A new diatom genus Spargeria gen.nov.(Bacillariophyceae)from Xizang,China,and the description of two new species

During our investigation of diatom biodiversity in Xizang,two species exhibited unique morphological features discriminative from all previously known genera.Herein we describe these two species and describe as new the genus,Spargeria gen.nov.The new genus features narrow to wide rectangular valves,narrow valve mantles,filiform raphe branches that occur on the valve face only,terminal raphe fissures straight or slightly deflected to same side,bow-tie shaped central areas,chambered striae present on the valve face only,being absent from the mantle,wider striae near the axial area and very narrow near the margin,multiseriate striae with small and round areolae that are occluded externally.Comparatively,Spargeria zhuii sp.nov.has larger and robust valves,radiate striae,with one divergent stria near the apices,while Spargeria chenia sp.nov.is smaller,with narrow valves,striae slightly radiate in the middle,becoming convergent or parallel near apices.This new genus belongs to the family Pinnulariaceae,and it was compared and contrasted with other genera of this family.Our work suggests the need for continued studies to document the biodiversity of diatoms in Xizang.

Effectively Modulating Oxygen Vacancies in Flower‑Likeδ‑MnO_(2)Nanostructures for Large Capacity and High‑Rate Zinc‑Ion Storage

In recent years,manganese-based oxides as an advanced class of cathode materials for zinc-ion batteries(ZIBs)have attracted a great deal of attentions from numerous researchers.However,their slow reaction kinetics,limited active sites and poor electrical conductivity inevitably give rise to the severe performance degradation.To solve these problems,herein,we introduce abundant oxygen vacancies into the flower-likeδ-MnO_(2)nanostructure and effectively modulate the vacancy defects to reach the optimal level(δ-MnO_(2)-x-2.0).The smart design intrinsically tunes the electronic structure,guarantees ion chemisorption-desorption equilibrium and increases the electroactive sites,which not only effectively accelerates charge transfer rate during reaction processes,but also endows more redox reactions,as verified by first-principle calculations.These merits can help the fabricatedδ-MnO_(2)-x-2.0 cathode to present a large specific capacity of 551.8 mAh g^(-1) at 0.5 A g^(-1),high-rate capability of 262.2 mAh g^(-1) at 10 A g^(-1) and an excellent cycle lifespan(83%of capacity retention after 1500 cycles),which is far superior to those of the other metal compound cathodes.In addition,the charge/discharge mechanism of theδ-MnO_(2)-x-2.0 cathode has also been elaborated through ex situ techniques.This work opens up a new pathway for constructing the next-generation high-performance ZIBs cathode materials.

Qinia gen.nov.(Bacillariophyceae:Cymbellales)from Yunnan Province,China

An interesting group of cymbelloid diatoms was collected from lakes in Yunnan Province,China,and observations on their valve morphology made using light and scanning electron microscopy.These cymbelloid species all have apical pore fields,slit-like areolae,and areolar occlusions,and they all lack of stigmata.In this paper we propose the new genus Qinia gen.nov.for these taxa and describe them as new:Q.lashii sp.nov.,Q.aequalis sp.nov.,and Q.daliensis sp.nov.The genus Qinia gen.nov.has lanceolate valves asymmetrical about their apical axes,raphe located in the middle of valve,distal raphe ends bent to the dorsal margin that bisects the apical pore fields(APFs),no stigmata,areolae with slit-like external openings and projections occluding the areolar openings internally.This genus resembles the genus Cymbella in the presence of APFs,but differs from Cymbella by a lack of stigmata,and by having external distal raphe ends that bisect the apical pore fields.Like Reimeria,the external distal raphe ends bisect the lobes of the APF,but Qinia species differ from Reimeria in that they have no stigmata and the distal raphe ends are deflected dorsally,not ventrally.Comparisons were made between Qinia and other cymbelloid genera whose members possess apical pore fields.Features that distinguish each species of the new genus are also discussed.

Seasonal shifts in assembly dynamics of phytoplankton communities in a humans-affected river in NE China

Identifying seasonal shift in phytoplankton community is essential for understanding the significance of eutrophication and finding biological indicators of ecological health of a lotic system.Phytoplankton communities,as well as the seasonal changes in the Ashi River Basin(ASRB)of Heilongjiang Province were investigated from April 2018 to January 2019.A survey in April(spring),July(summer),October(autumn),and January(winter)at 16 sampling sites was conducted.The composition,abundance,and biodiversity indices of phytoplankton were studied and 127 taxa of phytoplankton were identified.Among them,Bacillariophyta dominated the phytoplankton communities in the whole year.There were significant spatio-temporal changes in the structures of the phytoplankton communities during the study period.Trophic state index(TSI)show that the nutritional status of the ASRB was at mesotrophic-middle eutrophic levels.Redundancy analysis(RDA)revealed that total nitrogen(TN),water temperature(WT),oxidation reduction potential(ORP),pH,and dissolved oxygen(DO)were the critical factors in the dynamic phytoplankton community structure.The multivariate regression tree(MRT)analysis showed that Chlamydomonas microsphaerella Pascher et Jahoda,Melosira granulata(Ehrenberg)Ralfs,Merismopedia tenuissima Lemmermann,and Asterionella formosa Hassall were valuable indicators in the determination of water quality in ASRB.Our findings provide a scientific basis for water quality protection and management at basin scale.