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494
Systematic Botany (2005), 30(3): pp. 494–502
qCopyright 2005 by the American Society of Plant Taxonomists
Reassessing the Generic Status of Petalolophus (Annonaceae): Evidence for
the Evolution of a Distinct Sapromyophilous Lineage within Pseuduvaria
Y
VONNE
C. F. S
U
,
1
J
OHAN
B. M
OLS
,
2
W
AYNE
T
AKEUCHI
,
3
P
AUL
J. A. K
E
ß
LER
,
2
and
R
ICHARD
M. K. S
AUNDERS
1,4
1
Department of Ecology & Biodiversity, The University of Hong Kong, Pokfulam Road, Hong Kong, China;
2
Nationaal Herbarium Nederland, Universiteit Leiden branch, P.O. Box 9514, 2300 RA Leiden, The Netherlands;
3
Papua New Guinea National Forest Authority, Papua New Guinea Forest Research Institute, Lae 411,
Morobe Province, Papua New Guinea
4
Author for Correspondence (saunders@hkucc.hku.hk).
Communicating Editor: Thomas A. Ranker
A
BSTRACT
.The genus Petalolophus (Annonaceae) consists of only one species, P. megalopus, which is characterised by the
possession of elaborate perianth wings that extend abaxially from the midrib of the inner petals. Recently published mo-
lecular phylogenetic data suggest that Petalolophus is congeneric with Pseuduvaria. Morphological and anatomical character-
istics of both genera are critically re-examined and shown to support this conclusion: Petalolophus shares numerous charac-
teristics in common with Pseuduvaria (particularly species from New Guinea) and it is only the autapomorphic possession
of extended perianth wings that currently distinguish Petalolophus from Pseuduvaria.Petalolophus megalopus is accordingly
formally transferred to Pseuduvaria. Field observations reveal that the flowers of Pseuduvaria megalopus are visited by flies; it
is likely that pollination is sapromyophilous, and that the inner petal wings attract flies by mimicking carrion.
The genus Petalolophus K. Schum. (Annonaceae) con-
sists of a single species, Pe. megalopus K. Schum. (Figs.
1–3), which is endemic to tropical lowland forests in
Papua New Guinea (Schumann and Lauterbach 1905).
As with most Annonaceae, the flowers have a whorl
of three sepals, and two whorls of three petals each.
The inner petals are connivent over the reproductive
organs, and are unique in the family in possessing
large, outwardly projecting ‘‘wings’’ that extend abax-
ially from the midrib (Figs. 1A–D, 2B).
This strikingly distinct floral morphology led to the
recognition and continued acceptance of Petalolophus as
a separate genus in various classification schemes (e.g.,
Hutchinson 1923, 1964; Fries 1959; Heusden 1992; Set-
ten and Koek-Noorman 1992; Keßler 1993, 1995). Con-
tradictory ideas relating to the taxonomic affinities of
Petalolophus have arisen due to differing interpretations
of floral structure. Hutchinson (1923, 1964) erroneously
interpreted Petalolophus flowers as having only three
petals, and accordingly grouped it with other annon-
aceous genera with a reduced number of petals (Table
1). Most classifications have generally associated Petal-
olophus with other genera that have mitriform inner
petals, such as Orophea Blume, Mitrephora Hook.f.&
Thomson, and Pseuduvaria Miq. (Table 1), irrespective
of whether the classifications were based on floral data
(Fries 1959; Heusden 1992; Keßler 1993, 1995), pollen
data (Walker 1971) or fruit and seed data (Setten and
Koek-Noorman 1992).
None of these studies specifically addressed the
phylogenetic relationships of Petalolophus.Molsetal.
(2004), however, recently investigated the phylogenetic
relationships within the tribe Miliuseae (sensu Keßler
1993) and related genera (including Pe. megalopus), us-
ing rbcL and trnL-trnF plastid DNA sequence data. This
study showed that Pe. megalopus was located within a
clade of four Pseuduvaria species, viz.: Ps. ‘‘brachyantha’’
Y. C. F. Su & R. M. K. Saunders (ined.), Ps. ‘‘coriacea’’
Y. C. F. Su & R. M. K. Saunders (ined.), Ps. rugosa
(Blume) Merr., and Ps. pamattonis (Miq.) Y. C. F. Su &
R. M. K. Saunders. Within this Pseuduvaria clade, Pe-
talolophus formed a comparatively robust clade with Ps.
brachyantha and Ps. coriacea (74% maximum parsimony
bootstrap support, 100% Bayesian posterior probabil-
ity), suggesting that Petalolophus and Pseuduvaria are
likely to be congeneric.
The genus Pseuduvaria was initially proposed by Mi-
quel (1858), and is currently recognised as comprising
51 species (Su 2002), although several of these species
still await formal publication. Pseuduvaria is widely dis-
tributed in Southeast Asia, extending from Myanmar
to northern Australia, and has a center of diversity in
New Guinea, where there are 19 species (Su 2002). The
genus is characterized by its small, axillary, and gen-
erally unisexual flowers, with outer petals that are
usually shorter than the inner, and with inner petals
that are apically connivent, forming a mitriform dome
over the reproductive organs.
The primary objective of this study is to critically
examine the morphology, anatomy and ultrastructure
of Pe. megalopus to determine whether the species
should be reclassified as a species of Pseuduvaria. Cor-
responding data on Pseuduvaria have been extracted
from the monographic revision recently completed by
Su (2002). The occurrence and distribution of calcium
oxalate crystals are investigated because they have
been shown to be diagnostically important in distin-
guishing Pseuduvaria from other annonaceous genera
2005] 495SU ET AL.: GENERIC STATUS OF PETALOLOPHUS (ANNONACEAE)
F
IG
.1. Pseuduvaria (5Petalolophus)megalopus. A. Flowering branch. B. Flower with proximal inner petal removed. C. Clawed
inner petal (adaxial), with extended undulating wing. D. Enlargement of base of (C). E. Isolated stamen. F. Fruit. (A, W. Takeuchi
& D. Ama 15599; B–E, W. Takeuchi & D. Ama 16666;F,W. Takeuchi & D. Ama 15682). Scale bars: A, C 52 cm; B 55 mm; D 5
4 mm; E 51 mm; F 53 mm. Drawing by J. H. van Os.
496 [Volume 30SYSTEMATIC BOTANY
F
IG
.2. Pseuduvaria (5Petalolophus)megalopus. A. Habit, showing pendent fruit (arrowed) and flowers, with long pedicel and
peduncle. B. Flower and immature fruit (lower left). (A, W. Takeuchi & D. Ama 17070;B,W. Takeuchi & D. Ama 16666).
2005] 497SU ET AL.: GENERIC STATUS OF PETALOLOPHUS (ANNONACEAE)
F
IG
. 3. Distribution of Pseuduvaria (5Petalolophus)megalo-
pus in New Guinea.
T
ABLE
1. Previously suggested relationships between Petalolophus and other genera. Nomenclature follows Keßler (1993).
1
Based on
flower characters.
2
Based on fruit and seed characters.
3
Additional, doubtfully associated genera: Anomianthus,Fissistigma,Mitrella,Neo-
uvaria,Papualthia,Phaeanthus,Popowia,Pyramidanthe,Trivalvaria.
Reference Taxon/informal group Genera included
Hutchinson (1923)
1
Tribe Unoneae, subtribe Xylopi-
ineae, series Tripetalae
Dasymaschalon, Dennettia, Eburopetalum (5Anax-
agorea), Enantia (5Annickia), Petalolophus,
Thonnera (5Uvariopsis)
Fries (1959)
1
‘‘Orophea group’’ Atopostema, Exellia, Goniothalamus, Mitrephora,
Oreomitra, Orophea, Petalolophus, Phaeanthus,
Platymitra, Popowia, Pseuduvaria, Richella, Schef-
feromitra, Trivalvaria
Hutchinson (1964)
1
Tribe Unoneae, subtribe Xylopi-
ineae, ‘‘group C’’
Anaxagorea, Dasymaschalon, Dennettia, Enantia (5
Annickia), Petalolophus, Thonnera (5Uvariopsis)
Heusden (1992)
1
‘‘Mitrephora group’’ Fitzalania, Mezzettiopsis (5Orophea), Mitrephora,
Oreomitra, Orophea, Petalolophus, Platymitra, Po-
powia, Pseuduvaria
Setten and Koek-Noorman
(1992)
2
‘‘Group 9’’ Mitrephora, Monocarpia, Petalolophus, Piptostigma,
Platymitra, Polyceratocarpus, Pseuduvaria
Keßler (1993, 1995)
1
‘‘Pseuduvaria group’’ Friesodielsia, Goniothalamus, Melodorum, Mitrepho-
ra, Oreomitra, Petalolophus, Pseuduvaria, Richel-
la, Schefferomitra
3
(Jovet-Ast 1942). Functional and evolutionary interpre-
tations of the elaborate inner petal wings are also dis-
cussed, following extensive field observations.
M
ATERIALS AND
M
ETHODS
Calcium oxalate leaf crystals were examined by boiling herbar-
ium leaf specimens (Millar NGF 13801) in water for 15 mins and
bleaching (1:2 chlorox:water) overnight, and then peeling the ad-
axial and abaxial epidermal layers using fine forceps. Acid solu-
bility tests, with 2% hydrochloric acid and 5% glacial acetic acid
(Macnish et al. 2003), were used to tentatively determine crystal
chemical composition.
Stamen and pollen structure were studied with scanning elec-
tron microscopy (SEM) using herbarium specimens (Hartley 11333
and Takeuchi & Ama 16235). Pollen was gently shaken from de-
hiscing anthers onto adhesive conducting carbon tabs on specimen
stubs. All stub preparations were then sputter-coated with a mix-
ture of gold and palladium, and viewed using a Leica Cambridge
Stereoscan 440 SEM at 12 kV.
The herbarium specimens of Pe. megalopus examined are listed
in Appendix 1. Comparative morphological data on Pseuduvaria
species were abstracted from the recent taxonomic revision by Su
(2002). Field observations on the floral biology of Pe. megalopus
were made using naturally occurring populations in Morobe Prov-
ince, Papua New Guinea.
R
ESULTS
Comparative data on selected morphological char-
acters of Petalolophus and Pseuduvaria are presented in
Table 2. Three species of Pseuduvaria from New Guinea
(Ps. dolichonema (Diels) J. Sinclair, Ps. nova-guineensis J.
Sinclair, and Ps. sessilifolia J. Sinclair) are emphasised,
as they bear a particularly strong resemblance to Pe.
megalopus.
Habit. Petalolophus megalopus is a monocaul or spar-
ingly branched treelet to ca. 4 m, whereas Pseuduvaria
species are variably treelets to medium-sized trees,
ranging from less than 1 m (Ps. costata (Scheff.) J. Sin-
clair, from New Guinea) up to 40 m (Ps. rugosa, from
western Malesia).
Leaf Structure. Petalolophus megalopus leaves are es-
sentially sessile; in contrast, most Pseuduvaria species
have leaves that are petiolate, although two New Guin-
ea species, Ps. sessilifolia and a new, currently unde-
scribed species, are epetiolate.
Crystals are found in both the ad- and abaxial leaf
epidermal layers of both Petalolophus megalopus and all
species of Pseuduvaria. The crystals completely dis-
solved in 2% hydrochloric acid but only partially dis-
solved when pretreated with 5% acetic acid, suggest-
ing that they are composed of calcium oxalate (Mac-
nish et al. 2003). The adaxial foliar epidermis in Pe.
megalopus possesses druse crystals (Fig. 4A), whereas
the crystals in the abaxial epidermis are rhombic (Fig.
4B). Druse crystals are the predominant type in Pseu-
duvaria, although various other shapes also occur, in-
cluding book-shaped, rectangular, rhombic, and
square crystals.
498 [Volume 30SYSTEMATIC BOTANY
T
ABLE
2. Comparison of important morphological characteristics of Petalolophus megalopus and Pseuduvaria species.
Morphological
character Pe. megalopus Ps. dolichonema Ps. nova-guineensis Ps. sessilifolia Other Pseuduvaria spp.
Petiole length 6absent 4–6 mm 2–6 mm 6absent Generally 2–10(–15) mm
Leaf crystals
(adaxially)
Druse ? Druse Druse Variable, but predominantly
druse
Leaf crystals
(abaxially)
Rhombic ? Rhombic Rhombic Variable, but predominantly
rhombic
Rachide length ,5mm ,5mm ,5mm ,5 mm Short (most species) to 35
mm (Ps. filipes)
Flowering pe-
duncle length
100–165(–270) mm ca. 200 mm 50–100 mm 44–92 mm Short (most species) to 35
mm (Ps. aurantiaca and Ps.
filipes)
Flowering pedi-
cel length
(50–)65–95 mm ca. 27 mm 14–42 mm (2–)4–9 mm Short (most species) to ca. 60
mm (e.g., Ps. multiovulata)
Floral sex Androdioecious Dioecious? Hermaphro-
ditic
Dioecious Monoecious or dioecious, oc-
casionally androdioecious
or hermaphroditic
Inner petal wing Present Absent Absent Absent Absent
Inner petal
gland(s)
Absent Absent Present Absent Present or absent
Stamen number 60 (bisexual),
90 (staminate)
ca. 42 ca. 90 31–42 16–153
Carpel number ca. 15 ? ca. 5 ca. 5 (1–)2–30
Pollen exine Scabrate ? Rugulate Psilate Variably rugulate, verrucate,
scabrate or psilate
Monocarp stipe
length
Absent ? 1.5–7 mm Absent Absent, or up to 10(–20) mm
As with all Annonaceae, the leaves of both Petalolo-
phus and Pseuduvaria are hypostomatic with paracytic
stomata (Fig. 4B). The stomata are somewhat sunken
below the epidermal layer in Petalolophus, a feature that
is also observed in several Pseuduvaria species (Su
2002).
Inflorescence Structure. Inflorescence structure in
Petalolophus is essentially the same as that in Pseudu-
varia. Each inflorescence consists of a terminal flower
with a varying number of lateral rhipidia (Fig. 1A): in
Ps. sessilifolia, for example, the continued growth of
rhipidia produces up to 13 flowers, and Pe. megalopus
similarly produces up to five flowers (Fig. 1A).
Despite these similarities, Pe. megalopus differs from
Pseuduvaria in terms of the lengths of the rachides, pe-
duncles and pedicels, depending on specific species.
The internodal length in Ps. sessilifolia, for example, is
very short, resulting in very short rachides (ca. 5 mm
long), whereas the internodes are very long in Ps. filipes
(Lauterb. & K. Schum.) J. Sinclair, resulting in rachides
up to ca. 35 mm long. Petalolophus megalopus has short
rachis internodes (Fig. 1A), similar to those of most
Pseuduvaria species.
Flowering peduncles have proved to be very impor-
tant in species circumscription within Pseuduvaria,
since they are very variable in length (Su 2002). Petal-
olophus megalopus has remarkably long flowering pe-
duncles, generally 100–165(–270) mm long (Figs. 1A,
2A); similarly long peduncles are encountered in four
Pseuduvaria species from New Guinea, viz., a new, un-
described species (120–210 mm long), Ps. dolichonema
(ca. 200 mm long), Ps. nova-guineensis (50–100 mm
long), and Ps. sessilifolia (44–92 mm long). Petalolophus
megalopus has long flowering pedicels, (50–)65–95 mm
long (Figs. 1A, 2A), as well. Most Pseuduvaria species
have shorter pedicels (4–20 mm long), although com-
paratively long pedicels (up to 60 mm long) are ob-
served in some species, including Ps. multiovulata (C.
E. C. Fisch.) J. Sinclair.
Floral Sex. Although most species of Pseuduvaria
are monoecious or dioecious, with separate staminate
and pistillate flowers, it has recently been demonstrat-
ed (Su 2002) that several species from New Guinea
have bisexual flowers: Ps. grandifolia (Warb.) J. Sinclair
and Ps. pulchella (Diels) J. Sinclair are androdioecious,
and Ps. beccarii (Scheff.) J. Sinclair and Ps. nova-guineen-
sis appear to be wholly bisexual, with only hermaph-
roditic flowers. Although earlier reports suggested that
the flowers of Pe. megalopus are bisexual (Heusden
1992; Keßler 1993), the species is actually androdioe-
cious.
Perianth Structure. Contrary to the reports by
Hutchinson (1923, 1964), Pe. megalopus flowers consist
of six petals, not three. The perianth of Pe. megalopus
and all Pseuduvaria species are essentially the same: the
calyx consists of three small sepals, and the corolla
consists of two whorls of three petals each, with the
inner petals generally markedly longer than the outer
(Fig. 1B). The inner petals of both Petalolophus and
Pseuduvaria are apically connivent over the reproduc-
2005] 499SU ET AL.: GENERIC STATUS OF PETALOLOPHUS (ANNONACEAE)
F
IG
. 4. Leaf crystals of Pseuduvaria (5Petalolophus)megalopus. A. Adaxial leaf surface, showing druse crystals. B. Abaxial
leaf surface, showing rhombic crystals. (A, B, A. N. Millar NGF 13801). Scale bars: 50 mm.
tive organs; the base of the inner petals is clawed, re-
sulting in a dome-shaped structure with three lateral
apertures that enable entry of pollinators (Fig. 1B). The
claws are narrow, but their lengths vary significantly
between species.
The most notable diagnostic feature of Pe. megalopus
is the presence of the extraordinary undulating wings
that extend abaxially from the midrib of the inner pet-
als (Figs. 1A, 2B). These wings are large (ca. 30–70 mm
long, 20–45 mm wide) and deep red-purple. Pseudu-
varia species lack these wings entirely.
Within Pseuduvaria, the inner petals possess glands
that are diagnostically very important, since they ex-
hibit substantial taxonomic variation in both number
and shape. One or two glands are commonly located
on the inner surface of the inner petals, although some
species lack inner petal glands. Inner petal glands are
absent in Petalolophus.
Androecial Structure. Pseuduvaria species typically
have uvarioid stamens (sensu Prantl 1891), in which
the anthers are covered by broadened and flattened
connectives. This feature also occurs in Pe. megalopus
(Figs. 1E, 5A). Stamen number is diagnostically im-
portant within Pseuduvaria, with variation between 16
and 153 per flower, according to species. Petalolophus
megalopus flowers possess ca. 60 and 90 stamens in bi-
sexual and staminate flowers respectively.
Gynoecial Structure. The number of carpels per
flower is similarly useful taxonomically in Pseuduvaria,
in which species have (1–)2–30 carpels. Petalolophus me-
galopus has ca. 15 carpels per flower, and is therefore
within the range for Pseuduvaria species. The structure
of the carpels in Pe. megalopus is similar to those of
Pseuduvaria: they are free, lack styles, and are ellipsoid
and very densely hispid. There are approximately six
ovules per carpel, arranged in two rows with lateral
placentation.
Pollen Structure. The structure of the pollen of 42
species of Pseuduvaria has recently been described by
Su and Saunders (2003). The pollen is consistently re-
leased as acalymmate tetrads, and is inaperturate, is-
opolar, and radially symmetrical, with four basic pat-
terns of exine sculpturing, viz. rugulate, verrucate, sca-
brate and psilate. The pollen of Pe. megalopus shares
these tetrad arrangement, aperture and shape features
(Walker 1971), and has a scabrate exine (Fig. 5B). Su
and Saunders (2003) also highlighted different mech-
anisms of cohesion between pollen grains of Pseudu-
varia, both within and between tetrads, including short
exinal connections and non-sporopollenin pollen-con-
necting threads; similar cohesion mechanisms occur in
Pe. megalopus (Fig. 5C, D).
Fruit and Seed Morphology. Petalolophus and Pseu-
duvaria have essentially similar fruits. Petalolophus mon-
ocarps are globose, smooth, and sessile (Figs. 1F, 2B).
Monocarp shape is not very variable in Pseuduvaria,
being predominantly globose, or sometimes ellipsoid,
ovoid, or obovoid; Pseuduvaria monocarps are further-
more variably smooth, rugulose or rugose, and are also
variably sessile or stipitate. The seeds of Pe. megalopus
and most Pseuduvaria species are rugose.
D
ISCUSSION
Generic Status of Petalolophus. Recent molecular
phylogenetic analyses of the tribe Miliuseae and relat-
ed genera (Mols et al. 2004) have shown that Pe. me-
galopus is nested within a clade of four Pseuduvaria spe-
cies, providing strong evidence that the two genera are
congeneric. The morphology of Pe. megalopus has never
previously been critically examined, and many struc-
tural features are reported or described here for the
first time, including leaf crystal structure and distri-
bution, stomatal structure, inflorescence structure, car-
500 [Volume 30SYSTEMATIC BOTANY
F
IG
. 5. Stamen and pollen of Pseuduvaria (5Petalolophus)megalopus (scanning electron micrographs). A. Isolated stamen. B.
Pollen in tetrads. C. Short exinal connections (arrowed) linking pollen grains of adjacent tetrads. D. Pollen-connecting thread
(arrowed) linking grains within a tetrad. (A, T. G. Hartley 11333; B–D, W. Takeuchi & D. Ama 16235). Scale bars: A 5500 mm;
B520 mm; C, D 55mm.
pel and stamen number and shape, and pollen ultra-
structure. It is clear that Pe. megalopus shares many
characteristics with Pseuduvaria, and that the only sig-
nificant morphological difference is the possession of
elaborate perianth wings, extending abaxially from the
midribs of the three inner petals. Previous descriptions
of the large size of the inner petals in Pe. megalopus
refer to the size of these wings: the main lamina of the
inner petal is actually small, as in all Pseuduvaria spe-
cies. There are therefore no convincing morphological
criteria to support the continued acceptance of Petalo-
lophus as a distinct genus, since the presence of large
lateral wings on the inner petals is autapomorphic. The
formal transfer of Pe. megalopus to Pseuduvaria is ac-
cordingly validated below.
Taxonomic Affinities. Pseuduvaria megalopus has
greatest similarities with several other Pseuduvaria spe-
cies (Table 2), which are significantly also from New
Guinea (Su 2002). Remarkably long flowering pedun-
cles are observed in four species in addition to Ps. me-
galopus, viz. Ps. dolichonema,Ps. nova-guineensis,Ps. ses-
silifolia, and a new, undescribed species. These species
are also broadly united by the absence of petioles, ex-
cept Ps. dolichonema and Ps. nova-guineensis, which have
short petioles, 2–6 mm long. Within this group of pu-
tative relatives, Ps. megalopus is arguably most similar
to Ps. nova-guineensis, since they both have long pedi-
cels (although this is a feature observed in several oth-
er species, including Ps. mulgraveana Jessup, Ps. multio-
vulata,Ps. reticulata (Blume) Miq., and Ps. villosa Jes-
sup).
Although the majority of Pseuduvaria species are di-
oecious or monoecious, with unisexual flowers, a lim-
ited degree of variability is evident in the species from
New Guinea: the androdioecy reported here for Ps. me-
galopus is also found in Ps. grandifolia and Ps. pulchella;
2005] 501SU ET AL.: GENERIC STATUS OF PETALOLOPHUS (ANNONACEAE)
and solely hermaphroditic flowers are observed in Ps.
beccarii (Scheff.) J. Sinclair and Ps. nova-guineensis.Itcan
be assumed that there has been an evolutionary tran-
sition within Pseuduvaria from hermaphroditic flowers
(which is the widespread condition in the Annonaceae,
and therefore presumably plesiomorphic) to unisexual
flowers (often with sterile staminodes in the pistillate
flowers), possibly via androdioecious intermediates.
On the basis of these characteristics, it is tentatively
suggested that Ps. megalopus is most closely related to
Ps. nova-guineensis.
Evolution of Sapromyophily. Pijl (1961) was the
first to provide a functional interpretation of floral
structure in Pseuduvaria with respect to pollination sys-
tem. In the absence of field observations, he suggested
that the genus is fly-pollinated based on the floral
structure, particularly the mitriform inner petals and
petal pigmentation. This has subsequently been con-
firmed for three Australian species, viz. an unidenti-
fied species which is assumed here to be Ps. mulgra-
veana var. glabrescens Jessup on the basis of published
photographs (Morawetz 1988), and Ps. froggattii (F.
Muell.) Jessup and Ps. hylandii Jessup (Silberbauer-
Gottsberger et al. 2003). The latter study was more de-
tailed, but all three species appear to show the same
basic features. Initial anthesis is diurnal, with the outer
petals spreading open to reveal apertures between the
claws of the inner petals. As the flowers mature, spe-
cific areas of the inner petals become progressively
darker red-purple, and glands located marginally on
the adaxial surface of the inner petals enlarge and be-
gin secreting nectar. The flowers of Ps. froggattii are
reported to emit a strong odor of ‘‘old dishwater and
vomit’’ (Silberbauer-Gottsberger et al. 2003). These fea-
tures suggest that these species of Pseuduvaria are sap-
romyophilous, in which flies are attracted by the scent
and appearance of rotting meat. The pollinators were
identified as small flies in both studies (Morawetz
1988; Silberbauer-Gottsberger et al. 2003), and specifi-
cally Drosophilidae in the case of P. froggattii (Silber-
bauer-Gottsberger et al. 2003).
Although the pollination ecology of other Pseuduvar-
ia species has not been studied, it is suggested here
that sapromyophily is not ubiquitous in the genus:
many species (such as Ps. rugosa) have basically light
yellow petals and lack the prominent glands and lo-
calized pigmentation described above. These species
are presumably myophilous, but attract flies with
sweet nectar rather than by mimicking carrion.
The elaborate inner petal wings observed in Ps. me-
galopus are presumably adaptations for pollinator at-
traction. The wings are dark purple and have an irreg-
ular, undulating appearance, reminiscent of carrion
(Fig. 2B). Field observations have revealed that the
flowers are visited by comparatively large flies, and
the species is therefore also likely to be sapromyophil-
ous. Casual observations did not reveal any specific
odor, nor the occurrence of inner petal glands; it is
possible, however, that the absence of these features is
correlated with immaturity of the flowers observed. It
is suggested that the large inner petal wings are visual
stimuli for flies, and that the species is sapromyophil-
ous. If this is true, the species represents a distinct sap-
romyophilous lineage within Pseuduvaria, in which the
attractant for the flies are massively enlarged perianth
wings rather than the small pigmented glands ob-
served in other species.
N
EW
N
OMENCLATURAL
C
OMBINATION
Pseuduvaria megalopus (K. Schum.) Y. C. F. Su & J.
B. Mols, comb. nov.—Petalolophus megalopus K.
Schum. in K. Schum. & Lauterb., Nachtr. Fl.
Deutsch. Schutzg. Su¨ dsee 265. 1905.—T
YPE
:N
EW
G
UINEA
: precise locality not known, without date,
G. Bamler 42 (lectotype: WRSL [photo!], designat-
ed by Diels 1913: 162).
Specimens Examined. PAPUA NEW GUINEA. M
A
-
DANG
: north of Walium station, Ramu subprovince, 58
309S, 1458249E, S. H. Sohmer & P. Katik LAE 75132
(LAE).—M
OROBE
: Atzera range, 2 miles N of Lae, T. G.
Hartley 11333 (K, LAE); Oomsis, near Lae, 68359S, 1468
259E, E. E. Henty NGF 10676 (LAE); Oomsis logging
area, Lae, 68409S, 1468459E, E. E. Henty NGF 14900
(L, LAE); Oomsis logging road, near Oomsis river, Lae,
68459S, 1478209E, P. Katik LAE 77973 (L, LAE); 3 mile
agriculture station, near Lae, 68459S, 1478E, P. Katik
& J. S. Womersley NGF 24872 (LAE); Lae, 68459S, 1478
E, A. N. Millar NGF 13801 (LAE); Atzera range, ridge
adjacent to 7–8 mile settlement, 68419S, 1468579E, W.
Takeuchi 9260 (L), 9260B (LAE); near Bubia, 68409S,
1468569E, W. Takeuchi & D. Ama 15599 (L), 15682 (L),
16235 (L, LAE); hills near Taraka, Lae, W. Takeuchi &
D. Ama 16666 (L); Kamiali wildlife management area,
N of Tabare (Tabali) river, 78169S, 1478069E, W. Tak-
euchi, D. Ama & A. Towat i 15167 (L, LAE); near Surin-
umu, Sogeri region, Central district, 98259S, 1478259
E, J. S. Womersley NGF 19131 (LAE).
A
CKNOWLEDGEMENTS
. Financial support for this project was
provided by grants from the Hong Kong Research Grants Council
(HKU 7358/03M, awarded to RMKS), and The University of Hong
Kong CRCG (awarded to YCFS and RMKS). We are also grateful
to the directors of K, L, and LAE for the loan of material; Dr
Krzysztof Swierkosz (WRSL) for providing a photograph of the
lectotype; J. H. van Os for the excellent line drawing; staff of the
Electron Microscope Unit at the University of Hong Kong for tech-
nical assistance; and David Johnson, Tom Ranker and an anony-
mous reviewer for their comments.
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