Biosystematic studies on the genusIsoetes (Isoetaceae) in Japan. III. Variability within qualitative and quantitative morphology of spores

Qualitative and quantitative characteristics of mega- and microspores from all the cytotypes of JapaneseIsoetes are described based on the voucher specimens whose chromosome numbers were known. InI. japonica, the hexaploid possessed reticulate megaspores and levigate microspores, while the octaploid and the heptaploid had echinate microspores. Mega- and microspores of the hexaploid and the octaploid were of normal appearance, while those of the heptaploid displayed polymorphism. The tetraploid and the hexaploid ofI. sinensis resembled each other, since they both possessed cristate megaspores and echinate microspores. Echinate megaspores and levigate microspores characterized the diploidI. asiatica. The spore size was largely variable within each cytotype, while the size of the megaspores varied more than that of the microspores. The microspore length was closely correlated with polyploid level. InI. sinensis, the mean microspore length of the tetraploid was 27.6 μm while that of the hexaploid was 31.9 μm, hence these two cytotypes were easily distinguishable. In the hexaploidI. japonica, variations in mega-and microspore size displayed geoclinal variation showing a positive correlation (r=0.43–0.55) with the longitude and the latitude of the populations. A palynological key for cytotypes is presented.     

Ornamentation ofIsoetes (Isoetaceae, Lycophyta) microspores

More than any other taxonomic character, megaspores have been used in the genusIsoetes (known by the English common name of “quillwort”), despite the fallacy of a single-character taxonomy. Microspores, on the other hand, have been largely neglected in taxonomic schemes. Like megaspores, terms for microspore ornamentation (also known as “sculpturing”) have not been standardized. I examined microspore ornamentation, including both macroornamentation and microornamentation, of 52 taxa from Africa, Asia, Australasia, Europe, North America, and South America with the scanning electron microscope. Macroornamentation is discernible with light microscopy; microornamentation requires scanning electron microscopy. Ornately sculptured spores were much more frequent than were laevigate or psilate patterns: 21 taxa had an echinate pattern; 19 had an aculeate pattern; 6 were cristate; 5 were psilate; and 1 was laevigate. The proximal and distal ridges and surfaces may vary in both the type and density of ornamentation. Distinct macroornamentation patterns characterize certain species groups. Microornamentation types include granulate, bacillate, fimbriate, and filamentose: of the microspores I examined, virtually all were partially granulate; 11 were bacillate; 4 were fimbriate; and 1 was filamentose. Based on this limited sampling, species with a higher ploidy level often have larger microspores, but no clear relationship between microspore ornamentation and ploidy level was established, nor were any geographical or ecological trends clear. Like megaspores, microspore ornamentation is strongly convergent. Although microspores are often attached to megaspores, the role of spore ornamentation in coordinated dispersal remains unclear.     

中国四种卷柏科植物孢子的形态观察

利用光学显微镜和扫描电子显微镜对睫毛卷柏（Selaginella ciliaris (Retz.) Spring）、甘肃卷柏（S.kansuensis Ching）、墨脱卷柏（S.mutensis Ching）、毛枝卷柏（S.trichoclada Alston）等4种中国产卷柏科（Selaginellaceae）植物的大、小孢子进行了详细的观察。结果表明,4种卷柏的大、小孢子在表面纹饰方面存在明显的差异,而在每一种内,孢子形态是基本稳定的。因此,孢子形态特征可以作为区分种的重要依据。4种卷柏的大、小孢子的孢壁多为混合纹饰类型,且近极面纹饰比远极面的细密。     

中国四种卷柏科植物孢子的形态观察

利用光学显微镜和扫描电子显微镜对睫毛卷柏(Selaginella ciliaris(Retz.)Spring)、甘肃卷柏(S.kansuensis Ching)、墨脱卷柏(S.mutensis Ching)、毛枝卷柏(S.trichoclada Alston)等4种中国产卷柏科(Selaginellaceae)植物的大、小孢子进行了详细的观察.结果表明,4种卷柏的大、小孢子在表面纹饰方面存在明显的差异,而在每一种内,孢子形态是基本稳定的.因此,孢子形态特征可以作为区分种的重要依据.4种卷柏的大、小孢子的孢壁多为混合纹饰类型,且近极面纹饰比远极面的细密.     

Speciation pathway of Isoetes (Isoetaceae) in East Asia inferred from molecular phylogenetic relationships

Polyploidy plays an important role in the speciation of Iso?tes. Increasing our knowledge about the specific origin of each polyploid or phylogenetic relationship among species has been hampered because of conserved morphological variation and scarce habitats. We present several hypotheses concerning the speciation pathways of Iso?tes species distributed in East Asia. Our hypotheses are inferred from phylogenetic relationships that were elucidated using sequences of the internal transcribed spacer regions of nuclear ribosomal DNA, a second intron of LEAFY, and chloroplast DNA trnS-psbC spacer regions. These inferred phylogenetic relationships indicated that (1) the Chinese tetraploid, I. sinensis, is closely related to I. yunguiensis; (2) the Korean endemic species, I. hallasanensis, is an autotetraploid derived from I. taiwanensis or closely related taxa; (3) the hexaploid I. coreana forms a clade and has its closest evolutionary relationships with I. taiwanensis or I. hallasanensis; and (4) the Japanese hexaploid I. japonica is closely related to I. taiwanensis-I. coreana and I. sinensis-I. yunguiensis. These results suggest that interspecific hybridization and polyploidization have played central roles in speciation of East Asian Iso?tes. Furthermore, I. taiwanensis, an endemic species in Taiwan, has been involved in at least three cases of autopolyploid or allopolyploid speciation in East Asia.     

Studies on Annalepis from Middle Triassic Along the Yangtze River and Its Bearing on the Origin of Iso?tes

Specimens of Annalepis have been found from the Middle Triassic Series in the Yangtze River valley and described, including a new species. Annalepis is similar to the living plant, Isoëtes , in many aspects, such as the herb with a corm, more or less clustering sporophylls, presence of a ligule, monolete suture microspores of Aratrisporites -type and trilete megaspores, etc. The similarities of features between the two plants indicate their close affmities and that A. brevicystis might be the ancestry of Isoëtes . Since there is a ligule on the sporophyll of Pleuromeia, the Pleuromeiaceae represented by Pleuromeia could be allied to the Isoëtaceae, and both families should belong to Isoëtales. Isëtales represents a distinct evolutionary sequence and is inferred as being evolved probably from Palaeozoic SigiUaria . In Mesozoic age, two evolutionary lines are proposed: one as a line from Pleuromeia to Nathorstiana in relation to wood-monopolar rhizophore; the other as a line from Annalenis to lsoOtes related to herb-bipolar corm. Annalepis appeared almost simultaneously in the Yangtze River valley in early Middle Triassic, but the distribution of Annalepis was concentrated from east to west during middle-late Middle Triassic, in relation to the marine regression which occurred cyclically from east to west on the Yangtze Platform during that time.     

Different spore structures in sympatric Isoetes histrix populations and their relationship with gross morphology, chromosome number, and ribosomal nuclear ITS sequences

Traditionally, megaspores have supplied the most relevant character for the taxonomy of Isoetes at several systematic levels, including discriminant features usually used in species identification and diagnosis. Isoetes histrix Bory is a terrestrial circum-Mediterranean quillwort characterized by dark, shiny, and persistent phyllopodia with megaspore sporangia completely covered by a velum and tuberculate megaspores. Specimens of this species from Sardinian temporary wetlands showed the sympatric presence of two kinds of individuals with correlated variation in size, ornamentation, and radial ridges of megaspores, and in ornamentation of microspores. However, they showed the same diploid chromosome number (2n = 20), ITS ribotype, and macromorphological feature. No intermediate individuals, showing mixed characters of each spore types as well as malformed or aborted spores have been detected. These results suggest that the gene flow between both kinds of I. histrix plants is heavily restricted, if not limited at all. On the basis of the cytogenetic and molecular uniformity detected in I. histrix in this study, genomic incompatibilities do not seem to be the main reasons involved in the maintenance of the two kinds of I. histrix individuals. Prezygotic barriers involving changes in phenology (e.g. spore maturation) or differential gamete dispersal should be further assessed to gain insights in this topic. The presence of two kinds of individuals in I. histrix differing in significant spore features used in quillwort taxonomy, whatsoever the causes involved in its origin, could be the basis of an incipient differentiation process upon which selective pressures could ultimately lead to speciation.     

Scanning electron microscopy of Penicillium conidia

The morphology of conidia in 211 species and 12 varieties belonging to the genus Penicillium Link ex Gray have been studied and compared.According to surface ornamentation, conidia have been classified into six groups: A, smooth-walled (7% of the species); B, delicately roughened (13%); C, warty (28%); D, echinate (10%); E, striate with low irregular ridges (36%); and F, striate with scarce high ridges or bars (6%). Whereas the first two groups are closely related in both shape and average size, a gradual reduction was observed in size and in the length/width (l/w) ratio in the remaining groups. Echinate conidia were globose, having the largest average size. Only four species produced conidia not surpassing 2 m in diameter. Maximum length observed was 8 m, and most elongated conidia had a l/w ratio of 3.5. Forty per cent of the species studied had globose conidia.Conidia of the monoverticillate species were generally smaller, more globose and frequently with ridges. In the Asymmetrica, the conidia were generally larger, and showed ridges in comparatively few species. Conidia of the Symmetrica, which were frequently striate with ridges, presented the most elongated forms. The largest average size was found in the conidia of the Polyverticillata which were generally warty. Finally, we have considered the variations in surface ornamentation of conidia during the evolution of the genus Penicillium and drawn attention to their possible relationship with certain habitats and ways of conidial dispersion.     

Two new species ofIsoetes (Isoetaceae) from Jeju Island, South Korea

We name and describe two new species,Isoetes jejuensis and I.hallasanensis, from Jeju Island, South Korea. These taxa are compared with related species in East Asia, including I.coreana andI. sinensis. The rugulate megaspore ornamentation ofI. jejuensis differs from those otherIsoetes species. Furthermore,I. hallasanensis varies fromI. asiatica in its microspore ornamentation and chromosome number, although both species have an echinate megaspore ornamentation. These new species are tetraploid (2n = 44), whereasI. coreana is hexaploid (2n = 66).     

ULTRASTRUCTURAL STUDIES OF IN SITU DEVONIAN SPORES: BARINOPHYTON CITRULLIFORME

Each sporangium in the Upper Devonian taxon Barinophyton citrulliforme contains both microspores and megaspores. Microspores range up to 50 μm in diam and possess a homogeneous sporoderm characterized by an outer separable layer. The sporoderm of the megaspores (up to 900 μm) is constructed of sporopollenin units that are loosely arranged in the outer portion of the wall, and that give the megaspore wall a spongy organization. Ultrastructural evidence suggests that the small spores were not abortive megaspores, but that both spore types were functional. The spores of this plant, as well as other Devonian spores that show less dramatic size differences, are suggested as demonstrating a phase in the evolution of heterospory where sex determination was established in spores within the same sporangium prior to the evolution of micro- and megasporangia.     

甘薯属10种植物花粉形态扫描电镜观察

对用于育种研究的甘薯属(Ipomoea)10种植物花粉形态进行扫描电镜观察研究,以补充该属植物花粉形态学信息. 结果表明,甘薯属植物花粉粒的形状均为近球形,体积较大;花粉萌发孔多为散孔,少数萌发孔不明显;表面纹饰有3种:刺状类型、网状带刺类型和网状类型.根据花粉粒大小、刺的长短、萌发孔特征和表面纹饰类型等可以把这10种植物区分开来,同时发现I.wrightii与已有报道存在较大差异.     

鳞毛蕨科的孢子形态研究

对鳞毛蕨科及其相近类群的19属65种的孢子形态进行了光学显微镜观察,并对其中12属30种进行了扫描电镜观察。鳞毛蕨科的孢子左右对称,极面观为椭圆形、近球形,赤道观为肾形,极轴/赤道轴的比值为0.60～0.86;单缝孢,裂缝长度约为孢子全长的1/2～3/4,属中至大型孢子。鳞毛蕨科具有多样性的外壁纹饰:不仅包括刺状、瘤状、颗粒状、脊状、窗孔状、耳状、片状及翅状等几种基本类型,而且还存在一些中间过渡类型。根据孢子形态特征,对本科的属间关系进行了探讨。孢子形态特征的相似性支持假复叶耳蕨属、肉刺蕨属、球盖蕨科与鳞毛蕨属的近缘关系,黔蕨属与复叶耳蕨属间的近缘关系。玉龙蕨属的两个种的孢子纹饰与耳蕨属的部分种一致,支持将玉龙蕨属作为耳蕨属的异名处理。拟贯众属独特的翅状纹饰支持将其从鳞毛蕨科中分离出去。     

云南产8种卷柏科植物的孢子形态

利用光学显微镜和扫描电子显微镜首次观察了云南产8种卷柏科(Selaginellaceae)植物：钝叶卷柏Selaginella amblyphylla Alston;双沟卷柏S．bisulcata Spring;勃固卷柏S．kwrzii Baker;疏穗卷柏S．laxistrobilis K．H．Shing;微齿钝叶卷柏S．ormata(Hook．et Grev．)Spring;耳叶卷柏S．pseudopaleifera Hand.-Mazz;高雄卷柏S．repanda（Desv．ex Poir)Spring;泰国卷柏S．siamensis Hieron．的大、小孢子形态。研究结果表明卷柏科植物大、小孢子为辐射对称、三裂缝,其表面纹饰复杂,8种卷柏植物的大、小孢子在孢壁纹饰上存在着较明显差异。为卷柏科形态学和系统演化的研究提供了有价值的基础资料。     

中国水韭属两个四倍体新种

水韭属(Isoëtes)是起源最为古老的水生维管植物,全属物种均被列为国家一级重点保护植物。通过对全国水韭属植物的调查和研究发现,不同产地的四倍体植株在形态上存在显著差异。基于形态学、孢粉学和细胞学证据,将分布于中国湖南省长沙地区和怀化地区的四倍体居群分别命名为隆平水韭(Isoëtes longpingii)和湘妃水韭(I. xiangfei),并详细描述了其形态特征。隆平水韭形态上与中华水韭(I. sinensis)相似,不同之处在于其大孢子具小的瘤状或冠状纹饰,叶细长而柔弱,长达60 cm; 该种也与六倍体东方水韭(I. orientalis)相似,不同之处在于其染色体44条,大孢子具瘤状或冠状纹饰。湘妃水韭的大孢子纹饰虽与二倍体云贵水韭(I. yunguiensis)相似,但在小孢子纹饰、孢子囊形状和染色体数目方面却不同。隆平水韭仅少数植株生长于湖南省宁乡市一处池塘,完全沉水生长,而湘妃水韭则分布于怀化市通道县和会同县的湿地。由于这两个新种的分布区狭窄,野生居群数量和个体数较少,栖息地环境受到人为干扰,因此根据IUCN红色名录评估标准,将隆平水韭评为极危(CR)等级,湘妃水韭评为易危(VU)等级。所编制的中国已知水韭属物种的分种检索表,为本属物种的鉴定和保护工作提供了重要参考。     

ARIADNAESPORITES AND GLOMERISPORITES IN THE LATE CRETACEOUS: ANCESTRAL SALVINIACEAE

Glomerisporites and Ariadnaesporites are two genera based on megaspores and microspores from the late Cretaceous. Each has megaspores with characteristics shared with other late Cretaceous Salviniaceae, including numerous floats, an acrolamella, and a complex perispore. Microspores are borne singly, however, not in characteristic salviniaceous massulae. Microspores of Glomerisporites have a pseudovacuolate basal region and a single spore in an apical neck. Microspores of Ariadnaesporites are structurally like the megaspores but of smaller size. Ariadnaesporites varius occurs in the Cenomanian Stage (early late Cretaceous) and is the oldest presumed member of the Salviniaceae.     

A new species of Discinites (Noeggerathiales) from the Upper Permian of Weibei Coalfield, North China

A new species of Discinites is described from the Late Permian Upper Shihhotse Formation of the Weibei Coalfield, Shaanxi Province, China. D. hanchengensis sp. nov. has decurrent and disk-like sporophylls with deep-toothed apices, elliptical sporangia and rectangular epidermal cells. The spores are generally of the Calamospora type. The megaspores and microspores are 300–380 and 45–90 μm in diameter, respectively. The microspores are similar in size to those of all other species of Discinites that contain Calamospora, but the megaspores are remarkably smaller. The new species represents the first record of Discinites with Calamospora from China and from the Cathaysian flora. Finally, we summarize the associated foliages of Discinites in the Cathaysian flora and find that they are all markedly different from those found in the Euramerican flora.     

A Study on the Spore Morphology of Bryum Hedw. in China

Spore morphology of thirteen species of the genus Bryum Hedw. were observed by LM and SEM. The results show that the ornamentation of spore exine could be divided into three types: Type I , blunt at the top of baculate processes, to which four species belong: Bryum argenteum, B. lonchocaulon , B. uliginosum and B. arcticum. Type Ⅱ, sharp or with small processes at the top of baculate processes, represented by seven species: B. pallescens, B. caespiticium, B. pallens, B. pseudotriquetrum, B. paradoxum, B. alpinum and B. thomsoii. Type Ⅲ, expanded into hemispherical-shaped at the top of baculate processes, represented by two species: B.coronatum and B.sauteri. The Bryum species may also be divided into three groups according to the variation of spore diameter. Group I , with spore diameter under 10 μm, including one species, B. uliginosum. Group Ⅱ, with spore diameter 11～20 μm, including seven species: B. argenteum, B. alpinum, B. coronatum, B. pallens, B.paradoxum, B.sauteri, B.thomsonii. Group Ⅲ, spore diameter 21～30 μm, with five species: B. pallescens, B. caespiticium, B. pseudotriquetrum, B. lonchocaulon, B. arcticum. There are resemblances of spore morphology and exine ornamentation among the thirteen species. In the view of palynology, the genus Bryum is a natural taxon which is more advanced than the genus Pohlia Hedw. But spores of thirteen species are different at some characters such as diameter, shape ofproximal leptoma, etc., which indicates the genetic differentiation in the genus Bryum.     

中国水韭属植物的染色体数目及其分类学意义

利用细胞学方法观察统计了中国4种水韭属Isoestes植物的染色体数目。结果发现4个种的染色体基数均为x=11,其中高寒水韭I．hypsophila Hand.-Mazz．为2n=22,为首次报道;台湾水韭 I．taiwanensis DeVol为2n=22;中华水韭I．sinensis Palmer 2n=44为四倍体;而产于云南贵州一带并一直被当作是宽叶水韭I．japonica A．Br．的水韭属植物2n=22,与文献报道的宽叶水韭(2n=66,67,77,87,88,89)完全不同,应重新予以认识和评价。依据本文和其他相关的研究结果,对东亚水韭属植物进行了分类处理。     

23种顶蒴藓类孢子形态的观察

报道了中国２３种顶蒴藓类孢子的形态特征。观察结果显示：孢子形状有两类,球形和卵球形。孢子直径可分为４组：１０μm以下、１１－２０μm、２１－３０μm和３１μm以上。萌发孔有３种类型：近极薄壁区、单裂缝和无萌发孔。外壁纹饰有４种：棒状、瘤状、疣状和鼓槌状。孢子颜色有６种：黄褐色、黑褐色、金黄色、草绿色和紫红色。藓类孢子体积不同物种间有差异,但球形和卵球形是基本类型。苔藓孢子的萌发孔有３种类型：三裂缝为类     

The Discovery of Diploid Lycoris radiata (L′Her.) Herb. from Anhui

Lycoris radiata (L′Her. ) Herb. containing wild and cultural types, is distributed in China and Japan. The karyotype variation in three populations of the species from Anhui is studied in this paper. (1) Wuhu wild population has a karyotype 2n=21+1B= 1m+12st +8t+1B. The chromosomes range in length from 7.50 to 14.10 µm with the ratio of the longest to the shortest 1.88. The karyotype belongs to Stebbins’(1971) 3A. (2) Huangshan wild population has two cytotypes: 2n=22 and 2n=22+1B. Type Ⅰ: The karyotype formula is 2n=22=12st+10t. The chromosomes range in length from 6.85 to 9.95 µm. with the ratio of the longest to the shortest 1.45. The karyotype belongs to 4A. Type Ⅱ: The karyotype formula is 2n=22+1B=6st+14t+2T+1B (plate 1: 7,8). The chromosomes range in length from 6.50 to 11.02 µm. with the ratio of the longest to the shortest 1.70. The karyotype belongs to 4A. (3) Wuhu cultural type has a karyotype 2n=33=30st +3t. The chromosomes range in length from 7.10 to 9.35 µm with the ratio of the longest to the shortest 1.32. The karyotype belongs to 4A. This result agrees well with the previous reports. The diploid types of Lycoris radiata (L´Her.) Herb. are found in Anhui for the firsttime.