澳大利亚轮藻植物LYCHNOTHAMNUS BARBATUS(MEYEN)LEONHARDI藏卵器统计分析及与欧洲同类植物的对比研究

Lychnothamnus(Characeae)为一分布于欧洲和大洋洲的单型属,该类植物日趋衰落。过去十年中,仅在澳大利亚昆士兰州华莱士湾发现数量丰富生长良好的L．barbatus(Meyen)Leonhardi。本文对澳大利亚现生L．barbatus藏卵器进行描述、统计分析和扫描照相,并与其它地区同类现生和化石藏卵器进行对比,结果表明澳大利亚的藏卵器除形状偏长球形、宽度较小、钙化较弱外,其余特征与欧洲植物较为一致。钙化减弱的原因可能与澳大利亚热带地区由季风造成的洪水泛滥降低了水体中离子的浓度有关。     

LYCHNOTHAMNUS BARBATUS(轮藻植物)的生态与保护研究

轮藻植物属Lychnothamnus(Rupr．)Leonh．自晚始新世即有化石代表,在上新世繁盛且分布广泛,此后分异度降低、分布范围缩减,延续至今仅存1种：L．barbatus(Meyen)Leonh．。上世纪末叶前该种还曾广泛分布于欧洲、印度、中国、巴布亚新几内亚和澳大利亚,而后该种在澳大利亚曾经留有记录的产地消失,直到1996年才被再次发现。本文描述了澳大利亚L．barbatus的居群特征,包括植株、卵囊球和藏卵器形态特征以及萌发生态学的实验研究结果。讨论该种的野外生态学、共生种、全球范围的分布与丰度特征,探讨该种衰落的原因并提出植物保护方案。     

柴达木盆地宗马海湖地区始新统下干柴沟组 轮藻植物群

柴达木盆地北缘宗马海湖地区始新统下干柴沟组在一道沟剖面出露良好, 本文详细描述了该剖面下干柴沟组的岩性特征, 该组以棕红色泥岩为主, 局部夹浅灰绿色含石膏中细砂岩、含钙质粉砂质细砂岩及少量含砾中粗砂岩、褐红色灰岩。在该剖面发现轮藻化石2属2种: Lamprothamnium ganchaigouensis (Tang and Di) Li et al. comb. nov.和Lychnothamnus vectensis (Groves) Soulié-M?rsche, 前者为新联合属种。L. vectensis主要发现于欧洲始新统?渐新统, 在我国始新统系首次报道。本文以居群为单位, 讨论了L. vectensis的种内形态变化, 包括藏卵器尺寸和顶部装饰的连续变化。欧洲L. vectensis居群的藏卵器尺寸随着纬度的升高有变大的趋势, 而柴达木盆地的纬度低于欧洲埃布罗盆地和巴黎盆地的纬度, 它所产的L. vectensis居群藏卵器尺寸却更大, 推测与柴达木盆地古湖泊水体清澈度和/或温度更高相关。     

轮藻植物在澳大利亚的重新发现之探密

澳大利亚轮藻植物研究历史悠久,迄今约有95种被描记。在Wood(1972)对澳大利亚轮藻植物的修订研究中,一些种因为标本遗失或已损坏而未包括在内,其中有的种近年来又被重新发现。本文重点介绍Nitella hookeri A．Br．var．arthroglochin A．Br．,Lychnothamnus barbatus(Meyen)Leonh．和Nitella partita Nordst．的发现过程及其产地生态环境,探讨了季节性湿地对轮藻植物的保护意义。N．hookeri var．arthroglochin早在1854年就发现于澳大利亚,并于1887年再次作为澳大利亚特有物种而被记录,然而从此销声匿迹,直至1989年才再度问世,它重新出现的地点为新南威尔士州高海拔花岗岩风化土壤地区的季节性溪流中。L．barbatus则为R．D．Wood首次发现于1960年,嗣后一再搜寻并无踪迹,直到1996年才于昆士兰东南地区亚热带阵发性溪流中被再次发现。昆士兰中部干旱地区1889年一度见到的N．partita,也是近一百年后才在新南威尔士州西北干旱地区的季节性湿地再次发现。     

巴尔干半岛现生轮藻植物综述

欧洲东南部巴尔干轮藻植物由于其产地生境的差异及以镶嵌状分布的模式,具有较高的生物分异度,计有44种,归属于现生属Nitella(10),Tolypella(4),Nitellopsis(1),Lychnothamnus(1),Lamprothamnium(1) and Chara(27).巴尔干半岛产有4种土著类型Chara rohlenae,Chara ohridana,Chara corfuensis and Chara visianii.建立1新种Chara hydropitys.该地区轮藻植物分布不均衡,部分类型例如Chara strigosa,Chara kokeilii,Chara muscosa,Chara fragifera,Chara imperfecta,Lychnothamnus barbatus为稀有品种,仅在少数地点发现.巴尔干地区轮藻植物之丰富多彩远远超过已知的程度,有待于深入研究.     

哈萨克斯坦斋桑盆地新生代轮藻植物组合

斋桑盆地自晚白垩世以来即为淡水湖泊环境,其始新世至中新世湖相及湖边缘相沉积物产有丰富的轮藻化石。文中建立三个轮藻化石组合：(1)Harrisichara mitella—Peckisphaera zajsanica组合(中始新世早期);(2)Lychnothamnus formosus—Peckichara组合(中始新世晚期--渐新世早期);(3)Gyrogona aralica—sphaerochara clearus组合(中--晚渐新世)。斋桑盆地轮藻化石出现的最高层位为下中新统且化石稀少,推测系盆地环境日益干旱所致。     

美洲绵霉超微结构的初步研究

对美洲绵霉(Achlya americana Humphrey)有性器官的壁结构,细胞核相及一些细胞器的结构进行了初步的超微结构研究,我们发现藏卵器壁由两层组成,卵孢子壁至少由三层组成,而藏卵器横隔膜则由两层壁和中间一层原生质体组成。在细胞核分裂过程中发现有明显的染色体的形成和存在,这是第一次在电子显微镜下看到卵菌的染色体,并对染色体的存在进行了讨论。     

乌头霜霉卵孢子的发现

本文第一作者于1979年发表乌头霜霉 Peronospora aconiti Yu新种时缺乏对卵孢子的描述,现在四川雅安的乌头 Aconitum cramichaeli Dexb.上发现了该菌的卵孢子,特予补充描述:藏卵器亚球形或卵形,平滑,直径25.8—51.6(平均39.42±4.47)μm;卵孢子球形,浅黄褐色,平滑,单生,不充满藏卵器,直径22.4—37.8(平均28.76±2.96)μm;卵孢子壁厚,其厚度为 2.84—5.04(平均3.77±0.61)μm。     

广东南雄古新世岭南(犭亚)兽一新种

记述了在广东南雄盆地中古新世地层中发现的岭南(犭亚)兽一新种——进步岭南(犭亚)兽(Linnania progressus sp．nov．)。新种比属型种罗佛(犭亚)兽(L．lofoensis)下臼齿下前尖退化、跟座增长。     

华北泥河湾盆地植被、气候与早期人类生存环境研究进展

中国北方泥河湾盆地可以与非洲奥杜威峡谷相媲美, 它们具有十分相似的地质演化过程, 这里河湖相沉积发育, 并且蕴藏着丰富的古生物化石和大量古人类遗迹, 是研究东亚早期人类生存环境变化的重要区域。基于前人积累的晚上新世以来植被、气候及早期人类生存环境的大量研究资料, 经分析发现在大约2.6 Ma (百万年), 泥河湾盆地的植被由阔叶林转变为以针叶林为主; 大约1.92 Ma以后, 植被以温带森林-草原(主要是松属、蒿属及藜科)/温带草原(主要是蒿属和禾本科等)为主。通过对比发现, 晚上新世以来中国北方从西部到中部, 由森林转变为以森林-草原为主的植被类型出现的时段呈现明显的阶梯型。此外, 泥河湾盆地气候出现了13个冷暖旋回, 15个干湿旋回, 显著的冷干事件发生在2.8 Ma、2.6 Ma、1.92 Ma及143.8 ka (千年), 湿润事件发生在43、32和6.6 ka。早期人类生活在森林-草原或以草原为主的植被环境中, 气候冷暖干湿波动较大, 水源丰富, 大量哺乳动物共存。建议在建立泥河湾人类遗址更为精细地层的年代框架下, 开展古气候温度与降水参数的定量化研究, 将有助于精准重建古人类生存环境及揭示其变化规律。     

Quaternary and recent Lamprothamnium groves (Charophyta) from Argentina

Only recently have extant Lamprothamnium species been reported from the American continent. L. succinctum (A. Br. in Asch.) R. D. W. was found in Lago Titicaca, Bolivia and L. haesseliae Dont. en Laguna Luro and Laguna La Salada, Argentina.Fossil gyrogonites of L. succinctum and L. haesseliae, however, are here reported to be widely distributed in Quaternary sediments of Argentina, associated with other charophytes, ostracods and foraminiferans. Localities include Laguna del Siasgo, Laguna Salada Grande, Laguna Mar Chiquita, Laguna La Amarga and Salina del Bebedero. Lamprothamnium is a genus that prefers shallow, alkaline, hyposaline to mesosaline environments. Analysis of the characteristics of Laguna La Salada contributes information on the factors that influence the distribution of the genus.The morphology characteristics of the gyrogonites and oospores of L. haesseliae and the gyrogonites of L. succinctum are described. The use of Lamprothamnium as a biomarker and its application in the reconstruction of Quaternary saline environments are also discussed.     

Chara zeylanica Wildenow（现生轮藻）藏卵器几个特征的统计分析

本文对采自广西涠洲岛的现生轮藻Ｃｈａｒａ ｚｅｙｌａｎｉｃａ藏卵器的几个特征作了统计分析,结果表明,藏卵器的最大长度,最大宽度和螺旋环数等性状的变异有一定范围,服从统计规律,单变量的变化呈正态分布,具一明显峰值;ＬＰＡ是ＬＥＤ的线性函数,呈正相关。藏卵器乌黑细胞的钙化程度与成熟度有关。未成熟藏卵器的顶部构造为典型的轮藻型,成熟藏卵的顶部构造与有盖轮藻型接近。因此认为,Ｃｒａｍｂａｓｔｉｃｈａｒａ     

Temperature dependence of the membrane resistance in Characeae cells

Changes in the electrical resistance of internodal cells of Nitellopsis obtusa (Desv. in Lois) J. Gr. and Lychnothamnus barbatus (Meyen) Leonh., produced by short-lasting temperature changes (3-min intervals) in the range of 4⇌48°C were measured. In the whole temperature range examined the electrical resistance of the cell membranes underwent from 5 to 9 distinct changes; the overall changes were approximately hyperbolic, while in certain narrow temperature ranges they were non-monotonic, and in others linear. Arrhenius plots of these dependencies provide data which suggest a specific, stepwise character of changes in the permeability to ions, produced by temperature alterations and probably connected with corresponding modifications of cell membrane fluidity. This seems to support the view that the cell membranes of the examined plant species may exist in different, discrete, physiological states characteristic of certain temperature ranges.     

New charophyte assemblage from middle Miocene lacustrine deposits of Moneva (Ebro Basin,Spain)

Two new fossil charophyte species from middle Miocene lacustrine deposits of Moneva (Ebro Basin, NE Spain) are described and illustrated. Sphaerochara miocenica nov. sp. is represented by medium sized gyrogonites with a characteristic spheroidal shape and ornamented with numerous small and regularly spaced tubercles arranged along the spiral cells. Several specimens show an unusual carbonate encrusted layer that covers completely or partially the gyrogonite. Psilochara monevaensis nov. sp. is characterized by large gyrogonites, with typical prolate shape and protruding apical poles. A second population of S. miocenica nov. sp. from a distant early upper Miocene lacustrine basin located in the Middle East (Bekaa Valley, Lebanon), identified in a previous study as Sphaerochara sp., is described and illustrated here, allowing the comparison of these distant populations. Ecologically, the associated fauna and facies from both localities suggest that these taxa grew in very shallow athalassic lakes. Interestingly, S. miocenica nov. sp. having a wide geographic distribution in peri-Mediterranean lakes with variable salinity, may become a fossil guide for the Miocene, providing at the same time important palaeoecological information.     

Palynofacies distribution in a lacustrine basin

The Miocene basin of La Cerdanya (Pyrenees, Catalonia, Spain) consist of lacustrine diatomites and fan-deltaic (palustrine) lutites with lignites. A multidisciplinary analysis of palynofacies, organic geochemistry, taphofacies of plant macroremains and sedimentology was carried out in order to characterise taphonomically this basin. Palustrine facies contain highly diverse assemblages of palynomorphs and other palynological matter. The presence of relatively high amount of planar organic remains, mostly cuticles, in this palynofacies is indicative of deposition in the proximal parts of the basin. The organic content is low (1% TOC) except in the case of lignites, where it reaches up to 50%. Generally the Hydrogen Index (HI) values of the palustrine sediments are also relatively low (HI 70-189). Diatomite samples from the lake centre are characterised by high amount of the chlorococcalean alga Botryococcus and sapropelic organic matter and a HI above 500. In contrast, samples from the lake margins comprise Botryococcus, bisaccates and other anemophilous angiosperm pollen and have HI below 410. The TOC of lacustrine samples may reach levels of up to 45.5%. Palynofacies distribution shows a positive correlation with plant taphofacies only in the palustrine sediments but not in the lacustrine facies of the basin. Taphofacies of plant macroremains in the lacustrine sediments display a downslope polarity whereas palynofacies are distributed radially. A variety of transport mechanisms and different origins of palynological matter in comparison to plant macroremains account for this difference.