物种与科属的数量关系——以中国鸟类为例

许多研究表明,物种与高级分类阶元在数量上密切相关,这种关系在地区物种数量预测中具有很高的应用价值。应用中国不同地理类型(保护区、行政区和动物地理亚区)的鸟类物种名录,研究物种与科属的数量相关关系和频次分布规律,结果表明(1)物种与高级分类阶元在数量上有着极显著相关关系(P<0.01),其中物种—属的相关关系要显著于物种—科,且在对数、乘幂、指数和线数4种模型中,用乘幂模型拟合最好;(2)物种在科属间的频次分布具有规律性(P<0.05),随着物种数/科属的增加,频次迅速减少,在4种模型中,乘幂模型拟合最好,属的规律性较科显著。根据以上结果,物种与科属间的数量强相关关系与物种数量在科属间有规律的频次分布有关。     

物种与科属的数量关系——以中国鸟类为例

许多研究表明，物种与高级分类阶元在数量上密切相关，这种关系在地区物种数量预测中具有很高的应用价值。应用中国不同地理类型(保护区、行政区和动物地理亚区)的鸟类物种名录，研究物种与科属的数量相关关系和频次分布规律，结果表明：(1)物种与高级分类阶元在数量上有着极显著相关关系(P<0.01)，其中物种—属的相关关系要显著于物种—科，且在对数、乘幂、指数和线数4种模型中，用乘幂模型拟合最好；(2)物种在科属间的频次分布具有规律性(P<0.05)，随着物种数/科属的增加，频次迅速减少，在4种模型中，乘幂模型拟合最好，属的规律性较科显著。根据以上结果，物种与科属间的数量强相关关系与物种数量在科属间有规律的频次分布有关。     

广东省自然保护区尺度陆生脊椎动物物种多样性与高级分类单元的关系

利用广东省自然保护区陆生脊椎动物名录,分析保护区尺度上物种与高级分类单元在数量上的关系.结果表明,属、科在数量上都随着物种数的增加而增加,且具有相似的增长趋势.物种-属、物种-科在数量上呈现出极显著相关关系(P<0.01,r>0.8),在乘幂模型、线性模型、指数模型和对数模型拟合中,乘幂模型拟合最好.结果显示了,保护区...     

云南省吸虱昆虫区系及物种多样性

吸虱是寄生于真兽类哺乳动物体表的专性吸血寄生虫,广布于世界各地。云南省已知吸虱昆虫9科13属44种,分别占中国已知吸虱科、属、种的81.82%,59.09%,45.83%。文章参考大量相关文献,从分类阶元、特有物种、动物地理区划和宿主动物4个方面分析云南省吸虱的物种多样性。云南省吸虱特有种有13种,占云南省已知吸虱种类的29.55%,27种为东洋种,15种为古北和东洋两界兼有种,广布种9种。吸虱在5个地理小区的分布,以横断山中部和横断山南部2个地理小区的吸虱物种多样性较高,其它3个区的物种多样性较低。相对于全国而言,云南省吸虱物种多样性较高,吸虱的宿主动物种类丰富。但蚤、恙螨和革螨等其它体表寄生虫相比较,兽类宿主动物体表吸虱的物种多样性明显低于其它体表寄生虫,1科(属)阶元的吸虱其宿主多为相对一致的1个科(属)动物阶元,反映了吸虱宿主特异性较高的事实,吸虱昆虫与其对应的宿主动物已经形成了比较稳定的"一对一"的寄生关系,这是吸虱昆虫与其宿主动物协同进化的生态学表现。     

中国吸虱昆虫区系及物种多样性研究

吸虱是寄生于真兽类哺乳动物体表的专性吸血寄生虫,广布于世界各地.我国已知吸虱11科22属96种.分别占世界已知科、属、种的64.71%、45.83%、17.14%.从分类阶元、特有物种、动物地理区划和宿主动物4个方面分析了我国吸虱的物种多样性.中国特有种吸虱27种.中国横跨古北和东洋两界,吸虱分布以东洋界和占北界共有属级分布型最丰富,有13属29种;其次为东洋界特有分布型,有6属41种,种类丰富;古北界特有分布型仅2属,但种类丰富,有24种.吸虱在7个地理区分布,以华中区、华南区、西南区3个地理区的吸虱物种多样性较高,其它4个区的物种多样性较低.我国吸虱物种多样性较为丰富,吸虱的物种分布受宿主动物地域分布的影响较大.吸虱的宿主动物种类丰富,但宿主动物体表吸虱的物种多样性低,一科(属)阶元的吸虱其宿主多为相对应的一科(亚科)动物阶元,反映了吸虱宿主特异性较高的事实,是吸虱与其宿主协同进化的生态学表现.     

菲律宾海脊索动物多样性评估: 基于OBIS数据库

菲律宾海邻近全球生物多样性和进化的中心, 分布着多种重要生物资源。了解本区生物多样性及受威胁物种的分布特征可对掌握其生物多样性现状, 以及未来实施有效的生物多样性保护管理策略提供重要依据。本文利用海洋生物地理信息系统(Ocean Biogeographic Information System, OBIS)数据库, 并参考世界自然保护联盟濒危物种红色名录(IUCN Redlist)的物种濒危程度评估结果, 构建了菲律宾海脊索动物生物多样性和受威胁物种数据库, 结合海洋生态因子特征对该海区脊索动物的物种多样性和不同等级受威胁物种的数量空间分布格局进行了初步分析, 并对脊索动物不同分类阶元生物多样性与生态因子的关系进行了相关性分析。结果表明, 本区海洋脊索动物门已报道11纲56目320科1,171属2,876种。其中在菲律宾海的边缘区域, 特别是菲律宾群岛、台湾岛、日本群岛、马里亚纳群岛及中央的九州-帕劳海脊附近海域, 生物多样性水平相对较高, 而中央海盆区的生物多样性较低。本海域鱼类生物多样性尤其丰富, 共计4纲45目292科1,105属2,768种, 在物种水平上占本区脊索动物物种数的96%。各分类阶元水平的多样性与初级生产力呈显著正相关, 而与水深呈显著负相关。本区脊索动物门受威胁物种共计54种, 其中极危3种、濒危5种、易危22种、近危24种, 分别约占全区脊索动物总种数的0.10%、0.17%、0.76%、0.83%。与本区生物多样性分布格局相似, 受威胁物种多分布于菲律宾海边缘区域, 在中央海脊和深水盆地区域分布较少。本研究表明, 对菲律宾海脊索动物特别是受威胁物种的保护应当以边缘区域优先; 但考虑到当前菲律宾海深海区域生物多样性数据的不足, 也应加强对中央海脊和深水盆地等区域的生物多样性普查。     

甘肃省蚜虫类物种多样性研究

在已有标本采集记录和资料的基础上,从分类阶元、寄主植物、寄生部位、动物地理区系的角度探讨了甘肃省蚜虫类的物种多样性。结果表明甘肃省蚜虫种类丰富,已知9科90属220种;分布在华北区、蒙新区、青藏区、华中区和西南区,其中华北区、蒙新区和青藏区的种类最为丰富,因此甘肃省蚜虫区系以古北界成分为主;寄主植物种类繁多,已知有46科111属;寄生部位多样化,以叶片和茎为主要为害部位。另外就甘肃省所处地理位置的特殊性,初步讨论了在不同地理区划交界处物种生物多样性所受的影响。     

中国淡水蟹分类与分布名录(十足目: 拟地蟹科, 溪蟹科)

中国是世界上淡水蟹物种多样性最高的国家。然而, 迄今为止还没有一个系统的、涵盖全国范围的淡水蟹分类和分布名录。本文收集了涉及中国淡水蟹分类和分布的文献, 采用国际上更新的短尾下目淡水蟹类高级阶元分类系统, 通过系统梳理, 汇编成中国淡水蟹分类与分布名录。该名录共收录了截至2018年1月记述的所有中国淡水蟹类, 共计2科45属311种。其中, 拟地蟹科(Gecarcinucidae Rathbun, 1904) 1属28种; 溪蟹科(Potamidae Ortmann, 1896) 44属283种及亚种; 中国特有属共计38属, 占总数的84%; 特有种共计302种, 占97%。对各省淡水蟹的分布分析发现, 云南是中国淡水蟹物种多样性最丰富的省份, 已记述16属50种; 其次为台湾(4属41种)。本名录首次全面概括了中国淡水蟹类的分类和分布, 可为深入开展全国范围的淡水蟹类生物多样性保护提供科学依据。     

云南不同地区和生境代表性热带植物区系的物种组成比较

云南热带植物区系地理成分复杂,生物多样性极其丰富。为了解不同地区和生境热带植物区系的物种组成差异,本文选取云南南部和东南部3个有代表性的热带植物区系——西双版纳龙脑香林植物区系(DFX)、西双版纳石灰岩山植物区系(LFX)和文山古林箐石灰岩山植物区系(LFG)为研究对象,比较不同植物区系的科属数量结构、科内多样性、科属分布区类型及植物区系相似性。研究结果显示:(1)3个热带植物区系均具有较高的物种多样性,但种类组成、科属数量结构及科内多样性差异较大;(2)热带分布的科、属在3个热带植物区系中均占绝对优势;(3)3个热带植物区系的共有物种极少,而专有物种(即在3个植物区系之间相对专有)相对较多,植物区系之间的种级相似性极低。云南不同地区和生境热带植物区系强烈的热带亲缘、物种组成的多样性和复杂性以及较低的植物区系相似性,揭示了地理和生境差异会影响各地热带植物区系的演化与发展。     

土壤动物的分子分类预测策略评估

土壤动物类群包含庞大的生物多样性, 由于传统的形态学鉴定技术很难满足该类群多样性调查和监测的巨大需求, 基于DNA等遗传物质的分子层面的鉴定技术(分子分类预测)逐渐登上舞台。然而, 分子分类预测能否在参考分子序列严重匮乏的土壤动物分类研究中实现有效鉴定、如何利用分子分类预测更为准确高效地获取土壤动物的分类信息, 是当下分子分类预测在土壤动物应用中的两大难题。为探究这两大难题, 本文基于宏条形码技术, 对5款常用的分子分类预测软件(VSEARCH、HS-BLASTN、EPA-NG、RAPPAS和APPLES; 前两款基于相似度算法, 其余基于系统发育位置算法)进行了准确性(科和属阶元)、运行速度和内存占用等性能的比较和评估。其中, 预测准确性的评估基于4类土壤动物(弹尾纲, 蜱螨亚纲, 环带纲和色矛纲)和3种分子标记(COI、16S和18S)展开。结果表明: EPA-NG在大部分场合下准确性最高, 尤其是在使用COI标记时, 准确性远高于其他工具。VSEARCH和HS-BLASTN准确性也较高, 基于16S和18S标记时, 它们的准确性和EPA-NG相当。此外, VSEARCH在所有软件中运行速度最快且内存占用最小, 这使得它在16S和18S的应用中比EPA-NG更具竞争力。RAPPAS和APPLES具有较低的假阳性, 但假阴性很高, 相对保守的算法使得它们无法将一些物种鉴定到低阶元。总体来说, 即使是在参考数据库缺少目标物种且小部分物种在分类上存在界定争议的前提下, 5款分子分类预测软件都能极为准确地将土壤动物预测至科级阶元, 因此分子分类预测在土壤动物应用中前景远大。COI标记在土壤动物科、属和种阶元上的覆盖度最广且能有效实现分子鉴定, 在目前最适合作为土壤动物尤其是土壤节肢动物的分子标记。在应用COI标记且参考数据库规模不大时, EPA-NG是分子分类预测的最佳选择; 而在应用16S、18S标记或参考数据库规模较大时, 更推荐使用VSEARCH。     

宁夏野生维管植物编目

物种编目是区系研究、生物多样性监测和珍稀濒危生物保护的基础。宁夏维管植物编目对该区植物多样性保护和资源植物开发利用具有重要意义。本文在《宁夏植物志(第二版)》的基础上, 结合多年野外实地调查数据和相关文献资料, 按照APG Ⅳ分类系统修订了宁夏野生维管植物名录。结果显示: 宁夏有野生维管植物127科597属1,754种, 排名前10的优势科分别是菊科、禾本科、豆科、蔷薇科、毛茛科、苋科、唇形科、莎草科、石竹科和伞形科, 这10科共有物种939种, 占宁夏野生维管植物总数的53.53%; 科的组成以物种数小于20种的科为主, 属主要以小于5种的属为主; 2007年至今累计发现新记录植物230种; 宁夏有珍稀濒危植物25科44属65种; 外来归化、逸生及入侵植物9科22属28种。就国土面积和地理位置而言, 宁夏野生维管植物较为丰富。本研究结果可为《宁夏植物志(第三版)》修订和生物多样性监测与保护提供基础数据。     

琅琊山国家森林公园蝶类多样性

报道了安徽滁州市琅琊山国家森林公园蝶类多样性的研究结果,共采集了蝴蝶4454只,隶属8科、40属、57种。应用Margalef物种丰富度模型及Shannon-Wiener生物多样性指数分析了该地蝶类物种的丰富度及多样性。蝴蝶物种丰富度由大到小为森林林地(7.2747)>山缘农田(5.3499)>裸岩(3.3008),物种多样性指数由大到小为森林林地(3.3081)>裸岩(2.4628)>山缘农田(2.0009);结果表明琅琊山蝶类物种较为丰富,多样性指数说明琅琊山的生态环境良好。     

太行山东北部哺乳动物区系及多样性

为研究太行山东北部的哺乳动物区系及多样性格局, 2019年7月1日至10月30日间, 作者采用样线调查和红外相机监测、访谈、文献查阅等多种方法, 对该区域的哺乳动物进行调查, 分析了区系构成, 并基于多样性指数比较了太行山片区和燕山片区哺乳动物多样性及动物分布型的差异。结果表明: 太行山东北部区域分布有哺乳动物7目22科68种, 其中啮齿目种类最多(24种), 灵长目最少, 仅猕猴(Macaca mulatta) 1种; 区域内分布有2种国家I级(金钱豹Panthera pardus、豺Cuon alpinus)和10种国家II级重点保护野生动物。太行山片区和燕山片区的哺乳动物区系的平均动物区系相似性(average faunal resemblance)系数为0.844, 相似性较大, 太行山片区的哺乳动物种数(66)高于燕山片区(50), 其科的多样性指数(D_F= 2.994 ± 0.251, n = 13)和属的多样性指数(D_G = 2.443 ± 0.161, n = 13)也略高于燕山片区(D_F = 2.458 ± 0.170, D_G = 2.259 ± 0.149, n = 10), 但无显著差异(P> 0.05)。太行山片区哺乳动物G-F指数(D_G-F= 0.145 ± 0.022, n = 13)显著高于燕山片区(0.078 ± 0.014, n = 10) (P< 0.05)。研究结果表明, 太行山片区和燕山片区的哺乳动物的科、属组成相同, 但太行山片区的物种多样性高于燕山片区; 太行山东北部区域分布的哺乳动物以古北界物种为主, 太行山片区和燕山片区均有10类动物分布型的哺乳动物; 因太行山片区的纬度相对较低, 其东洋界物种比例(19.11%)略高于燕山片区(17.64%)。     

中国两栖、爬行动物更新名录

本文在2015年发表的爬行动物名录及同年《中国两栖类信息系统》发布的两栖动物名录的基础上, 通过整理新发表的分类学研究及先前名录遗漏的部分早期文献, 更新了截至2019年底中国现生本土两栖、爬行动物物种名录。2015-2019年间, 中国两栖动物新记录1科, 新描述2属, 恢复1属有效性, 新记录1属, 新描述或恢复有效种74种, 新增国家纪录18种; 另6属、8种的有效性未得到近年研究证据支持(在此视为次定同物异名而未做收录, 后同)。同期, 中国爬行动物新恢复5科, 新描述1亚科, 新描述1属, 恢复3属有效性, 新记录3属, 新描述、恢复或提升有效种43个, 新增国家纪录10种; 另有5属、4种的有效性未得到近年研究证据支持, 并移除1属、4种在我国的分布纪录。此外, 通过整理2015年前文献, 爬行动物增补3属, 提升3亚种至种级地位, 增补国家新纪录3种, 另有3属、2种的有效性未得到近年研究证据支持, 同时移除1种在我国的分布纪录。综上, 截至2019年底, 我国共记录现生本土两栖动物3目13科62属515种(蚓螈目1科1属1种, 有尾目3科14属82种, 无尾目9科47属431种), 爬行动物3目35科135属511种(鳄形目1科1属1种, 龟鳖目6科18属34种, 有鳞目蛇亚目18科73属265种、蜥蜴亚目10科43属211种)。此外, 本文还对先前名录中部分爬行动物的中文名提出了修改建议, 建议恢复部分物种的惯用中文名。2015-2019年, 新物种及新纪录已知物种数量占现两栖、爬行动物物种总数的17.1%和10.2%。近年来, 我国发表的两栖、爬行动物新物种和已知物种的新纪录数量持续增加, 分类体系也在研究中不断完善, 建议今后及时地进行阶段性总结, 同时对存在的问题提出讨论, 以推动中国两栖、爬行动物分类学研究工作的进一步开展。     

湖南省德夯风景区蕨类植物区系的研究

德夯风景区位于湖南省西北部吉首市之西。海拔１８９．４～９６４．６ｍ,面积２５２ｋｍ２。该区蕨类植物有２８科,５１属,１１８种,区系特点是：（１）种类丰富而密度大,以鳞毛蕨科,水龙骨科,蹄盖蕨科,卷柏属（Ｓｅｌａｇｉｎｅｌｌａ）,铁角蕨属（Ａｓｐｌｅｎｉｕｍ）,凤尾蕨属（Ｐｔｅｒｉｓ）等为优势类群,科内、属内种数贫乏;（２）属的地理成分以热带成分为主,温带与亚热带成分次之,无特有属。种的地理成分以亚热带成分为主,热带与温带成分次之,特有种类丰富;（３）东亚成分（尤其是中国—日本成分）众多。可能是东亚成分分布中心的一部分;（４）与天平山、佼母溪关系最密切,与庐山、黄山、大瑶山关系较密切,与神农架、鼎湖山较疏远。     

Checklist of the species of the aseptate gregarine families Aikinetocystidae,Diplocystidae, Allantocystidae,Schaudinnellidae, Ganymedidae,and Enterocystidae

The genera and species in six families of the eugregarine suborder Aseptatorina Chakravarty, 1960, are reviewed and the presently accepted ones are listed: Aikinetocystidae Bhatia, 1930 (two genera and two species); Diplocystidae Bhatia, 1930 (one genus and eight species); Allantocystidae tocystidae Bhatia, 1930 (one genus and one species); Schaudinnellidae Poche, 1913 (one genus and one species); Ganymedidae Huxley, 1910 (one genus and one species); and Enterocystidae Codreanu, 1940 (one genus and eight species). A list of 22 synonyms and lapsi calami is also given. Species which might be of value in the biological control of disease vectors are indicated.     

The influence of species pools and local processes on the community structure: a test case with woody plant communities in China's mountains

Understanding how patterns of biodiversity vary among taxonomic levels can provide insights into the mechanisms that regulate the assembly of ecological communities. In this study, we examined the scale and environmental dependence of the relationship between number of species and number of genera/families in woody plant communities to investigate the influences of species pool and local ecological processes on the taxonomic structures of local communities. The data we used are based on a large number of forest plots collected across the eastern part of China and the globe. The results showed that the ratio of the number of genera/families:species and the taxonomic exponents, i.e. the exponents of the genus/family–species relationship, were generally lower than null expectations based on the regional species pool, suggesting that abiotic filtering (e.g. environmental filtering and dispersal limitation) is more important than interspecific competition in shaping local communities. The extent of species pool and the area sampled for local communities both influenced our ability to infer whether local ecological processes were important. In particular, the deviation of the taxonomic ratios and exponents between empirical and null patterns increased as the extent of species pool increased, and the taxonomic exponents declined as area of the local community increased, due partly to the reduced effect of interspecific competition. We conclude that regional species pools and local processes both influenced the taxonomic structure of local woody plant communities, but their effects vary substantially among spatial scales.     

New Chromosome Counts of Some Dicots in the Sino-Japanese Region and Their Systematics and Evolutionary Significance

New somatic chromosome numbers for nine species eight families and eight gen era in the Sino-Japanese Region are reported here as shown in Table 1. Data of six genera are previously unknown cytologically. The bearings of these new data on the systematics and evolution of the related species, genera or families are discussed as follows: (1) Platycarya strobilacea Sieb. et Zucc. (Juglandaceae). The chromosome number of this species is 2n=24, with a basic number of x=12, which deviates from 2n=32 occurred in Juglans, Carya, Pterocarya and Engelhardtia with the basic number x= 16. The Juglandaceae appears to be fundamentally paleotetraploid, with an original basic number of x = 6 in Platycarya and x-8 in the other four genera, although secondary polyploidy occurs in Carya. Based on the remarkable morphological differences between Platycarya and the rest seven genera of the family, Manning (1978) established two subfamilies: Platycaryoideae for Platycarya and Juglandoideae for the other genera. Iljinskaya (1990), however, recently established a new subfamily: Engelhardioideae for Engelhardtia. Lu (1982) points out that because of a great number of primitive characters occurring in Platycarya, the genus could not be derived from any other extant juglandaceous taxa but probably originated with the other groups from a common extinct ancestor. The present cytological data gives support to Manning′s treatment. We are also in favor of Lu′s supposition and suggest that basic aneuploid changes, both ascending and descending, from a common ancestor with the original basic number x=7, took place during the course of early evolution of the Juglandaceae and led to the origin of taxa with x=6 and 8. Subsequent polyploidy based on these diploids occurred and brought forth polyploids of relic nature today, whereas their diploid progenitors apparently have become extinct. (2) Nanocnide pilosa Migo (Urticaceae). The chromosome number of this Chinese endemic is 2n-24, with a basic number of x=12. An aneuploid series occurs in the Urticaceae, with x--13, 12, I1, 10, 9, 8, 7, etc. According to Ehrendorfer (1976), x = 14, itself being of tetraploid origin, is the original basic number of the whole Urticales, and descending aneuploid changes took place in the early stage of evolution of the Urticaceae and Cannabinaceae. In addition to Nanocnide, x= 12 also occurs in Australina, Hesperonide and Lecanthus, and partly in Chamabainia, Elatostema, Girardinia, Pouzolzia and Urtica. (3--4) Sedum sarmentosum Bunge and S. angustifolium Z. B. Hu et X. L. Huang (Crassulaceae). The former is a member of the Sino-Japanese Region, while the latter is only confined to eastern China. The chromosome number of Sedum is remarkably complex with n=4-12, 14-16…74, etc. S. angustifolium with 2n=72 of the present report is evidently a polyploid with a basic number of x =18 (9^?) Previous and present counts of S. sarmentosum show infraspecific aneupolyploidy: n = c. 36 (Uhl at al. 1972) and 2n=58 (the present report). These two species are sympatric in eastern China and are morphologically very similar, yet distinguishable from each other (Hsu et al. 1983) S. sarmentosum escaped from cultivation in the United States gardens exhibited high irregularity in meiosis (Uhl et al. 1972). Uhl (pets. comm. ) suspected strongly that it is a highly sterile hybrid. R. T. Clausen (pets. comm.) found that plants of S. sarmentosum naturalized in the American Gardens propagated by means of their long stolons and broken stem tips, and could not yield viable seeds. Hsu et al. (1983) found that some of the plants of S. sarmentosum and S. angustifolium did yield a few seeds, but other did not. These species are, therefore, by the large vegetatively apomictic. (5) Glochidion puberum (L. ) Hutch. (Euphorbiaceae). The genus Glochidion includes about 300 species, but only eigth species from the Himalayas have been studied cytologically, with n= 36 and 2n= 52, having a basic number of x= 13. The present count for the Chinese endemic G. puberum establishes the tetraploid chromosome number 2n= 64, and adds a new basic number x= 16 to the genus. (6) Orixa japonica Thunb. (Rutaceae). Orixa is a disjunct Sino-Japanese monotypic genus. Out of the 158 genera of the Rutaceae, chromosome numbers of 65 genera have hitherto been investigated, of which 42 genera are with x=9 (66.61%), some with x=7, 8 and 10, and rarely with x=13, 15, 17 and 19. The present count of 2n=34 for O. japonica may have resulted from a dibasic tetraploidy of n=8+9. (7) Rhamnella franguloides (Maxim.) Weberb. (Rhamnaceae). The chromosome number of this member of the Sino-Japanese Region is 2n= 24. with a basic number of x= 12. The basic number x= 12 also occurs in Hovenia, Paliurus, Sageretia, Ceanothus and Berchemia. Hong (1990) suggested that x= 12 in Rhamnaceae may be derived from descending aneuploidy of a paleotetraploid ancestor. (8) Sinojackia xylocarpa Hu (Styracaceae). The chromosome number of this rare Chinese endemic is 2n= 24, with a basic number of x =12, which is identical with that in Halesia and Pterostyrax, but deviates from that in Styrax (x=8). The basic number x=8 in the Styracaceae may be derived from the original basic number x=7 by ascending aneuploidy in the early stage of evolution of the family, and x=12 may be derived from polyploidy. (9) Thyrocarpus glochidiatus Maxim. (Boraginaceae). The chromosome number of this Chinese endemic species is 2n=24, with a basic number of x=12. An extensive aneuploid sequence of x = 4-12 occurs in the Boraginaceae, of which x = 8, 7 and 6 are the most common. The basic number x=12 also occurs in Cynoglossum and Mertensia. It is evident that aneuploid changes, both descending and ascending, from an ancestor with x = 7, have taken place in the primary phase of evolutionary diversification of the Boraginaceae, and subsequent polyploidy has given rise to x=15, 17 and 19 in a few genera (e. g. Amsinskia and Heliotropium). The origin of x=12 is not certain. Either it be a result of ascending aneuploidy, or a product of polyploidy on the basis of x = 6. The present authors are in favorof the latter.