首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Two types of foliar trichomes, both T-shaped with a uniseriate stalk and a single transverse cell, are used to document natural hybridization betweenVernonia lindheimeri Engelm. & Gray andV. interior Small in central Texas. The putative hybrid, known asV. guadalupensis Heller, has the same type of foliar trichomes but their stalks are neither as long as those ofV. interior nor as short as those ofV. lindheimeri. The transverse cells of the more conspicuous trichome type are also of intermediate size.  相似文献   

2.
3.
There have been recent disagreements as to how many taxa of titi monkeys, genus Callicebus, occur in the region between the Purus and Madeira rivers in western Brazilian Amazonia. Three parapatric taxa were proposed for the area: Callicebus caligatus, Callicebus stephennashi, and Callicebus dubius, but the latter has recently been considered a synonym of C. caligatus, even though both form monophyletic groups and are morphologically distinct. We analyzed the geographic variation in the pelage of Callicebus occurring between the Madeira and Purus rivers and concluded that the phenotypes attributed to C. caligatus and C. dubius are not individual morphs, but rather well-marked and geographically restricted varieties. For this reason, we classify Callicebus caligatus as a polytypic species with two subspecies: Callicebus caligatus caligatus and Callicebus caligatus dubius. This classification is corroborated by molecular evidence as well. The morphological and distributional data indicate that Callicebus stephennashi is a hybrid form of C. c. caligatus and C. c. dubius, due to the presence of intermediate characters. Therefore, until more precise locality records are provided and further evidence is presented, we consider Callicebus stephennashi to be a homonym of the two parental forms.  相似文献   

4.
The generaAmblostoma, Lanium, andStenoglossum are discussed, and it is concluded that all three should be included inEpidendrum.Lanium is treated as a section, and new names are proposed for two species whose epithets are preoccupied inEpidendrum: E. macrum (forAmblostoma gracile) andE. stiliferum (forLanium subulatum).  相似文献   

5.
6.
Trichasteropsis Eck, from the Muschelkalk of Germany is the only Triassic asteroid known from more than fragmentary material. Most spécimens representT. weissmanni (Münster) whereasT. senfti ECK,T. bielertorum n. sp., andBerckhemeraster charistikos n. gen. et n. sp., are each known from few individuals.Parsimony analysis hère treats the füll Ordovician to Récent history of the Asteroidea using a somasteroid (a pre-asteroid stelleroid) outgroup. Ambulacral évolution is critical in echinoderm history; the ambulacral arrangement of crown-group asteroids first appears in Paleozoic sister groups, and the subclass Ambuloasteroidea n. subcl. is proposed for Paleozoic and younger taxa with critical ambulacral apomorphies. Muschelkalk asteroids are assigned to the family Trichasteropsiidae n. fam., superorder Forcipulatacea. The recently described Triassic genusNoriaster belongs to the extant family Poraniidae, superorder Valvatacea.Trichasteropsis andNoriaster represent separate major phylogenetic branches of the post-Paleozoic infraclass Neoasteroidea, and together they indicate that diversification of modern-type asteroids was under-way during the Triassic, although the Mesozoic marine révolution largely was a Jurassic and later event. Post-Paleozoic asteroids appear to hâve returned to Paleozoic life modes in spite of new morphological expressions. Trichasteropsis is skeletally robust, suggesting protection from wave impact or predators. It is found in sédiments associated with shell banks but not from within the banks.Trichasteropsis senfti commonly occurs with brachiopods whereasT. weissmanni does not, although brachiopods are found in associated strata. Aspects of morphology of both species are similar to those of récent predatory Asteriidae suggesting similar behavior, but feeding habits ofTrichasteropsis are unverified.  相似文献   

7.
The expressions of Wolfet al. (1951) and Renkin (1956) for the kinetics of artificial kidneys are generalized to include the effects of filtration. IfB is the bath volume,b the relevant volume of distribution,f the filtration rate,t the time, andA 0,B 0,b 0 representA, B, andb at timet=0, then the plasma concentrationA is given by
$$\frac{A}{{A_0 }} = \frac{{B_0 }}{{B_0 + b_0 }}e^{ - \frac{{\left( {B_0 + b_0 } \right)}}{{B_0 }}\frac{{D_f }}{{b_0 }}K\left( {ft} \right)t} + \frac{{b_0 }}{{B_0 + b_0 }}$$  相似文献   

8.
Some species ofAsterigerina are described and discerned, as they occur in different levels of the sequence from Eocene to Miocene in northwestern Germany.Asterigerina bartoniana (Dam) in the Eocene is followed byAsterigerina rotula haeringensis Lühr andAsterigerina brandhorstiana n. sp. in the Lower Oligocene (sensuBeyrich).Asterigerina gürichi gürichi (Franke), typical for the lowermost part of sequences of Upper Oligocene age, is furnished with a lectotype out ofFrankes material. This species is substituted by the subspeciesAsterigerina gürichi staeschei (Dam & Reinhold) in the Miocene. The localities of Lower Oligocene in littoral facies near Bünde (Westfalia) are mentioned and described. (Localities “Brandhorst” resp. “Hof Fahrenkamp” and newer outcrops).  相似文献   

9.
The study of the cell wall structure was performed for ten species of Euastrum: E. ansatum (Ehrenb.) Ralfs, E. bidentatum Näg., E. binale (Turp.) Ehrenb. ex Ralfs, E. dubium Näg., E. elegans (Bréb.) Kütz. ex Ralfs, E. germanicum (Schmidle) W. Krieger, E. oblongum (Grev.) Ralfs ex Ralfs, E. pectinatum Bréb. ex Bréb. in Ralfs, E. validum West et G.S.West, E. verrucosum (Ehrenb.) ex Ralfs. The investigation of the cell wall ultrastructure has established for the first time that the pore canal in 6 of 10 species always has a coiled form to some degree. Three species (E. germanicum, E. pectinatum, and E. verrucosum) have both coiled and straight canals, and E. ansatum has only straight ones. A new type of pores (P7), typical only for representatives of the genus Euastrum, was also noted. In addition, a simple and effective method of preparing desmidium algal cells for investigation with transmission electron microscope has been developed.  相似文献   

10.
The diatom assemblages of the surface sediments have been studied in 53 urban ponds and lakes of St. Petersburg for the first time. In total, 350 species and infraspecific taxa have been registered; the species of Achnanthidium, Cocconeis, Cyclostephanos, Cyclotella, Gomphonema, Lemnicola, Navicula, Nitzschia, and Stephanodiscus genera were the most common. The wide distribution of small centric planktonic taxa, Cyclostephanos dubius, C. invisitatus, Cyclotella pseudostelligera, Stephanodiscus hantzschii, and S. minutulus, is preconditioned by the depletion of dissolved silica, which is a result of the high phosphorus load. The high abundance of macrophytes in the shallowest sites favors the dominance of epiphytic Fragilaria, Staurosira, and Staurosirella taxa. Bottom-living diatoms in the shallow eutrophic and hypereutrophic urban ponds are light-limited; this is a result of either macrophytes or phytoplankton development. Alkaliphilous and alkalibiontic species prevail among the pH-indicative species, while eutraphentic and hypereutraphentic diatoms, as well as those thriving in a wide range of trophic conditions, dominate over other trophic groups. The β- and α-mesosaprobic species are the most common saprobity-indicative taxa.  相似文献   

11.
The new genusViriatellina Bou?ek, 1964 unites the two older species namedNovakia gemündina Runzheimer, 1932 andTentaculites fuchsi Kutscher, 1931. ThusViriatellina gemuendina (Runzheimer) is cancelled, on the other handViriatellina fuchsi (Kutscher) remains valid. RecentlyViriatellina fuchsi (Kutscher) has been found in the tentaculitiferous limestone of Thuringia.  相似文献   

12.
Chromosome numbers are reported for 19 species of North AmericanSalix, one natural hybrid, and one introduced species. The following 17 species are here examined cytologically for the first time:Salix amygdaloides Anderss.,S. arbusculoides Anderss.,S. brachycarpa Nutt.,S. Candida Willd.,S. discolor Muhl.,S. exigua Nutt.,S. kumilis Marsh.,S. interior Rowlee,S. lutea Nutt.,S. maccalliana Rowlee,S. monticola Rydb.,S. myrtillifolia Anderss.,S. pellita Anderss.,S. petiolaris J. E. Sm,S. scouleriana Barr.,S. silicicola Raup, andS. subcoerulea Piper. Of the 19 native North American species 11 are diploid, four are tetraploid, one is triploid, one hexaploid, one dodecaploid, and one exhibits more than one ploidal level.  相似文献   

13.
14.
The behavioral response of the larval parasitoid Spintherus dubius (Hymenoptera: Pteromalidae) to volatile compounds derived from its Apion weevil hosts was investigated in two-choice bioassays. Odor source candidates were the larval and adult stages of weevils, clover flowers, and feces from adult weevils. Despite S. dubius being a larval parasitoid, the odor of weevil larvae isolated from the clover flowers was not attractive to female parasitoids. Surprisingly, S. dubius females were instead attracted by the odor from the feces of adult weevils. The female parasitoids were similarly attracted to the feces produced by the two main hosts, the red clover weevil (A. trifolii) and the white clover weevil (A. fulvipes). Chemical analysis of the volatile composition of feces produced by the two hosts revealed qualitatively similar odor profiles, correlating with the observed attraction by the parasitoid towards both odor sources. Some of the identified volatile compounds are commonly present in clover plant headspace fractions and may function as a kairomone to facilitate orientation by S. dubius to Apion-infested clover flowers. Larval and adult weevils were not attractive for parasitoid females, whereas, for the white clover weevil-plant association, infested flowers were highly attractive. These data show the use by the clover weevil parasitoid of an alternative source of olfactory information for locating its host.  相似文献   

15.
Chromosome numbers for 98 plants ofF. pallens, 19 ofF. psammophila, F. belensis andF. vaginata, and 44 ofF. ovina (originating from Austria, the Czech Republic, Germany, Slovakia and Latvia) are given. In addition to theF. ovina andF. pallens groups, chromosome counts for the following taxa are also reported:F. alpestris (2n=14) reported for the first time in this work,F. amethystina subsp.amethystina (2n=28),F. brevipila (2n=42),F. cinerea (2n=28),F. rupicola subsp.rupicola (2n=42) andF. versicolor subsp.versicolor (2n=14).InF. pallens, two ploidy levels (2n=2x=14+0-1B, 2n=4x=28+0-1B) as well as two natural triploid plants (2n=21+0-1B), were found. In addition to the fourF. pallens types that have been distinguished in Austria, one new tetraploid type (F. pallens “scabrifolia”) from the Czech Republic and Germany is reported and its taxonomy is discussed. The distributions of the Oberösterreich-Niederösterreich and Pannonisches-HügellandF. pallens types outside of Austria are documented.Only the diploid chromosome number (2n=14) was found inF. psammophila andF. vaginata. Chromosome numbers forF. psammophila subsp.muellerstollii andF. belensis (both 2n=14) were determined here for the first time. Two ploidy levels, 2n=14+0-5B corresponding toF. ovina subsp.ovina and 2n=28 corresponding toF. ovina subsp.guestphalica andF. cf.duernsteinensis were confirmed inF. ovina. Differences in chromosome structure (simple and multiple secondary constrictions) betweenF. pallens as opposed toF. psammophila andF. vaginata are discussed. A complete survey of published chromosome counts for Central European species from theF. ovina andF. pallens groups is included.  相似文献   

16.
New species ofBletia from Mexico are described and illustrated:B. concolor, B. similis, andB. urbana. The identity ofB. campanulata Llave & Lex. is discussed, andB. reflexa Lindl. is considered to be a distinct species. Several South American epithets are treated as synonyms ofB. campanulata. A key to the recognized species ofBletia is given.  相似文献   

17.
Friedrich von Hagenow is renowned for his seminal inventory of the diverse invertebrate fauna from the lower Maastrichtian chalk (Upper Cretaceous) of the Isle of Rügen, Germany. Tragically, his immense collection at Stettin (today Szczecin, Poland) was almost completely destroyed during World War II, including the type material of hundreds of species established by him during the first half of the 19th century. Seven belemnite specimens from his collection rediscovered at the Museum für Naturkunde Berlin, as well as 14 belemnites traced at the Museum für Mineralogie und Geologie at the Senckenberg Naturhistorische Sammlungen Dresden, include syntypes of four Talpina ichnospecies, labelled T. ramosa, T. solitaria, T. foliacea and T. sentiformis. To document this material, a new ‘digital cylinder seal technique’ was applied. The rediscovered material allows lectotype designations for T. ramosa and T. solitaria (now Trypanites solitarius), whereas T. foliacea and T. sentiformis, which where not formally published by von Hagenow, are regarded as nomina nuda. As a consequence, the non-topotypical neotypes of T. ramosa and T. solitaria, as designated by Ehrhard Voigt in 1972, are obsolete.  相似文献   

18.
Ten new species of the genera Eurytoma (8 species) and Tetramesa (2 species) from Yemen are described (Eurytoma lahji Zerova, E. thoraxica Zerova, E. cyrtophorae Zerova, E. longipes Zerova, E. yemeni Zerova, E. mabari Zerova, E. tibiaspinae Zerova, E. longitarsis Zerova, Tetramesa sanai Zerova, and T. rujumi Zerova). The type specimens of the new species are deposited in the collection of the Institute of Zoology, National Academy of Sciences of Ukraine, Kiev.  相似文献   

19.
Five new species and two varieties from the sectionMultifidae are described from the Sino-Himalayan region. They are referred to the affinity ofP. multifida L. andP. griffithii Hook. f.; one of the new species is probably related toP. gerardiana Lindl. and one is intermediate between the species of the sectionsMultifidae andNiveae.  相似文献   

20.
An endemic, yellow ray-flowered species ofTownsendia is described asT. aprica from Sevier Co., Utah. It is apparently most closely related toT. montana Nutt. of western Montana and Wyoming south to southern Utah andT. mensana M. E. Jones of northern and western Utah and adjacent Nevada.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号