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1.
Summary A new budding yeast species isolated from soil is described. Its outstanding features are, firstly, the formation of asci containing up to sixteen long oval to reniform ascospores and, secondly, a fermentative as well as oxidative metabolism. The assimilation of nitrate is absent and no pseudomycelium is formed. The taxonomic position of the yeast is discussed and it is pointed out that, due to its exceptional ascospore number (1–16), it cannot be classified in any of the existing fermentative genera of theEndomycetaceae (in sensu Lodder et Kreger-van Rij). The reniform shape of its ascospores indicates, however, its close relationship with the multispored genusKluyveromyces, on the one hand, and the newly proposed one to four-spored genusDekkeromyces on the other. The species is provisionally classified as aKluyveromyces species,Kluyveromyces africanus nov. spec., until further information regarding its sexual characteristics becomes available. By virtue of its more or less intermediate ascospore number, it establishes the direct derivation of the genusDekkeromyces fromDipodascus uninucleatus via the multispored yeast genusKluyveromyces.  相似文献   

2.
Erséus  Christer  Grimm  Reinmar 《Hydrobiologia》2002,468(1-3):77-81
The freshwater oligochaetes of the subantarctic islands are reviewed and new records are given. Ainudrilus dartnalli sp.n. (subfamily Rhyacodrilinae) is described from freshwater sites on South Georgia (South Atlantic Ocean). It differs from the closely related, southwest Australian, A. nharna Pinder & Brinkhurst, by its longer clitellum, the longer upper teeth of its ventral somatic chaetae, its straighter and fewer penial chaetae, and by the proportions of its spermathecae. Range extensions are given for two widespread naidids, Nais variabilis Piguet and N. communis Piguet, from the Falkland Islands (S. Atlantic). Moreover, new material of N. elinguis Müller is recorded from Macquarie Island (Southern Ocean, SW of New Zealand).  相似文献   

3.
The dwarf perennial seaside or sandhill pansy, Viola tricolor L. subsp. curtisii (Forst.) Syme is illustrated and described. The history of its discovery by William Curtis, founder of this magazine, is given, and its relationships and nomenclature are considered.  相似文献   

4.
5.
Ambrosia artemisiifolia L. from Ambrosia of the Heliantheae of the Asteraceae family is a recognized harmful weed worldwide and one of the major invasive foreign plants in China. In this study, we investigated its reproductive features, focusing on its microsporogenesis, microgametogenesis, and pollen morphology. The results show that (1) Ambrosia artemisiifolia L. is a dicotyledonous plant and has spherical, tricolpate pollen grains with spiny outer wall; (2) its anther wall comprises four layers, namely epidermis, endothecium, middle layers, and amoeboid tapetum; (3) cytokinesis of microspore mother cells is successive; (4) most of tetrads are tetrahedral; and (5) mature pollen grains are three-celled. In conclusion, although Ambrosia artemisiifolia L. is a dicotyledonous plant with tricolpate pollen, its microsporogenesis is successive, which is different from typical dicots.  相似文献   

6.
Sargassum thunbergii growing on the sheltered coast of Maizuru Bay, which faces the Japan Sea, has been ecologically studied. The alga is perennial, its basal part (holdfast and stem) persisting even after its primary laterals have decayed. The alga forms a conspicuous zone especially in the summer. In the winter the plant is small and its growth is very slow. After that, with the rising of both temperature and tidal levels the alga grows progressively both in length and weight, and also forms numerous lateral branches. In summer (July to August) when the tidal levels are high (+21 cm to +43 cm), the alga is always submerged. At this time, the water temperature reaches the highest in the year (27–29 C), and the alga attains its maximum length and weight. Simultaneously, maturation occurs, and soon afterwards its primary laterals rapidly decay away, while young primary laterals beging to grow. Formae ofSargassum thunbergii (f.typicum, f.latifolia, f.nipponicum and f.swartzianum), which were established by Yendo (1907) and by Okamura (1923) are also discussed in terms of their ecology.  相似文献   

7.
Primulina curvituba B. Pan, L.H. Yang & M. Kang, a new species of Primulina (Gesneriaceae) from Guangxi, China, is described and illustrated. This new species is mainly diagnosed by its strongly curved corolla tube, which is a rare character in Primulina. The morphological relationship and differences between this species and its related congeners are discussed. The conservation status of P. curvituba is assessed as ‘Critically Endangered’ (CR) according to IUCN.  相似文献   

8.
The recognition of species proceeds by two fairly distinct phases: (1) the sorting of individuals into groups or basic taxa (‘discovery’) (2) the checking of those taxa as candidates for species-hood (‘justification’). The target here is a rational reconstruction of phase 1, beginning with a discussion of key terms. The transmission of ‘meaning’ is regarded as bimodal: definition states the intension of the term, and diagnosis provides a disjunction of criteria for recognition of its extension. The two are connected by a spectrum, with purely theoretical definition at one pole and purely ‘operational’ diagnosis at the other, with the more operational elements explained by the more theoretical. The current plethora of species concepts provides a good example. Accepting the Ghiselin–Hull thesis, that a species is an individual, a basic taxon is therefore also an individual with organisms as its parts. In a generalised synchronic individual its parts are conceptually integrated by an integrating principle (IP), which consists of a relation applying within a plan or rule. Fully developed, such an IP ensures the maximisation of the information content of the individual. A diachronic individual is then the set of its component synchronic parts, and its IP is provided by near-identity in an appropriate space-time (not necessarily physical). The integration of parts of an individual is illuminated by Gasking's concept of a proper group (in this case a chain-group), whose members are related by the relation serially fitting together with, the IP completed by an appropriate plan or rule. Gasking also applied the term cluster to a proper group persisting over a substantial period of time, individuated by any member acting as focus. A basic taxon is therefore a cluster of individuals, integrated by the relation significantly taxonomically similar and the rule in character-space-time. The nature of those concepts is discussed and defended. A species will inherit certain of the attributes of the preceding basic taxon (taxa). In at least the synchronic version its parts (individuals) will resemble each other significantly, providing the intuitive applicability of ‘members of’ and ‘instances of’ a species. Also, the notion that a species’ name is given by pure ostension, via a name-bearer (holotype) is empirically incoherent: the name cannot be applied in practice without an appropriate set of diagnostic traits.  相似文献   

9.
The new species Platycarpum vriesendorpiae N. Dávila (Rubiaceae, Henriquezieae) is described from Peru, where it is restricted to white‐sand forests and peatlands in the Tapiche and Blanco River watersheds in southeastern Loreto Region. The new species is generally similar to P. acreanum Rogers of western Brazil in its phyllotaxy, leaf pubescence, and fruit shape and size. However, P. vriesendorpiae differs in its triangular stipules that are 2‐ or 3‐angled at the base and in its smaller corolla.  相似文献   

10.
Dactylostomum nicolli n. sp. is described from the intestine of the goatfish Upeneichthys lineatus (Bloch & Schneider) (Mullidae) caught off Point Peron, Western Australia. The problem of assigning the new species to the appropriate genus, especially with regard to its close resemblance to Paropecoelus Pritchard, 1966, which also infects goatfishes, is discussed. This is the second report of Dactylostomum Woolcock, 1935 from an Australian marine fish. The new species is distinguished by its elongate form, simple ventral sucker papillae and irregularly shaped ovary.  相似文献   

11.
The host-specificity and biology ofChamaesphecia doryliformis (Ochsenheimer) [Lep.: Sesiidae] are described and the insect is assessed for its potential as a biological control agent for weeds of the genusRumex (Polygonaceae) in Australia. The insect is found in the western Mediterranean region, chiefly in north Africa. Adults emerge from pupation in late spring to summer when they lay eggs. The larvae feed inside the roots of post-reproductive plants belonging to the subgeneraRumex andAcetosa. In host-specificity tests 1st instar larvae attacked only plants of thePolygonaceae. The insect was judged safe to release in Australia after assessing its level of host-specificity, and attributes of its biology which indicate that native AustralianPolygonaceae will not be endangered.   相似文献   

12.
The phage N15 protelomerase enzyme (TelN) is essential for the replication of its genome by resolution of its telRL domain, located within a telomerase occupancy site (tos), into hairpin telomeres. Isolation of TelN for in vitro processing of tos, however, is a highly complex process, requiring multiple purification steps. In this study a simplified protocol for crude total protein extraction is described that retains the tos-cleaving activity of TelN for at least 4 weeks, greatly simplifying in vitro testing of its activity. This protocol may be extended for functional analysis of other phage and bacterial proteins, particularly DNA-processing enzymes.  相似文献   

13.
As a result of ongoing studies of the Rubiaceae of Gabon, the new species Colletoecema gabonensis is here described and illustrated. It is endemic to Gabon, where it is the only species of the genus, and is so far only known from three collections from the Ogooué-Lolo and Ngounié provinces. The new species is morphologically intermediate between its two congeners, C. dewevrei (from Cameroon, Central African Republic, Republic of the Congo, DR Congo, and Angola) and C. magna (endemic to Cameroon). The new species agrees with C. dewevrei in having flowers with exserted anthers and style, but differs in its sessile flowers and fruits. In the latter characters, it resembles C. magna, from which it can be separated by its smaller fruits and leaves, and by its different floral morphology. An IUCN conservation assessment has been made and the species is provisionally assessed as Vulnerable, based on its restricted area of occupancy and the small number of known locations.  相似文献   

14.
The expression of parasporal crystal protein (δ-endotoxin) coding gene(s) ofBacillus thuringlensis var.israelensis and its association, if any, with sporulation was studied in sporogenicBacillus cereus and its asporogenic mutant strains. Five asporogenous mutants ofBacillus cereus blocked at different stages of sporulation, were isolated from a streptomycin-resistant strain, The transconjugants isolated from the plasmid transfer experiments betweenBacillus thuringiensis var.israelensis and streptomycin resistantBacillus cereus and its asporogenous mutants, showed larvicidal activity. The crystal protein gene(s) are, therefore, expressed both in sporulating and in non-sporulating mutant strains ofBacillus cereus suggesting that the expression of crystal protein gene(s), is independent of sporulation specific functions inBacillus cereus. Part of the work was carried out at Biotechnology Programme, Jadavpur University, Calcutta 700 032, India.  相似文献   

15.
The new species Mollugo viscosa Thulin & Harley is described from Minas Gerais in eastern Brazil. It was previously part of the recently published M. brasiliensis Thulin & Harley, a species that was found to be non‐monophyletic in molecular phylogenetic analyses. Mollugo brasiliensis is here divided into a northern species (M. brasiliensis s.str.) in Bahia and a southern species (M. viscosa sp. nov.) in Minas Gerais. The new species differs from M. brasiliensis in its denser and more viscous indumentum, and in its distinctly smaller seeds with smaller tubercles and a smaller hilar peg, and from its sister species M. ulei by being a perennial herb with bisexual flowers.  相似文献   

16.
A new freshwater epiphytic Prorocentrum species, Prorocentrum rivalis, from the temperate region of the Haute-Vienne, France, is described. This species is the third freshwater species identified among approximately 60 marine Prorocentrum species. This new species is described using scanning electron microscope and phylogenetic analyses by a polyphasic approach (LSU rRNA sequences combined with 9 morphological characters). The phylogenetic analysis attests that P. rivalis is close to other planktonic freshwater species and the freshwater Prorocentrum clade is evolutionarily derived from an epiphytic freshwater prorocentroid ancestor. The unique marine species in the freshwater clade results from an ecophysiological reversion. P. rivalis differs from other epiphytic taxa by its rarity, its temperate distribution and its ecophysiological needs. The phylogeny confirms also that all planktonic Prorocentrum species are evolutionarily derived from epiphytic/benthic ancestors.  相似文献   

17.
Black scale Saissetia oleae (Olivier) (Hemiptera: Coccidae) is a widespread olive pest in California and Europe. Metaphycus lounsburyi (Howard) (Hymenoptera: Encyrtidae) is often one of its main parasitoids. Augmentative releases of M. lounsburyi have been proposed in those areas in which biological control is ineffective. In this paper, we study the relationship between black scale and M. lounsburyi in the field. According to our data, M. lounsburyi parasitizes mainly ovipositing females of black scale. Parasitism rates of ovipositing females reach high levels. In those scales, M. lounsburyi develops as a gregarious parasitoid, with an average of 13 and a maximum of 40 parasitoids developing per scale. The secondary sex ratio is female biased (proportion of males = 0.13) and appears to be brood size dependent. Metaphycus lounsburyi eggs are encyrtiform; however, its egg load is much higher than other Metaphycus that also parasitize black scale. The implications of these results on the behavioral ecology of M. lounsburyi and its use in biological control of black scale are discussed.  相似文献   

18.
Brienomyrus niger fires its electric organ in short pulses of approximately 0.3 ms duration, at a rather irregular rate, which rapidly increases in novel situations. The animal electrolocates objects in its near field by evaluating electroreceptive feedback from its ownelectricorgandischarges (EODs). Electrolocation performance is measured by the critical distance at which an approaching nonconducting object of standard size and velocity is detected (Figs. 1, 3).Electrolocation performance is impaired when foreign pulses of sufficient intensity consistently coincide with the animal's own EODs, whereas noncoinciding pulses, even at intensities 10 times higher than that of the animal's own near field, have no effect. The animal needs at least 4 to 8 uncontaminated successive EODs to electrolocate optimally (Figs. 4, 5).  相似文献   

19.
20.
The first marine fish digeneans recorded from Shark Bay, Western Australia are described from the flatfish Pseudorhombus jenynsi. Macvicaria dampieri n. sp. differs from the other members of the genus in its undivided, straight, saccular seminal vesicle, and the definition of the genus is extended to include this feature. The following new combinations are made: Macvicaria branchiostegi (Yamaguti, 1937) [originally Plagioporus] and M. cynoglossi (Madhavi, 1975) [originally P.]. Cainocreadium alanwilliamsi n. sp. is distinguished by the variable anterior extent of its excretory vesicle, which reaches to a level ranging between the posterior margin of the ventral sucker and just into the forebody, and by its relatively short forebody.  相似文献   

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