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1.
2.
Gametophytes and embryos of Actinostachys wagneri, A. pennula, and Schizaea elegans are described along with a few observations on those of 5. dichotoma, A. digitata, A. spirophylla, Ophioglossum pendulum, Danaea simplicifolia, Botrychium virginianum, B. dissectum, and Psilotum nudum. Variation in the gametophyte and embryo at the interspecific level within the Schizaeaceae is discussed.  相似文献   

3.
Schizaea pusilla is a rare fern that occurs in acidic bogs and is one of the few fern species that maintains a filamentous gametophyte throughout its development. To expand our knowledge of the physiology of this fern, phototropic responses were examined in young gametophytes. In contrast to germ filaments of other fern species, apical protonemata of young gametophytes are negatively phototropic in continuous white, red and blue light at all fluence rates tested. The expression of phototropic curvature is not limited by time since apical protonemata are also negatively phototropic when they are given brief exposures of light and then placed in the dark. In other lower plant groups such as mosses and some algae, the direction of phototropic curvature can change depending on light quality and intensity, but in young gametophytes of Schizaea, negative phototropic curvature was observed in all conditions studied. Blue light is the most effective in promoting the negative phototropic response in Schizaea.  相似文献   

4.
The zygote of Schizaea dichotoma divides transversely and the outer cell thus produced divides longitudinally. The three cells probably establish the organs: root, stem, and foot. The first leaf is not embryonic in origin but forms on the relatively old sporeling. Some general comments on gametophyte and embryo phylogeny are presented.  相似文献   

5.
The lens-shaped, dorsiventral gametophytes of Ophioglossum crotalophoroides are superficially different from the cylindrical gametophytes of other species of Ophioglossum. However, they have the same features as other Ophioglossum gametophytes (fundamentally axial organization, radially symmetrical apical meristem, radial distribution of gametangia) except that the cylindrical axis is reduced in length. Young sporophyte development is unique in the genus: all primary organs clearly arise from the embryo and develop simultaneously. The length of the life cycle of O. crotalophoroicles is considerably shorter than that of some other species in the Ophioglossaceae. A timetable for gametophyte and young sporophyte development is postulated. Spores germinate soon after they are released in the spring, and mature gametophytes develop by the next growing season. Fertilization occurs approximately one year after spore dispersal, and after two years, the photosynthetic first leaf of the young sporophyte emerges.  相似文献   

6.
Bryopsidella ostreobiformis sp. nov. is presented as the second species of the genus. The latter is amended to accomodate this new species. The derbesioid sporophyte is capable of producing three- to eight-rayed stellate propagules. The dioecious gametophyte is a heterotrichous thallus with branched, prostrate filaments and unbranched, erect ones, and does not resemble Bryopsis. The life cycle is distinctly diplohaplontic, with a diploid sporophyte and a haploid gametophyte. B. ostreobiformis is postulated as the starting point of a hypothetical evolutionary sequence of life histories in the Derbesia/Bryopsis complex.  相似文献   

7.
Abstract: This study involves bryophyte fossils from the Teresina Formation (Permian–Guadalupian) collected in the Rio Preto Quarry in the state of Paraná, southern Brazil. Two new genera are proposed, with two new species: Capimirinus riopretensis sp. nov. and Yguajemanus yucapirus sp. nov. C. riopretensis sp. nov. included a lateral sporophyte that was organically attached to a gametophyte and is thus one of the oldest pleurocarpous fossils known today. This discovery provides clear evidence of the evolution of mosses during the Permian, because an acrocarpous moss from this period was also found in India. The preservation of such a fragile structure demonstrates that no prefossilization displacement took place and that the sediments accumulated in a low‐energy, fresh‐water environment, similar to a lake fed by rain, and isolated from the direct influence of the sea. Campimirinus riopretensis may be placed within the earlier pleurocarps, and Yguajemanus yucapirus sp. nov. may belong to the Bryalean families. However, we were not able to place neither of these species in any existing family today.  相似文献   

8.
An approximately 1400‐bp region of the 16S rRNA gene was sequenced for 10 polar or near‐polar strains putatively placed in the Oscillatorialean genera Oscillatoria, Phormidium, and Lyngbya obtained from the University of Toronto Culture Collection to assess phylogenetic relationships. The strains were also examined for thylakoid structure and cell division type with TEM as well as traditional morphology with LM. Phylogenetic trees constructed using parsimony, distance, and maximum likelihood methods were similar in topology. If the original epithets applied to the sequenced strains (both polar and those from GenBank) were used, it was clear that taxa were not monophyletic. However, using the revised taxonomic system of Anagnostidis and Komárek, we were able to reassign these strains to their current correct taxa (species, genus, and family). When these assignments were made, it was determined that the molecular sequence data analyses were congruent with morphology and ultrastructure. Nine of the polar strains were found to be new species, and eight were described as such: Arthronema gygaxiana Casamatta et Johansen sp. nov., Pseudanabaena tremula Johansen et Casamatta sp. nov., Leptolyngbya angustata Casamatta et Johansen sp. nov., Phormidium lumbricale Johansen et Casamatta sp. nov., Microcoleus glaciei Johansen et Casamatta sp. nov., Microcoleus rushforthii Johansen et Casamatta sp. nov., Microcoleus antarcticus Casamatta et Johansen sp. nov., Microcoleus acremannii Casamatta et Johansen sp. nov. Some genera (Leptolyngbya and Microcoleus) were clearly not monophyletic and require future revision.  相似文献   

9.
Abstract The present paper describes 2 new genera, viz:Dimelaphis Zhang, gen. nov and Siciforda Zhang, gen. nov, 5 new species viz: Chaetogeoica ulmidrupa Zhang sp. nov, D. obtusifalcata Zhang, sp. nov., Forda auralenta Zhang et Qiao, sp. nov., F. multicoma Zhang, sp. nov. and S. sexiarticulata Zhang, sp.nov. and 1 new subspecies Paracletus cimiciformis zhanhuanus Zhang, ssp. nov. from China. All type specimens are deposited in the Institute of Zoology, Academia Sinica.  相似文献   

10.
The life history in culture of Akkesiphycus lubricus Yamada et Tanaka, an alga which has been placed in the Coilodesmaceae or the Punclariaceae, Dictysiphonales, was studied. In culture the species alternates between a microscopic filamentous gametophyte and a macroscopic polystichous sporophyte, a pattern common to the Dictyasiphonales and Laminariales. However, it has a unique anisogamous dioecious gametophyte. Fusions between mac-ro-gametes and micro-gametes were not observed, Macro-gametes or zygotes germinated, mostly developing into sporophytes that formed unilocular sporangia and the rest developed into reduced gametophytic flaments again. The gametophyte matures in 50C short-day conditions, corresponding to winter in Hokkaido. The sporophyte develops normally and matures only in low-temperature conditions irrespective of daylength. In regard to iits systematic position, Akkesiphycus lubricus is considered to have a closer relationship with the Laminariales than with the Dietyosiphonales in the following characters; lack of pyrenoids; early stages of parenchyma formation in the sporophyte; direct development of sporophytes from gametes or zygotes without forming a besal system zoospore becomes almost empty after germination by the migration of cell contents into a germ lube; formation of macro-gametangia by direct conversions of mother cells of mother cells of fertile branches; and micro-gametangia formed in clusters showing closeresemblance to the antheridia of Pseudochorda nagii (Tokida) Inagaki.  相似文献   

11.
Observations on the initiation and growth of the fertile digits and of their assemblages in Schizaea and Actinostachys as well as of the entire frond in S. dichotoma are presented. The leaf of S. dichotoma, although dichotomous in appearance at maturity, goes through a series of dichotomous and lateral ramifications during ontogeny. It is compared with the entire frond (“aerial shoot”) of Psilotum nudum. The sporangiate fructifications of Schizaea develop as their mature form suggests, i.e., by acropetal initiation and development of pinnately arranged digits. The counterpart in Actinostachys, irrespective of fertile digit number, develops as only three pinnae, two lateral and one terminal. It cannot be said, therefore, that the condition in Actinostachys, i.e., the digitate arrangement of fertile parts, is fundamentally the condition which exists in Schizaea but with a very short rachis. The fundamental difference is in pinna number and frequency of dichotomies which establish the final digit number.  相似文献   

12.
In addition to the complete lack of the usual spiral bands of thickenings in the elaters, the new genus Steereella is unique among the Hepaticae for the resemblance of its cellular organization in the thalloid gametophyte to that of some moss leaves. The taxon recognized is one genus, Steereella, gen. n., and one species S. linearis (Swartz) Kuwah. comb. nov., in which the variable nature of the gametophyte is particularly noted. The genus appears to be restricted to the West Indies.  相似文献   

13.
Characteristically, land plants exhibit a life cycle with an ‘alternation of generations’ and thus alternate between a haploid gametophyte and a diploid sporophyte. At meiosis and fertilisation the transitions between these two ontogenies take place in distinct single stem cells. The evolutionary invention of an embryo, and thus an upright multicellular sporophyte, in the ancestor of land plants formed the basis for the evolution of increasingly complex plant morphologies shaping Earth's ecosystems. Recent research employing the moss Physcomitrella patens revealed the homeotic gene BELL1 as a master regulator of the gametophyte‐to‐sporophyte transition. Here, we discuss these findings in the context of classical botanical observations.  相似文献   

14.
Meicai Wei 《Insect Science》1997,4(4):295-305
Abstract A key is given for the known Palaearctic and Oriental genera of the family Argidae including a new genus from China. Ortasiceros gen. nov. with five new species, O. nigriceps sp. nov., O. zhengi sp. nov., O. breoicornis sp. nov., O. curvata sp. nov. and O. elevata sp. nov. are described and figured. A new tribe, Ortasicerini trib. nov., is erected for the new genus and Copidocerus Forsius 1921. The type specimens are deposited in the Insect Collection of Central South Forestry University, Zhuzhou, China.  相似文献   

15.
简要记述了中国陕西省侧跗叶蜂属研究状况。描述了侧跗叶蜂属7新种:中原侧跗叶蜂 Siobla centralia Niu & Wei sp. nov.,弯毛侧跗叶蜂S.curvata Niu & Wei sp.nov.,S. listoni Niu & Wei sp. nov.,柔刃侧跗叶蜂S. pseudoplesia Niu & Wei sp. nov.,秦巴侧跗叶蜂S. qinba Niu & Wei sp. nov.,陕西侧跗叶蜂S.shaanxi Niu & Wei sp. nov.,狭颊侧跗叶蜂S. vulgaria Niu & Wei sp. nov.编制了陕西省26种侧跗叶蜂的分种检索表。  相似文献   

16.
The present paper reports thirty‐three species of the genus Cryptolechia in China. Fifteen species are described as new to science: C. deflecta sp. nov., C. kangxianensis sp. nov., C. microbyrsa sp. nov., C. falsivespertina sp. nov., C. zhengi sp. nov., C. neargometra sp. nov., C. paranthaedeaga sp. nov., C. cornutivalvata sp. nov., C. fascirupta sp. nov., C. stictifascia sp. nov., C. jigongshanica sp. nov., C. mirabilis sp. nov., C. anthaedeaga sp. nov., C. gei sp. nov. and C. varifascirupta sp. nov. The genital structures of the new species are illustrated.  相似文献   

17.
Abstract: Bulk sampling of phosphate‐rich horizons within the British Coniacian to Campanian (Upper Cretaceous) yielded very large samples of shark and ray teeth. All of these samples yielded teeth of diverse members of the Carcharhiniformes, which commonly dominate the fauna. The following species are recorded and described: Pseudoscyliorhinus reussi ( Herman, 1977 ) comb. nov., Crassescyliorhinus germanicus ( Herman, 1982 ) gen. nov., Scyliorhinus elongatus ( Davis, 1887 ), Scyliorhinus brumarivulensis sp. nov., ?Palaeoscyllium sp., Prohaploblepharus riegrafi ( Müller, 1989 ) gen. nov., ?Cretascyliorhinus sp., Scyliorhinidae incertae sedis 1, Scyliorhinidae incertae sedis 2, Pteroscyllium hermani sp. nov., Protoscyliorhinus sp., Leptocharias cretaceus sp. nov., Palaeogaleus havreensis Herman, 1977 , Paratriakis subserratus sp. nov., Paratriakis tenuis sp. nov., Paratriakis sp. indet. and ?Loxodon sp. Taxa belonging to the families ?Proscylliidae, Leptochariidae and Carcharhinidae are described from the Cretaceous for the first time. The evolutionary and palaeoecological implications of these newly recognised faunas are discussed.  相似文献   

18.
拟爪绵蚜新属及三新种记述 (同翅目:蚜总科:瘿绵蚜科)   总被引:4,自引:0,他引:4  
该文记述了瘿绵蚜科一新属拟爪绵蚜属SiciunguisZhangetQiaogen.nov.和这个属的二个新种,即十绵蚜S.decimaZhangetQiao,sp.nov.,九绵蚜S.novenaZhangetHu,sp.nov.,另外还记述了爪绵蚜属AphidounguisTakahashi,1963一个新种,苹果根爪绵蚜A.pomiradicolaZhangetHu,sp.nov.,模式标本存放在中国科学院动物研究所.拟爪绵蚜新属SiciunguisZhangetQiaogen.nov.模式种:十绵蚜SiciunguisdecimaZhangetQiao,sp.nov.本新属与爪绵蚜属AphidounguisTakahashi,1963和绵蚜属EriosomaLeach,1818有较近的亲缘关系,不同在于:有翅孤雌蚜腹管位于腹部背片Ⅵ,隆起,周围有毛环绕(前者:位于背片Ⅵ,不隆起,无毛环绕;后者:位于背片Ⅴ,隆起,有毛环绕);触角稍长,至少为体长0.35,具有线形次生感觉圈;后者:稍长,至少为体长0.40,具有环形次生感觉圈)。十绵蚜SiciunguisdecimaZhangetQiao,sp.nov  相似文献   

19.
The morphology of strains of Skeletonema Greville emend Sarno et Zingone was examined in LM, TEM, and SEM and compared with sequence data from nuclear small subunit rDNA and partial large subunit rDNA. Eight distinct entities were identified, of which four were known: S. menzelii Guillard, Carpenter et Reimann; S. pseudocostatum Medlin emend. Zingone et Sarno; S. subsalsum (Cleve) Bethge; and S. tropicum Cleve. The other four species were new: S. dohrnii Sarno et Kooistra sp. nov., S. grethae Zingone et Sarno sp. nov., S. japonicum Zingone et Sarno sp. nov., and S. marinoi Sarno et Zingone sp. nov. Skeletonema species fell into four morphologically distinct groups corresponding to four lineages in the small subunit and large subunit trees. Lineage I included S. pseudocostatum, S. tropicum, S. grethae, and S. japonicum. All have external processes of the fultoportulae with narrow tips that connect with those of sibling cells via fork‐, knot‐, or knuckle‐ like junctions. Lineage II included only the solitary species S. menzelii. Lineage III comprised S. dohrnii and S. marinoi. This latter pair have flattened and flared extremities of the processes of the fultoportulae, which interdigitate with those of contiguous valves without forming knots or knuckles. Lineage IV only contained the brackish water species S. subsalsum. Some species also differ in their distribution and seasonal occurrence. These findings challenge the concept of S. costatum as a single cosmopolitan and opportunistic species and calls for reinterpretation of the vast body of research data based on this species.  相似文献   

20.
Yamagishi T  Hishinuma T  Kataoka H 《Planta》2004,219(2):253-260
Protoplasts of the marine coenocytic macrophyte Bryopsis plumosa (Hudson) C. Agardh. [Caulerpales] can easily be obtained by cutting gametophytes or sporophytes with sharp scissors. When a protoplast isolated from a gametophyte was fused with a protoplast isolated from a sporophyte of this alga, it germinated and developed into either one of two completely different forms. One plant form, named Type G, appeared quite similar to a gametophyte, and the other, named Type S, looked similar to a sporophyte. While the Type G plant contained many small nuclei of gametophyte origin together with a single giant nucleus of sporophyte origin, the Type S plant contained many large nuclei of uniform size. These large nuclei in the Type S plant had metamorphosed from the gametophytic nuclei, and were not formed through division of the giant nucleus of sporophyte origin. Fragments of the Type S plant, each having such a large nucleus, developed into creeping filaments that look very similar to sporophytes. While cell walls of gametophytes and Type G plants were stained by Congo-red, those of the thalli of regenerated Type S plants and sporophytes were not stained by the dye. This indicated that the large nuclei of the Type S plant did not express genes for xylan synthesis, which are characteristic of gametophytes. Two-dimensional gel electrophoretic analysis revealed that most of the proteins synthesized in the Type S plant were identical to those of sporophytes. These results strongly suggest that in the Type S plant, the gametophytic nuclei are transformed into sporophyte-like nuclei by an unknown factor(s) produced by the giant nucleus of sporophyte origin and that the transformed nuclei express the set of genes characteristic of sporophytes. Despite morphological similarity, however, the regenerated Type S plant could not produce zoospores, because its large nuclei did not divide normally. The transformed large nuclei of gametophyte origin still seemed to be in the haploid state.Abbreviations DAPI 4,6-Diamidino-2-phenylindole - DIC Differential interference contrast - IEF Isoelectric focusing - PES Provasolis enriched seawater  相似文献   

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