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1.
Thirty-six species of coccidia, all members of the genus Eimeria, have been described from 3 of the 9 genera and 11 of the more than 48 species in the lagomorph family Leporidae. All these are described briefly in the present paper and their synonymies are given. Coccidia have been described from the single species of Oryctolagus, from 4 of the 13 species of Sylvilagus and from 6 of the 26 species of Lepus. These genera have 12, 12, and 14 known species of Eimeria, of which only 2 are shared by Oryctolagus and Sylvilagus. Lepus has none of the coccidia of these genera. One species is known to occur in the bile ducts of the liver, 13 in the intestine, and the location of 22 is unknown. Life cycles have been determined for 9 of the species, of which 8 have been worked out in the domestic rabbit Oryctolagus and 1 in the cottontail Sylvilagus.  相似文献   

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The orchid genera Masdevallia and Dracula bear very strange and bizarre flowers. They are, however, very popular with plant enthusiasts and there is a fair amount of commercial trade in these genera. The genera belong to a sub-tribe of the orchids, the Pleurothallidinae, which otherwise mostly have small and insignificant flowers. The majority of the species of Masdevallia and Dracula have been reported from single localities and approximately two thirds of all species are found at three or fewer sites. Most genera in the sub-tribe have similar distribution patterns. Using published deforestation rates and species distribution profiles we calculate that 402 of the total 3405 pleurothallid species may have been driven to extinction by random deforestation events. It is possible that as many as 46 Masdevallia species and 14 Dracula species have already been lost and that annual extinction rates for the two genera are 1 and 0.3 species per year respectively. It has been suggested that the two genera should be protected, by listing them in CITES Appendix I. It is unlikely that embargoes on trade would change extinction rates caused by forest conversion. Such embargoes might actually hamper ex situ conservation efforts.  相似文献   

4.
Synopsis There has been a decline, and in some cases an almost total disappearance, of many of the native fish species of lakes Victoria and Kyoga in East Africa since the development of the fisheries of these lakes was initiated at the beginning of this century. The Nile perch, Lates niloticus, a large, voracious predator which was introduced into these lakes about the middle of the century along with several tilapiine species, is thought to have caused the reduction in the stocks of several species. But overfishing and competition between different species also appear to have contributed to this decline. By the time the Nile perch had become well established, stocks of the native tilapiine species had already been reduced by overfishing. The Labeo victorianus fishery had also deteriorated following intensive gillnetting of gravid individuals on breeding migrations. L. niloticus is, however, capable of preying on the species which haven been overfished and could have prevented their stocks from recovering from overfishing. L. niloticus is also directly responsible for the decline in populations of haplochromine cichlids which were abundant in these lakes before the Nile perch became established. Even without predation by Nile perch, it has been shown that the haplochromine cichlids could not have withstood heavy commercial exploitation if a trawl fishery had been established throughout Lake Victoria. Their utilisation for human food has also posed some problems. The abundance of the native tilapiine species may also have been reduced through competition with introduced species which have similar ecological requirements. At present, the Nile perch and one of the introduced tilapiine species, Oreochromis niloticus, form the basis of the fisheries of lakes Victoria and Kyoga.Invited editorial  相似文献   

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All freshwater calanoids in southern Africa belong to the family Diaptomidae of which there are two subfamilies, the Paradiaptominae (Lovenula, Paradiaptomus and Metadiaptomus) and Diaptominae (Tropodiaptomus and Thermodiaptomus). The Paradiaptominae are endemic to Africa, while the Diaptominae have one endemic African genus Thermodiaptomus, and the other genus Tropodiaptomus, occurs in other parts of the world as well as Africa. Knowledge of distribution of the Diaptomidae has been hampered by incomplete taxonomic knowledge and lack of co-ordination of available information. Distribution patterns of 19 described species and 11 new species confirm that the majority of species have a limited distribution, and that the Paradiaptominae are arid-adapted and belong to temporary pool communities. Six species are endemic to coastal pans and vleis of the western and southern Cape Province. Only those species with a wider distribution have been recorded as colonising man-made lakes. The four Lovenula species are predators and often co-exist with a Metadiaptomus species as prey. Synapomorphies of widely separated species of the Paradiaptominae, provide interesting insights into how their evolution may have been governed by vicariance, dispersal and palaeoenvironments of the African continent.  相似文献   

7.
The Drosophila parasitoid system is an excellent model for the study of biological and ecological interactions. In Japan, extensive studies have been carried out on Drosophila parasitoids since the early 2000s. Here we provide up-to-date information on their diversity, distributions, host use and reproductive mode. Until now, 45 wasp species have been recorded. In addition, four genetically distinct groups (tentatively assigned as “races”) have been found in Ganaspis brasiliensis (Figitidae). Most of them are larvo-pupal parasitoids belonging to the families Figitidae and Braconidae, and some are pupal parasitoids of the families Pteromalidae and Diapriidae. A species of Encyrtidae was also recorded. Their major hosts are indicated with information on the host's breeding sites. Except Ganaspis xanthopoda and two races of G. brasiliensis that are distributed both in tropical and temperate regions, they are divided into tropical and temperate species. The tropical species are mainly distributed in Southeast Asia, and their distributions in Japan are restricted to the Ryukyu islands, particularly Iriomote-jima. The temperate species have been recorded from the main islands of Japan and surrounding islands but not from the Ryukyu islands, except two braconid species, Asobara japonica and Phaenocarpa sp. TK1. Some of the temperate species have also been recorded from Korea, China, Europe and/or North America. Among the 45 Japanese parasitoid species, at least seven are assumed to be thelytokous.  相似文献   

8.
B. G. Murray 《Chromosoma》1975,49(3):299-308
Chromosome numbers have been determined and karyotypes studied in several species of the genus Briza L. Nuclear DNA amounts have also been determined for some of the species and show a considerable variation between the species. The evolution of the karyotypes, particularly that of B. minor, is discussed and an attempt made to relate nuclear DNA content to karyotypes, breeding systems and habit in the different species.  相似文献   

9.
Abstract: Since the brachiopod Order Lingulida has been greatly revised in recent years, with particular emphasis on Cambrian and Ordovician genera, many well‐established Silurian linguloid species from the British Isles have been left without an appropriate genus in which to place them. This is rectified here by allocating the various species, mostly erected in the nineteenth or early twentieth centuries, to a variety of genera which have been mainly erected within the last forty years. Two new genera are erected, Mergliella, with type species Lingula bechei Davidson, 1866 , and Striatilingula, with type species Lingula? striata J. de C. Sowerby, 1839 .  相似文献   

10.
Evolution of karyotypes in snakes   总被引:2,自引:0,他引:2  
Dr. L. Singh 《Chromosoma》1972,38(2):185-236
Karyotype analysis and morphometric measurement of the chromosomes of 17 species of snakes have been done. Chromosomes of different species so far worked out in each family have been compared using quantitative methods to derive chromosomal affinities between species of different taxonomic categories. The following conclusions have been drawn: (i) It is suggested that the retention of Xenopeltidae as a separate family is unnecessary and the only species Xenopeltis unicolor referred to in that group should be included in the family Boidae. (ii) The subfamilies, Boinae and Pythoninae cannot be distinguished chromosomally. (iii) On the basis of chromosomal similarities, the cytologically known species of Colubridae. have been put into 13 different groupings which do not always correspond to the views of the present day colubrid taxonomists. (iv) In Hydrophiidae, speciation seems to have occurred through changes in the 4th pair of autosomes and sex chromosomes in general and the W chromosome in particular. Evidences are presented to show that fission and inversion have played an important role in bringing about the structural rearrangements in this group. (v) Family Viperidae according to taxonomists is divided into two subfamilies. Both the subfamilies are chromosomally very similar.  相似文献   

11.
Summary Since the success of Agrobacterium-mediated transformation of rice in the early 1990s, significant advances in Agrobacterium-mediated transformation of monocotyledonous plant species have been achieved. Transgenic plants obtained via Agrobacterium-mediated transformation have been regenerated in more than a dozen monocotyledonous species, ranging from the most important cereal crops to ornamental plant species. Efficient transformation protocols for agronomically important cereal crops such as rice, wheat, maize, barley, and sorghum have been developed and transformation for some of these species has become routine. Many factors influencing Agrobacterium-mediated transformation of monocotyledonous plants have been investigated and elucidated. These factors include plant genotype, explant type, Agrobacterium strain, and binary vector. In addition, a wide variety of inoculation and co-culture conditions have been shown to be important for the transformation of monocots. For example, antinecrotic treatments using antioxidants and bactericides, osmotic treatments, desiccation of explants before or after Agrobacterium infection, and inoculation and co-culture medium compositions have influenced the ability to recover transgenic monocols. The plant selectable markers used and the promoters driving these marker genes have also been recognized as important factors influencing stable transformation frequency. Extension of transformation protocols to elite genotypes and to more readily available explants in agronomically important crop species will be the challenge of the future. Further evaluation of genes stimulating plant cell division or T-DNA integration, and genes increasing competency of plant cells to Agrobacterium, may increase transformation efficiency in various systems. Understanding mechanisms by which treatments such as desiccation and antioxidants impact T-DNA delivery and stable transformation will facilitate development of efficient transformation systems.  相似文献   

12.
Unilocular cystocarps, with ostioles opening to one frond surface, have traditionally distinguished Pterocladia from Gelidium, described as having bilocular cystocarps, with ostioles opening to both surfaces; however, unequally developed locules have been described in Pterocladia and differences in cystocarpic architecture between Pterocladia capillacea and the type species of the genus, P. lucida, have been recently found. As heterogeneity in cystocarp architecture raises questions of basic intergeneric distinction, a survey of reproductive morphology of species in both genera is presented in this study. Six morphologically-different types of cystocarps are distinguished among the five species of Pterocladia and the seven species of Gelidium examined.  相似文献   

13.
Summary An ultrastructural study of the mucous cells of the intestinal epithelium of four lacertilian species (Lacerta lepida, Lacerta hispanica, Psammodromus algirus and Acanthodactylus erythrurus) is here reported. Two types of mucous cells have been found in these species: common mucous cells and granular mucous cells. Immature and mature forms of both types have been observed. The common mucous cells or typical goblet cells have the same characteristics in all four species. The granules of the granular mucous cells of the two species of Lacerta are similar but differ from those of the other two species.  相似文献   

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据观察,沫蝉科Sphenorhina属的3个种都以菊科的Crassocephalum cerpidioidesChromolaena ordorata 作为寄主植物,热带菊科植物与固氮植物有关,沫蝉可以作为菊科一些固氮植物的间接指示物,目前尚未得到很好研究。  相似文献   

16.
Material of 85 species of Brassica and genera closely related to it was examined cytologically, and the chroiftosome counts are reported. These confirm records published by other workers for 42 species, two contradict earlier records, and 41 counts are believed to be new. Different species with the same chromosome number have been cross-pollinated, and those found to be interfertile have been grouped into cytodemes. For the most part species found to be interfertile have long been regarded as closely akin, but three cases of interfertile intergeneric hybrids are reported. Altogether the material has been classified into 45 cytodemes: 35 diploids with chromosome numbers ranging from n= 7 to n= 13, and 10 derived tetraploids. This enumeration is possibly not exhaustive of the world's genomes closely related to the crop Brassicas and a list is appended of the wild species which need examination before the enumeration might be considered to be complete.  相似文献   

17.
Chinch bugs are associated with several species of monocots, and species of Gramineae are the principal plants utilized. In Mexico, 24 species of Blissidae have been recorded. The immature stages of Ischnodemus sallei (Signoret), Toonglasa munda (Slater & Wilcox), and T. tumorosis (Slater & Wilcox) are described and illustrated. These species have been recorded from several species of bamboo. Distributional records in Mexico and the host plants of these chinch bugs are also included.  相似文献   

18.
Summary A taxonomic study of the members of the family Choanephoraceae was undertaken. Almost all the species of the family have been isolated from various sources in India. Two genera, viz.,Blakeslea andChoanephora have been recognized and a key to the genera has been given. The genusBlakeslea includes only one speciesB. trispora and the genusChoanephora five species. A key to the species has also been given. A new variety ofChoanephora circinans, viz.,C. circinans var.prolifera Mehrotra andMehrotra based on the proliferating vesicular apices of the sporangiophores has been described.  相似文献   

19.
This paper presents an eco‐taxonomic study of the Neotropical representatives of the Thyreodon genus‐group (Hymenoptera: Ichneumonidae) present in Costa Rica, i.e. species of the genera Thyreodon and Rhynchophion. These ichneumonids are koinobiont endoparasitoids of the larvae of Sphingidae and Saturniidae. Intensive sampling in Costa Rica, conducted over 15 years, has revealed the presence of 23 species (12 of which are described here as new –Rhynchophion woodi, Thyreodon woodleyi, T. papei, T. whitfieldi, T. deansi, T. walkerae, T. sharkeyi, T. zitaniae, T. delvarei, T. schauffi, T. darlingi and T. carmeani), whereas earlier studies recognized only nine species in the same area. Several of the additional species we found are simply very scarce and thus unlikely to be encountered except by the type of intensive survey that, in the tropics, has only been conducted in Costa Rica. In some other cases, it has become apparent that more than one species has previously been confused under a single name. Thyreodon rufothorax Cameron is shown to be morphologically and biologically distinct from T. atriventris (Cresson), with which it has long been synonymized, and the relatively well‐known, chromatically distinctive species ‘T. laticinctus Cresson’ and ‘T. morosus Smith’ are both shown to be complexes of sibling species. Reared series have been essential in facilitating the separation of the species in these complexes. An illustrated key is provided to separate all taxa using simple morphological characters. Fourteen of the 23 species have been reared, and all have been found to be restricted to one or a few species of hosts, species of Thyreodon primarily on macroglossine Sphingidae (with one species on Saturniidae) and species of Rhynchophion on sphingine sphingids of the genus Manduca. No two species of these ichneumonids attack the same host caterpillar species, and not all species of macroglossines present in the study area are attacked by species in this genus‐group. Most species are apparently rather rare. Many have only been collected by rearing on a few occasions, other species have been collected at light (six in total) or in Malaise traps (ten in total), or by hand‐netting (20 in total), but no one method collected all of the species present in the principal study area, the Area Conservacion de Guanacaste. The two New World genera Rhynchophion and Thyreodon are found to be related to the Old World genera Dictyonotus and Euryophion, the former of which comprises species that are also sphingid parasitoids, whereas species of the latter attack the caterpillars of other large bombycoid moths, Saturniidae and Eupterotidae. A cladistic analysis shows that Thyreodon is the sister‐lineage to Dictyonotus, and Euryophion is the most basal lineage in the genus‐group. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 141 , 297–351.  相似文献   

20.
The Paradiaptominae, a subfamily of the large Diaptomidae family, is a small group of freshwater calanoids of which 24 species in four genera have been described. They are endemic to Africa with the exception of four species, Metadiaptomus asiaticus (Asia and Mongolia), M. gauthieri (Africa and Madagascar), Paradiaptomus greeni (India and Sri Lanka) and Neolovenula alluaudi (Canary Islands, North Africa, Baltic and Mediterranean countries). The North African species Metadiaptomus chevreuxi extends its range into Iraq and Iran. The Paradiaptominae are widely distributed in semi-permanent water bodies in the drier areas of Africa although most individual species have a restricted distribution. Only a few species have the ability to colonise permanent waters and these species are usually located at higher altitudes. The Paradiaptominae have not been recorded from the wet equatorial lowland areas of Africa. It seems likely that they are Gondwanian in origin as evidenced by their distribution (Africa, Madagascar, India and Sri Lanka). Neolovenula alluaudi (Mediterranean) shares morphological characters tenuously linked to the other species in the group and may either have a different origin or have branched off at an early stage in evolution of the group.  相似文献   

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