The Rotifera of Malaysia and Singapore with remarks on some species

Summary An intensive and extensive sampling of all types of Malaysian and Singaporean freshwaters for zooplankton gave 165 species, sub-species and varieties of Rotifera, mainly belonging to the Monogononta. Bdelloida were rarely identified. The present records bring Malaysia and Singapore in line with other well studied tropical countries as far as Rotifera records are concerned. 7 new genera and over 50 species, subspecies, varieties and forms have been added to the Malaysian and Singaporean Rotifera records and interesting and marked morphological and size variation in species from previous records, have been noted.The richest (in species) fauna of Rotifera occurs in rice fields and ponds which have a seasonal succession of dry to wet conditions and vegetation which shelters the rotifers.The Malaysian and Singaporean Rotifera fauna is typically tropical with a dominance of the genus Brachionus over temperate genera like Keratella. Also very rare or missing are typical temperate genera like Ploesoma, Notholca and Synchaeta. The dominance of Brachionus in Malaysia is less evident than expected because only a very small proportion of samples were taken in limnetic situations where Brachionus clearly dominates in the tropics.     

Freshwater gomphonemoid diatom phylogeny: preliminary results

A cladistic analysis of eleven freshwater gomphonemoid diatom taxa yielded three equally most parsimonious cladograms. The three cladograms suggest Gomphoneis Cleve is non-monophyletic as originally and recently circumscribed. Gomphoneis elegans and G. transsilvanica (Pant.) Krammer are more closely related to Gomphopleura Reichelt ex Tempère than to other members of the genus. Gomphoneis geitleri Kociolek & Stoermer appears to represent a monotypic lineage. Among the taxa with differentiated apical pore fields Gomphonema kaznakowi Mereschkowsky appears to be primitively astigmate.The three cladograms vary with regard to systematic affinities among the Gomphoneis herculeana (Ehrenberg) Cleve group, Miocene gomphonemoid species from Idaho (USA), gomphonemoid taxa from East Africa and Gomphonema sensu stricto. Despite variability in number of puncta rows per stria and presence of an axial plate in the Miocene species from North America, inclusion of these taxa in the analysis provided better resolution of relationships than if they were excluded.     

Numerical taxonomic studies of the genus Notholca

The genus Notholca has been subjected to taxonomic analysis, using cluster analysis and ordination by principal coordinates analysis, based on 67 phenetic characters. All analyses converge on essentially identical groupings, but fail to inject new hypotheses to remedy the confusing and overlapping taxonomy of the genus. This shortcoming is ascribed to the incompleteness of the character set which currently lacks biochemical and genetic parameters. We suggest to invalidate the subspecies' of N. striata into a single species and consider the pros and cons combining N. haueri and N. latistyla.     

Old and new data on Seisonidea (Rotifera)

Class Seisonidea consists of one marine genus, Seison, with two species (S. nebaliae and S. annulatus) which are epizoic on the crustacean Nebalia. Seisonidea are the only rotifers whose reproduction is strictly bisexual. They also possess the unusual feature of having well-developed males. In this paper we review the literature concerning biogeographical distribution, relationships with their host, and morphology, and present new information obtained with SEM and optical microscopy of both living animals and serial sections.Some seisonid characters, such as the paired retrocerebral organ, nervous system, and trophi, suggest that they hold a primitive position within phylum Rotifera. However, they do share features with other rotifers: paired gonads and an unusual locomotory behavior with Bdelloidea; lateral antennae, cellular stomach wall, arrangement of intracytoplasmic lamina, and other characters with Monogononta. Some features are peculiar to Seison: obligatory amphimixis, endolecythal eggs, encysted spermatozoa, unique mastax, and absence of copulatory organ in males and of vitellaria in females. Reduction of the corona and absence of resistant stages in Seisonidea may be related to their habitat and to their life style. We propose a closer relationship of Seisonidea to Monogononta than previously asserted.     

Molecular evidence for Acanthocephala as a subtaxon of Rotifera

Rotifers are free-living animals usually smaller than 1 mm that possess a characteristic wheel organ. Acanthocephalans (thorny-headed worms) are larger endoparasitic animals that use vertebrates and arthropods to complete their life cycle. The taxa Acanthocephala and Rotifera are considered separate phyla, often within the taxon Aschelminthes. We have reexamined the relationship between Rotifera and Acanthocephala using 18S rRNA gene sequences. Our results conclusively show that Acanthocephala is the sister group of the rotifer class Bdelloidea. Rotifera was nonmonophyletic in all molecular analyses, which supports the hypothesis that the Acanthocephala represent a taxon within the phylum Rotifera and not a separate phylum. These results agree with a previous cladistic study of morphological characters. Correspondence to: J.R. Garey     

Early contributions of molecular phylogenetics to understanding the evolution of Rotifera

The past decade has seen the application of DNA sequence data to phylogenetic investigations of Rotifera, both expanding and challenging our understanding of the evolution of the phylum. Evidence that Acanthocephala, long regarded as a separate but closely related phylum, is a highly derived class of Rotifera demonstrates the potential of molecular analyses to suggest relationships not obvious from morphological analysis. Phylogenies based on the sequence of the gene for the small ribosomal RNA suggest that rotifers and acanthocephalans are associated with Platyhelminthes and Gastrotricha, perhaps in a clade with Gnathostomula and Cycliophora; at present, this group lacks a clear morphological synapomorphy. A more complete resolution of the molecular phylogeny of Rotifera will require surveying multiple genes and several species from each clade under investigation.     

Interrelationships of the Gastrotricha and their place among the Metazoa inferred from 18S rRNA genes

The phylum Gastrotricha includes about 700 species. They are small worm‐like organisms abundant among marine and freshwater meiobenthos. In spite of their ubiquity, diversity and relative abundance, phylogenetic relationships of these animals remain enigmatic due to the conflicting results of morphological and molecular cladistic analyses. Also unclear are the alliances within the phylum. In order to best estimate the position of Gastrotricha among the Metazoa and to shed some light on the ingroup phylogenetic relationships, small subunit (SSU) ribosomal DNA (rDNA) from 15 species of Chaetonotida (eight genera) and 28 species of Macrodasyida (26 genera) were included in an alignment of 50 metazoan taxa representing 26 phyla. Of the gastrotrich SSU rDNA sequences, eight are new and, along with published sequences represent eight families, including the five marine most speciose. Gastrotricha were resolved within a monophyletic Lophotrochozoa as part of a clade including Micrognathozoa, Rotifera and Cycliophora. The Gnathostomulida were sister to this clade. Nodal support was low for all of these relationships except the grouping of the Micrognathozoa, Rotifera and Cycliophora. Bayesian inference resolved the Gastrotricha as monophyletic with weak nodal support; the Macrodasyida were resolved as paraphyletic with many basal nodes poorly supported. Within the Chaetonotida, the monotypic Multitubulatina Neodasys was found in alliance with the macrodasyidan Urodasys while all the Paucitubulatina were found to form a single, well‐supported clade, with Musellifer as the most basal member. Among the more densely sampled Macrodasyida the Lepidodasyidae and Macrodasyidae were each found to be polyphyletic while monophyly was well supported for the Turbanellidae and Thaumastodermatidae. The congruence of our results with those of the cladistic analysis based on morphological traits provides confidence about the value of each dataset, and calls for widening of the research to include additional taxa of particular phylogenetic significance such as the Dactylopodolidae, Diuronotus, Heteroxenotrichula and Draculiciteria. The study highlights the problems in working with small species, the need for voucher specimens and the confused taxonomic status and membership of various gastrotrich families.     

On the evolutionary pathways of speciation in the genus Notholca

An attempt is undertaken to determine criteria and limits of taxonomic rank in the genus Notholca proceeding from the standpoint of level-values of the characters evolution. Level-values of characters were established using Vavilov's principle of homologic series of hereditary variability. As a result of taxonomic revision such terms as group of species, species and subspecies are recommended. Analysis of the scheme of relations between representatives of the genus and data on their ranges gives a clue to relations between phylogeny and geographic distribution of the group over the vast territory of the Asian continent which may have been its centre of speciation.     

On species of the genus Lophocharis Ehrenberg, 1838 (Rotifera: Monogononta) from Uzbekistan

Three species of Lophocharis (Rotifera: Monogononta), collected from lakes and ponds of Uzbekistan, are described. Two are new to science, and one is recorded for the first time from Uzbekistan. Some data on the variability of these species are given.     

Whole-genome comparison clarifies close phylogenetic relationships between the phyla Dictyoglomi and Thermotogae

The anaerobic thermophilic bacterial genus Dictyoglomus is characterized by the ability to produce useful enzymes such as amylase, mannanase, and xylanase. Despite the significance, the phylogenetic position of Dictyoglomus has not yet been clarified, since it exhibits ambiguous phylogenetic positions in a single gene sequence comparison-based analysis. The number of substitutions at the diverging point of Dictyoglomus is insufficient to show the relationships in a single gene comparison-based analysis. Hence, we studied its evolutionary trait based on whole-genome comparison. Both gene content and orthologous protein sequence comparisons indicated that Dictyoglomus is most closely related to the phylum Thermotogae and it forms a monophyletic group with Coprothermobacter proteolyticus (a constituent of the phylum Firmicutes) and Thermotogae. Our findings indicate that C. proteolyticus does not belong to the phylum Firmicutes and that the phylum Dictyoglomi is not closely related to either the phylum Firmicutes or Synergistetes but to the phylum Thermotogae.     

Study of the Trophi of <Emphasis Type="Italic">Testudinella</Emphasis> Bory de St. Vincent and <Emphasis Type="Italic">Pompholyx</Emphasis> Gosse (Rotifera: Testudinellidae) by Scanning Electron Microscopy

The fine morphology of the trophi of Pompholyx sulcata and nine species of Testudinella (Rotifera, Monogononta, Flosculariacea, Testudinellidae) was studied by scanning electron microscopy. The number of unci teeth and arched rami scleropili, and the shape of the major unci teeth and fulcrum are considered to be reliable additional characters for identification.     

Coloniality in the phylum Rotifera

Coloniality in the phylum Rotifera is defined and reviewed. Only two families of rotifers contain truly colonial forms: Flosculariidae and Conochilidae (order Gnesiotrocha, suborder Flosculariacea). Most species form intraspecific colonies ranging in size from a few to about 200 individuals, but species that produce enormous colonies (> 1000 individuals) are also known. All seven genera of the Flosculariidae contain species that form colonies to widely varying degrees (Beauchampia, Floscularia, Lacinularia, Limnias, Octotrocha, Ptygura, Sinantherina). All four species of the monogenetic Conochilidae (Conochilus) are colonial, but two species form colonies of only an adult and a few young. At least one other family (Philodinidae; Bdelloida) contains a species that exhibits a form of coloniality (Philodina megalotrocha). Two hypotheses that attempt to explain the adaptive significance of coloniality (Energetic Advantage and Predatory Avoidance) are reviewed and new information concerning the former is presented. Evolution of coloniality is discussed briefly.     

典型生境巨菌草根内生固氮菌的群落多样性

【目的】探究不同生境巨菌草内生固氮菌群落组成多样性及其分异规律。【方法】采用高通量测序固氮酶nif H标靶基因方法,研究了我国6个典型地区的巨菌草内生固氮菌群,包括福建闽侯县、新疆墨玉县、内蒙古阿拉善左旗、青海贵德县、甘肃安定区、海南那大镇,结合地理气候因子统计,分析了固氮菌多样性的环境驱动机制。【结果】共获得64122条nif H基因的有效序列,640个OTUs,归属于6个门、10个纲、17个目、24个科、33个属和39个种。不同地区巨菌草中优势内生固氮菌群的种类和丰度存在较大的差异。在门水平上,福州闽侯县、甘肃安定区、新疆墨玉县、内蒙古阿拉善左旗和青海贵德县5个地区的优势菌门均为变形菌门,海南那大镇的优势菌门为变形菌门和蓝藻菌门;属水平上,不同地区巨菌草最优势内生固氮菌类群分别为:福州闽侯县(变形菌门中未定属,80.56%);新疆墨玉县(变形菌门中未定属,33.14%);内蒙古阿拉善左旗(变形菌门中未定属,76.23%);甘肃安定区(α-变形菌纲中的未定属,53.78%);海南那大镇(变形菌门中未定属,38.37%);青海贵德县(变形菌门中未定属,46.12%)。Alpha多样性和Beta多样性分析表明,不同地区巨菌草内生固氮菌群落的多样性存在较大的差异,海南那大镇样本中巨菌草各类内生固氮菌群的多样性及丰富度最高,福建闽侯县样本中巨菌草各类内生固氮菌群的多样性及丰富度最低。典范对应分析(CCA)结果表明,年均降雨量和年均气温是影响巨菌草内生固氮菌群变化的主要因素,其次是土壤有机质、土壤全氮和土壤p H。【结论】不同地区巨菌草内生固氮菌群落的组成及丰度存在着较大的差异,海南那大镇巨菌草内生固氮菌群的种类及相对丰度较高,本研究可为巨菌草内生固氮菌群的资源开发及其固氮微生物肥料的菌种选育和生产应用提供理论支持。     

Reproductive mode evolution in nematodes: insights from molecular phylogenies and recently discovered species

The Phylum Nematoda has long been known to contain a great diversity of species that vary in reproductive mode, though our understanding of the evolutionary origins, causes and consequences of nematode reproductive mode change have only recently started to mature. Here we bring together and analyze recent progress on reproductive mode evolution throughout the phylum, resulting from the application of molecular phylogenetic approaches and newly discovered nematode species. Reproductive mode variation is reviewed in multiple free-living, animal-parasitic and plant-parasitic nematode groups. Discussion ranges from the model nematode Caenorhabditis elegans and its close relatives, to the plant-parasitic nematodes of the Meloidogyne genus where there is extreme variation in reproductive mode between and even within species, to the vertebrate-parasitic genus Strongyloides and related genera where reproductive mode varies across generations (heterogony). Multiple evolutionary transitions from dioecous (obligately outcrossing) to hermaphroditism and parthenogenesis in the phylum are discussed, along with one case of an evolutionary transition from hermaphroditism to doioecy in the Oscheius genus. We consider the roles of underlying genetic mechanisms in promoting reproductive plasticity in this phylum, as well as the potential evolutionary forces promoting transitions in reproductive mode.     

共头霉的单孢孢子囊变种

我们从江苏、浙江两省采到的一些样品中分离得到六株毛霉菌种并鉴定为分别属于三个变种的同一个新种,即单孢共头霉原变种(Syncephalastrum monosporum Zheng et al.sp. nov. var. monosporum),单孢共头霉冠囊变种(Syncephalastrum monosporum Zheng et al. var. cristatum Zheng et al. var. nov.),以及单孢共头霉多重生变种(Syncephalastrum monosporum Zheng et al. var. pluriproliferum Zheng et al. var. nov.).它们与共头霉属的唯一已知种总状共头霉(Syncephalastrum racemosum Cohn ex Schroeter)的主要区别在于全部孢子囊都是单孢的小型孢子囊(柱孢囊)而不是像后者一样孢子成单行排列的多袍柱孢囊.我们把这些菌归人共头霉属而没有为它们专门成立一个新属的理由除因它们与总状共头霉有明显的亲缘关系外,主要还因我们认为在不具备其它重要区别特征的情况下,在毛霉目的分类中,无论在科级或属级的水平上,都不应过分强调单孢孢子囊的作用.尽管单孢共头霉是毛霉目内唯一具单孢子柱孢囊的种,我们仍然把它们归入共头霉属内.至于我们为什么要把这六株菌鉴定为一个种的三个变种而不是三个各自独立的种,则是由于我们承认共头霉属的唯一已知种总状共头霉是一个变异性很大的种而并没有把它分成许多不同的种,因此,我们对这个属的另外一个种,即单孢共头霉同样采用较大的种概念.     

New data on perittocrinids and hybocrinids (Crinoidea, Echinodermata) from the Middle Ordovician of the Baltic region

Age variation of radial plates of perittocrinids and aberrant cups of the hybocrinid genus Hoplocrinus from the Middle Ordovician of the St-Petersburg region are examined. Three patterns for the development of folds on the radial plates of perittocrinids are recognized. The differences between patterns are of species level. It is proposed here that the folded structures of perittocrinids (as well as the pore-structures of other pelmatozoans) were not only used for respiration, but also very likely for feeding. Tetracionocrinus transitor is a young individual of a species of the genus Perittocrinus or a paedomorphic species of this genus. The study of aberrant cups of Hoplocrinus suggests that its ancestor could have had biserial arms. Phylogenetic implications of this interpretation are discussed, and homologies within the phylum Echinodermata, reassessed. The three-armed genus Baerocrinus may be an aberrant form of a species of the genus Hoplocrinus.     

Hidden diversity of Ctenophora revealed by new mitochondrial COI primers and sequences

The mitochondrial gene cytochrome-c-oxidase subunit 1 (COI) is useful in many taxa for phylogenetics, population genetics, metabarcoding, and rapid species identifications. However, the phylum Ctenophora (comb jellies) has historically been difficult to study due to divergent mitochondrial sequences and the corresponding inability to amplify COI with degenerate and standard COI “barcoding” primers. As a result, there are very few COI sequences available for ctenophores, despite over 200 described species in the phylum. Here, we designed new primers and amplified the COI fragment from members of all major groups of ctenophores, including many undescribed species. Phylogenetic analyses of the resulting COI sequences revealed high diversity within many groups that was not evident from more conserved 18S rDNA sequences, in particular among the Lobata (Ctenophora; Tentaculata; Lobata). The COI phylogenetic results also revealed unexpected community structure within the genus Bolinopsis, suggested new species within the genus Bathocyroe, and supported the ecological and morphological differences of some species such as Lampocteis cruentiventer and similar undescribed lobates (Lampocteis sp. “V” stratified by depth, and “A” differentiated by colour). The newly designed primers reported herein provide important tools to enable researchers to illuminate the diversity of ctenophores worldwide via quick molecular identifications, improve the ability to analyse environmental DNA by improving reference libraries and amplifications, and enable a new breadth of population genetic studies.     

Phylogenetics and evolutionary morphology of the Neotropical true bug genus Epipolops (Hemiptera: Heteroptera: Geocoridae)

Species of Epipolops Herrich‐Schaeffer (Hemiptera: Geocoridae), comprising the largest genus of Pamphantinae, are among the most bizarre true bugs because of their striking morphology. To elucidate evolutionary morphology in Epipolops, a phylogenetic analysis was performed using 17 species and 36 adult morphological characters. Two cladograms were obtained under equal and implied weight analyses, showing slight differences between them. Two new species, E. stridulatus sp.n . and E. univallensis sp.n ., are described, and E. meridionalis Pirán is resurrected from synonymy with E. frondosus Herrich‐Schaeffer. A key to the known species of Epipolops is provided. The systematic relevance of the unique characters of the genus is discussed and the sequence of character state transformations for both the anterior and posterior lateral processes of the pronotum are optimized on the cladogram obtained under implied weights. Species of Epipolops are found in the Neotropical region and the Mexican Transition Zone, with some clades and species restricted to certain South American subregions. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:CB72D5DA‐D86B‐4B91‐93A2‐88894F7120C9 .     

黄枝衣科中国新记录属和种

报道了中国黄枝衣科(Teloschistaceae)的一中国新记录属粉黄衣属(新拟)(Xanthomendoza)和一中国新记录种漫粉黄衣(新拟)(Xanthomendoza ulophyllodes)及石黄衣属(Xanthoria)的一新记录种裂芽黄衣(新拟)(Xanthoria calcicola)。对漫粉黄衣的ITS序列进行了测定和系统发育分析,并对相关类群的形态和分子数据进行了讨论。对2新记录种的形态特征、生境与分布进行了详细描述,并提供了形态特征图。     

Phylogenetic analysis of the genus Hordeum using repetitive DNA sequences

A set of six cloned barley (Hordeum vulgare) repetitive DNA sequences was used for the analysis of phylogenetic relationships among 31 species (46 taxa) of the genus Hordeum, using molecular hybridization techniques. in situ hybridization experiments showed dispersed organization of the sequences over all chromosomes of H. vulgare and the wild barley species H. bulbosum, H. marinum and H. murinum. Southern blot hybridization revealed different levels of polymorphism among barley species and the RFLP data were used to generate a phylogenetic tree for the genus Hordeum. Our data are in a good agreement with the classification system which suggests the division of the genus into four major groups, containing the genomes I, X, Y, and H. However, our investigation also supports previous molecular studies of barley species where the unique position of H. bulbosum has been pointed out. In our experiments, H. bulbosum generally had hybridization patterns different from those of H. vulgare, although both carry the I genome. Based on our results we present a hypothesis concerning the possible origin and phylogeny of the polyploid barley species H. secalinum, H. depressum and the H. brachyantherum complex.