Two new species of the diatom genusChaetoceros (Bacillariophyta)

Two new planktonic diatom species of the genusChaetoceros are described herein:Ch. octagonus andCh. rectus, from material of Baja California coasts and the Gulf of California, respectively;Ch. rectus was also found in a sample from Australian waters.Ch. octagonus is a robust species, with a characteristic pyramidal valve shape, heavily silicified valves and setae, and one central rimoportula on every valve in the chain; it is compared with related species, which show a similar morphology, especially by electron microscopy. It belongs into subg.Chaetoceros, sect.Borealia. Ch. rectus is placed in subg.Hyalochaete, and provisionally within sect.Anastomosantia. Its major characters are: chains, cells, and setae are delicate and fragile, cells are joined in the chain by a bridge which connects sibling intercalary setae, valves and setae are weakly silicified, and one rimoportula is present on terminal valves only. Comparison is made with another species of the same section.Ch. rectus shows a different manner of chain-forming within the genus than previously described in the literature.     

Phylogenetic systematics of New WorldIpomoea (Convolvulaceae) based on chloroplast DNA restriction site variation

Chloroplast DNA restriction site variation was studied in 31 New World species ofIpomoea, representing a majority of the New World sections and series within the genus. Using 14 endonucleases, a total of 124 phylogenetically informative restriction sites was detected. Dollo parsimony, Wagner parsimony, and bootstrap methods were employed to construct phylogenetic trees and evaluate confidence intervals of monophyletic groups. With a few exceptions, groups circumscribed on the basis of morphological variation are in agreement with groupings based on restriction site variation. Relationships between subgeneric groupings, however, disagree substantially with those proposed in the past. Although conflicting hypotheses for some intersectional relationships are not presently resolvable, cpDNA restriction site analyses propose the following refinements of existing classification schemes.Ipomoea ser.Setosae is divided into distantly related groups, as is sect.Pharbitis. SeriesTyrianthinae, a proposed segregate of sect.Pharbitis, is associated with sect.Calonyction and the Tricolor complex (subg.Quamoclit).Ipomoea sect.Batatas is segregated from other herbaceous groups of the heterogeneous subg.Quamoclit sensu lato and aligned as a derivative ofI. setosa, subg.Eriospermum. To test for homology of key characters weighted in traditional schemes, morphological features were studied with respect to their distribution on lineages defined by restriction site data. Characters such as setose sepals, foliose-pubescent sepals, and erect growth habit, among others, are interpreted as having multiple origins, while 3-locular ovaries, 4-locular ovaries, and long-haired seeds have evolved only once.     

Bulb tunic anatomy and its taxonomic implication in Allium L. (Amaryllidaceae: Allioideae)

Abstract

Allium is taxonomically a difficult genus with blurred taxonomic borders at all taxonomic ranks. In this research, anatomy and morphology of bulb tunics in 42 species of the genus representing its 16 currently recognized sections and 6 subgenera (Allium, Cepa, Reticulatobulbosa, Amerallium, Polyprason and Melanocrommyum) were investigated. Our results indicated the following characters to be most informative at sectional and subgeneric levels: features of calcium oxalate crystals and subepidermal cell layer of the outermost bulb tunic, type of tracheids, and bulbils presence. Three main types of crystals, i.e. prismatic, sand and druses, were fairly common among the investigated species except for the members of A. sect. Acanthoprason (A. subg. Melanocrommyum) that often lack crystals. The subepidermal layers of outer tunics were mostly composed of hexagonal, rectangular, or elongated cells but A. paradoxum (A. subg. Amerallium, sect. Briseis) showed the pentagonal type and A. longisepalum (A. subg. Amerallium, sect. Molium) the elliptic type of subepidermal cells. The members of A. sub. Melanocrommyum showed various types of tunic cells and crystals.     

Phylogenetic analysis of <Emphasis Type="Italic">IRIS</Emphasis> L. from China on chloroplast <Emphasis Type="Italic">TRN</Emphasis>L-F sequences

Phylogenetic relationships among the six Iris subgenera were reconstructed by chloroplast trnL-F sequences data using maximum likelihood. The entire matrix of aligned bases analyzed includes 1043 characters and the length of all sequences varied from 747 bp to 893 bp, and mutation sites accounted for 18.79% of the total length. The cluster analysis results accorded well with the subgeneric classification of Chinese Iris species. Results suggested rhizomes and sepals lacking ornament are ancestral characters, and subg. Xyridion and subg. Limniris are more primordial than another four subgenera. Subgenus Nepalensis and subg. Xyridion were resolved as monophyletic.     

RAD sequencing resolved phylogenetic relationships in European shrub willows (Salix L. subg. Chamaetia and subg. Vetrix) and revealed multiple evolution of dwarf shrubs

The large and diverse genus Salix L. is of particular interest for decades of biological research. However, despite the morphological plasticity, the reconstruction of phylogenetic relationships was so far hampered by the lack of informative molecular markers. Infrageneric classification based on morphology separates dwarf shrubs (subg. Chamaetia) and taller shrubs (subg. Vetrix), while previous phylogenetic studies placed species of these two subgenera just in one largely unresolved clade. Here we want to test the utility of genomic RAD sequencing markers for resolving relationships at different levels of divergence in Salix. Based on a sampling of 15 European species representing 13 sections of the two subgenera, we used five different RAD sequencing datasets generated by Ipyrad to conduct phylogenetic analyses. Additionally we reconstructed the evolution of growth form and analyzed the genetic composition of the whole clade. The results showed fully resolved trees in both ML and BI analysis with high statistical support. The two subgenera Chamaetia and Vetrix were recognized as nonmonophyletic, which suggests that they should be merged. Within the Vetrix/Chamaetia clade, a division into three major subclades could be observed. All species were confirmed to be monophyletic. Based on our data, arctic‐alpine dwarf shrubs evolved four times independently. The structure analysis showed five mainly uniform genetic clusters which are congruent in sister relationships observed in the phylogenies. Our study confirmed RAD sequencing as a useful genomic tool for the reconstruction of relationships on different taxonomic levels in the genus Salix.     

Phylogeny of Allium L. subg. Melanocrommyum (Webb et Berth.) Rouy based on DNA sequence analysis of the internal transcribed spacer region of nrDNA

 Sequence analysis of the ITS region of nuclear ribosomal DNA from subgeneric representatives of Allium L. produced phylogenetic trees which concurred with previous conclusions based on classical taxonomy. Phylogenetic analysis revealed a closer relationship between Nectaroscordum siculum and Allium cernuum (representing Amerallium) than between A. cernuum and the rest of the Allium species employed in this study. The phylogeny of subg. Melanocrommyum based on ITS sequences largely agreed with inferences made by previous researchers based on morphology or a restriction analysis of chloroplast DNA. However, the phylogenetic positions of Allium protensum and Allium macleanii based on ITS sequences did not correspond to their morphological similarity with Allium schubertii and Allium giganteum, respectively. Received: 15 February 1998 / Accepted: 12 March 1998     

An updated classification for the hyper-diverse genus Corydalis (Papaveraceae: Fumarioideae) based on phylogenomic and morphological evidence

The genus Corydalis, with ca. 530 species, has long been considered taxonomically challenging because of its great variability. Previous molecular analyses, based on a few molecular markers and incomplete taxonomic sampling, were clearly inadequate to delimit sections and subgenera. We have performed phylogenetic analyses of Corydalis and related taxa, using 65 shared protein-coding plastid genes from 313 accessions (including 280 samples of ca. 226 species of Corydalis) and 152 universal low-copy nuclear genes from 296 accessions (including 271 samples of Corydalis) covering all 42 previously recognized sections and five independent “series”. Phylogenetic trees were inferred using Bayesian Inference and Maximum Likelihood. Eight selected morphological characters were estimated using ancestral state reconstructions. Results include: (i) of the three subgenera of Corydalis, two are fully supported by both the plastid and nuclear data; the third, subg. Cremnocapnos, is weakly supported by plastid DNA only, whereas in the nuclear data the two included sections form successive outgroups to the rest of the genus; (ii) among all 42 sections and five “series”, 25 sections and one “series” are resolved as monophyletic in both data sets; (iii) the common ancestor of Corydalis is likely to be a perennial plant with a taproot, yellow flowers with a short saccate spur, linear fruits with recurved fruiting pedicels, and seeds with elaiosomes; (iv) we provide a new classification of Corydalis with four subgenera (of which subg. Bipapillatae is here newly described), 39 sections, 16 of which are consistent with the previous classification, 16 sections have been recircumscribed, one section has been reinstated and six new sections are established. Characters associated with lifespan, underground structures, floral spur, fruit and elaiosomes are important for the recognition of subgenera and sections. These new phylogenetic analyses combined with ancestral character reconstructions uncovered previously unrecognized relationships, and greatly improved our understanding of the evolution of the genus.     

A new infrageneric classification and phylogenetic trends in the genusRhododendron (Ericaceae)

Recent studies have improved the infrageneric classification ofRhododendron, including my own investigations on flavonoids and anthocyanins as chemosystematic markers. From a synoptical comparison of morphological, anatomical and phytochemical characters a new system for the genus is proposed. Phylogenetic character progressions and relationships among subgenera, sections and subsections are discussed and illustrated. Key positions for subg.Candidastrum between chori subgenerumRhododendron andNomazalea, and for subg.Choniastrum between chori subgenerumHymenanthes andNomazalea are suggested.     

凤仙花属棒凤仙亚属(凤仙花科)植物花粉形态的分类学意义

棒凤仙亚属代表着凤仙花属最先分化出的一支,以多年生草本,多于5朵花的总状花序,侧生萼片4枚,3沟花粉,心皮四室且每室具1枚种子,果实棒锤状,种子椭圆形以及三沟花粉其极面观为三角形而区别于其它种类。该亚属主要分布于中国南部,少数种类辐射分布至华中和中南半岛地区。已有报道证实花粉的形态特征对凤仙花属植物的属下分类具有重要意义,但对棒凤仙亚属的种类少有涉及。为了进一步探讨该亚属花粉的形态特征及其分类学价值,该研究应用扫描电镜技术对国产棒凤仙亚属植物的14种以及凤仙花亚属的窄萼凤仙花的花粉进行了观察。结果表明：棒凤仙亚属的花粉以单粒存在,具3条萌发沟,辐射对称,极面观为三角形或三角状圆形,花粉粒外壁具均匀的网状纹饰,网脊平滑或具波状边缘,网眼中具不同密度的颗粒状突起。棒凤仙亚属的花粉形态与水角属的花粉形态相似,表现出了其原始性;其花粉形态特征与花部形态性状等相关性差,对该亚属的组级分类意义较小,但对于该亚属的种间界定具有重要意义;而其花粉的极面观形状、赤道面观形状以及网状纹饰等变异相对稳定,对于界定该亚属具有重要的分类学价值。     

CHLOROPLAST-DNA PHYLOGENETICS AND BIOGEOGRAPHY IN A RETICULATING GROUP: STUDY IN POA (POACEAE)

Cladistic analysis of Poa chloroplast DNA (cpDNA) restriction sites tested previously hypothesized relationships within the genus. Forty-six taxa representing 19 sections or groups and three subgenera of Poa and two out-group genera, Puccinellia and Bellardiochloa, are analyzed. Five major and several minor cpDNA groups are identified. The cpDNA cladogram is generally congruent with the subgeneric taxonomy of Poa. Exceptions are reclassified or are discussed in terms of character incompatibilities and possible reticulation events. The cpDNA tree detected relationships among sections that were unresolved using traditional character sets and provides a basis for polarization of morphological character states. An assessment of biogeographic events based on the cpDNA tree suggests: 1) Poa originated in Eurasia; 2) at least six groups of species independently colonized North America; and 3) two of the latter groups colonized South America, and one closely related group colonized New Zealand and Australia. The cpDNA tree provided a conservative estimate of the number of amphi-neotropical disjunctions when compared to the known number of species disjunctions.     

A molecular phylogenetic study of Hemsleya (Cucurbitaceae) based on ITS, rpl16, trnH-psbA, and trnL DNA sequences

This paper presents the first molecular phylogeny of the genus Hemsleya using nuclear ITS and plastid trnH-psbA, rpl16, and trnL DNA sequences to examine the relationships among Hemsleya species. Phylogenetic relationships were elucidated using a combined analysis of all four datasets, however, the number of parsimony-informative characters was still insufficient to resolve all relationships. Parsimony and Bayesian trees were highly congruent. Twenty-three species of Hemsleya split into two major clades corresponding to two subgenera, i.e., subg. Graciliflorae and subg. Hemsleya. These results are partly in agreement with Li’s sectional classification. However, the molecular data are inconsistent with Li’s classification at the subsectional level. The molecular phylogeny revealed a striking overall correlation between the phylogenetic relationships of the species and their geographical distribution. The Kangdian ancient landmass could be the center of origin of the genus.     

ITS sequences from nuclear rDNA suggest unexpected phylogenetic relationships between Euro-Mediterranean, East Asiatic and North American taxa ofQuercus (Fagaceae)

Nucleotide sequences from the internal transcribed spacer (ITS) regions of the 18S–26S nuclear ribosomal DNA have been studied from ten species ofQuercus (representing four subgenera),Castanea sativa andFagus sylvatica, as a preliminary molecular contribution to the still poorly understood systematics and evolution ofFagaceae. The resulting matrix has been used to calculate pair-wise sequence divergence indices and to construct a maximum parsimony tree forQuercus coding indels as a fifth state. Divergence is greater forQuercus vs.Fagus than forQuercus vs.Castanea. The tree for theQuercus taxa studied reveals two clearly divergent clades. In clade I the evergreen W MediterraneanQ. suber appears in a basal position as sister to more distal deciduous taxa, i.e. the E MediterraneanQ. macrolepis and the E AsiaticQ. acutissima (all formerly united as different sections under the apparently polyphyletic subg.Cerris), andQ. rubra (a representative of the N American subg.Erythrobalanus), forming a pair withQ. acutissima. In clade II the evergreen southeastern N AmericanQ. virginiana is basal and sister to the remaining three branches, i.e. a pair of evergreen Mediterranean taxa withQ. ilex andQ. coccifera (subg.Sclerophyllodrys), the deciduous but otherwise plesiomorphic SE European/SW AsiaticQ. cerris (type species of subg.Cerris), and the related but more apomorphic European pairQ. petraea andQ. robur (subg.Quercus). These results partly conflict with current taxonomic classification but are supported by some anatomical and morphological characters. They document polyphyletic lines from evergreen to deciduous taxa and suggest Tertiary transcontinental connections within the genus.     

Phylogenetic relationships betweenVicia faba (Fabaceae) and related species inferred from chloroplasttrnL sequences

The chloroplasttrnL intron from 46 differentVicia accessions, representing five of the nine sections of the genusVicia subg.Vicia sensuMaxted (1991a) were amplified by the Polymerase Chain Reaction (PCR) using oligonucleotide primers homologous to conserved regions intrnL. The products fell into two distinct groups; those of approximately 250 nt and those of around 450 nt in length. Of these, products from 17 differentVicia species were cloned and their nucleotide sequences determined. Multiple alignments were assembled and phylogenetic trees constructed by the weighted least-squares distance method. ALathyrus latifolius trnL intron sequence was used as an outgroup. The resulting trees clearly group and separate the sectt.Narbonensis, Bithynica andFaba species but were less able to distinguish species from sectt.Hypechusa andPeregrinae. Based on these sequence data,V. faba appears to be more distant from sect.Narbonensis than sectt.Hypechusa andPeregrinae. The results are in general agreement with a recent treatment ofVicia subg.Vicia (Maxted 1993) and lend further support to placingV. faba in the monospecific sect.Faba.     

Iron,silicate, and light co-limitation of three Southern Ocean diatom species

The effect of combined iron, silicate, and light co-limitation was investigated in the three diatom species Actinocyclus sp. Ehrenberg, Chaetoceros dichaeta Ehrenberg, and Chaetoceros debilis Cleve, isolated from the Southern Ocean (SO). Growth of all species was co-limited by iron and silicate, reflected in a significant increase in the number of cell divisions compared to the control. Lowest relative Si uptake and drastic frustule malformation was found under iron and silicate co-limitation in C. dichaeta, while Si limitation in general caused cell elongation in both Chaetoceros species. Higher light intensities similar to SO surface conditions showed a negative impact on growth of C. dichaeta and Actinocyclus sp. and no effect on C. debilis. This is in contrast to the assumed light limitation of SO diatoms due to deep wind driven mixing. Our results suggest that growth and species composition of Southern Ocean diatoms is influenced by a sensitive interaction of the abiotic factors, iron, silicate, and light.     

Palynological study of Potentilla subg. Potentilla (Rosaceae) in the Western Mediterranean

A palynological study by LM and SEM was made of 26 taxa of Potentilla L. subg. Potentilla. It is more precise on material from 110 populations, mainly from the western Mediterranean. On the basis of morphometry, the subg. Potentilla can be said to have a stenopalynous nature, due to the absence of significant differences between the taxa studied and to the high degree of overlapping shown by their range of variation. With respect to ornamentation, which is striate, only P. rupestris pollen can be separately identified by a much more marked striation than the other species studied. An attempt was made to observe the taxonomic and phylogenetic relationships between the species of the natural groups of Potentilla on the basis of their pollen characters.     

Species relationships and taxonomy inTulipa subg.Tulipa (Liliaceae)

Principal component and canonical variate analyses were used to analyse the variation of 34 morphological characters measured in 98 accessions ofTulipa subg.Tulipa, formerly known as sect.Leiostemones. In addition 43 accessions were analysed cytogenetically by means of C-banding methods. Based on the encountered variation and on geographical distribution data 30 species in five sections were recognized, of which the synonymy is stated. Seven new series in two different sections have been designated.