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Following the production of a near-comprehensive generic phylogenetic analysis of African angraecoid orchids, paraphyly of the genus Rhipidoglossum relative to Cribbia, Margelliantha and Rhaesteria was in need of being resolved by integrating morphological observations into this newly available molecular framework. Accordingly, we critically revised the diagnostic traits of each genus by examining about 700 herbarium specimens ascribable to 50 species of Rhipidoglossum and its satellite genera. Cribbia, Margelliantha and Rhaesteria are here lumped with Rhipidoglossum, along with Angraecopsis pusilla and Diaphananthe millarii. The presence of pollinaria with two separate disk-shaped viscidia, a trilobed, non-papillate rostellum with midlobe more prominent than lateral lobes and an undivided lip are diagnostic of this more inclusive concept of Rhipidoglossum. In line with this new taxonomic arrangement, 11 new combinations in Rhipidoglossum are made, and Margelliantha lebelii is moved to Diaphananthe and first reported for Uganda.
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Phytotaxa 349 (3): 247–256
http://www.mapress.com/j/pt/
Copyright © 2018 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Mark Chase: 18 Apr. 2018; published: 15 May 2018
https://doi.org/10.11646/phytotaxa.349.3.5
247
A revised concept of Rhipidoglossum (Angraecinae, Orchidaceae)
JOÃO N. M. FARMINHÃO1,2*, PIERRE MEERTS1,2, PASCAL DESCOURVIÈRES3, VINCENT DROISSART1,4,5,6,
MURIELLE SIMO-DROISSART6 & TARIQ STÉVART1,5,7
1Herbarium et Bibliothèque de Botanique africaine, C.P. 265, Université Libre de Bruxelles, Campus de la Plaine, Boulevard du Triom-
phe 1050, Brussels, Belgium; E-mail: jnunesde@ulb.ac.be
2Plant Ecology and Biogeochemistry, C.P. 244, Université Libre de Bruxelles, Campus de la Plaine, Boulevard du Triomphe, 1050,
Brussels, Belgium
3UMR 7207 CNRS-MNHN-UPMC, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, 57 rue Cuvier, CP 48, FR
75005, Paris, France
4AMAP, IRD, CIRAD, CNRS, INRA, Univ de Montpellier, Montpellier, France
5Missouri Botanical Garden, Africa and Madagascar Department, P.O. Box 299, St. Louis, Missouri 63166-0299, USA
6Plant Systematics and Ecology Laboratory, Higher Teachers’ Training College, University of Yaoundé I, P.O. Box 047, Yaoundé, Cam-
eroon
7Botanic Garden Meise, Domein van Bouchout, Nieuwelaan 38, B-1860 Meise, Belgium
Abstract
Following the production of a near-comprehensive generic phylogenetic analysis of African angraecoid orchids, paraphyly
of the genus Rhipidoglossum relative to Cribbia, Margelliantha and Rhaesteria was in need of being resolved by integrating
morphological observations into this newly available molecular framework. Accordingly, we critically revised the diagnostic
traits of each genus by examining about 700 herbarium specimens ascribable to 50 species of Rhipidoglossum and its satel-
lite genera. Cribbia, Margelliantha and Rhaesteria are here lumped with Rhipidoglossum, along with Angraecopsis pusilla
and Diaphananthe millarii. The presence of pollinaria with two separate disk-shaped viscidia, a trilobed, non-papillate
rostellum with midlobe more prominent than lateral lobes and an undivided lip are diagnostic of this more inclusive concept
of Rhipidoglossum. In line with this new taxonomic arrangement, 11 new combinations in Rhipidoglossum are made, and
Margelliantha lebelii is moved to Diaphananthe and first reported for Uganda.
Abstract (French)
Suite à des analyses phylogénétiques presque exhaustives pour les genres d’orchidées angraecoïdes d’Afrique, la paraphylie
du genre Rhipidoglossum par rapport à Cribbia, Margelliantha et Rhaesteria avait besoin d’être revisée en intégrant des
observations morphologiques dans ce nouveau cadre moléculaire. En conséquence, nous avons procédé à une révision cri-
tique des caractères diagnostiques de chaque genre en examinant environ 700 spécimens d’herbiers appartenant à 50 espèces
de Rhipidoglossum et à ses genres satellites. Cribbia, Margelliantha et Rhaesteria sont à regrouper avec Rhipidoglossum,
ainsi qu’Angraecopsis pusilla et Diaphananthe millarii. La présence de pollinies avec deux viscidies discoïdales séparées,
un rostellum trilobé non papilleux, avec son lobe médian plus proéminent que les lobes latéraux, et un labelle entier, sont
les caractères diagnostiques de ce concept plus inclusif du genre Rhipidoglossum. Conformément à ce nouvel arrangement
taxonomique, 11 nouvelles combinaisons de Rhipidoglossum sont proposées et Margelliantha lebelii est transférée dans
Diaphananthe. Margelliantha lebelii est pour la première fois signalée en Ouganda.
Key words: African orchids, angraecoids, Angraecopsis, Cribbia, Diaphananthe, Epidendroideae, Margelliantha, Mysta-
cidium, orchid taxonomy, Rhaesteria, Sphyrarhynchus, stigmatic callus,Vandeae
Introduction
Rhipidoglossum Schlechter (1918: 81) is part of the mostly Afro-Malagasy subtribe Angraecinae, which has undergone
a spectacular radiation event in the past five million years (Givnish et al. 2015). Generic boundaries in Angraecinae are
FARMINHÃO ET AL.
248 Phytotaxa 349 (3) © 2018 Magnolia Press
considered by Chase et al. (2015) as one of the major remaining unresolved issues in Epidendroideae taxonomy and
have thus been the focus of a large project concerning the taxonomy of this large group (Simo-Droissart et al. 2018) of
about 760 species (Pridgeon et al. 2014).
Rhipidoglossum was first revised by Summerhayes (1937), who designated Rhipidoglossum xanthopollinium
(Reichenbach 1885: 382) Schlechter (1918: 81) as type species. As most recently circumscribed (Cribb 2014a),
Rhipidoglossum also includes taxa formerly placed in the defunct genera Sarcorhynchus Schlechter (1918: 104) and
Crossangis Schlechter (1918: 141), comprising 38 accepted species confined to tropical and southern Africa (Govaerts
et al. 2017). Based on an overall morphological similarity, Summerhayes (1960) subsumed Rhipidoglossum under
Diaphananthe Schlechter (1915: 53) as a section of the later, and this treatment was subsequently adopted by several
authors working on the flora of Tropical Africa (e.g. Hall 1974, Rasmussen 1974, Cribb 1989, Geerinck 1992, la Croix &
Cribb 1998). However, an enlarged concept of Diaphananthe including Rhipidoglossum was shown to be polyphyletic
by the molecular studies in Carlsward et al. (2006) and Freudenstein & Chase (2015) and a recently produced broad
phylogenetic analysis of Angraecinae (Simo-Droissart et al. 2018), in which Rhipidoglossum is retrieved as sister to
Mystacidium Lindley (1837: 205), Angraecopsis Kränzlin (1900: 171) and Sphyrarhynchus Mansfeld (1935: 706). This
finding has given credit to the taxonomic treatment of Garay (1972), who was the first to reinstate Rhipidoglossum,
drawing attention to the distinctive morphology of the pollinaria with two separate viscidia versus a single viscidium
found in Diaphananthe. Molecular phylogenetics has also shown that Rhaesteria Summerhayes (1966: 191), Cribbia
Senghas (1985: 19), part of Margelliantha Cribb (1979: 329) and Angraecopsis pusilla Summerhayes (1951: 258) are
nested in Rhipidoglossum (Simo-Droissart et al. 2018). Also, Margelliantha caffra (Bolus 1893: t. 8) Cribb & Stewart
(1985: 413) and Diaphananthe millarii (Bolus 1905: 147) Linder (1989: 318), were found to be sister to Rhipidoglossum
plus the satellite genera, Cribbia, Margelliantha and Rhaesteria (Simo-Droissart et al. 2018). Accordingly, Simo-
Droissart et al. (2018) suggested that all these taxa should be lumped into a broad concept of Rhipidoglossum. Here we
critically review the morphological traits that support the taxonomic rearrangements proposed by Simo-Droissart et al.
(2018). A short account of the nomenclatural history is provided for each genus or group of species to be moved into
Rhipidoglossum, and the necessary nomenclatural changes, consisting of 11 new combinations in Rhipidoglossum, are
also presented.
Materials and methods
About 700 specimens of 48 species of Rhipidoglossum, Rhaesteria, Cribbia, Margelliantha, Angraecopsis pusilla
and Diaphananthe millarii, were examined using standard herbarium practices (de Vogel 1987), including material
housed in BM, BR, BRLU, COI, K, LISC, LISU, MO, NU, P and UPS (acronyms following Thiers 2017, continuously
updated). Additionally, the type specimens of Diaphananthe millarii and Margelliantha caffra were not available in
these herbaria and were examined through the Global Plants facility (JSTOR 2000-2017). Photographs of living plants,
retrieved from Orchidaceae of Central Africa (Droissart et al. 2017) and from the World orchid iconography (WOI
2015-2017) of the Swiss Orchid Foundation at the Herbarium Jany Renz and the Botanical Institute of the University
of Basel, were also examined. The distribution of character states indicated as diagnostic for each genus in protologues
and other relevant literature were critically reviewed considering a comprehensive phylogenetic analysis of the African
angraecoids presented in Simo-Droissart et al. (2018). Accordingly, generic boundaries were reassessed adopting a
strictly phylogenetic view of Linnaean taxonomy (e.g. Bateman 2009, Chase et al. 2015).
Taxonomic treatment
New generic boundaries and diagnostic traits of Rhipidoglossum
Rhipidoglossum forms a well-supported clade if Rhaesteria, Cribbia, part of Margelliantha (i.e. excluding M. caffra
and M. lebelii Eb.Fisch. & Killmann in Killmann & Fischer 2007: 745), and Angraecopsis pusilla are subsumed under
it. This group of taxa can be recognised morphologically by the shared presence of pollinaria with two separate disk-
shaped viscidia, a trilobed non-papillate rostellum with midlobe more prominent than lateral lobes and an entire lip.
Overall, presence of two separate viscidia in African angraecoids is relatively infrequent and can only be found in
A REVISED CONCEPT OF RHIPIDOGLOSSUM Phytotaxa 349 (3) © 2018 Magnolia Press 249
Dolabrifolia (Pfitzer 1889: 216) Szlachetko & Romowicz (2007: 54) apart from the Sphyrarhynchus-Angraecopsis-
Mystacidium-Rhipidoglossum clade (Simo-Droissart et al. 2018). Two separate viscidia can also be found in Angraecum
claessensi De Wildeman (1916: 184) and A. firthii Summerhayes (1958: 267), but in this case the two viscidia initially
adhere to each other and come away together when removed from the column (Summerhayes 1958).
Margelliantha caffra and Diaphananthe millarii form a clade sister to this more inclusive concept of Rhipidoglossum,
and since they also share the same general floral morphology (e.g. non-papillate rostellum with a prominent midlobe),
they too are here included in Rhipidoglossum. In turn, Sphyrarhynchus, Angraecopsis and Mystacidium together are
sister to this inclusive concept of Rhipidoglossum, and the four genera share the same trilobed rostellar structure. This
observation led Rice (2005) to move Cribbia, Margelliantha and part of Rhipidoglossum into Angraecopsis, creating the
new subgenera Cardiochilos Rice (2005: 19) and Angraecopidoglossum Rice (2005: 21) within the last to encompass
these species. Contrary to what is stated by Cribb (2014a: 433), Rice (2006) did not formally move Rhipidoglossum
into Mystacidium, despite his claim that no clear differences could be found among Rhipidoglossum, Angraecopsis
and Mystacidium. However, Angraecopsis and Mystacidium present a distinctive trilobed lip and a rostellum in which
lateral lobes are longer or subequal in length to the midlobe, which sets them apart from Rhipidoglossum. Additionally,
in the case of Mystacidium, the lateral lobes of the rostellum are covered in conspicuous papillae absent in any other
closely related taxa. In Angraecopsis sect. Coenadenium Summerhayes (1951: 259), in Mystacidium pulchellum
(Kränzlin 1900: 374) Schlechter (1918: 126) and in Sphyrarhynchus, the two visicidia are connate. A taxonomic
revision of Sphyrarhynchus, Angraecopsis and Mystacidium (the ‘SAM clade’) is presented by Martos et al. (2017),
shedding further light on the taxonomy of the SAM alliance and Rhipidoglossum. Martos et al. (2017) have notably
found Mystacidium to be polyphyletic, with Mystacidium tanganyikense Summerhayes (1945: 113) from Tanzania
and the Zambezian region located in Rhipidoglossum and satellite genera. Despite presence of conspicuous papillae
on the rostellum arms that sets the species apart (Martos et al. 2017), the prominent midlobe of the rostellum of M.
tanganyikense together with overall floral morphology also suggest that it is best treated in Rhipidoglossum. Finally,
future revisionary work should focus on exploring the phylogenetic affinities of poorly known species of Rhipidoglossum
(e.g. Rhipidoglossum stellatum (Cribb 1989: 538) Szlachetko & Olszewski 2001: 850, Rhipidoglossum oxycentron
(Cribb 1977: 180) Senghas 1986: 1111) and the SAM clade (i.e. Mystacidium nguruense Cribb 1989: 596 and M.
pulchellum) endemic to East Africa. Considering their overall floral morphology, M. nguruense may be best treated in
Rhipidoglossum, whereas M. pulchellum with its single viscidium and zig-zag inflorescence axis (Schuiteman 1981)
is probably best placed in Sphyrarhynchus. Inclusion of these species in a comprehensive molecular phylogenetic
framework will be key to further clarify relationships of Rhipidoglossum and putatively morphologically similar
taxa.
Margelliantha caffra and Diaphananthe millarii:—These two species (Fig. 1F) form a well-supported clade
(Simo-Droissart et al. 2018) characterised by short stems, white tepals contrasting with a green column, slender floral
pedicels, an elongate cylindrical lip spur and a peg-like median rostellar lobe. Both species were formerly placed in
Mystacidium (Bolus 1905) and are endemic to eastern South Africa (Govaerts et al. 2017). Rostellar structure and overall
floral morphology of the two species are similar to those of Rhipidoglossum curvatum (Rolfe 1897: 174) Garay (1972:
195) (Fig. 1B), and the white conspicuously pedicellate flowers with a contrasting green anther cap are reminiscent
of those of Margelliantha and Cribbia thomensis la Croix & P.J.Cribb in Cribb & la Croix (1997: 745). The latter
led Cribb & Stewart (1985) to move Mystacidium caffrum (Bolus) Bolus (1905: 145) to Margelliantha. Afterwards
Linder (1989), recognising the clear similarity of Mystacidium millarii Bolus (1905: 147) and Margelliantha caffra,
moved both into Diaphananthe, drawing attention to their rostellar structure and that of Rhipidoglossum montanum
(Piers 1969: 248) Senghas (1986: 1111) (see also Cribb & Stewart 1985), then regarded as part of Diaphananthe.
Carlsward et al. (2006) were the first to retrieve D. millarii as sister to Rhipidoglossum and Cribbia, a relationship
confirmed by Simo-Droissart et al. (2018), who found this species together with M. caffra as sister of Rhipidoglossum.
We preliminarily considered creating a new genus that would be sister to Rhipidoglossum to accommodate these two
species, but their overall floral resemblance to Rhipidoglossum led us to move both into a morphologically diverse
(Fig. 1) and geographically widespread Rhipidoglossum. In this way, we follow the general prescription of avoiding
the recognition of small genera with little grouping information (Bateman 2009). Mystacidium tanganyikense was
found to be nested in the same clade grouping D. millarii and M. caffra by Martos et al. (2018), who pointed out the
presence of a penicillate callus in the mouth of the spur as a feature common to the three species. In habit, with its short
stem and pendent wiry inflorescences, M. tanganyikense presents some similarities to Rhipidoglossum melianthum
(Cribb 1979: 335) Senghas (1986: 1110) from Tanzania. In turn, regarding its floral morphology, M. tanganyikense is
morphologically similar to R. stellatum and Rhipidoglossum tanneri (P.J.Cribb in Cribb & Stewart 1985: 411) Senghas
(1986: 1111), also from Tanzania, with which it shares a similar midlobe of the rostellum with a conspicuous bifid apex.
FARMINHÃO ET AL.
250 Phytotaxa 349 (3) © 2018 Magnolia Press
Whether these morphological traits of M. tanganyikense and these Rhipidoglossum species are due to common descent
or a result of convergent evolution associated to a common pollinator guild is something to be ascertained in future
phylogenetic studies of Rhipidoglossum. Without a more comprehensive molecular sampling of Rhipidoglossum and
SAM species, notably from East Africa, we prefer not to transfer M. tanganyikense to Rhipidoglossum at this time.
.
FIGURE 1. An overview of floral diversity in Rhipidoglossum, including species formerly placed in Rhaesteria, Cribbia and Margelliantha.
A. Rhipidoglossum xanthopollinium. B. Rhipidoglossum curvatum. C. Rhipidoglossum densiflorum. D. Rhipidoglossum rutilum.
E. Rhipidoglossum eggelingii. F. Rhipidoglossum millarii. G. Rhipidoglossum leedalii. H. Rhipidoglossum burttii. I. Rhipidoglossum
clavatum. J. Rhipidoglossum thomense. K. Rhipidoglossum brachyceras. L. Rhipidoglossum confusum. M. Rhipidoglossum pendulum. N.
Rhipidoglossum pusillum. Photographs A & K by Vincent Droissart; B by Thomas Couvreur; C, D, J, L & M by Tariq Stévart; E, H & N
by Eberhard Fischer; F by Benny Bytebier; G by Phillip J. Cribb; I by E. Tanner via the World orchid iconography.
Rhaesteria:—Rhaesteria eggelingii Summerhayes (1966: 191; Fig. 1E), the single species of Rhaesteria, was
found to be deeply embedded in Rhipidoglossum (Simo-Droissart et al. 2018). This Albertine Rift endemic is only
A REVISED CONCEPT OF RHIPIDOGLOSSUM Phytotaxa 349 (3) © 2018 Magnolia Press 251
known from the montane forests of Uganda and Rwanda (Fischer et al. 2010, Govaerts et al. 2017). Specimens
attributed to this taxon were misidentified by Geerinck (1988, 1990) as Angraecum humile Summerhayes (1958:
269) and A. pettersonianum Geerinck (1990: 181; Delepierre & Lebel 2001). The morphological uniqueness of the
genus supposedly rests on the presence of a hammer-shaped median rostellar lobe and connation of tepals along their
basal third (Summerhayes 1966). Comparative morphological analysis revealed, however, that an identical hammer-
shaped rostellum can also be found in some species of Rhipidoglossum, notably R. melianthum, R. ochyrae Szlachetko
& Olszewski (2001: 868), R. stellatum and R. tanneri, and the basal tepal connation, although not as evidently, is
also observed in R. adoxum (Rasmussen 1974: 229) Senghas (1986: 1110). Rice (2005) pointed out the similarity of
Rhaesteria to some species of Rhipidoglossum, notably to R. melianthum and R. stellatum, for which he created the
section Malleiform Rice (2005: 20) within Angraecopsis. Molecular results of Simo-Droissart et al. (2018) indicate,
however, a close relationship of Rhaesteria to R. rutilum (Reichenbach 1885: 382) Schlechter (1918: 81), but a more
comprehensive sampling of Rhipidoglossum is needed to clarify infrageneric taxonomy. In any case, all results strongly
support inclusion of Rhaesteria in Rhipidoglossum.
Margelliantha:—The genus as circumscribed by Cribb (2014b) was revealed to be polyphyletic by Simo-Droissart
et al. (2018) with M. lebelii being nested in Diaphananthe, and M. caffra sister to D. millarii, as previously discussed.
We will first discuss the four species of Margelliantha s.s. originally enumerated by Cribb (1979) in his description of
the genus: Margelliantha leedalii Cribb (1979: 333; Fig. 1G), the type species, Margelliantha globularis Cribb (1979:
331), Margelliantha clavata Cribb (1979: 331) and Margelliantha burttii Summerhayes (1937: 82) Cribb (1979: 331).
These four species form a morphologically cohesive group. Margelliantha burtii (Fig. 1H) is nested in Rhipidoglossum
as sister to Cribbia plus Angraecopsis pusilla (see Simo-Droissart et al. 2018). Margelliantha burttii was originally
described by Summerhayes (1934) in Diaphananthe but later transferred to Rhipidoglossum (Summerhayes 1937).
This species differs from the other three Margelliantha in its larger size and occurrence in the Albertine Rift (Govaerts
et al. 2017). Cribb (1979) based the description of Margelliantha on the shared campanulate pearly white flowers,
ecallose lip, thin-textured rostellum and prominent rim on the lower margin of the stigma. However, none of these
character states is mutually exclusive relative to Rhipidoglossum, and Geerinck (1992) was the first to question whether
Margelliantha should instead be included in Rhipidoglossum (then Diaphananthe sect. Rhipidoglossum). A lip callus
can actually be found in M. clavata (Fig. 1I), challenging the original description and delimitation of Margelliantha.
A prominent lower rim on the stigma, which we suggest being termed a stigmatic callus, also occurs in Cribbia (being
particularly conspicuous in C. pendula la Croix & Cribb in P.J.Cribb & la Croix (1997: 747) and in some species of
Rhipidoglossum such as R. candidum (Cribb 1979: 335) Senghas (1986: 1110) and R. tenuicalcar (Summerhayes 1945:
109) Garay (1972: 196). Although the median rostellar lobe of Margelliantha (and Cribbia) has been described as thin-
textured and digitiform and thus different from the peg-like one reported for Rhipidoglossum, intermediate states can
be observed among Rhipidoglossum species, with R. kamerunense (Schlechter 1906: 161) Garay (1972: 195), and
R. mildbraedii (Kränzlin 1909: 342) Garay (1972: 195), illustrating such morphological variation. Rhipidoglossum
mildbraedii, a little known-species endemic to the volcano belt of eastern Democratic Republic of the Congo (Govaerts
et al. 2017), is particularly close to Margelliantha in its overall morphology. Finally, the striking similarity in floral
morphology among Margelliantha, C. thomensis and M. caffra/D. millari is possibly due to convergent evolution
associated with a shared group of pollinators. We therefore propose to lump Margelliantha with Rhipidoglossum.
Finally, the presence of a single viscidium and a thickened inflorescence axis, reminiscent of that of Diaphananthe
divitiflora (Kränzlin 1895: 28) Schlechter (1918: 98), together with molecular data support the inclusion of M. lebelii
in Diaphananthe. Here, we also report the first record of this species for Uganda and propose a new combination in
agreement with this taxonomic treatment.
Cribbia:—All four species of Cribbia (Fig. 1J–M) were found to be nested in Rhipidoglossum with Angraecopsis
pusilla as their sister (Simo-Droissart et al. 2018). Senghas (1985) described Cribbia as including only C. brachyceras
(syn. Rangaeris biglandulosa Summerhayes 1936: 228). It was a segregate of Rangaeris Summerhayes (1936: 227),
and Senghas alluded to its divergent pollinarium structure comprising two viscidia. Later, Senghas (1986) suggested
a close relationship between Cribbia and Rhipidoglossum based on distinctiveness of their two separate viscidia,
an opinion confirmed by Carlsward et al. (2006) in their molecular analysis. Cribb (1996) and Cribb & la Croix
(1997) described three additional species in the genus from the Atlantic side of central Africa, including two endemics
from São Tomé (Stévart & Oliveira 2000). The column of Cribbia is similar to that of Margelliantha, and the same
comparative considerations relative to Rhipidoglossum also apply here. The most distinctive traits of Cribbia are their
narrowly ovate and not orbicular to flabellate sepals, petals and lip that also occur in most species of Rhipidoglossum.
However, Rhipidoglossum microphyllum Summerhayes (1945: 93) and R. montanum also have narrowly ovate tepals,
and the overall floral appearance of the former is reminiscent of that of Cribbia. Molecular data are pending to clarify
whether this species is closely related to Cribbia. The molecular results of Simo-Droissart et al. (2018) identify a clade
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252 Phytotaxa 349 (3) © 2018 Magnolia Press
comprising A. pusilla, Cribbia, Margelliantha, Rhipidoglossum arbonnieri (Geerinck in Arbonnier & Geerinck 1993:
256) Fischer et al. (2011: 445) and R. kamerunense. These taxa share the same habit with short stems and possess
conspicuously pedicellate flowers disposed along a distichous inflorescence and a dorso-ventrally flattened median
rostellar lobe. This set of character states is divergent from most species of Rhipidoglossum, which develop long stems
and have short pedicels. However, additional molecular sampling is needed to resolve the infrageneric taxonomy of
our recircumscribed concept of Rhipidoglossum. Meanwhile, considering all evidence, Cribbia is to be subsumed in
Rhipidoglossum.
Angraecopsis pusilla:—This species (Fig. 1N) was identified as sister to Cribbia by Simo-Droissart et al. (2018),
and consequently it is also embedded in Rhipidoglossum. This dwarf epiphytic species endemic to the Albertine Rift
(Fischer et al. 2010) was described by Summerhayes (1951), who erected the new section Cardiochilos based on its
entire lip to accommodate this “aberrant species” of Angraecopsis. Its ovate lip, two separate viscidia and rostellar
structure corroborate its relationships as highlighted by Martos et al. (2017) and Simo-Droissart et al. (2018), and,
thus, we propose to move this species to Rhipidoglossum. Two other species of Angraecopsis were included in section
Cardiochilos, Angraecopsis lovettii Cribb (1989: 601) and Angraecopsis malawiensis P.J.Cribb in la Croix et al. (1983:
26), by Cribb & la Croix (1998), but to clarify their position relative to A. pusilla a detailed morphological examination
and molecular analysis is needed for Rhipidoglossum and species in the SAM clade.
New combinations in Diaphananthe and Rhipidoglossum
Diaphananthe lebelii (Eb.Fisch. & Killmann) Descourvières & Stévart comb. nov.
Basionym: Margelliantha lebelii Eb.Fisch. & Killmann in Killmann & Fischer (2007: 745). Type:—RWANDA.
Western Province, Nyungwe National Park, km 76.5 Butare–Cyangugu, 19 December 2007, Fischer & Lebel 14123
(holotype: BR!, BR0000006782504)
Additional specimens examined:—UGANDA. sin. loc., 22 December 1960, Burgess in Mason 691 (K!,10296).
Rhipidoglossum Schlechter (1918: 80). Type species (designated by Summerhayes 1937: 80): Rhipidoglossum
xanthopollinium (Rchb.f.) Schlechter (1918: 81).
Margelliantha Cribb (1979: 329). Type species: Margelliantha leedalii Cribb (1979: 333).
Cribbia Senghas (1985: 19). Type species: Cribbia brachyceras (Summerh.) Senghas (1985: 19).
Rhaesteria Summerhayes (1966: 191). Type species: Rhaesteria eggelingii Summerhayes (1966: 191).
Rhipidoglossum brachyceras (Summerh.) Farminhão & Stévart, comb. nov.
Basionym: Aerangis brachyceras Summerhayes (1934: 213). Type:—DEMOCRATIC REPUBLIC OF THE
CONGO. Virunga Mts.: E. of Mt. Namlagira, Kanamaharargi Lavas, January 1931, Burtt 3123 (holotype: K!,
K000306405).
Homotypic synonyms:
Rangaeris brachyceras (Summerh.) Summerhayes (1936: 228).
Cribbia brachyceras (Summerh.) Senghas (1985: 19).
Azadehdelia brachyceras (Summerh.) Braem nom. superfl. (1988: 34).
Angraecopsis brachyceras (Summerh.) Rice (2005: 19).
Heterotypic synonym:
Rangaeris biglandulosa Summerhayes (1936: 228). Type:—GUINEA. Fouta Djallon: Dalaba Plateau, Diaguissa, 1000–
1300 m, October 1907, Chevalier 18782 (holotype P!, MNHN-P-P00388173; isotype P!, MNHN-P-P00388172).
Rhipidoglossum caffrum (Bolus) Farminhão & Stévart, comb. nov.
Basionym: Angraecum caffrum Bolus (1893: t. 8). Type:—SOUTH AFRICA. Pondoland: Emagusheni inter Fort
William and Umtamvuna, 3500 ft, January 1886, Tyson 2841 (lectotype: BOL image!, BOL149998; isolectotype:
K).
Homotypic synonyms:
Mystacidium caffrum (Bolus) Bolus (1905: 145).
Margelliantha caffra (Bolus) Cribb & Stewart (1985: 413).
Diaphananthe caffra (Bolus) Linder (1989: 318).
Angraecopsis caffra (Bolus) Rice (2005: 19), nom inval..
Rhipidoglossum clavatum (P.J.Cribb) Farminhão & Stévart comb. nov.
Basionym: Margelliantha clavata Cribb (1979: 331). Type:—TANZANIA. Lushoto District: W Usambara Mts,
Magamba Forest Reserve, fl. in cult., 6 March 1943, Eggeling in Moreau 400 (holotype K!, K000284750; isotype
EA).
A REVISED CONCEPT OF RHIPIDOGLOSSUM Phytotaxa 349 (3) © 2018 Magnolia Press 253
Homotypic synonym:
Angraecopsis clavata (P.J.Cribb) Rice (2005: 21).
Rhipidoglossum confusum (P.J.Cribb) Farminhão & Stévart, comb. nov.
Basionym: Cribbia confusa Cribb (1996: 359). TYPE:—CAMEROON. Mt Cameroon, Mapanja to Mann’s Spring, 6
October 1992, Thomas 9365 (holotype: K!, K000107356; isotype: YA).
Homotypic synonyms:
Angraecopsis confusa (P.J.Cribb) Rice (2005: 19).
Rhipidoglossum eggelingii (Summerh.) Farminhão & Stévart, comb. nov.
Basionym: Rhaesteria eggelingii Summerhayes (1966: 191). Type:—UGANDA. Kigezi: Impenetrable Forest, on
small savanna tree in grassland on outskirts, November 1948, Eggeling 5849 (holotype: K!, K000306602).
Heterotypic synonym:
Angraecum petterssonianum Geerinck (1990: 181). Type:—RWANDA. Nyungwe: 2300 m, 1975, Troupin 15744
(holotype: BR!, BR0000008814753).
Rhipidoglossum globulare (P.J.Cribb) Farminhão & Stévart, comb. nov.
Basionym: Margelliantha globularis Cribb (1979: 331). Type:—TANZANIA. Morogoro District: Uluguru Mts,
1250 m, 25 September 1932, Wallace 172 (holotype: K!, K000354425).
Homotypic synonym:
Angraecopsis globularis (P.J.Cribb) Rice (2005: 21).
Rhipidoglossum leedalii (P.J.Cribb) Farminhão & Stévart, comb. nov.
Basionym: Margelliantha leedalii Cribb (1979: 333). Type:—TANZANIA. Morogoro District: Uluguru Mts, Bondwa,
track up to E ridge of peak, 23 January 1976, Cribb & Grey-Wilson 10380 (holotype: K!, K000284733).
Homotypic synonym:
Angraecopsis leedalii (P.J.Cribb) Rice (2005: 21).
Rhipidoglossum millarii (Bolus) Farminhão & Stévart, comb. nov.
Basionym: Mystacidium millarii Bolus (1905: 147). Type:—SOUTH AFRICA. Natal: near Durban, 8 January 1902,
Millar in Medley-Wood 8437 (holotype: BOL image!, BOL149999).
Homotypic synonyms:
Diaphananthe millarii (Bolus) Linder (1989: 318).
Angraecopsis millarii (Bolus) Rice (2005: 19).
Rhipidoglossum pendulum (la Croix & P.J.Cribb) Farminhão & Stévart, comb. nov. Basionym: Cribbia pendula
la Croix & P.J.Cribb in Cribb & la Croix (1997: 747). Type:—SÃO TOMÉ AND PRÍNCIPE. Pico São Tomé: 28
February 1995, Brune in la Croix ST38A (holotype: K!, K000220048).
Homotypic synonym:
Angraecopsis pendula (la Croix & P.J.Cribb) Rice (2005: 20).
Rhipidoglossum pusillum (Summerh.) Farminhão & Stévart, comb. nov.
Basionym: Angraecopsis pusilla Summerhayes (1951: 258). Type:—DEMOCRATIC REPUBLIC OF THE
CONGO. Parc National Albert: Nyamlagira–Tsambene, 1700 m, 16 January 1945, Germain 3432 (holotype: BR!,
BR0000008809872; isotype: K!, 10664.000).
Rhipidoglossum thomense (la Croix & P.J.Cribb) Farminhão & Stévart, comb. nov.
Basionym: Cribbia thomensis la Croix & P.J.Cribb in Cribb & la Croix (1997: 745). Type:—SÃO TOMÉ AND
PRÍNCIPE. Pico São Tomé: Brune in la Croix ST38 (holotype : K!, K000306404).
Homotypic synonym:
Angraecopsis summerhayesii Rice (2005: 20), published as a nom. nov.
Acknowledgements
We thank the curators and staff of BM, BR, BRLU, COI, K, LISC, LISU, MO, NU, P and UPS for making their
collections available and kindly allowing us to use the facilities of their institutions. Lab work and herbarium visits were
supported by the U.S. National Science Foundation (1051547, T. Stévart as PI, G. M. Plunkett as Co-PI.). Additionally,
within the framework of the first author’s MSc and ongoing PhD work, funding was obtained from a TROPIMUNDO
Erasmus Mundus Category B scholarship and by a grant of the Fund for Research Training in Industry and Agriculture
(FNRS-FRIA). We are grateful to the American Orchid Society for support of the three last authors’ work in Central
FARMINHÃO ET AL.
254 Phytotaxa 349 (3) © 2018 Magnolia Press
Africa. We thank Benny Bytebier, Eberhard Fischer, Phillip J. Cribb and Thomas Couvreur for making available their
photos of Rhipidoglossum. Finally, we thank editor Mark W. Chase and two anonymous reviewers for their comments
and corrections, which helped to improve this manuscript substantially.
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