel Hervouet, 8.XII.2007]

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How many species are there in the holomycotrophic genus Didymoplexis Griff. (Orchidaceae) in Madagascar? – 49
Fig. 4. – Didymoplexis recurvata P. J. Cribb, Nusb. & L. Gaut. A. Flower, front view; B. Flower from below, bud and pedicel.
[Nusbaumer & Ranirison 1763bis] [Photos: L. Nusbaumer, 12.XII.2005]