On Circumscription of the Genus Prenanthes L. and Notoseris Shih — A New Genus of Compositae from China

After having examined all specimens of the genus Prenanthes L. of Compositae in the Herbarium of Institute of Botany, Academia Sinica, I find that the classic concept on the genus Prenanthes established by G. Bentham in 1873 has not been held exactly by some of European, American, Japanese and Chinese botanists. For example, W. B. Hemsley, S. T. Dunn, A. Franchet, S. Kitamura and C. C. Chang placed plants from China which belong to other groups into the genus; I also find that the classic concept of the genus is not clear. The present paper makes a revision not only on the classic concept of the genus, but also on its concept assumed by the above-mentionded botanists. With the combination of numerous (25-35), white or yellow ligular florets, numerous ribs of achenes, Prenanthes alba L. (Nabalus albus (L.) Shih, comb. nov.) is distinctly different from Prenanthes purpurea L., which has the combination of purple, few (5-15) ligular florests and few ribs of achenes. Nabalus Cass., as a genus established early (1825) by H. Cassini, should be restored. It is not reasonable to treat Nabalus as a subgenus (E. B. Babcock et al. 1947) or a section (S. Kitamura, 1956) or as a synonym (G. Bentham, 1983) of the genus Preanathes L. The present author recognizes seven species in the new revised genus Prenanthes L. in China, 4 of which are described as new. In the genus Nabalus Cass. only one species, N. ochroleuca Maxim., is distributed in Northeast China. As Lactuca melanantha Franch. (1895), Prenanthes henryi Dunn (1903), P. glandulosa Dunn (1903), Lactuca triflora Hemsl. (1888) (it was transferred to Prenanthes L. by C. C. Chang in 1934), Prenanthes formosana Kitam. (1934) and P. wilsoni Chang (1934) all have campanulate involucres, purple phyllaries, purple dorsi-ventrally compressed achenes, longitudinal rids 6-9 on each side of achene truncate and beakless at its apex and pilose tubes of corollae, they should be placed neither into the genus Prenanthes with obtusely tri-or pentagonous, subterete achenes and glabrous tubes of corollae, nor into the genus Lactuca with beak achenes. Besides the above-mentioned species misnamed by some of foreign and Chinese botanists, 6 other species also have the same structure in achenes and corollae. Evidently, they fall into a new genus with the name Notoseris Shih. The new genus Notoseris Shih of the tribe Lactuceae of Compositae seems to be more reminiscent of Lactuca L. than of Prenanthes L. emend. All the 12 species of the genus Notoseris Shih are endemic to China and distributed in the area of south of Yantze River. Of them 6 are new combinations and 6 are described as new.     

中国筇竹属植物志资料

筇竹属是近年来新建立的一个属。本属原发表时仅有3种,标本採自四川、云南、贵州及湖北西部。以后又陆续发表了4种。作者在编写中国植物志筇竹属的过程中,对本属又做了初步整理,其中包括一新种及一新变型也在此一并发表。本文引证的标本均藏于本院标本室(代号SWFC)。     

Middle and Late Cambrian sponge spicules from Hunan, China

Abundant and well-preserved assemblages of disarticulated sponge spicules occur in Middle and Late Cambrian platform carbonates of western Hunan, China. Assemblages recovered from 11 stratigraphic horizons include calcisponges, demosponges, and hexactinellids. Hexactinellida, in particular, are both abundant and diverse in Upper Cambrian carbonates. Comparison with spicule assemblages from Australia indicates that many of these taxa have long stratigraphic ranges, limiting their use in correlation. The morphological diversity of these spicules exceeds that known for living siliceous sponges, supporting the observation that during the Cambrian radiation, sponges, like other metazoans, evolved a variety of architectural forms not observed in later periods. Like conodonts, individual sponges can produce more than one spicule form; thus, an "apparatus genus" concept based on multiple co-occurring elements may eventually prove useful in the biostratigraphic and paleobiological interpretation of disarticulated sponge spicules. Four distinctive forms are recognized as new taxa: Australispongia sinensis new genus and species, Flosculus gracilis new genus and species, Pinnatispongia bengtsoni new genus and species, and Nabaviella paibiensis new species.     

Species concepts and malaria parasites: detecting a cryptic species of Plasmodium.

Species of malaria parasite (phylum Apicomplexa: genus Plasmodium) have traditionally been described using the similarity species concept (based primarily on differences in morphological or life-history characteristics). The biological species concept (reproductive isolation) and phylogenetic species concept (based on monophyly) have not been used before in defining species of Plasmodium. Plasmodium azurophilum, described from Anolis lizards in the eastern Caribbean, is actually a two-species cryptic complex. The parasites were studied from eight islands, from Puerto Rico in the north to Grenada in the south. Morphology of the two species is very similar (differences are indistinguishable to the eye), but one infects only erythrocytes and the other only white blood cells. Molecular data for the cytochrome b gene reveal that the two forms are reproductively isolated; distinct haplotypes are present on each island and are never shared between the erythrocyte-infecting and leucocyte-infecting species. Each forms a monophyletic lineage indicating that they diverged before becoming established in the anoles of the eastern Caribbean. This comparison of the similarity, biological and phylogenetic species concepts for malaria parasites reveals the limited value of using only similarity measures in defining protozoan species.     

镰刀菌属分类进展

镰刀菌是真菌中最难鉴定和最具经济价值的属之一。自从1935年德国的Wollen-weber & Reinking发表了第一个以16组65种为内容的分类系统以来,人们对该属的分类展开了长期的研究和讨论,在国际上陆续出现了10种以此系统为基础的,而又各具特色的分类系统。它们是Snyder & Hansen(1940s,美国)的9种系统;Paйлло(1950,苏联)的55种系统;Gordon(1952,加拿大)的26种系统;Билай(1955,苏联)的26种系统;Messiaen & Cassini(1968,法国)的9种和9变种系统;Booth(1971,英国)的44种系统;松尾卓见(Matuo,1972,日本)的10种系统;Joffe(1974,以色列)的33种系统;Gerlach& Nirenberg(1982,德国)的90多种和变种的系统;Nelson等(1983,美国)的30种系统。本文重点论述了其中5种在国际上颇具影响的系统,并列表加以详细比较。     

Molecular phylogeny of parmotremoid lichens (Ascomycota, Parmeliaceae)

Parmotrema is one of the larger genera segregated from Parmelia s. lat. Additional genera recently have been segregated from this large genus based mainly on morphological and chemical features. We have employed molecular data from three genes to continue a revision of the generic concept within the parmelioid lichens. A Bayesian analysis of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences was performed. The genera Canomaculina, Concamerella, Parmelaria and Rimelia appear nested within Parmotrema. Alternative hypotheses to maintain the independence of Canomaculina, Concamerella and Rimelia are shown to be highly unlikely and are rejected. As a consequence these three genera are reduced to synonymy with Parmotrema. An alternative topology segregating Parmelaria from Parmotrema s. lat. cannot be rejected with the dataset at hand. However we have established that this genus is closely related to Parmotrema rather than to cetrarioid species as was considered previously. The revised genus Parmotrema includes species that have an upper cortex consisting of a palisade plectenchyma or rarely paraplectenchyma with vaults, have a pored or fenestrated epicortex, lack pseudocyphellae, have or lack cilia, have laminal, perforate or eperforate apothecia, usually have simple rhizines and filiform, cylindrical, bacilliform or sublageniform conidia. It is closely related to Flavoparmelia but the status of these genera requires further investigation. Nineteen new combinations are made.     

Molecular epidemiology and evolutionary genetics of Leischmania parasites

In order to illustrate the relevance of the concepts and methods of evolutionary genetics in the understanding of the epidemiology of pathogenic agents, we develop in this paper the case of the Leishmania, a genus of parasitic protozoa. An extensive study of various natural populations of Leishmania in different countries (Old and New World) was carried out by using Multilocus Enzyme Electrophoresis (MLEE) and Random Amplified Polymorphic DNA fingerprinting (RAPD) as genetic markers. The data have been interpreted in evolutionary genetic terms. The main benefit of this approach has been to better define the concept of species in the genus Leishmnania, on rigorous phylogenetic bases. As a matter of fact, a sound taxonomical background is a prerequisite for any epidemiological approach. Since the biological concept of species is difficult or impossible to apply for most pathogenic microorganisms, we recommend relying on criteria of both phylogenetic discreteness and of epidemiological/medical relevance to describe new species of Leishmania. Through this approach, for example, we have shown that the species status of L. ( V.) perzzl.ianza can be supported. On the contrary, we have been unable to clearly distinguish L. (V.) panamensis from L. (V.) guyanensis with genetic tools. Additionally, we have shown that the epidemiological inferences based on a limited set of genetic markers can be misleading. As a matter of fact, we have demonstrated that a collection of L. (L.) infantum stocks identified as zymodeme 'MON 1' by other authors present additional genetic heterogeneity and do not correspond to a distinct 'Discrete Typing Unit' DTU, and are actually polyphyletic. Lastly, in the samples that were conveniently designed, we have confirmed that Leishmania parasites have a basically clonal population structure. As the clonal model specifies it, occasional bouts of genetic exchange remain nevertheless possible. Telling comparisons are drawn with the evolutionary genetics of other pathogens Trypanosoma cruzi and Trypanosoma congolense.     

Pandanus tectorius Parkins, in Australia: a conservative view

Pandanus tectorius Parkins, is a widespread and variable species with many forms, often local, some of which have been considered as distinct species. Fourteen binomials are here considered as synonyms of P. tectorius, but several of them warrant retention at varietal rank. Comments on the variability and its relation to a species concept in the genus Pandanus are included.     

Taxonomic synopsis of Hippophae (Elaeagnaceae)

The small genus Hippophae (Elaeagnaceae) was thoroughly revised by Rousi in 1971. Several systematic treatments have since then confused the concept. Recent reports from China have added new subspecies, taxa with possible hybrid origin, and invalidly published names. Phylogenetic work on morphology and molecular markers agrees to Rousi's view of terminal taxa and seven species are currently recognised. Hippophae rhamnoides is a highly variable species and circumscribes eight subspecies. Recent work also confirms hybrid origins of two Chinese taxa. The purpose of this paper is to present a taxonomic synopsis of the genus with all currently accepted taxa and known types, especially in a situation of growing economic interest in Hippophae. We also provide a key and a map of the generic distribution.     

SPECIES CONCEPTS IN THE GENUSUSNEA(LICHENIZED ASCOMYCETES)

Practically most of the taxonomists working on vascular plants and fungi are using the so-called taxonomic species concept, relying largely on morphological criteria or other observable patterns of discontinuity and assuming that these patterns are reflecting the underlying genetic integrity of species. Such a concept is described in detail here for the genusUsnea. The typological view versus the populational view of species are discussed. The diagnostic value of characters used by previous and recent taxonomists of the genus is analysed. The fact thatUsneahas such a bad taxonomic reputation is discussed. The use by J. Motyka, author of the world monograph published in the thirties, of characters that are strongly modified by environmental factors together with a typological view of species are thought to be mainly responsible for this. More than 770 names have been published worldwide so far and it is suggested that around 50% are to be considered as synonyms.     

Flavonoid patterns in the farina of goldenback and silverback ferns

Most species of the fern genus Pityrogramma show a farinose indument caused by a deposit of exuded flavonoid aglycones. Some 220 samples, comprising 14 species, have been studied for the chemical composition of their farinas. Flavones, flavonols and C-methylated flavonoid are rarely found. The presence of certain chalcones and dihydrochalcones, however, appears to be to some extent characteristic for the genus. In some cases the farina flavonoid pattern is species-specific; in one species also variety-specific patterns and even chemotypes are observed. In general, the flavonoid chemistry in Pityrogramma parallels frond morphology to a great extent. This supports the concept that around a core of generalized species a few variant species exist which are best treated as belonging to Pityrogramma.     

On the origin of prokaryotic "species": the taxonomy of halophilic Archaea

The consistent use of the taxonomic system of binomial nomenclature (genus and species) was first popularized by Linnaeus nearly three-hundred years ago to classify mainly plants and animals. His main goal was to give labels that would ensure that biologists could agree on which organism was under investigation. One-hundred fifty years later, Darwin considered the term species as one of convenience and not essentially different from variety. In the modern era, exploration of the world's niches together with advances in genomics have expanded the number of named species to over 1.8 million, including many microorganisms. However, even this large number excludes over 90% of microorganisms that have yet to be cultured or classified. In naming new isolates in the microbial world, the challenge remains the lack of a universally held and evenly applied standard for a species. The definition of species based on the capacity to form fertile offspring is not applicable to microorganisms and 70% DNA-DNA hybridization appears rather crude in light of the many completed genome sequences. The popular phylogenetic marker, 16S rRNA, is tricky for classification since it does not provide multiple characteristics or phenotypes used classically for this purpose. Using most criteria, agreement may usually be found at the genus level, but species level distinctions are problematic. These observations lend credence to the proposal that the species concept is flawed when applied to prokaryotes. In order to address this topic, we have examined the taxonomy of extremely halophilic Archaea, where the order, family, and even a genus designation have become obsolete, and the naming and renaming of certain species has led to much confusion in the scientific community.     

Molecular phylogeny of the diatom genera Amphora and Halamphora (Bacillariophyta) with a focus on morphological and ecological evolution

The taxonomic history of the diatom genus Amphora is one of a broad early morphological concept resulting in the inclusion of a diversity of taxa, followed by an extended period of revision and refinement. The introduction of molecular systematics has increased the pace of revision and has largely resolved the relationships between the major lineages, indicating homoplasy in the evolution of amphoroid symmetry. Within the two largest monophyletic lineages, the genus Halamphora and the now taxonomically refined genus Amphora, the intrageneric morphological and ecological relationships have yet to be explored within a phylogenetic framework. Critical among this is whether the range of morphological features exhibited within these diverse genera are reflective of evolutionary groupings or, as with many previously studied amphoroid features, are nonhomologous when examined phylogenetically. Presented here is a four‐marker molecular phylogeny that includes 31 taxa from the genus Amphora and 77 taxa from the genus Halamphora collected from fresh, brackish, and salt waters from coastal and inland habitats of the United States and Japan. These phylogenies illustrate complex patterns in the evolution of frustule morphology and ecology within the genera and the implications of this on the taxonomy, classification, and organization of the genera are discussed.     

Evidence for high degrees of specialisation, evolutionary diversity, and morphological distinctiveness in the genus Bremia

Bremia lactucae is one of the most important pathogens in lettuce production. Recent molecular?studies revealed considerable genetic variation in this species complex. However, only few accessions from the same host have been examined for most species and no study investigating the morphological distinctiveness of phylogenetic lineages of Bremia has so far been reported. Thus it is believed that morphological species delimitation in Bremia is not feasible. In the present study, multiple accessions of neglected species, which had been described decades ago, but have not been widely accepted, were investigated, considering both multi-gene phylogenies and morphological characters. All previously described species from host genera other than Lactuca investigated, Bremia microspora, Bremia ovata, Bremia saussureae, and Bremia sonchicola, could be confirmed as distinct, host-specific entities. Also, morphological characteristics of their conidiophores and conidia allowed delimitation of these species. Therefore, not only the wide species concept to merge all Bremia species on the Asteraceae under B. lactucae is inappropriate but also their delimitation on the basis of morphological characters seems feasible. In addition, it has been shown that Bremia elliptica is phylogenetically distinct from the other species infecting the genus Lactuca, B. lactucae. It is therefore concluded that B. lactucae is most likely limited to Lactuca sativa and closely-related species, and that most species of Bremia are highly host specific. This finding might stimulate the search for durable resistance genes in genera closely related to the genus Lactuca and in divergent species of the genus itself.     

The Inadequacy of Morphology for Species and Genus Delineation in Microbial Eukaryotes: An Example from the Parabasalian Termite Symbiont Coronympha

Background

For the majority of microbial eukaryotes (protists, algae), there is no clearly superior species concept that is consistently applied. In the absence of a practical biological species concept, most species and genus level delineations have historically been based on morphology, which may lead to an underestimate of the diversity of microbial eukaryotes. Indeed, a growing body of molecular evidence, such as barcoding surveys, is beginning to support the conclusion that significant cryptic species diversity exists. This underestimate of diversity appears to be due to a combination of using morphology as the sole basis for assessing diversity and our inability to culture the vast majority of microbial life. Here we have used molecular markers to assess the species delineations in two related but morphologically distinct genera of uncultivated symbionts found in the hindgut of termites.

Methodology/Principal Findings

Using single-cell isolation and environmental PCR, we have used a barcoding approach to characterize the diversity of Coronympha and Metacoronympha symbionts in four species of Incisitermes termites, which were also examined using scanning electron microscopy and light microcopy. Despite the fact that these genera are significantly different in morphological complexity and structural organisation, we find they are two life history stages of the same species. At the same time, we show that the symbionts from different termite hosts show an equal or greater level of sequence diversity than do the hosts, despite the fact that the symbionts are all classified as one species.

Conclusions/Significance

The morphological information used to describe the diversity of these microbial symbionts is misleading at both the genus and species levels, and led to an underestimate of species level diversity as well as an overestimate of genus level diversity. The genus ‘Metacoronympha’ is invalid and appears to be a life history stage of Coronympha, while the single recognized species of Coronympha octonaria inhabiting these four termites is better described as four distinct species.     

Polyphyletic distribution of bristle formation in Chlorellaceae: Micractinium, Diacanthos, Didymogenes and Hegewaldia gen. nov. (Trebouxiophyceae, Chlorophyta)

In the traditional sense, several families of Chlorococcales sensu lato , such as Golenkiniaceae, Micractiniaceae, and Scenedesmaceae contained taxa with bristle formation, whereas the Chlorellaceae contained only genera without bristles. However, phylogenetic analyses of the small subunit (SSU) and internal transcribed spacer (ITS) rDNA sequences have shown that the genera Micractinium, Diacanthos (formerly Micractiniaceae) and Didymogenes (formerly Scenedesmaceae) are closely related to the genus Chlorella . The bristle formation within the Chlorella -clade is originated independently in four lineages: Micractinium pusillum, Diacanthos belenophorus, Didymogenes anomala , and Micractinium parvulum (also known as Golenkinia minutissima ). The latter species is to exclude from the genus Micractinium . Consequently, we proposed the new genus Hegewaldia and transferred M. parvulum to this genus. In contrast, Diacanthos belenophorus is closely related to Micractinium pusillum . As a result, the new combination ( Micractinium belenophorum comb. nov.) is proposed. Comparisons of the secondary structure of ITS-1 and ITS-2 rDNA sequences among the strains of Didymogenes and Hegewaldia are provided to support the species concept in these genera.