陷胸式蜂亚科（昆虫纲）化石在我国辽西上侏罗统的发现及其系统演化

描述产自辽宁北票上园地区黄半吉沟上侏罗统义县组下部膜翅目昆虫化石1新属新种Trematothoracoides liaoningensis gen.et sp.nov.,归入薤式产（Sepulcidae)中的陷胸茎蜂亚科（Trematothoracinae)。这是首次在我国发现可行的陷胸茎蜂化石,也是该亚科在侏罗纪的产次报道,分支分析结果表明Trematothoracinae为一单系类群。Thoracotrema与Prosyntexis进化程度较高,构成一对姊妹群,同时又是Trematothorax的姊妹群,Trematothoracoides最为原始,为Thoracotrema Prosymtexis Trematothorax的姊妹群。     

Abundance and habitat segregation in Mediterranean grassland species: the importance of seed weight

Abstract. We analysed the relationship between seed traits (weight, shape and dispersal structures) and the abundance and habitat segregation of Mediterranean grassland species. To take into account possible correlations with other plant traits, the study also includes 5 vegetative traits (growth form, plant longevity, clonality, onset of flowering and plant size) of commonly accepted functional importance. Data were recorded for 85 species from dehesa grasslands in central Spain. Species abundance was measured in upper (dry and less productive, high stress) and lower (moist and more productive, low stress) slope zones in the same area. Habitat segregation was estimated using an index based on the relative frequencies of species in upper and lower slope zones. Multiple regression models were fitted using species, as well as phylogenetically independent contrasts, as data points. Annual small‐seeded species without specialised dispersal structures are over‐represented in dehesa grasslands. Abundance was negatively related to seed weight in upper slope zones. None of the recorded plant traits were related to abundance in the lower slope zones. Habitat segregation was mainly related to seed weight, but also to some vegetative traits. Annual, early flowering and small‐seeded species were relatively more abundant in the upper than the lower slope zones. This pattern is independent of phylogeny. Our results suggest that in dry Mediterranean grasslands, abundance of many species is determined by dispersal (production of numerous small seeds) rather than by competitive ability.     

内蒙古自治区上侏罗统最原始的蠼螋昆虫化石(昆虫纲:革翅目:始螋亚目)

我国上侏罗统牛津阶-基末利阶（163-150Ma)保存有完好的最原始的蠼螋昆虫化石,首次描述,分析和讨论了原始蠼螋后翅脉序特征,认为与现代生存的蠼螋后翅基本相同。因此,提出了与西方某些蠼螋昆虫分类学者不同的意见,认为始螋亚目（Aechidermaptera)应归入于革翅目（Dermaptera)之中,且视其为一个最原始的类群较为合理,内蒙古自治区这个原始类群的下列重要特征皆为首次发现;胸骨具有特殊的形态结构;革翅锁具（Tegmina locking device)和刺脊突（spiny crest)发育;前,中,后足跗节皆为5节;后足基节显著伸长;颈部被划分为前,后两个颈片;革翅后缘收缩变尖,上述5项被视为厚原始蠼螋特有的祖征,下列特征应为早期蠼螋共有的原始性状;虫体扁平,通常具毛;腹部侧缘彼此近平行;触角显长,丝状,多节（通常多于11节）;两只单眼发育;上颚具齿;中胸小盾片显大;革翅较长,通常具有明显的翅脉;股节具隆脊;爪和爪垫通常发育;腹部各节背板与腹板不重叠（两者位置非简单的上,下关系）;尾须柔软,多节,雌性产卵器鞘显著外伸,本文建立了始螋亚目1新科Sinopalaeo-dermatidae和2新属2新种Sinopalaeodermata neimonggolensis gen.et sp.nov,Jurassimedeola orientalis gen,et sp.nov。同时,对蠼螋昆虫的起源和演化重新进行了讨论,做出了与西方某些蠼螋昆虫研究者结论不同的推断。     

Variations in the Size of Mitotic Cells in the Root Meristem

Variations in the length of mitotic and interphase cells were analyzed in various tissues of wheat roots and in the cortex of maize roots. Reliable differences were shown in the length of mitotic cells in individual file clones of cells of the same tissue. The mean lengths of dividing cells in different roots differed to a lesser extent than those of different files in the same tissue of one root. Within the file, the length of the sister simultaneously dividing cells differed the least, while the difference of lengths of the neighbor simultaneously dividing nonsister cells was bigger. The mean length of interphase cells in any file was always less than that of mitotic cells by a factor of 1.45. This ratio was almost invariable for files and tissues in both the plants we studied and corresponded to that of an exponentially growing cell population. In addition, a very small number of cells were found (less than 1%) in meristems, which are longer than the mitotic cells. The length of these cells exceeded those of mitotic cells by less than twice. The origin of such cells is discussed. The length of mitotic cells near the quiescent center is more variable than in the middle of the meristem in the cortex of both plants. In the meristem basal part, the mitotic cells were no longer than those in the middle of the meristem but there were no small dividing cells. In the wheat epidermis, the cells are differentiated into trichoblasts and atrichoblasts and, therefore, the length of the dividing cells is highly variable. The cell length is essential for their transition to mitosis for all studied proliferating meristem cells.     

铁线莲属研究随访（Ⅳ）

（1）Eichler(1958)在研究马来西亚铁线莲属植物时也深入地研究了中国、越南、泰国、缅甸及喜马拉雅山区的该属标本,认为根据我国台湾标本描述的Clematis taiwaniana Hayata可能为C.javanaDC.的异名。本文作者在研究了有关的南洋群岛、中国台湾及日本琉球群岛的标本之后同意Eichler的归并意见;此外,C.grataWall.var.ryukiuensis Tamura,C.sikkimensis(Hook.f.&Thoms.)Drumm.ex Burkill,C.connata DC.var.bipinnata M.Y.Fang,C.kilungensis W.T.Wang & M.Y.Fang等拉丁学名也被归并为异名。（2）对大叶铁线莲组sect.Tubulosae做出了新的分类系统。特产日本的Clematis takedana Makino自发表后一直被认为是C.apiifolia DC.和C.stans Sieb. & Zucc.（大叶铁线莲C.heracleifolia DC.的近缘种之一）的杂交种。此种为木质藤本植物,具三出复叶,腋生花序有多数两性花,呈圆锥状,而相似于C.apiifolia DC.（萼片水平开展,雄蕊无毛,花药狭长圆形,药隔顶端不突出）,但其萼片向斜上方开展（花萼宽钟状）,花丝上部有疏柔毛,花药条形,药隔顶端有短突起而不同。笔者发现,特产我国河北西部和北京山地的羽叶铁线莲C.pinnata Maxim.（叶为具5小叶的羽状复叶）具有与C.takedanaMakino相同的花构造,二者在亲缘关系上极为相近,组成一个自然小群。这二种与特产北京的细花铁线莲C.tatarinowii Maxim.（花两性,萼片直立,花丝上部有疏柔毛,花药狭长圆形,背面有疏柔毛,药隔顶端不突出）组成大叶铁线莲组sect.Tubulosae的原始群——羽叶铁线莲亚组subsect.Pinnatae。而原来的大叶铁线莲C.heracleifolia DC.等种组成此组的进化群——大叶铁线莲亚组subsect.Tubulosae,其特征为花通常单性,萼片直立,雄蕊常有疏柔毛,茎直立,草质至木质。此外,还对C.siamensis Drumm.ex Burkill的4变种和C.connata DC.的5变种进行了分类。（3）描述了3新系、3新种和4新变种。（4）做出了6新组合和3新等级。     

Meiosis: how to create a specialized cell cycle

During the meiotic cell cycle, a single round of DNA replication precedes two nuclear divisions. Recent work has shown that the proteins controlling the mitotic cell cycle are either replaced by homologous proteins only expressed during the meiotic cell cycle or modulated by meiosis-specific factors to bring about this specialized cell cycle.     

Sympatric sister species in rodents are more chromosomally differentiated than allopatric ones: implications for the role of chromosomal rearrangements in speciation

A meta‐analysis approach was used to test for chromosomal speciation in rodents. Forty‐one pairs of sister species, identified in the two most species‐rich rodent families (Cricetidae and Muridae), were used as phylogenetically independent data points, each resulting from a speciation event. About 30% of sister species have an identical karyotype. There was a significant difference in the number of chromosomal differences between sympatric and allopatric sister species, compatible with a direct role of chromosomal rearrangements in speciation.     

New Mesozoic and early Cenozoic spicular Nassellaria and Nassellaria-like Radiolaria

This paper continues a former study (Rev. Española Micropaleontol. 14 (1982b) 401), where the author described spicular nassellarian and entactinarian Radiolaria found in the Middle Triassic samples available at that time. Based on the study of new samples bearing well preserved radiolarians collected during the 20 years that followed the former publication, samples coming from Triassic, Jurassic, Cretaceous, and Paleogene deposits, the author found that spicular Nassellaria are extremely rare in the post-Fassanian radiolarian faunas. Their fossil record is punctuated, their occurrences being separated by very long gaps. And even so, when they occur their number is usually reduced to one, two, or several specimens of a single species. Spicular Nassellaria are rare or very rare in the upper Spathian and Anisian, frequent in the upper Anisian-lower Ladinian, practically absent in the upper Ladinian and the whole upper Triassic and pre-Toarcian Lower Jurassic, rare in lower Toarcian, very rare in the Bajocian, rare in the lower Tithonian. No specimens were recorded in the other stages of the middle and upper Jurassic and in the whole Cretaceous, except for one in the Coniacian. In the Paleogene only five species belonging to four genera have been recorded in the upper Paleocene-middle Eocene. In the Neogene the only genus known so far is Neosemantis that occurs sporadically since the lower Miocene. A wider diversity is recorded in the living plankton or Recent sediments that comprise all genera and species described in the literature before 1970. It is suggested that this scarcity reflects their real scarcity in the tropical or subtropical seas of the past, but this scarcity was probably magnified by selective preservation. The idea of origination of spicular Nassellaria once or several times from shell-bearing Nassellaria by the reduction of shell during some environmental crises of the Mesozoic and Cenozoic or by hybridization is rejected because the group is rather unitary in its spicular structure and it shows a certain evolution from taxa with massive spines to taxa with three-bladed spines. Nassellarian-like spicular Radiolaria range within the boundaries of the Triassic; they seem to have disappeared by the end on the Norian.In order to give a complete inventory of these radiolarians all taxa known in the Mesozoic and lower Cenozoic are described, discussed, or just mentioned. They comprise 44 species of which 20 are new, 14 genera of which six are new (Palaeosemantis, Molzaxis, Daniplagia, Verticiplagia, Jeanpierria and Nandartia), three subfamilies of which one (Zaldacriinae) is new, and two families (Plagiacanthidae and Archaeosemantidae).