Raymond W. J. M. van der Ham

Molecular and Morphological Characterization of a New Monotypic Genus of Annonaceae, Mwasumbia , from Tanzania

Abstract The coastal lowland rain forests of eastern Africa are well known for their high levels of plant endemism. A new genus of Annonaceae, Mwasumbia, is described from Tanzania, underscoring this high biodiversity and represented by a single species, Mwasumbia alba. The new genus presents several morphological characters suggesting a close relationship to two other African genera, Greenwayodendron and Polyceratocarpus. Maximum parsimony and Bayesian molecular phylogenetic analyses based on two plastid markers, rbcL and the trnLtrnF region, strongly support the close relationship of these three genera to one another as well as to two other African genera, Annickia and Piptostigma. Together these five genera form a moderately supported clade within the so-called short-branch clade of Annonaceae. A detailed morphological and palynological comparison between Mwasumbia and the four other genera shows that this new genus exhibits a combination of features unique within this group: intermediate tertiary leaf venation, exclusively bisexual flowers, slightly imbricate sepals, valvate petals, outer and inner petals equal in length, numerous stamens, four carpels, few and uniseriate ovules, few and sessile monocarps, and verrucate sulculate pollen grains. Phylogenetic analyses also suggest the genus Piptostigma, as currently circumscribed, to be paraphyletic. An IUCN conservation status of VU D2 is proposed, reflecting the narrow distribution of the single species.

Pollen morphology of the Flueggeinae (Euphorbiaceae, Phyllanthoideae)

A total of 129 species from the subtribe Flueggeinae of the tribe Phyllantheae (Euphorbiaceae, Phyllanthoideae) were investigated using light and scanning electron microscopy, and 10 species using transmission electron microscopy, in order to evaluate the relationships between the eight constituent genera: Breynia, Flueggea, Glochidion, Margaritaria, Phyllanthus, Reverchonia, Richeriella, and Sauropus. Of these genera, Flueggea, Margaritaria and Richeriella share pollen with a prolate spheroidal meridional outline and a 3-colporate aperture system. Pollen of Reverchonia is also 3-colporate, but differs from that of the Flueggea alliance by its clearly prolate shape, tilioid ornamentation and absence of costae endopori. Breynia and Sauropus have 4–12 and 3–16-colporate pollen, respectively, with diploporate colpi. Two pollen types are recognised in Breynia, and four in Sauropus, one of which supports the recognition of Sect. Hemisauropus. Glochidion pollen is 3–6-colporate, and similar to that of Breynia in having reticulate sculpture with Y-shaped sexine structures, but it has monoporate colpi. Of the genus Phyllanthus, only species with pollen with diploporate colpi have been studied. Seven types are described. Diploporate Phyllanthus pollen can be distinguished from that of Breynia and Sauropus by its distinct colpus margins consisting of parallel muri. Colpal irregularities and endoaperture configurations in the subtribe are discussed, and pollen morphological trends are hypothesised. Placed in the successiform aperture series, the Flueggea alliance and Reverchonia form a basal group. Glochidion is considered intermediate, giving rise to the Breynia-Sauropus group. The relationship with Phyllanthus remains unclear.

Pollen morphology of Miliusa and relatives (Annonaceae)

In order to provide additional data for the subdivision of the palaeotropical genus Miliusa (Annonaceae), its pollen was examined using light, scanning and transmission electron microscopy, including 20 of the 30 – 40 species. Further, species of the other genera in the former tribe Miliuseae (Alphonsea, Mezzettia, Orophea, Platymitra; Phoenicanthus not available) and of the Polyalthia cerasoides group, the sister group to Miliusa in a recent molecular analysis, were included. The pollen of Mezzettia and Platymitra is described for the first time with scanning and transmission electron microscopy. The pollen of all species studied with transmission electron microscopy appeared to possess an inaperturate exine, but apertural areas (‘germination zones’) were observed in the intine. The pollen morphological variation within Miliusa does not correlate with the macromorphological subdivision of the genus. It appeared to be impossible to define distinct pollen types. The former tribe Miliuseae cannot be characterised or subdivided with the help of pollen characters either. All genera fit in the larger miliusoid clade (25 genera). The pollen of the Polyalthia cerasoides group deviates in its finely and densely granular infratectum.

Pollen morphology and phylogeny of the Alyxieae (Apocynaceae)

The pollen of the tribe Alyxieae, including Alyxia , Chilocarpus , Condylocarpon , Lepinia , Lepiniopsis , Plectaneia and Pteralyxia , has been studied with light, scanning electron and transmission electron microscopy. It is characterised by relatively large, irregularly disposed and - unequal-sized pores. 2-porate grains are most common in the Alyxieae, and occur in all genera except for Condylocarpon . 1-, 3-, 4- and 5-porate pollen grains are less common. The orientation of the polar axis and the equatorial plane could not be determined in any of the genera. Within the Alyxieae, Chilocarpus and Plectaneia are the nearest to other Apocynaceae, showing an essentially similar exine ultrastructure. Alyxia , Lepinia , Lepiniopsis and Pteralyxia make up a derived group, characterised by large pollen grain size and a remarkable nexine structure. Pollen of Lepinia and Lepiniopsis might be derived on the basis of their fossulate-verrucate ornamentation. Condylocarpon pollen shows a deviating set of pollen features (tetrads, inaperturate, reduced exine) that suggest it to be neotenic. Pollen morphology supports preliminary results of cladistic analyses of chloroplast data, in which the tribe is a monophyletic group nested in a 3-colporate environment, Chilocarpus and Condylocarpon are sisters at the base of the tree, Plectaneia is sister to a clade made up by Alyxia , Pteralyxia , Lepinia and Lepiniopsis , of which Lepinia and Lepiniopsis are the most derived.

Evolutionary trends in Winteraceae pollen

The Winteraceae, being considered as one of the most basal angiosperm families, has been extensively studied palynologically. The present study reviews the characters dispersal unit (monad versus tetrad) and size of the lumina in the tectum in the light of recent molecular research. Monads and small-meshed reticula appear to be derived from large-meshed tetrads. The fossil record supports the apomorphic state of a small-meshed tectum. In contrast to earlier reports, genuine monads are unknown as fossils. The fossil monads recorded so far are considered to be detached from permanent tetrad configurations.The Winteraceae, being considered as one of the most basal angiosperm families, has been extensively studied palynologically. The present study reviews the characters dispersal unit (monad versus tetrad) and size of the lumina in the tectum in the light of recent molecular research. Monads and small-meshed reticula appear to be derived from large-meshed tetrads. The fossil record supports the apomorphic state of a small-meshed tectum. In contrast to earlier reports, genuine monads are unknown as fossils. The fossil monads recorded so far are considered to be detached from permanent tetrad configurations.

A PHYLOGENETIC ANALYSIS OF ALYXIEAE (APOCYNACEAE) BASED ON RBCL, MATK, TRNL INTRON, TRNL-F SPACER SEQUENCES, AND MORPHOLOGICAL CHARACTERS1

Abstract Within Rauvolfioideae (Apocynaceae), genera have long been assigned to tribes based mainly on only one or two superficial fruit and seed characters. Taxa with drupaceous fruits were included in Alyxieae. To elucidate relationships within Alyxieae, we analyzed phylogenetically a data set of sequences from four plastid DNA regions (RbcL, matK, TrnL intron, and TrnL-F intergenic spacer) and a morphological data set for 33 genera of Apocynaceae, including representatives of all genera previously included in Alyxieae and two non-Apocynaceae species. Results of parsimony analysis indicate that Alyxieae as previously delimited are polyphyletic, with most genera falling into two main clades. The Alyxia clade includes seven genera: Alyxia Banks ex R. Br., Lepinia Decne., Lepiniopsis Valeton, Pteralyxia K. Schum., and Condylocarpon Desf. together with Plectaneia Thouars. (earlier included in Plumerieae) and Chilocarpus Blume (earlier included in Chilocarpeae). The Vinca clade includes eight genera: Cabucala Pichon, Petchia Livera, Rauvolfia L., Catharanthus G. Don, Vinca L., Neisosperma Raf., Ochrosia Juss., and Kopsia Blume. Vallesia Ruiz & Pav. and Anechites Griseb. are not related to either clade and come out as sister to Aspidosperma Mart. & Zucc. (Aspidospermeae) and Thevetia L. (Plumerieae), respectively. The fruit and seed characters previously used to demarcate Alyxieae are homoplasious, as are other morphological characters such as style head structure and syncarpy versus apocarpy. Conversely, pollen morphology, which has not previously played much of a role in tribal delimitation, was shown to be the most useful morphological character for delimiting Alyxieae from other tribes of Rauvolfioideae.

Pollen morphology within the Monodora clade, a diverse group of five African Annonaceae genera

Pollen morphology has played a major role in elucidating infrafamiliar‐level systematics and evolution within Annonaceae, especially within the African genera. The Monodora clade is composed of five genera, Asteranthe, Hexalobus, Isolona, Monodora and Uvariastrum, which are restricted to Africa and contain together c. 50 species. A molecular phylogeny of the family showed that the monophyly of the Monodora clade is strongly supported and that it is part of a larger clade of 11 African genera. In order to support classification a detailed survey was made of the pollen morphological variation within the Monodora clade, using scanning and transmission electron microsopy. For the two most species‐rich genera, Isolona and Monodora, a molecular species‐level phylogeny was used to assess the taxonomic usefulness of the pollen characters. The survey showed a wide range of pollen morphological diversity. The most conspicuous variation concerned the occurrence of monads without a thicker outer foliation in the basal exine layer in Isolona in contrast to tetrads with a thicker outer foliation in Asteranthe, Hexalobus, Monodora and Uvariastrum. At the infrageneric level, Hexalobus, Isolona and Monodora showed the largest diversity, with various pollen types based on tectum morphology. Hexalobus is exceptional with three types within only five species. The pollen types defined in this study are hardly useful in characterizing major groups identified within both Isolona and Monodora, but they do illustrate relationships within smaller groups.

Spore movement driven by the spore wall in an eusporangiate fern

Abstract We report the ejection of spores on sporangium dehiscence in the eusporangiate fern genus Angiopteris (Marrattiaceae, Marattiales). Using normal and high-speed video we document movement of the spores and using light and electron microscopy we study the structural changes associated with the movement. The sudden and spontaneous movement covering distances of up to several mm cannot be ascribed to action of the sporangium. We find that cavitation between exospore and perispore wall is the most likely responsible mechanism. We suggest that spore ejection by movement of a spore wall layer may have driven the evolution of an elaborate multilayered spore wall in ferns.

Pollen morphology of Zehneria s.l. (Cucurbitaceae)

In order to provide additional data for the proposed subdivision of the palaeotropical genus Zehneria (Cucurbitaceae, tribe Benincaseae, subtribe Cucumerinae) by De Wilde and Duyfjes (2006) into five genera (Indomelothria, Neoachmandra, Scopellaria, Urceodiscus and Zehneria s.s.) pollen was examined using light and scanning electron microscopy for 18 Zehneria species including representatives of each of the proposed subdivisions, plus one species of the neotropical genus Melothria to which Zehneria once belonged. The pollen of Indomelothria, Scopellaria and Urceodiscus are described for the first time. Indomelothria, Neoachmandra and Zehneria s.s. have the same pollen type (3‐colporate, microreticulate to reticulate), which cannot be distinguished from that of Melothria. Scopellaria deviates by its irregularly striate‐reticulate ornamentation and short colpi, and Urceodiscus by its striate‐reticulate ornamentation. This result supports separation of Scopellaria and Urceodiscus as separate genera, but neither supports or rejects the segregation of Indomelothria and Neoachmandra. The pollen type shared by Indomelothria, Neoachmandra and Zehneria s.s. fits very well in the Cucumerinae. However, the striate‐reticulate ornamentation of Scopellaria and Urceodiscus pollen is unknown within this subtribe, and leaves some doubt with respect to the (sub)tribal assignment of both Scopellaria and Urceodiscus. Based on pollen morphology alone, the African Neoachmandra(?) peneyana does not belong to the tribe Benincaseae. Within the Cucurbitaceae, the 6‐aperturate pollen type of Neoachmandra (?) peneyana occurs only in the exclusively neotropical tribe Sicyeae.

Fevilleoideae pollen (Cucurbitaceae): a study in striate ornamentation

Abstract An exhaustive search into the Cucurbitaceae pollen literature and own observations were used to arrive at a sharper delimitation of the pollen of subfamily Fevilleoideae against that of the other subfamily, the Cucurbitoideae. Pollen data of 125 out of the 128 genera including all 19 Fevilleoideae genera were available. In view of a broad overlap, pollen grain size is not a reliable criterium to separate both subfamilies. Striate and microstriate ornamentation appeared to be very useful in identifying cucurbitaceous plants as Fevilleoideae. The perforate-rugulate type of Alsomitra is unique in the family. Gerrardanthus cannot be indicated as a member of the Fevilleoideae with pollen features alone, its relatively large (micro)reticulate pollen being similar to that of several Cucurbitoideae. On the basis of outgroup comparison, either striate or perforate-rugulate might be considered as the plesiomorphic ornamentation state in the family Cucurbitaceae. The (micro)reticulate type occurring commonly in the Cucurbitoideae evolved later, probably from a striate ancestral type and parallel to the (micro)reticulate type of the fevilleoid genus Gerrardanthus. The more or less striate (reticulate-striate) ornamentation found in seven genera in three Cucurbitoideae tribes probably evolved at least five times from (micro)reticulate ancestors.