Speciation of the genus Arthricocephalus Bergeron, 1899 (Trilobita) from the late Early Cambrian and its stratigraphic significance

The genus Arthricocephalus Bergeron, 1899 is revised, and Halipanktos Balker & Peel, 1997 is suggested here as a senior synonym. The subgenus Arthricocephalus (Arthricocephalites) Chien & Lin in Lu et al., 1974 is considered as a separate genus. Of the 20 previously assigned species of Arthricocephalus (Arthricocephalus) Bergeron, 1899, Arthricocephalus (Arthricocephalites) Chien & Lin in Lu et al., 1974, Arthricocephalus (Euarthricocephalus) Ju, 1983 are lumped into eight species. The speciation trend of Arthricocephalus and Arthricocephalites is demonstrated based on their stratigraphic occurrences. It not only enhances the resolution of the biostatigraphic zonation in the uppermost Lower Cambrian, but also represents a potential candidate to define the Duyunian stage. The base of the stage is suggested at the first appearance datum (FAD) of Arthricocephalus chauveaui Bergeron, 1899 within the evolutionary lineage from Ar. jiangkouensis Yin in Yin & Li,1978 to Ar. chauveaui in a global scale.     

Speciation of the genus Arthricocephalus Bergeron, 1899 (Trilobita) from the late Early Cambrian and its stratigraphic significance

The genus Arthricocephalus Bergeron, 1899 is revised, and Halipanktos Balker & Peel, 1997 is suggested here as a senior synonym. The subgenus Arthricocephalus (Arthricocephalites) Chien & Lin in Lu et al. , 1974 is considered as a separate genus. Of the 20 previously assigned species of Arthricocephaius (Arthricocephalus) Bergeron, 1899, Arthricocephalus (Arthricocephalites) Chien & Lin in Lu et al. , 1974, Arthricocephalus (Euarthricocephalus) Ju, 1983 are lumped into eight species. The speciation trend of Arthricocephalus and Arthricocephalites is demonstrated based on their stratigraphic occurrences. It not only enhances the resolution of the biostatigraphic zonation in the uppermost Lower Cambrian, but also represents a potential candidate to define the Duyunian stage. The base of the stage is suggested at the first appearance datum (FAD) of Arthricocephalus chauveaui Bergeron, 1899 within the evolutionary lineage from Ar. jiangkouensis Yin in Yin & Li, 1978 to Ar. chauveaui in a global scale.     

Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning, China: New 40Ar/39Ar dating of the Yixian and Tuchengzi

We report new ⁴⁰Ar/³⁹Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion ⁴⁰Ar/³⁹Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion ⁴⁰Ar/³⁹Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca/K ratios, excellent reproducibility and gave a mean age of 125.0 ± 0.18 (1SD) ± 0.04 (SE) Ma. Single sanidine crystal total fusion ⁴⁰Ar/³⁹Ar analyses of the Hengdaozi tuff gave a mean age of 125.0 ± 0.19 (1SD) ± 0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4 ± 0.19 (1SD) ± 0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.     

New fossil elaterids （Insect： Coleoptera： Polyphaga： Elateridae） from the Middle Jurassic of Inner Mongolia, China

A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N41°18.979′, E119°14.318′), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Protagrypnini. Some primitive characters of the new genus and new species shed light on the ages between the Jiulongshan Formation in Inner Mongolia and the Yixian Formation in the western Liaoning Province of China. The habitat of the new species is briefly discussed.     

A restudy of Oryctocephalus indicus (Reed, 1910)

Restudy on morphology of Oryctocephalus indicus (Reed, 1910), based on specimens from Guizhou, China and Nevada USA, suggests that the subspecies regarded previously as Oryctocephalus indicus indicus (Reed, 1910), O. indicus latus Zhao et Yuan 2002, and O. indicus kobayashi Saito, 1934, are synonymous, and Oryctocephalus americanus Sundberg et McCollum, 2003 is a similar form of O. indicus. Oryctocephalus indicus is rediagnosed as having a glabella that is subconical in outline and tapering forward slightly; a thorax that comprises 12 segments, and a small pygidium that bears 2?3 axial rings with a terminal piece and a postaxial ridge. Oryctocephalus indicus is widely distributed in eastern Guizhou and ranges through a great interval of Kaili Formation. Its first appearance is almost identical with these events of trilobite extinction-recovery occurring at the end of the Early Cambrian, the alternation of acritach assemblages, the change of trace elements (REE) and stable isotopes (carbon) at the Wuliu-Zengjiaya section. As one of the key forms for defining the traditional Lower - Middle Cambrian boundary (the base of Cambrian Series 3 and Stage 5 in the new Cambrian chronstratigraphic standard), O. indicus has received detailed study and has more advantages than other species such as Ovatoryctocara granulata Tchernysheva, 1962 or Arthricocephalus chauveaui Bergeron, 1899.     

Further support for a Cretaceous age for the feathered-dinosaur beds of Liaoning,China:New 40Ar÷39Ar dating of the Yixian and Tuchengzi Formations

We report new ⁴⁰Ar÷³⁹Ar dating results obtained from total fusion and incremental-heating analyses of sanidine and biotite from three tuffs found interbedded within the fossil-bearing deposits of Liaoning, northeast China. The first is a new sample of the Bed 6 Sihetun tuff from the Yixian Formation, previously dated by our team as middle Early Cretaceous, and recently considered by Lo et al., partially reset due to metamorphism from a nearby basaltic sill. The second is the Yixian Bed 9 tuff from Hengdaozi considered by Lo et al. to be unaffected by metamorphism and whose age, based on total fusion ⁴⁰Ar÷³⁹Ar dating of biotite, argues for a Jurassic age for the Yixian Formation. The third tuff is a previously undated tuff from the upper part of the underlying Tuchengzi Formation. Single crystal total fusion ⁴⁰Ar÷³⁹Ar analyses of the Sihetun sanidine showed homogeneous radiogenic Ar, Ca÷K ratios, excellent reproducibility and gave a mean age of 125.0±0.18 (1SD)±0.04 (SE) Ma. Single sanidine crystal total fusion ⁴⁰Ar÷³⁹Ar analyses of the Hengdaozi tuff gave a mean age of 125.0±0.19 (1SD)±0.04 (SE) Ma, which is indistinguishable from the Sihetun tuff. The Tuchengzi Formation tuff gave a mean age of 139.4±0.19 (1SD)±0.05 (SE) Ma. Detailed laser incremental-heating analyses of biotite from Sihetun, Hengdaozi, and Tuchengzi tuffs show disturbed Ar release patterns and evidence of trapped argon components. We conclude from these analyses that the total fusion dates on biotite by Lo et al. are erroneously old and isotopic dating of both biotite and sanidine from tuffs of the Yixian Formation point to a middle Early Cretaceous age. The upper part of the Tuchengzi Formation can be referred to the Early Cretaceous.     

A restudy of Oryctocephalus indicus (Reed,1910)

Since both Chinese[1]and American Palaeontolo-gists[2]proposed separately to mark the beginning ofthe Middle Cambrian based on the first appearancedatum (FAD) ofOryctocephalus indicus[3]in thesame year ,the suggestion has been considered seri-ously and adoptedfrequently[4—18].The InternationalSubcommission on Cambrian Stratigraphy (ISCS) hasorganized the Working Group,chaired by L.B. Mc-Collum,to select candidate sections that bear poten-tial to become a GSSPfor the traditional Lowe…     

A restudy of Oryctocephalus indicus (Reed, 1910)

Restudy on morphology of Oryctocephalus indicus (Reed, 1910), based on specimens from Guizhou, China and Nevada USA, suggests that the subspecies regarded previously as Oryctocephalus indicus indicus (Reed, 1910), O. indicus latus Zhao et Yuan 2002, and O. indicus kobayashi Saito, 1934, are synonymous, and Oryctocephalus americanus Sundberg et McCollum, 2003 is a similar form of O. indicus. Oryctocephalus indicus is rediagnosed as having a glabella that is subconical in outline and tapering forward slightly; a thorax that comprises 12 segments, and a small pygidium that bears 2?3 axial rings with a terminal piece and a postaxial ridge. Oryctocephalus indicus is widely distributed in eastern Guizhou and ranges through a great interval of Kaili Formation. Its first appearance is almost identical with these events of trilobite extinction-recovery occurring at the end of the Early Cambrian, the alternation of acritach assemblages, the change of trace elements (REE) and stable isotopes (carbon) at the Wuliu-Zengjiaya section. As one of the key forms for defining the traditional Lower - Middle Cambrian boundary (the base of Cambrian Series 3 and Stage 5 in the new Cambrian chronstratigraphic standard), O. indicus has received detailed study and has more advantages than other species such as Ovatoryctocara granulata Tchernysheva, 1962 or Arthricocephalus chauveaui Bergeron, 1899.     

Investisations into the perplexing interrelationship of the Genus Takifugu Abe, 1949 （Tetraodontiformes,Tetraodontidae）

The phylogenetic relationships within the genus Takifugu Abe, 1949 （Tetraodontiformes, Tetraodontidae） remain unresolved. Because of the use of Takifugu as model organisms, the resolution of these relationships is crucial for the interpretation of evolutionary trends in biology. Pufferfishes of this genus are comprised of a comparatively small number of species and are mainly distributed along the coastal region of the western part of the Sea of Japan and the coastline of China. Mitochondrial gene sequences were employed to test the phylogenetic hypotheses within the genus. Seventeen species of the genus were examined. Molecular phylogenetic trees were constructed using the maximum parsi- mony, neighbor-joining, maximum likelihood and Bayesian methods. Our hypothesis of internal relationships within the genus differs from previous hypotheses. Our results indicate that （1） the genus Takifugu is a monophyletic assemblage; （2） the genus is divided into 6 subgroups based on the moecular data; and （3） there is low genetic diversity among the species within this genus. In addition, speciation within Takifugu appears to be driven by hybridization and isolation by distribution. Our results also suggested that the taxonomy in the genus should be clarified based on both molecular and morphological data.     

中国白肩天蛾属记述与一新记录种(鳞翅目:天蛾科)

白肩天蛾属(Rhagastis RothschildJordan,1903)在中国分布有9种.于2017年上半年和2018年上半年分别对贵州荔波县茂兰自然保护区和海南乐东县尖峰岭地区进行考察并采集到一些天蛾标本.在对长喙天蛾族(Macroglossini Harris,1839)的标本进行整理之后发现,其中一些标本为宽缘白肩天蛾(Rhagastis acuta Walker,1856),这是该种首次在中国境内被记录.对该新记录种雄性成虫的形态进行了描述且附图,并对中国白肩天蛾属目前已知的种类进行了记述.     

Theoretic study of the reaction mechanism between （Me）3CO· radical and trans-3-hexene

The reaction mechanism between （Me）3CO· radical and trans-3-hexene in benzene was studied for the first time at the B3LYP/6-311＋＋G（d,p）//B3LYP/6-31G（d）＋ZPVE level. Two distinct elementary channels were identified as： （1） abstraction-addition; （2） addition-addition-elimination. Analysis of the potential energy surface demonstrates that for the title reaction, channels （1） and （2） have the major and minor contribution, respectively. Our calculated results can well explain the recently observed product distribution by Coseri et al. （J. Org. Chem. 2005, 70, 4629）. However, we found that the addition-abstraction channel proposed by Coseri et al. is kinetically infeasible.     

On the Symmetry Classes of Functions

Let R be an integral domain of characteristic zero such that the corresponding group rings have block decompositions. We first prove that the submodule consisting of all the R-valued ξi-symmetric functions of several variables is a symmetry class, where ξi is any block character. Then we present a relationship among certain operators introduced for block character. Then we present a relationship among certain operators introduced for block characters. As a consequence, we obtain a decomposition of an arbitrary R-valued function of several variables. Finally, we describe the symmetry property of such summands and determine all the symmetry classes.     

Chemical states of the atoms in magnetic multilayers Ta/NiO x /Ni81Fe19/Ta and Co/AlO x /Co

Ta/NiO _x /Ni₈₁Fe₁₉/Ta and Co/AlO _x /Co multilayers were prepared by rf reactive and dc magnetron sputtering. The exchange coupling field (H _ex) and the coercivity (H _c) of NiO _x /Ni₈₁Fe₁₉ as a function of the ratio of Ar to O₂ during the deposition process were studied. The composition and chemical states at the interface region of NiO _x /NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique. The results show that when the ratio of Ar to O₂ is equal to 7 and the argon sputtering pressure is 0.57 Pa, the x value is approximately 1 and the valence of nickel is +2. At this point, NiO _x is antiferromagnetic NiO and the corresponding H_ex is the largest. As the ratio of Ar/O₂ deviates from 7, the H _ex will decrease due to the presence of magnetic impurities such as Ni⁺³ or metallic Ni at the interface region of NiO _x /NiFe, while the H _c will increase due to the metallic Ni. Al layers in Co/AlO _x /Co multilayers were also studied by angle-resolved XPS. Our finding is that the bottom Co could be completely covered by depositing an Al layer about 1.8 nm. The thickness of AlO _x was 1.2 nm.     

Asian origin for Polystichum （Dryopteridaceae） based on rbcL sequences

Chloroplast rbcL sequences of 60 species of Polystichum sensu lato (s.l.), including 23 new sequences from southwest China, were used to assess the phylogenetic relationships within the genus. On the basis of estimated evolution rate of rbcL gene and the genetic distance data that passed relative-rate tests, we further estimated the divergence times between some clades of the genus. The phylogenetic relationships were inferred using the neighbor-joining and maximum-parsimony methods, both methods producing trees with completely congruent topology. These trees reveal that all species of Polystichum s.l. in this study (including Cyrtomium and Cyrtomidictyum) form a monophyletic group. The basal split in Polystichum s.l. separates a clade with all Asian members from a clade containing other species from all over the world. The phylogenetic and divergence time estimation results lead us to suggest that Polystichum s.l. originated in Asia in the late Late Cretacous (≈76 Ma) and migrated into other places in the world in early Eocene(≈46 Ma).     

解变分包含的增生算子方程带误差的三重迭代的收敛性分析

研究了Banach空间中一类ϕ-强增生型变分包含问题,在实的自反的光滑Banach空间中,证明了这类变分包含问题解的存在唯一性及修改的具误差的三重迭代序列{x_n}的收敛性.所得结果是曾六川教授等人的早期与最近结果的改进和推广.     

Pollen Morphology of Artemisia L. and Its Systematic Significance

The pollen of 57 species representing 7 sections of Artemisia was examined hy light microscope and scanning microscope for the purpose to elucidate the systematic relationships of the genus. The examination indicates that the pollen grains present high concordance which is characterized by the globular or the appruximate shape. 3-lobed circular from polar view while granular or ellipse sphere from tropical plate with tricolporate structure. The exinc of pollen has an obvious double structure of inner and outer layers (including the tecturn and columnar layers) where the outer is thicker than the inner and the sculpture of exine degenerates into small spinules easily distinguishable from other genera of the Compositae. Based on cxine sculpture, the pollen grains of Artemisia can be divided into two types: Myriantha type and Mongolica type, which possesses 4 subtypes according to the distribution forms of spinulc: (1) Sacrorum subtype, (2) Oligocarpa subtype, (3) Lavandulaefolia subtype. (4) Anomale subtype.     

二倍体及三倍体马氏珠母贝核型

二倍体马氏珠母贝为广西北海野生贝,２龄－３龄。三倍体马氏珠母贝用６－ＤＭＡＰ诱导获得,１．５龄。核型分析结果,二倍体２Ｎ＝２８,核型公式为７Ｍ＋３ＳＭ＋３ＳＴ＋１Ｔ,ＮＦ＝４８,三倍体３Ｎ＝４２,核型公式为７Ｍ＋３ＳＭ＋３ＳＴ＋１Ｔ,ＮＦ＝７２。染色体按Ｌｅｖａｎ等人的标准分类。     

广东汕尾凹顶藻类(红藻门)的形态分类学研究

为了解中国南海北部凹顶藻物种的多样性以及加快该地的凹顶藻属物种资源开发和利用,本研究利用形态学和解剖学方法,对采自广东汕尾的大型海洋红藻凹顶藻类(Laurencia Complex)进行分类学研究。经鉴定共发现4个物种,即波状软凹藻(Chondrophycus undulatus (Yamada)Garbary et Harper)、凹顶藻(Laurencia chinensis Tseng)、三列凹顶藻(Lt.risticha Tseng,Chang,Xia et Xia)和小瘤栅凹藻(Palisada parvipapillata (Tseng)Nam)。文中对此4种凹顶藻类物种的内、外部形态特征进行了较详细的描述与介绍,并结合生物冷冻切片技术,获得了各个物种较清晰的解剖学特征图片,对未来凹顶藻类物种的鉴定提供一定分类学意义。     

Cloning and Characterization of the fecC Gene Necessary for Optimal Growth under Iron-Deficiency Conditions in the Cyanobacterium Anabaena sp. PCC 7120

The fecC gene encoding a putative iron (Ⅲ) dicitrate transporte rwas cloned from nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO3^- , NH1^- or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wildtype strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that the fecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed that fecC gene product is required for optimal growth under iron-deficient conditions in Anabaena sp. PCC 7120.     

广西湿地植物分布新纪录

首次报道广西湿地植物1个新纪录属和3个新记录种,它们分别是玄参科的泽番椒属Deinostema T.Yamazaki和该属的有腺泽番椒Deinostema adenocaula(Maximowicz)T.Yamazaki、莎草科的扁秆荆三棱Bolboschoenus planiculmis(F.Schmidt)T.V.Egorova和密穗莎草Cyperus eragrostis Lamarck。凭证标本存放于广西师范大学生命科学学院标本馆(GNU)。