What the Penaeaceae alliance (Myrtales) tells us about the nature of vestured pits in xylem

Molecular studies indicate that Penaeaceae, Oliniaceae, and the monospecific families Alzateaceae and Rhynchocalycaceae form a clade of Myrtales. Of these four families, Penaeaceae have tracheids with vestured pits, whereas the others have septate fibers lacking vestures; all have vestured pits in vessels. Tracheid presence in Penaeaceae may be related to the arid South African habitats of the family. Presence of vestures on tracheids in families with vestured vessel pits is one indication that imperforate elements are tracheids and are conductive cells, whereas fiber-tracheids and libriform fibers are non-conductive. Tracheids occur widely in angiosperms and may be plesiomorphies or apomorphies. Combretaceae, the first branch of the Myrtales clade, has a great diversity of vesture features in vessels compared to the Penaeaceae alliance families. Alzatea has vestures that spread over the inside of the vessels, whereas in most taxa of the alliance, vestures are confined to the pit cavities and pit apertures. Vestures in the alliance tend to be globular in shape, and are bridged together by strands of wall material. Lignotubers and roots in Penaeaceae have vestures much like those in stems. Only a few species and genera (notably Alzatea) of the alliance have vesture features the pattern of which correlates with the current taxonomic system. Vestured pits should be viewed from the inside surface of vessels as well as the outer surface, and although sectional views of vestured pits are infrequent, they are very informative. Studies that explore diversity from one order or family to another are needed and offer opportunities for understanding the evolutionary significance of this feature.     

Early Tertiary out-of-India dispersal of Crypteroniaceae: evidence from phylogeny and molecular dating

Abstract.— Pylogenetic analyses and molecular dating estimates based on chloroplast DNA sequences were used to establish the relationships of the southern and Southeast Asian Crypteroniaceae and elucidate their biogeographic history. Maximum parsimony and likelihood analyses of rbc L sequences suggested that Crypteroniaceae should be restricted to Crypteronia , Axinandra , and Dactylocladus and that Crypteroniaceae, so defined, are sister to a clade formed by three small African taxa (Oliniaceae, Penaeaceae, and Rhynchocalycaceae) and the monotypic Central and South American Alzateaceae. Three molecular dating approaches (maximum-likelihood under a molecular clock, Langley-Fitch, and penalized-likelihood) were used to infer the age of Crypteroniaceae using both paleobotanic and geologic calibrations. Comparisons among these three methods revealed significant lineage effects in rbc L sequences. Clock-independent dating estimates suggested that divergence of Crypteroniaceae from its African and South American relatives coincided with the breakup of Gondwana, and that India likely served as a "raft" transporting Crypteroniaceae to Asia, with later expansion to Southeast Asia. To our knowledge, Crypteroniaceae are the first plant group for which the out-of-India hypothesis is well corroborated by molecular-based estimates of divergence times.     

Comparative leaf anatomy of the Penaeaceae and its ecological Implications

The leaf anatomy of species representing all seven genera of the Penaeaceae was studied by light and scanning electron microscopy. Due to variability and inconsistency, leaf anatomical characters are not regarded as particularly useful for systematics within or among genera in this family. Across the family, a number of taxa exhibit a trend towards amphistomatous, isobilateral leaves, generally associated with increased leaf thickness and amount of palisade mesophyll. This trend is not apparent in closely related families, e.g. Alzateaceae, Cryp-teroniaceae, Oliniaceae and Rhynchocalycaceae. Most species are found in comparatively mesic habitats and it is difficult to postulate primary xeromorphic trends in leaf anatomy. The sclerophylly encountered across the family as a whole is likely to be related to paucity of soil nutrients rather than a response to water stress.     

Molecular phylogenetics of Melastomataceae and Memecylaceae: implications for character evolution

Melastomataceae are among the most abundant and diversified groups of plants throughout the tropics, but their intrafamily relationships and morphological evolution are poorly understood. Here we report the results of parsimony and maximum likelihood (ML) analyses of cpDNA sequences from the rbcL and ndhF genes and the rpl16 intron, generated for eight outgroups (Crypteroniaceae, Alzateaceae, Rhynchocalycaceae, Oliniaceae, Penaeaceae, Myrtaceae, and Onagraceae) and 54 species of melastomes. The sample represents 42 of the family's currently recognized ～150 genera, the 13 traditional tribes, and the three subfamilies, Astronioideae, Melastomatoideae, and Memecyloideae (= Memecylaceae DC.). Parsimony and ML yield congruent topologies that place Memecylaceae as sister to Melastomataceae. Pternandra, a Southeast Asian genus of 15 species of which five were sampled, is the first- branching Melastomataceae. This placement has low bootstrap support (72%), but agrees with morphological treatments that placed Pternandra in Melastomatacaeae because of its acrodromal leaf venation, usually ranked as a tribe or subfamily. The interxylary phloem islands found in Memecylaceae and Pternandra, but not most other Melastomataceae, likely evolved in parallel because Pternandra resembles Melastomataceae in its other wood characters. A newly discovered plesiomorphic character in Pternandra, also present in Memecylaceae, is a fibrous anther endothecium. Higher Melastomataceae lack an endothecium as do the closest relatives of Melastomataceae and Memecylaceae. The next deepest split is between Astronieae, with anthers opening by slits, and all remaining Melastomataceae, which have anthers opening by pores. Within the latter, several generic groups, corresponding to traditional tribes, receive solid statistical support, but relationships among them, with one exception, are different from anything predicted on the basis of morphological data. Thus, Miconieae and Merianieae are sister groups, and both are sister to a trichotomy of Bertolonieae, Microlicieae + Melastomeae, and Dissochaeteae + Blakeeae. Sonerileae/Oxysporeae are nested within Dissochaeteae, Rhexieae within Melastomeae, and African and Asian Melastomeae within neotropical Melastomeae. These findings have profound implications for our understanding of melastome morphological evolution (and biogeography), implying, for example, that berries evolved from capsules minimally four times, stamen connectives went from dorsally enlarged to basal/ventrally enlarged, and loss of an endothecium preceded poricidal dehiscence.     

The embryology and relationships ofPenaeaceae (Myrtales)

Two species ofPenaeaceae (Penaea mucronata andSaltera sarcocolla), a unique South African family ofMyrtales, were investigated embryologically.Penaeaceae clearly agrees with otherMyrtales in its basic embryological characteristics, and further is characterized by its highly specialized features: ephemeral endothecium, 16-nucleatePenaea-type embryo sac, and unique ovular form. A wider range of affinities of families includingPenaeaceae, Oliniaceae, Rhynchocalycaceae, Alzateaceae, andCrypteroniaceae sensu stricto, as well as a possible common divergence from an ancestral line leading toLythraceae and/orMelastomataceae, are discussed on embryological and other grounds.     

Phylogeny and classification of Ranunculales: Evidence from four molecular loci and morphological data

Previous phylogenetic analyses of Ranunculales, which have mostly been focused on an individual family and were based on molecular data alone, have recovered three main clades within the order. However, support for relationships among these three clades was weak. Earlier hypotheses were often hampered by limited taxon sampling; to date less than one-tenth of the genera in the order have been sampled. In this study, we used a greatly enlarged taxon sampling (105 species, representing 99 genera of all seven families in the order). Our study is, furthermore, the first to employ morphology (65 characters) in combination with sequence data from four genomic regions, including plastid rbcL, matK and trnL-F, and nuclear ribosomal 26S rDNA to reconstruct phylogenetic relationships within Ranunculales. Maximum parsimony and Bayesian inference were performed on the individual and combined data sets. Our analyses concur with those of previous studies, but in most cases provide stronger support and better resolution for relationships among the three main clades retrieved. The first, comprised solely of the monogeneric family Eupteleaceae, is the earliest-diverging lineage. The second clade is composed exclusively of taxa of Papaveraceae, which is sister to the third clade, the core Ranunculales, comprising the other five families of the order. Circaeasteraceae and Lardizabalaceae form a strongly supported clade. Pteridophyllum is supported as sister to Hypecoum, contradicting the viewpoint that the former is the earliest-diverging genus in Papaveraceae. Glaucidium is basalmost in Ranunculaceae. Within this phylogenetic framework, the evolution of selected characters is inferred and diagnostic morphological characters at different taxonomic levels are identified and discussed. Based on both morphological and molecular evidence, a classification outline for Ranunculales is presented, including the proposal of two new subfamilies, Menispermoideae and Tinosporoideae in Menispermaceae and a new tribe, Callianthemeae, for the genus Callianthemum (Ranunculaceae).     

Gunnerales are sister to other core eudicots: implications for the evolution of pentamery

Phylogenetic relationships among many lineages of angiosperms have been clarified via the analysis of large molecular data sets. However, with a data set of three genes (18S rDNA, rbcL, and atpB), relationships among lineages of core eudicots (Berberidopsidales, Caryophyllales, Gunnerales, Santalales, Saxifragales, asterids, rosids) remain essentially unresolved. We added 26S rDNA sequences to a three-gene matrix for 201 eudicots (8430 base pair aligned nucleotides per taxon). Parsimony analyses provided moderate (84%) jackknife support for Gunnerales, which comprise the two enigmatic families Gunneraceae and Myrothamnaceae, as sister to all other core eudicots. This position of Gunnerales has important implications for floral evolution. A dimerous or trimerous perianth is frequently encountered in early-diverging eudicots (e.g., Buxaceae, Proteales, Ranunculales, Trochodendraceae), whereas in core eudicots, pentamery predominates. Significantly, dimery is found in Gunneraceae and perhaps Myrothamnaceae (the merosity of the latter has also been interpreted as labile). Parsimony reconstructions of perianth merosity demonstrate lability among early-diverging eudicots and further indicate that a dimerous perianth could be the immediate precursor to the pentamerous condition characteristic of core eudicots. Thus, the developmental canalization that yielded the pentamerous condition of core eudicots occurred after the node leading to Gunnerales.     

Molecular systematics of the Catesbaeeae-Chiococceae complex (Rubiaceae): flower and fruit evolution and biogeographic implications

The classification of the Catesbaeeae and Chiococceae tribes, along with that of the entire Rubiaceae, has long been debated. The Catesbaeeae-Chiococceae complex (CCC) includes approximately 28 genera and 190 species primarily concentrated in the Greater Antilles (nearly 70% of the species), Central and South America, and in the western Pacific (three genera). Previous molecular studies, with broad sampling of the Rubiaceae, have shown the CCC to be a monophyletic group. The present study is a more detailed examination of the generic relationships within the CCC using two data sets, the nuclear ribosomal ITS regions and the trnL-F chloroplast intron and spacer. Maximum parsimony analyses lend further support to the previous hypotheses that the CCC is monophyletic and sister to Strumpfia maritima. However, within the complex several genera do not form monophyletic groups. Previous studies of the Rubiaceae suggest that the ancestral fruit type in the CCC is a multiseeded capsule. Indehiscent, fleshy fruits appear to have evolved three to four times within this lineage. Changes in floral morphologies within the complex tend to correspond to cladogenesis among and within genera. Finally, molecular analyses suggest one or possibly two long-distance dispersals from the Americas to the western Pacific.     

Further progress on the phylogeny of Noctuoidea (Insecta: Lepidoptera) using an expanded gene sample

Major progress has been made recently toward resolving the phylogeny of Noctuoidea, the largest superfamily of Lepidoptera. However, numerous questions and weakly supported nodes remain. In this paper we independently check and extend the main findings of multiple recent authors by performing maximum‐likelihood analyses of 5–19 genes (6.7–18.6 kb) in 74 noctuoids representing all the families and a majority of the subfamilies. Our results strongly support the six family system of Zahiri et al., with the former Lymantriidae and Arctiidae subsumed within the huge family Erebidae, and Noctuidae restricted largely to the subfamilies with so‐called trifine hindwing venation. Our data also strongly corroborate monophyly of the set of four families with quadrifid forewing venation, to the exclusion of Notodontidae, and removal from the latter of Oenosandridae. Other among‐family relationships, however, remain unsettled. Our evidence is equivocal on the position of Oenosandridae, which are sister group to either Notodontidae alone or to all other noctuoids. Like other recent nuclear gene studies, our results also provide no strong support for relationships among the four quadrifid forewing families. In contrast, within families our analyses significantly expand the list of robustly resolved relationships, while introducing no strong conflicts with previous molecular studies. Within Notodontidae, for which we present the largest molecular taxon sample to date, we find strong evidence for polyphyly for some, or all, recent definitions of the subfamilies Thaumetopoeinae, Pygaerinae, Notodontinae and Heterocampinae. Deeper divergences are incompletely resolved but there is strong support for multiple ‘backbone’ nodes subtending most of the subfamilies studied. Within Erebidae, we find much agreement and no strong conflict with a recent previous study regarding relationships among subfamilies, and somewhat stronger support. Although many questions remain, the two studies together firmly resolve positions for over half the subfamilies. Within Noctuidae, we find no strong conflict with previous molecular studies regarding relationships among subfamilies, but much stronger resolution along the ‘backbone’ of the phylogeny. Combining information from multiple studies yields strongly resolved positions for most of the subfamilies. Finally, our results strongly suggest that the tribes Pseudeustrotiini and Prodeniini, currently assigned to the largest subfamily, Noctuinae, do not belong there. In sum, our results provide additional corroboration for the main outlines of family‐level phylogeny in Noctuoidea, and contribute toward resolving relationships within families.     

Resolving and dating the phylogeny of Cornales--Effects of taxon sampling, data partitions, and fossil calibrations

The order Cornales descends from the earliest split in the Asterid clade of flowering plants. Despite a few phylogenetic studies, relationships among families within Cornales remain unclear. In the present study, we increased taxon and character sampling to further resolve the relationships and to date the early diversification events of the order. We conducted phylogenetic analyses of sequence data from 26S rDNA and six chloroplast DNA (cpDNA) regions using parsimony (MP), maximum likelihood (ML), and Bayesian inference (BI) methods with different partition models and different data sets. We employed relaxed, uncorrelated molecular clocks on BEAST to date the phylogeny and examined the effects of different taxon sampling, fossil calibration, and data partitions. Our results from ML and BI analyses of the combined cpDNA sequences and combined cpDNA and 26S rDNA data suggested the monophyly of each family and the following familial relationships ((Cornaceae-Alangiaceae)-(Curtisiaceae-Grubbiaceae))-(((Nyssaceae-Davidiaceae)-Mastixiaceae)-((Hydrostachyaceae-(Hydrangeaceae-Loasaceae))). These relationships were strongly supported by posterior probability and bootstrap values, except for the sister relationship between the N-D-M and H-H-L clades. The 26S rDNA data and some MP trees from cpDNA and total evidence suggested some alternative alignments for Hydrostachyaceae within Cornales, but results of SH tests indicated that these trees were significantly worse explanations of the total data. Phylogenetic dating with simultaneous calibration of multiple nodes suggested that the crown group of Cornales originated around the middle Cretaceous and rapidly radiated into several major clades. The origins of most families dated back to the late Cretaceous except for Curtisiaceae and Grubbiaceae which may have diverged in the very early Tertiary. We found that reducing sampling density within families and analyzing partitioned data sets from coding and noncoding cpDNA, 26S rDNA, and combined data sets produced congruent estimation of divergence times, but reducing the number and changing positions of calibration points resulted in very different estimations.     

Phylogenetic relationships of Lecythidaceae: a cladistic analysis using rbcL sequence and morphological data

This study examined in detail the rbcL sequence and morphological support for subfamilial relationships and monophyly of Lecythidaceae. Initially we needed to establish relationships of Lecythidaceae among other dicot families. To complete this we examined 47 rbcL sequences of 25 families along with molecular observations from several large analyses of rbcL data. All analyses strongly support the monophyly of the asterid III grouping. This analysis revealed Lecythidaceae to be paraphyletic and indicated potential outgroup relationships with Sapotaceae. Once relationships had been evaluated using molecular data we then concentrated on analyzing separate and combined morphological and molecular databases. The topology of the morphological data set was similar to the rbcL sequence and combined data sets except for the positioning of Napoleonaeoideae, Grias, Gustavia, and Oubanguia. According to the combined results, Planchonioideae, Lecythidoideae. and Foetidioideae are monophyletic, whereas the subfamily Napoleonaeoideae are paraphyletic. Nested within Napolconaeoideae, we found Asteronthos forms a strongly supported clade with Oubanguia (Scytopetalaceae). Foetidia, the only genus of Foetidioideae, is sister to Planchonioideae, and this clade is sister to Lecythidoideae. The [(Planchonioideae, Foetidioideae) Lecythidoideae are sister to Asteranthos/Oubanguia. Napoleonaeoideae are sister to the rest of Lecythidaceae.     

A phylogenetic analysis of Doronicum (Asteraceae, Senecioneae) based on morphological, nuclear ribosomal (ITS), and chloroplast (trnL-F) evidence.

A phylogenetic analysis of the Old World genus Doronicum (26 species, 4 subspecies) based on sequence data of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA, the chloroplast spacer trnL-F, and morphology is presented. Congruence among the three data sets was explored by the computing of several indices, all of which suggest homogeneity between only the two molecular matrices. We argue that the morphological data set contains poor phylogenetic signal and advocate simultaneous analysis of the three data sets (total evidence approach) so that morphological characters are tested for homology by congruence with molecular data. The resulting phylogenetic hypothesis allows several well-supported conclusions including the placement of a Corsican endemic (D. corsicum), sister to the remainder of the genus, and the inference that an early southern European or Mediterranean diversification took place in the genus. Shifts in morphological characters (e.g., homocarpy to heterocarpy) are confirmed to have evolved several times. Results from comparative studies of sequence data of the chloroplast gene ndhF support inclusion of Doronicum in tribe Senecioneae.     

Molecular phylogeny of Malagasy reed frogs, Heterixalus, and the relative performance of bioacoustics and color-patterns for resolving their systematics

The members of the genus Heterixalus constitute one of the endemic frog radiations in Madagascar. Here we present a complete species-level phylogeny based on DNA sequences (4876 base pairs) of three nuclear and four mitochondrial markers to clarify the phylogenetic relationships among and within all known species of this genus, as well as the phylogenetic position of the monospecific Seychellean Tachycnemis seychellensis. Although the performance to resolve supported clades of Heterixalus species differed among the investigated gene fragments when analyzed separately, we could identify five well-supported species groups within Heterixalus in the combined analysis of all gene fragments. Our data strongly support a Heterixalus-Tachycnemis clade, and indicate the probable monophyly of Heterixalus placed sister to Tachycnemis. However, the diversification of these lineages may have happened in a short interval of time, leading to an unstable placement of Tachycnemis in the single-gene fragment phylogenies. Referring to the hitherto existing classification of Heterixalus, which is predominantly based on chromatic and bioacoustic characters, we examined the relative performance of these data sets relative to our molecular phylogeny. A Bayesian tree reconstructed with a bioacoustic data set yielded a higher resemblance to the molecular phylogeny than a tree constructed using a chromatic data set, which supports the importance of bioacoustic characters for systematic analyses of these anurans.     

Early floral development of Heliconia latispatha (Heliconiaceae), a key taxon for understanding the evolution of flower development in the Zingiberales

We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.     

Phylogenetic relationships of African microhylid frogs inferred from DNA sequences of mitochondrial 12S and 16S rRNA genes

The phylogenetic relationships of microhylid frogs are poorly understood. The first molecular phylogeny for continental African microhylids is presented, including representatives of all subfamilies, six of the eight genera, and the enigmatic hemisotid Hemisus. Mitochondrial 12S and 16S rRNA sequence data were analysed using parsimony, likelihood and Bayesian methods. Analyses of the data are consistent with the monophyly of all sampled subfamilies and genera. Hemisus does not nest within either brevicipitines or non-brevicipitines. It is possibly the sister group to brevicipitines, in which case brevicipitines might not be microhylids. Phrynomantis and Hoplophryne potentially group with non-African, non-brevicipitine microhylids, in agreement with recent morphological and molecular data. Within brevicipitines, Breviceps is recovered as the sister group to a clade of Callulina+Spelaeophryne+Probreviceps. The relationships among the genera within this latter clade are unclear, being sensitive to the method of analysis. Optimal trees suggest the Probreviceps macrodactylus subspecies complex might be paraphyletic with respect to P. uluguruensis, corroborating preliminary morphological studies indicating that P. m. rungwensis may be a distinct species. P. m. loveridgei may be paraphyletic with respect to P. m. macrodactylus, though this is not strongly supported. Some biogeographic hypotheses are examined in light of these findings.     

Phylogenetic analysis of the Malvadendrina clade (Malvaceae s.l.) based on plastid DNA sequences

Phylogenetic relationships within Malvaceae s.l., a clade that includes the traditional families Bombacaceae, Malvaceae s.str., Sterculiaceae, and Tiliaceae, have become greatly clarified thanks to recent molecular systematic research. In this paper, we use DNA sequences of four plastid regions (atpB, matK, ndhF, and rbcL) to study relationships within Malvadendrina, one of the two major clades of Malvaceae s.l. The four data sets were generally in agreement, but five terminal taxa manifested highly unexpected affinities in the rbcL partition, and the non-coding sequences of the trnK intron were found to provide limited phylogenetic information for resolving relationships at the base of Malvadendrina. The remaining data strongly support the existence of six major clades within Malvadendrina: Brownlowioideae, Dombeyoideae, Helicteroideae, Malvatheca (comprising Bombacoideae and Malvoideae), Sterculioideae, and Tilioideae. These data also resolve the placement of two problematic taxa: Nesogordonia (in Dombeyoideae) and Mortoniodendron (in Tilioideae). The relationships among the six clades are not definitively resolved, but the best-supported topology has Dombeyoideae as sister to the remainder of Malvadendrina (posterior probability PP=80%) and Sterculioideae as sister to Malvatheca (PP=86%). This early branching position of Dombeyoideae is supported by similarities in floral characters between members of that clade and outgroup taxa in Byttnerioideae. Similarly, the sister-group relationship of Sterculioideae and Malvatheca receives support from androecial characteristics, like subsessile or sessile anthers and an absence of staminodes, shared by these two clades.     

A multilocus phylogeny of archiheterodont bivalves (Mollusca,Bivalvia, Archiheterodonta)

The bivalve clade Heterodonta encompasses more than half of the extant bivalve species and is presently considered a derived group of the modern bivalves (Newell 1965 ; Waller 1998 ). Heterodonta is subdivided into two major lineages, the hyperdiverse Euheterodonta and Archiheterodonta. The latter comprises four relatively small extant families: Astartidae, Carditidae, Condylocardiidae and Crassatellidae, whose relationships and internal phylogeny are poorly understood. We assessed the phylogeny of archiheterodont bivalves using a multilocus data set comprised of molecular sequence data from six loci (18S rRNA, 28S rRNA, cytochrome c oxidase subunit I, cytochrome b, internal transcribed spacer 2 and histone H3). Resultant data sets of ~4 Kb of concatenated molecular sequence data were analysed using probabilistic approaches (maximum likelihood and Bayesian inference) and parsimony direct optimization. We recovered strong support for the monophyly of Archiheterodonta, within which Astartidae is the sister group of Crassatellidae, and these two constitute the sister clade of Carditidae, which is paraphyletic with respect to Condylocardiidae. The relationships among the constituent species groups were evaluated in the context of the archiheterodont fossil record through the estimation of divergence times. Diversification times of archiheterodont families were congruent with bounded estimates of origins based on palaeontological data: Archiheterodonta diversified during the Devonian, 373.1 Ma (95% highest posterior density interval [HPD] 325.8–428.2); Crassatelloidea around the Carboniferous, 330.1 Ma (95% HPD 291.0–372.7); Crassatellidae around the Triassic, 224.0 (95% HPD 140.6–320.2); Astartidae around the Permian, 288.2 Ma (95% HPD 269.2–307.3); and Carditoidea around the Jurassic, 178.8 Ma (95% HPD 120.9–228.3).     

A supermatrix approach provides a comprehensive genus-level phylogeny for Gentianales

Gentianales consist of Apocynaceae, Gelsemiaceae, Gentianaceae, Loganiaceae, and Rubiaceae, of which the majority are woody plants in tropical and subtropical areas. Despite extensive efforts in reconstructing the phylogeny of Gentianales based on molecular data, some interfamily and intrafamily relationships remain uncertain. We reconstructed the genus-level phylogeny of Gentianales based on the supermatrix of eight plastid markers (rbcL, matK, atpB, ndhF, rpl16, rps16, thetrnL-trnF region, and atpB-rbcL spacer) and one mitochondrial gene (matR) using maximum likelihood. The major clades and their relationships retrieved in the present study concur with those of previous studies. All of the five families of Gentianales are monophyletic with strong support. We resolved Rubiaceae as sister to the remaining families in Gentianales and showed support for the sister relationship between Loganiaceae and Apocynaceae. Our results provide new insights into relationships among intrafamilial clades. For example, within Rubiaceae we found that Craterispermeae were sister to Morindeae + (Palicoureeae + Psychotrieae) and that Theligoneae were sister to Putorieae. Within Gentianaceae, our phylogeny revealed that Gentianeae were sister to Helieae and Potalieae, and subtribe Lisianthiinae were sister to Potaliinae and Faroinae. Within Loganiaceae, we found Neuburgia as sister to Spigelieae. Within Apocynaceae, our results supported Amsonieae as sister to Melodineae, and Hunterieae as sister to a clade comprising Plumerieae + (Carisseae + APSA). We also confirmed the monophyly of Perplocoideae and the relationships among Baisseeae + (Secamonoideae + Asclepiadoideae).     

Phylogenetic relationships of bryophytes inferred from nuclear-encoded rRNA gene sequences

We investigate phylogenetic relationships among hornworts, liverworts and mosses, and their relationships to other green plant groups, by analysis of nucleotide variation in complete 18s rRNA gene sequences of three green algae, two hornworts, seven liverworts, nine mosses, and six tracheophytes. Parsimony and maximum-likelihood analyses yield a single optimal tree in which the hornworts are resolved as the basal group among land plants, and the liverworts and mosses are sister taxa that together form the sister clade to the tracheophytes. This phylogeny is internally robust as indicated by decay indices and by comparison (using both parsimony and likelihood criteria) to topologies representing five alternative hypotheses of bryophyte relationships. We discuss some possible reasons for differences between the phylogeny inferred from the rRNA data and those inferred from other character sets.     

Systematic affinities of Rhizophoraceae and Anisophylleaceae, and intergeneric relationships within Rhizophoraceae, based on chloroplast DNA, nuclear ribosomal DNA, and morphology

A cladistic analysis of sequences from the chloroplast gene rbcL was used to determine the systematic affinities of Rhizophoraceae and Anisophylleaceae. This analysis rejects close relationships of Rhizophoraceae with Celastraceae or Elaeocarpaceae, suggested previously, and identifies Erythroxylaceae as sister group within the Malpighiales, supported by several morphological and anatomical characters. Our molecular results also indicate that Anisophylleaceae are nested within Cucurbitales. Although this placement is novel, this affinity is also well supported by shared morphological characters. Tribal and generic relationships within Rhizophoraceae are evaluated with a combination of six molecular data sets (rbcL, atpB-rbcL intergenic spacer, trnL-trnF intergenic spacer, ITS1, ITS2, and 5.8S) and a morphological data set. These relationships are compared with results from previous morphological cladistic analyses. Against the background of the molecular results, we briefly discuss the evolution of morphological characters traditionally used for tribal subdivision as well as characters presumably significant for adaptation to mangrove habitats, namely, aerial stilt roots and vivipary.