共查询到20条相似文献,搜索用时 0 毫秒
1.
The fossil pollen genus Classopollis 总被引:2,自引:0,他引:2
SATISH K. SRIVASTAVA 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1976,9(4):437-457
The generic name Classopollis Pflug, 1953, is considered as a valid usable name for Mesozoic spherical pollen characterized by a subequatorial circumpolar canal, a thickened equatorial band, a distal cryptopore, and a proximal tetrad scar. A study of Classopollis exine revealed the absence of nexine. Classopollis has a worldwide distribution in Upper Triassic-Turonian strata. Plants producing Classopollis have affinity with araucarian and/or gnetalean conifers. They occupied well-drained soils of upland slopes and lowlands near coastal areas, preferring the warm climate of transgressive seas. 相似文献
2.
3.
4.
5.
Ralph I. Smith 《Journal of morphology》1992,213(3):365-393
A comparative morphological study of nephromixial systems in three Californian terebellid polchaetes currently assigned to the genus Pista shows that P. fimbriata has all attributes of the generic type, but that P. pacifica and P. elongata differ markedly. The features of typical Pista include (among others): two pairs of usually unequal branchiae, long-handled anterior uncini (hooks) of crested avicular (bird-head-like) from, muddy, unornamented tubes, one pair of anterior excretory nephromixia (ENMX), and two pairs of separate thoracic reproductive nephromixia (RNMX) with genital papillae on segments VI and VII. A review indicates that P. fimbriata shares these typical features with practically all adequately described Pista species. However, P. pacifica and P. elongata possess three pairs of branchiae, long-handled uncini of distinctive crochet-like form, and membranous tubes with apertural hoods. Both have two pairs of ENMX, the first supplied by one pair of ciliated renal funnels, the second by two pairs of such funnels. But they differ in their RNMX: P. pacifica has three pairs of complex RNMX, those on each side united by a common duct. P. elongata has 11–13 pairs of simple RNMX united by common ducts. Although these species do not fit into Pista, no genus has been found to accommodate them. Generic placement is complicated by the fact that no instances of intra-generic nephromixial variation have been reported in the Terebellidae, although inter-generic variation is well known. If they are congeneric, this would be the first example of intrageneric RNMX variation in Terebellidae. But if assigned to separate genera or subgenera on the basis of their RNMX, their similarity of anterior uncini might be attributable to parallel or convergent adaptation to life in comparable tubes. More evidence, including molecular analysis, is needed for phylogenetic studies of Terebellidae. © 1992 Wiley-Liss, Inc. 相似文献
6.
7.
The fossil record of Araceae pollen beginning in the late Early Cretaceous and peaking in the Paleocene/Eocene is very sparse
up to now, consisting of three highly distinctive types: zona-aperturate pollen of the Monstera or Gonatopus type (very similar to Proxapertites operculatus), an ulcerate-spiny type typical for Limnobiophyllum, and a polyplicate, omniaperturate pollen type (an ephedroid pollen with non-gnetalean affinities) which was recently reported
from the late Early Cretaceous (Mayoa portugallica). An extensive literature search has shown that some distinctive Ephedripites forms (the Paleogene Ephedripites vanegensis, and the Late Cretaceous Ephedripites elsikii) are very similar to pollen of Spathiphyllum and both species are here transferred from Ephedripites to Spathiphyllum (as comb. nov.). We also add new fossil findings to the Araceae record. The new findings include a zona-aperturate, microperforate
to microreticulate pollen type from the Palaeocene of Colombia, highly similar to extant Gonatopus or Zamioculcas or Monstera pollen (Araceae) and to fossil Proxapertites operculatus, which is currently seen as a fossil equivalent; and, an ulcerate, spiny pollen from the Eocene of Stolzenbach, Germany,
extending the range of Limnobiophyllum (Pandaniidites), which is thought to be an extinct member of extant Araceae. The three pollen types add considerably to the reliable fossil
record of the family that now contains more than 20 records of these three pollen types: with the zona-aperturate type recorded
from the tropical or subtropical regions of Northern and Southern America, Central Africa, Southern and Central Europe, from
the Indian subcontinent and the Malayan Archipelago; the ulcerate type occurring in North America and Europe; and the polyplicate
type mainly occurring in South America and South-West Europe. Now we have good evidence that some of the aroid subfamilies
were already in existence in the Cretaceous, increasing in diversity and worldwide distribution in the Paleogene.
Dedicated to Prof. Dr. Stefan Vogel on the occasion of his 80th birthday. 相似文献
8.
9.
In vitro pollen germination of five species and two interspecific hybrids from the genus Brassica was tested in four media. Genetically fixed differences in the demands for optimal pollen germination among species were found. The experiments were designed to define optimal content of mineral salts, sugar, and PEG for every investigated species or hybrids. The differences found among species are discussed in relation to the evolutionary trend. 相似文献
10.
Vladimir G. Klikushin 《Geobios》1982,15(3):299-325
The taxonomic scheme of the two families of the order Isocrinida (Isocrinidae and Pentacrinidae) is given. The first family is divided at five subfamilies: Balanocrininae, Isocrininae, Metacrininae, Diplocrininae and Isselicrininae. Six genera are included in subfamily Balanocrininae: Balanocrinus (four species found in USSR), Laevigatocrinus (USSR: 3 species), Margocrinus (USSR: 4 species), Percevalicrinus (USSR: 5 species), Singularocrinus nov. gen. (monotypic) and Terocrinus nov. gen. (USSR: 1 species). Five fossil genera are included in subfamily Isocrininae: Chariocrinus (USSR: 1 species), Chladocrinus (USSR: 4 species), Isocrinus (USSR: 6 species), Raymondicrinus nov. gen. (Oligocene of USA : 2 species) and Tyrolecrinus nov. gen. (6 triassic species). Fossil representatives of three genera, namely, Metacrinus (Miocene-Recent), Nielsenicrinus (USSR: 4 species) and Cainocrinus (USSR: 1 species) are noted in subfamily Metacrininae. Five genera are included in subfamily Isselicrininae: Austinocrinus (USSR: 5 species), Buchicrinus (USSR: 5 species), Doreckicrinus (USSR: 1 species?), Isselicrinus (USSR: 4 species) and Praeisselicrinus (USSR: 1 species). Two genera are included in family Pentacrinidae: Pentacrinus (USSR: 1 species) and Seirocrinus (USSR: 4 species). Besides, the localities of 24 isocrinid species, systematic position of which is unknown, are listed (from Triassic upon Cretaceous). Three erroneous attributions to Isocrinida in USSR are pointed out. In the conclusion an outline of the phylogeny of the Isocrinida is discussed. For a majority of the wide-spread species in USSR figures are given. 相似文献
11.
K. L. ALVIN F.L.S. A. HLUTÍK 《Botanical journal of the Linnean Society. Linnean Society of London》1979,79(3):231-241
Shoots of the fossil species Frenelopsis alata (K. Feistmantel) Knobloch (Cheirolopidiaceae) from the Cenomanian of Bohemia and Portugal demonstrate a type of branching not hitherto reported among conifers. It has been interpreted as a modification of conventional axillary branching on the basis of detailed observations on external morphology with the help of comparative studies on living species of the family Cupressaceae (e.g., Callitris species) and other fossils of frenelopsid affinity. The probable nature of the growth pattern of the shoot is discussed. 相似文献
12.
13.
14.
15.
16.
The pollen grains of 32 species, 1 subspecies and 4 varieties of Vitis and 1 species of
Muscadinia were scanned with Hitachi S-800 scanning electron microscope and described in the present paper. In Vitis, the pollen morphology is found to be valuable for the identification of species,
though it is of little significance in supraspecific classification and systematic consideration. The ornamentation of Vitis could be divided into four types: ( 1 ) The pollen grains are oblate or rarely
spheroidal (P/E =0.97 ~ 1.08) in shape, with colpi wide enough to show dense granulae inside.
The pollen grains of V. coignetiae Pull. Ex Planch. belong to this type. (2) The pollen grains are
prolate to subprolate (P/E = 1.25 ~ 1.76 ), with sparse granulae within the colpi. This type includes l0 species, 1 subspecies and 3 varieties, such as V. hui Cheng etc. (3) The pollen grains
of V. romanetii Roman du Caill. ex Planch. and V. davidii (Roman du Caill. ) Foex. var. ferruginea Merr. et Chun are prolate (P/E= 1.87 ~ 2.1), with colpi narrow and linear-shaped, but
rhombic in the equational region. (4) The pollen grains are prolate or perprolate (P/E= 1.30 ~ 2.
0), with narrow and linear-shaped colpi. The species with this type of pollen grains are Muscadiniarotundifolia (Michx.) Small and 20 species of Vitis. 相似文献
17.
葡萄属植物花粉形态的研究 总被引:3,自引:0,他引:3
利用扫描电子显微镜对葡萄属Vitis L.37个类群(包括32种、1亚种和4变种)以及其近缘属麝香
葡萄属Muscadinia(Planch.)Small一种植物的花粉进行了观察,结果表明,葡萄属植物的花粉形态特征
在区别并鉴定属下的种类时有较大价值,但对种以上的分类以及研究系统演化无多大意义。葡萄属植
物的花粉形态特征可以分为4类:(1)花粉粒扁球形或圆球形(P/E值为O.97-1.08),沟较宽,可见被有
较密颗粒状突起的沟膜,属于该类的有紫葛V.coignetiae Pull.ex Planch.;(2)花粉粒长球形至近长圆球
形(P/E值为1.25~1.76),沟较宽,可见有较疏颗粒状突起的沟膜,该类型包括了庐山葡萄V.hui Cheng
等共10种1亚种3变种;(3)花粉粒长圆球形(P/E值为1.87~2.1),沟边缘紧靠合呈直线状,但在赤道
轴萌发孔处沟边缘分开呈菱形,该类型有秋葡萄V.romanetii Roman du Caill.ex Planch.和锈毛刺葡萄V.
davidii(Roman du Caill.)Foex.var.ferruginea Merr.et Chun等1种1变种;(4)花粉粒长球形或超长球形
(P/E值为1.30~2.0),沟边缘紧靠成直线状,麝香葡萄Muscadinia rotundifolia(Michx .)Small等21种的花粉属于此类型。 相似文献
18.
Francisca Alba‐Sánchez José A. López‐Sáez Blas Benito‐de Pando Juan C. Linares Diego Nieto‐Lugilde Lourdes López‐Merino 《Diversity & distributions》2010,16(2):214-228
Aim Quaternary palaeopalynological records collected throughout the Iberian Peninsula and species distribution models (SDMs) were integrated to gain a better understanding of the historical biogeography of the Iberian Abies species (i.e. Abies pinsapo and Abies alba). We hypothesize that SDMs and Abies palaeorecords are closely correlated, assuming a certain stasis in climatic and topographic ecological niche dimensions. In addition, the modelling results were used to assign the fossil records to A. alba or A. pinsapo, to identify environmental variables affecting their distribution, and to evaluate the ecological segregation between the two taxa. Location The Iberian Peninsula. Methods For the estimation of past Abies distributions, a hindcasting process was used. Abies pinsapo and A. alba were modelled individually, first calibrating the model for their current distributions in relation to the present climate, and then projecting it into the past—the last glacial maximum (LGM) and the Middle Holocene periods—in relation to palaeoclimate simulations. The resulting models were compared with Iberian‐wide fossil pollen records to detect areas of overlap. Results The overlap observed between past Abies refugia—inferred from fossil pollen records—and the SDMs helped to construct the Quaternary distribution of the Iberian Abies species. SDMs yielded two well‐differentiated potential distributions: A. pinsapo throughout the Baetic mountain Range and A. alba along the Pyrenees and Cantabrian Range. These results propose that the two taxa remained isolated throughout the Quaternary, indicating a significant geographical and ecological segregation. In addition, no significant differences were detected comparing the three projections (present‐day, Mid‐Holocene and LGM), suggesting a relative climate stasis in the refuge areas during the Quaternary. Main conclusions Our results confirm that SDM projections can provide a useful complement to palaeoecological studies, offering a less subjective and spatially explicit hypothesis concerning past geographic patterns of Iberian Abies species. The integration of ecological‐niche characteristics from known occurrences of Abies species in conjunction with palaeoecological studies could constitute a suitable tool to define appropriate areas in which to focus proactive conservation strategies. 相似文献
19.
The recently extinct large-bodied New World monkey Protopithecus brasiliensis Lund 1836 was named based on a distal humerus and proximal femur found in the Lagoa Santa cave system in the southeastern Brazilian state of Minas Gerais. These bones are from an animal about twice the size of the largest extant platyrrhines. One hundred and seventy-five years later, a nearly complete skeleton was discovered in the Toca da Boa Vista caves in the neighboring state of Bahia and was allocated to the same taxon as it was the first platyrrhine fossil of comparable size found since the originals. Our detailed study of the equivalent elements, however, reveals important morphological differences that do not correspond to intraspecific variation as we know it in related platyrrhine taxa. The presence of both an expanded brachioradialis flange on the humerus and gluteal tuberosity on the femur of the Bahian skeleton distinguishes it from the Lagoa Santa fossil as well as from all other platyrrhines. Further cranial and postcranial evidence suggests a closer relationship of the former with the alouattine Alouatta, while the limited Lund material fits more comfortably with the ateline clade. Therefore, we propose to limit P. brasiliensis Lund to the distal humerus and proximal femur from Lagoa Santa and erect a new genus and species for the skeleton from Toca da Boa Vista. Cartelles coimbrafilhoi was a large-bodied frugivore with a relatively small brain and diverse locomotor repertoire including both suspension and climbing that expands the range of platyrrhine biodiversity beyond the dimensions of the living neotropical primates. 相似文献
20.
Dorota Wro��ska-Pilarek Andrzej M. Jagodzi��ski 《Plant Systematics and Evolution》2011,295(1-4):55-72
The aim of this study is verification of the taxonomic usefulness of the pollen grain features studied, based on pollen morphology of 32 wild species from all 4 subgenera and all 10 sections of the genus Rosa, mainly for delimitation of subgenera, sections, and species. The measurements and observations were carried out with both light microscopy and scanning electron microscopy. Only correctly formed pollen grains (30 per specimen) were measured, and 960 pollen grains were examined in total. They were analyzed for 14 quantitative features of pollen grains and exine sculpturing and the following qualitative ones: outline, shape, and operculum structure. Our study revealed that the diagnostic features of pollen grains studied were: exine sculpture, length of polar axis, and pollen shape (P/E ratio). On the basis of the above characters, five species were isolated and the remaining ones were included in several groups isolated on the basis of exine sculpture types. The following three exine sculpture types occurred in the species studied: granular-verrucate (in R.?stellata), striate-psilate (in R.?multibracteata and R.?multiflora), and striate (the remaining species). R.?banksiae is characterized by small pollen grains, while R.?setigera has strongly elongated pollen with P/E ratio >1.5. Exine sculpture features considered to be diagnostic should be treated as auxiliary because they fail to differentiate individual species, although they can be helpful in distinguishing groups of species of similar exine sculpture. The arrangement of the species examined on a dendrogram only slightly corroborates division of the Rosa genus into subgenera and sections currently adopted in taxonomy (Rehder 1940). An interesting result was reported for the species studied from the Caninae (R.?agrestis, R.?canina, R.?dumalis, R.?jundzillii, and R.?rubiginosa) section which, despite hybrid nature, with the exception of R.?villosa, grouped in the same, most separated group of species. 相似文献