Morphology, anatomy and histochemistry of Salicornioideae (Chenopodiaceae) fruits and seeds

BACKGROUND AND AIMS: The subfamily Salicornioideae (Chenopodiaceae) are a taxonomically difficult group largely due to the lack of diagnostic characters available to delineate tribal- and generic-level boundaries; a consequence of their reduced floral and vegetative features. This study examined the variation in fruits and seeds across both tribes of the Salicornioideae to assess if characters support traditional taxonomic sections. METHODS: Light microscopy, environmental scanning electron microscopy and anatomical ultra-thin sectioning were employed to examine variation in fruits and seeds. Sixty-eight representatives across 14 of the 15 genera currently recognized within the tribes Halopeplideae and Salicornieae were examined to determine whether characters support current taxonomic groups. KEY RESULTS: Characters such as seed coat structure, embryo shape, seed orientation, the forms of seed storage proteins and carbohydrates show variation within the Salicornioideae and may be phylogenetically useful. The campylotropous ovule typical of the Chenopodiaceae generally results in a curved embryo; however, many Halosarcia and Sclerostegia species have straight embryos and in Salicornia and Sarcocornia the large peripheral embryo appears bent rather than curved. Seed coat ornamentation of Microcnemum and Arthrocnemum is distinct from other Salicornioideae as the elongated epidermal cells of the exotesta have convex walls. Histochemical stains of anatomical sections of cotyledon cells showed protein bodies were variable in shape, and starch grains were present in some species, namely Salicornia bigelovii, S. europaea and Allenrolfea occidentalis. CONCLUSIONS: While fruits and seeds were found to be variable within the subfamily, no synapomorphic characters support the tribe Halopeplideae as these genera have crustaceous seed coats, curved embryos and abundant perisperm; features characteristic of many of the tribe Salicornieae. The endemic Australian genera are closely related and few seed and fruit characters are diagnostic at the generic level. Nineteen characters identified as being potentially informative will be included in future phylogenetic analyses of the subfamily.     

Molecular evidence for a Mediterranean origin of the Macaronesian endemic genus Argyranthemum (Asteraceae)

The internal transcribed spacers (ITS) of nuclear ribosomal DNA were sequenced for 52 species from 32 genera and eight subtribes of Anthemideae. Phylogenetic analyses of ITS data generated trees that are largely incongruent with the recent classification of Anthemideae; most of the subtribes examined are not resolved as monophyletic. However, ITS trees are congruent with morphological, isozyme, phytochemical, and chloroplast DNA (cpDNA) restriction site data in supporting a Mediterranean origin for Argyranthemum, the largest endemic genus of the Atlantic oceanic islands. A combined analysis of ITS sequences and cpDNA restriction sites indicates that Argyranthemum is sister to the other three genera of Chrysantheminae (i.e., Chrysanthemum, Heteranthemis, and Ismelia). Times of divergence of Argyranthemum inferred from the ITS sequences ranged between 0.26 and 2.1 million years ago (mya) and are lower than values previously reported from isozyme and cpDNA data (1.5-3.0 mya). It is likely that rate heterogeneity of the ITS sequences in the Anthemideae accounts for the low divergence-time estimates. Comparison of data for 20 species in Argyranthemum and Chrysantheminae indicates that the cpDNA restriction site approach provided much more phylogenetic information than ITS sequences. Thus, restriction site analyses of the entire chloroplast genome remain a valuable approach for studying recently derived island plants.     

Ribosomal ITS Sequences Allow Resolution of Freshwater Sponge Phylogeny with Alignments Guided by Secondary Structure Prediction

Freshwater sponges include six extant families which belong to the suborder Spongillina (Porifera). The taxonomy of freshwater sponges is problematic and their phylogeny and evolution are not well understood. Sequences of the ribosomal internal transcribed spacers (ITS1 and ITS2) of 11 species from the family Lubomirskiidae, 13 species from the family Spongillidae, and 1 species from the family Potamolepidae were obtained to study the phylogenetic relationships between endemic and cosmopolitan freshwater sponges and the evolution of sponges in Lake Baikal. The present study is the first one where ITS1 sequences were successfully aligned using verified secondary structure models and, in combination with ITS2, used to infer relationships between the freshwater sponges. Phylogenetic trees inferred using maximum likelihood, neighbor-joining, and parsimony methods and Bayesian inference revealed that the endemic family Lubomirskiidae was monophyletic. Our results do not support the monophyly of Spongillidae because Lubomirskiidae formed a robust clade with E. muelleri, and Trochospongilla latouchiana formed a robust clade with the outgroup Echinospongilla brichardi (Potamolepidae). Within the cosmopolitan family Spongillidae the genera Radiospongilla and Eunapius were found to be monophyletic, while Ephydatia muelleri was basal to the family Lubomirskiidae. The genetic distances between Lubomirskiidae species being much lower than those between Spongillidae species are indicative of their relatively recent radiation from a common ancestor. These results indicated that rDNA spacers sequences can be useful in the study of phylogenetic relationships of and the identification of species of freshwater sponges.     

Phylogeny and biogeography of the freshwater crayfish Euastacus (Decapoda: Parastacidae) based on nuclear and mitochondrial DNA

Euastacus crayfish are endemic to freshwater ecosystems of the eastern coast of Australia. While recent evolutionary studies have focused on a few of these species, here we provide a comprehensive phylogenetic estimate of relationships among the species within the genus. We sequenced three mitochondrial gene regions (COI, 16S, and 12S) and one nuclear region (28S) from 40 species of the genus Euastacus, as well as one undescribed species. Using these data, we estimated the phylogenetic relationships within the genus using maximum-likelihood, parsimony, and Bayesian Markov Chain Monte Carlo analyses. Using Bayes factors to test different model hypotheses, we found that the best phylogeny supports monophyletic groupings of all but two recognized species and suggests a widespread ancestor that diverged by vicariance. We also show that Euastacus and Astacopsis are most likely monophyletic sister genera. We use the resulting phylogeny as a framework to test biogeographic hypotheses relating to the diversification of the genus.     

Origin and evolution of the endemic Macaronesian Inuleae (Asteraceae): evidence from the internal transcribed spacers of nuclear ribosomal DNA

The tribe Inuleae (Asteraceae) has 10 species endemic to the Macaronesian islands, including the three endemic genera Allagopappus, Schizogyne, and Vierea. Phylogenetic analyses of DNA sequence data from the internal transcribed spacers (ITS) of the nuclear ribosomal DNA of 47 taxa were performed using all Macaronesian endemics and representative species from 21 of the 36 genera of the Inuleae. The resulting ITS phylogeny reveals that Allagopappus is sister to a large clade that contains all genera with a predominantly Mediterranean distribution. This finding suggests that Allagopappus may represent an ancient lineage that found refuge in the Canary Islands following the major climatic and/or geologic changes in the Mediterranean basin after the Tertiary. The Macaronesian endemic genus Schizogyne is sister to Limbarda from the Mediterranean. The third Macaronesian endemic genus, Vierea, is sister to Perralderia, which is restricted to Morocco and Algeria. Pulicaria canariensis is sister to P. mauritanica, a species endemic to Morocco and Algeria. In contrast, P. diffusa from the Cape Verde Islands is sister to a broadly distributed species, P. crispa, that occurs from North Africa to the Arabian peninsula. Based on the ITS data, the genera Blumea, Inula, and Pulicaria are not monophyletic. The ITS trees suggested that Blumea mollis belongs to the tribe Plucheeae, a finding that is congruent with recent morphological evidence. A possible southern African origin for the core of the Laurasian taxa of the Inuleae is also suggested.     

A molecular phylogeny of the wild onions (Allium; Alliaceae) with a focus on the western North American center of diversity

Nuclear ribosomal DNA (ITS and ETS) sequences from 39 native Californian (USA) Allium species and congeners were combined with 154 ITS sequences available on GenBank to develop a global Allium phylogeny with the simultaneous goals of investigating the evolutionary history (monophyly) of Allium in the Californian center of diversity and exploring patterns of adaptation to serpentine soils. Phylogenies constructed with ITS alone or ITS in combination with ETS provided sufficient resolution for investigating evolutionary relationships among species. The ITS region alone was sufficient to resolve the deeper relationships in North American species. Addition of a second marker (ETS) further supports the phylogenetic placements of the North American species and adds resolution within subgenus Amerallium, a clade containing many Californian endemics. Within the global phylogeny, the native North American species were found to be monophyletic, with the exception of Allium tricoccum and Allium schoenoprasum. All native Californian species included in the analysis fell into a monophyletic subgenus Amerallium section Lophioprason, although endemic Californian species were not monophyletic due to the inclusion of species with ranges extending beyond the California Floristic Province. The molecular phylogeny strongly supports previous morphology-based taxonomic groupings. Based on our results, serpentine adaptation appears to have occurred multiple times within section Lophioprason, while the ancestor of the Californian center of diversity may not have been serpentine-adapted.     

Toward a global phylogeny of the Brassicaceae

The Brassicaceae is a large plant family (338 genera and 3,700 species) of major scientific and economic importance. The taxonomy of this group has been plagued by convergent evolution in nearly every morphological feature used to define tribes and genera. Phylogenetic analysis of 746 nrDNA internal transcribed spacer (ITS) sequences, representing 24 of the 25 currently recognized tribes, 146 genera, and 461 species of Brassicaceae, produced the most comprehensive, single-locus-based phylogenetic analysis of the family published to date. Novel approaches to nrDNA ITS analysis and extensive taxonomic sampling offered a test of monophyly for a large complement of the currently recognized tribes and genera of Brassicaceae. In the most comprehensive analysis, tribes Alysseae, Anchonieae plus Hesperideae, Boechereae, Cardamineae, Eutremeae, Halimolobeae, Iberideae, Noccaeeae, Physarieae, Schizopetaleae, Smelowskieae, and Thlaspideae were all monophyletic. Several broadly defined genera (e.g., Draba and Smelowskia) were supported as monophyletic, whereas others (e.g., Sisymbrium and Alyssum) were clearly polyphyletic. Analyses of ITS data identified several problematic sequences attributable to errors in sample identification or database submission. Results from parsimony ratchet and Bayesian analyses recovered little support for the backbone of the phylogeny, suggesting that many lineages of Brassicaceae have undergone rapid radiations that may ultimately be difficult to resolve with any single locus. However, the development of a preliminary supermatrix including the combination of 10 loci for 65 species provides an initial estimate of intertribal relations and suggests that broad application of such a method will provide greater understanding of relationships in the family.     

Evolution of St Helena arborescent Astereae (Asteraceae): relationships of the genera Commidendrum and Melanodendron

The cladistic relationships of endemic Commidendrum (four species) and Melanodendron (one species) from St Helena were inferred from sequences of ITS1 and ITS2 of nuclear ribosomal DNA. Despite showing a range of morphological and ecological variation, the four species of Commidendrum , C. spurium , C. robustum , C. rotundifolium , and C. rugosum , form a closely related monophyletic group with percentage sequence divergence between 0.2 and 0.9%. Melanodendron integrifolium is sister to Commidendrum indicating that the two genera may have evolved from a common ancestor that arrived in St Helena via a single dispersal event. The closest relatives of Commidendrum and Melanodendron appear to be South African, in the predominantly shrubby genus Felicia , although further sampling of South African Astereae is required. We discuss the evolution and adaptive radiation of these rare and threatened species with particular reference to the possible role of heterochrony.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 69–83.     

Evolution of Caulanthus amplexicaulis var. barbarae (Brassicaceae), a rare serpentine endemic plant: a molecular phylogenetic perspective

Intra- and interspecific phylogenetic relationships of the rare serpentine endemic taxon Caulanthus amplexicaulus var. barbarae and related taxa in the "Streptanthoid Complex" of genera (Streptanthus, Caulanthus, Guillenia) were examined using nuclear ribosomal internal transcribed spacer (ITS) and chloroplast trnL intron sequences. Phylogenetic hypotheses generated from 81 variable ITS nucleotide sites and six variable trnL nucleotide sites indicate that Streptanthus and Caulanthus are nonmonophyletic groups. Caulanthus amplexicaulis var. barbarae and its more widespread nonserpentine sister taxon Caulanthus amplexicaulis var. amplexicaulis formed a distinct monophyletic group. Among the taxa in our study, C. amplexicaulis was most closely related to Streptanthus tortuosus. The ITS sequences supported monophyly of subgenus Euclesia, which includes the bulk of the serpentine endemics in the Streptanthoid Complex. The serpentine taxa were nonmonophyletic, occurring in at least three distinct clades, suggesting that tolerance to serpentine may be gained or lost through relatively few genetic changes. Intraspecific ITS1 and ITS2 sequence divergence within C. amplexicaulis (1.3-1.8%) was higher than in comparable species (0.0-0.3%); implications of this genetic differentiation for the conservation status of C. amplexicaulis var. barbarae are discussed. Evidence is presented that supports a "biotype depletion" model for the origin of this rare endemic taxon.     

Phylogeny and biogeography of Crinum L. (Amaryllidaceae) inferred from nuclear and limited plastid non-coding DNA sequences

The genus Crinum L. is the only pantropical genus of the Amaryllidaceae. Phylogenetic and biogeographical analyses of nrDNA ITS and plastid trnL-F sequences for all continental groups of the genus Crinum and related African genera are presented, with the genus Amaryllis used as outgroup. ITS indicates that C. baumii is more closely related to Ammocharis and Cybistetes than to Crinum sensu stricto . Three clades are resolved in Crinum s.s. One unites a monophyletic American group with tropical and North African species. The second includes all southern African species and the Australian endemic C. flaccidum . The third includes monophyletic Madagascar, Australasian and Sino-Himalayan clades, with southern African species. The trnL-F phylogeny resolves an American and an Asian/Madagscar clade, and confirms the relationship of C. flaccidum with species endemic to southern Africa. The salverform, actinomorphic perianths of subg. Crinum appear to have evolved several times in the genus from ancestors with zygomorphic perianths (subg. Codonocrinum ), thus neither subgenus is monophyletic. Biogeographical analyses place the origin of Crinum in southern Africa, as the region is optimized at all ancestral nodes in the tree topology, and in basal interior nodes of all but one of the major clades. The genus underwent three major waves of radiation corresponding to the three main clades resolved in our trees. Two entries into Australia for the genus are indicated, as are separate Sino-Himalayan and Australasian dispersal events.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 349–363.     

A Phylogenetic Study of Tribe Euphorbieae (Euphorbiaceae)

A phylogenetic investigation of a monophyletic lineage of spurge plants, tribe Euphorbieae, was conducted to elucidate evolutionary relationships, to clarify biogeographic patterns, and to reexamine the previous classification of Euphorbieae. Cladistic analyses of the 52 morphological characters of 61 species resulted in 2922 equally most parsimonious trees of 193 steps with a consistency index of 0.34. The strict consensus tree indicates genus Anthostema of subtribe Anthosteminae as a likely sister group to all other members of tribe Euphorbieae. The morphological data support a monophyletic origin of subtribe Euphorbiinae, but the subtribes Anthosteminae and Neoquillauminiinae did not form monophyletic groups. Although the previous taxonomic treatments within tribe Euphorbieae have supported the generic status of Pedilanthus, Monadenium, Synadenium, Chamaesyce, and Elaeophorbia, the results of this analysis do not support generic placement of them based on cladistic principles. Recognition of these groups as genera results in Euphorbia becoming a paraphyletic group. One solution to this problem in Euphorbieae is to divide the largest genus Euphorbia into several monophyletic genera and to keep the generic ranks for previously recognized genera. The distribution of basal endemic genera in Euphorbieae showed African and east Gondwanan affinities and strongly indicated that the ancestor of Euphorbieae originated prior to the breakup of Gondwanaland from an old group in Euphorbiaceae. However, some recent African taxa of Euphorbia should be interpreted by transoceanic dispersal from the New World ancestors.     

Molecular phylogeny of the scincid lizards of New Caledonia and adjacent areas: evidence for a single origin of the endemic skinks of Tasmantis

We use approximately 1900bp of mitochondrial (ND2) and nuclear (c-mos and Rag-1) DNA sequence data to recover phylogenetic relationships among 58 species and 26 genera of Eugongylus group scincid lizards from New Caledonia, Lord Howe Island, New Zealand, Australia and New Guinea. Taxon sampling for New Caledonian forms was nearly complete. We find that the endemic skink genera occurring on New Caledonia, New Zealand and Lord Howe Island, which make up the Gondwanan continental block Tasmantis, form a monophyletic group. Within this group New Zealand and New Zealand+Lord Howe Island form monophyletic clades. These clades are nested within the radiation of skinks in New Caledonia. All of the New Caledonian genera are monophyletic, except Lioscincus. The Australian and New Guinean species form a largely unresolved polytomy with the Tasmantis clade. New Caledonian representatives of the more widespread genera Emoia and Cryptoblepharus are more closely related to the non-Tasmantis taxa than to the endemic New Caledonian genera. Using ND2 sequences and the calibration estimated for the agamid Laudakia, we estimate that the diversification of the Tasmantis lineage began at least 12.7 million years ago. However, using combined ND2 and c-mos data and the calibration estimated for pygopod lizards suggests the lineage is 35.4-40.74 million years old. Our results support the hypothesis that skinks colonized Tasmantis by over-water dispersal initially to New Caledonia, then to Lord Howe Island, and finally to New Zealand.     

Structural, biochemical, and physiological characterization of photosynthesis in two C4 subspecies of Tecticornia indica and the C3 species Tecticornia pergranulata (Chenopodiaceae)

Among dicotyledon families, Chenopodiaceae has the most C(4) species and the greatest diversity in structural forms of C(4). In subfamily Salicornioideae, C(4) photosynthesis has, so far, only been found in the genus Halosarcia which is now included in the broadly circumscribed Tecticornia. Comparative anatomical, cytochemical, and physiological studies on these taxa, which have near-aphyllous photosynthetic shoots, show that T. pergranulata is C(3), and that two subspecies of T. indica (bidens and indica) are C(4) (Kranz-tecticornoid type). In T. pergranulata, the stems have two layers of chlorenchyma cells surrounding the centrally located water storage tissue. The two subspecies of T. indica have Kranz anatomy in reduced leaves and in the fleshy stem cortex. They are NAD-malic enzyme-type C(4) species, with mesophyll chloroplasts having reduced grana, characteristic of this subtype. The Kranz-tecticornoid-type anatomy is unique among C(4) types in the family in having groups of chlorenchymatous cells separated by a network of large colourless cells (which may provide mechanical support or optimize the distribution of radiation in the tissue), and in having peripheral vascular bundles with the phloem side facing the bundle sheath cells. Also, the bundle sheath cells have chloroplasts in a centrifugal position, which is atypical for C(4) dicots. Fluorescence analyses in fresh sections indicate that all non-lignified cell walls have ferulic acid, a cell wall cross-linker. Structural-functional relationships of C(4) photosynthesis in T. indica are discussed. Recent molecular studies show that the C(4) taxa in Tecticornia form a monophyletic group, with incorporation of the Australian endemic genera of Salicornioideae, including Halosarcia, Pachycornia, Sclerostegia, and Tegicornia, into Tecticornia.     

Molecular phylogenetic studies on the Diatrypaceae based on rDNA-ITS sequences

The order Diatrypales (Ascomycota) contains one single family, the Diatrypaceae. To obtain insight in the phylogenetic relationships within this family, the complete sequences of the ITS region (ITS1, 5.8S rRNA gene and ITS2) of 53 isolates from the five main genera in the family (Diatrype, Diatrypella, Cryptosphaeria, Eutypa and Eutypella) were determined and aligned for phylogenetic reconstruction. Sequence analysis revealed the presence of tandem repeated motifs 11 nucleotides-long, placed in homologous positions along the ITS1 region. Parsimony analysis established the existence of nine monophyletic groups and one branch with a single isolate of Eutypella quaternata. The phylogenetic relationships established by parsimony analysis did not correlate well with classical taxonomic schemes. None of the five genera included in this study was found to be monophyletic. The genera Diatrype, Eutypa and Cryptosphaeria each were divided into two groups. Isolates of Diatrype flavovirens appeared in a clade separated from the one that grouped Diatrype disciformis and the rest of Diatrype species. The Eutypa strains appeared distributed into two clades, one grouping Eutypa lata and related species (Eutypa armeniacae, Eutypa laevata, Eutypa petrakii), and another with the remaining species of the genus. Eutypella (excluding Eutypella quaternaria) appeared as an unstable monophyletic group, which was lost when the sequence alignment was subjected to neighbor-joining analysis. The genus Diatrypella was not associated with any monophyletic group, suggesting that the multisporate asci character has appeared several times during the evolution of the group. Overall, our study suggests the need to revise many of the concepts usually applied to the classification of members of the family.     

Phylogenetic relationships of the endemic Antarctic benthic hydroids (Cnidaria, Hydrozoa): what does the mitochondrial 16S rRNA tell us about it?

Hydroidolinan hydrozoans are widely represented in the benthic Antarctic ecosystem, mainly by some endemic and putative monophyletic groups, never included in molecular phylogenetic analyses. 38 partial sequences of the mitochondrial 16S rRNA gene were obtained for 38 species belonging to 14 families (six anthoathecates and eight leptothecates) and 20 genera (7 anthoathecates and 13 leptothecates). These sequences were combined with 108 additional sequences retrieved from the GenBank to investigate both the hypothetical monophyletism and the phylogenetic relationships of those endemic Antarctic groups; the potential use of the marker for barcoding was also investigated. Our results uphold the monophyly of some important hydroidolinan groups, such as the superfamily Plumularioidea (together with all its families, including Schizotrichidae, fam. nov.) and the Aplanulata. Concerning the Antarctic endemic groups, most results as monophyletic (Oswaldella, Schizotricha and Staurotheca), some genera form part of the expectable groups (e.g. Abietinella, located into the monophyletic Zygophylacinae clade) and, finally, others have shown a surprising position (e.g. Stegella, closely related to Lafoeinae, or Billardia and Stegopoma, allied with Hebellidae). Finally, our study has shown the utility of the marker to recognize the Antarctic species considered, but the low genetic divergence in some of the most important Antarctic groups suggests being careful when using it for DNA barcoding in the case of the original Antarctic hydroid fauna.     

Evolution of Lycopodiaceae Inferred from Spacer Sequencing of Chloroplast rRNA Genes

Nucleotide sequences of a chloroplast rDNA region including 8 bp from the 3" end of 23S rDNA–ITS2–4.5S rDNA–ITS3–5S rDNA–ITS4 (approximately 800 bp) were determined in 25 species of Lycopodiaceae and two species of the genus Isoetes. The rate of molecular evolution of spacers significantly varied in different Lycopsida taxa. A phylogenetic analysis by the neighbor-joining (NJ) method revealed that the family Lycopodiaceae is monophyletic. The topology of phylogenetic trees suggests the isolation of four or probably five genera in family Lycopodiaceae. For these genera, synapomorphic indels were detected. The obtained data were compared with the results of phylogenetic analysis of Lycopsida with regard to other sequences. The relationships of taxa within the family Lycopodiaceae is discussed.     

Phylogenetic relationships, morphological incongruence, and geographic speciation in the fontinalaceae (Bryophyta)

Nuclear ribosomal DNA (internal transcribed spacer region) and chloroplast DNA (trnL-trnF region) were sequenced from 40 samples representing all three genera (Brachelyma, Dichelyma, and Fontinalis) and 18 species of the aquatic moss family, Fontinalaceae. Phylogenetic reconstructions recovered from separate and combined analyses were used to test the hypotheses that Fontinalis and Dichelyma are monophyletic (Brachelyma is monotypic), that groups of species within Fontinalis based on leaf morphology (keeled, concave, plane) form monophyletic groups, and that species delineation based on morphological characters within Fontinalis are congruent with nr- and cpDNA gene trees. Using Brachelyma subulata to root the tree, both Dichelyma and Fontinalis are monophyletic and patristically divergent (each united by >15 synapomorphic mutations). Groups of species within Fontinalis defined by leaf morphology are polyphyletic and it is clear that leaf morphology is labile in the genus. As defined morphologically, species of Fontinalis are nonmonophyletic for both nr- and cpDNA sequences and populations of some morphological taxa are separated in widely divergent clades. Molecular evidence suggests that at least some morphospecies are artificial, defined by convergent leaf forms. The weight of the evidence indicates that F. antipyretica is positively paraphyletic, with European populations more closely related to (i.e., share a more recent common ancestor with) European endemic species than to North American populations that are morphologically conspecific. North American populations are more closely related to North American endemic species.     

Phylogenetic relationships of conifers inferred from partial 28S rRNA gene sequences

The conifers, which traditionally comprise seven families, are the largest and most diverse group of living gymnosperms. Efforts to systematize this diversity without a cladistic phylogenetic framework have often resulted in the segregation of certain genera and/or families from the conifers. In order to understand better the relationships between the families, we performed cladistic analyses using a new data set obtained from 28S rRNA gene sequences. These analyses strongly support the monophyly of conifers including Taxaceae. Within the conifers, the Pinaceae are the first to diverge, being the sister group of the rest of conifers. A recently discovered Australian genus Wollemia is confirmed to be a natural member of the Araucariaceae. The Taxaceae are nested within the conifer clade, being the most closely related to the Cephalotaxaceae. The Taxodiaceae and Cupressaceae together form a monophyletic group. Sciadopitys should be considered as constituting a separate family. These relationships are consistent with previous cladistic analyses of morphological and molecular (18S rRNA, rbcL) data. Furthermore, the well-supported clade linking the Araucariaceae and Podocarpaceae, which has not been previously reported, suggests that the common ancestor of these families, both having the greatest diversity in the Southern Hemisphere, inhabited Gondwanaland.     

Phylogeny of Melaleuca, Callistemon, and Related Genera of the Beaufortia Suballiance (Myrtaceae) Based on 5S and ITS-1 Spacer Regions of nrDNA

A phylogenetic analysis of genera within the informal suballiance Beaufortia (family Myrtaceae), largely endemic to Australia and New Caledonia, is presented based on separate and combined data sets for 5S and ITS-1 spacer regions of nuclear ribosomal DNA. The two sets were not in conflict but the 5S data set was more informative. Data were analysed using conventional parsimony, jackknife parsimony, and three-item parsimony analyses. Three-item analysis gave more resolved trees than conventional parsimony analysis. The Beaufortia suballiance includes two major clades, with all Australian representatives of Callistemon (shown to be monophyletic) and most Australian representatives of Melaleuca forming one of these. The sister clade comprises a well-defined group of endemic New Caledonian taxa (classified as Callistemon and Melaleuca ), some Australian species of Melaleuca , a clade including the Western Australia/Northern Territory genera Beaufortia, Lamarchea , and Regelia , and a clade including the south-west Western Australian genera Calothamnus, Eremaea, Conothamnus , and Phymatocarpus . All molecular analyses sup port the monophyly of Conothamnus and of Regelia , genera for which a number of species were included. Three-item analysis of the combined data set supports the monophyly of Beaufortia . The findings have implications for both taxonomy and biogeography.     

The phylogeny and taxonomy of genera Cystoderma and Cystodermella (Agaricales) based on nuclear ITS and LSU sequences

Species delimitation in Cystoderma and Cystodermella was evaluated based on ITS and LSU rDNA sequences as well as morphological data. Two species of Cystoderma are synonymised with C. carcharias and three species with C. jasonis, distinguishing the synonymised taxa as varieties of these accepted species. Analyses of partial LSU rDNA sequences revealed Cystoderma and Cystodermella as distinct monophyletic genera, with Ripartitella representing a well-supported sister group of the latter. Phaeolepiota aurea represents either an unsupported sister group or member of Cystoderma in the phylogenies based on LSU and ITS sequences rDNA data, respectively. The tribe Cystodermateae sensu Singer did not appear monophyletic according to analyses of LSU sequences. On the basis of these data, the phylogenetic relationships among most of the analyzed genera could not be resolved unequivocally.