摘要:

Somatic karyotypes of four characid fishes usually rearing in acquarium are presented. Family Lebiasinidae:Nannostimus beckfordihas 2n= 42 = 2M + 40A andNannobrycon equeshas 2n= 34 = 34A.Ctenolucius hujetifrom the family Ctenoluciidae has 2n= 36 = 26M, SM + 10ST, A, whileMetynnis lippicottianusfrom the family Serrasalmidae shows 2n= 62 = 30M + 30SM, ST + 2A. In the whole the order Characiformes is highly diversive from karyological point of view: chromosomal evolution passed off in the directions of increasing of chromosome numbers (Serrasalmidae) as well as of declining of 2n(Lebiasinidae, Ctenolucidae); the families Anostomidae, Curimatidae, Prochilodontidae, Hemiodontidae and Parodontidae appear to be cytogenetically closed group. Chromosomal evolution in Characiformes consider to be based on pericentric inversions and, in more advanced families, on sex chromosome differentiation, subchromosomal variability and appearance and variability of supernumerary chromosomes.

ISSN:0008-7114    

DOI:10.1080/00087114.1990.10797008

出版商:Taylor & Francis    

年代:1990

数据来源: Taylor

摘要:

Somatic karyotypes of 6 species belonging to the subfamily Tetragonopterinae, family Characidae, are described:Hyphessobrycon scholzei—2n= 50 = 8M + 20SM + 8ST + 14A;H. herbertaxelrodi—2n= 52 = 10M, SM + 42ST, A;H. flammeus—2n= 52 = 18M, SM + 32ST + 2A;Hasemania marginata—2n= 50 = 12 M + 18SM + 10ST + 10A;Hemigrammus hyanuary—2n= 52 = 22M, SM + 30ST, A;Nematobrycon palmeri—2n= 50 = 8M, SM + 10ST + 32A. On the basis of karyotypic evolution in the family Characidae there are numerous inversions which have produced high morphological variability of karyotypes with simultaneous relatively constant diploid chromosome numbers. The process of karyotype symmetrization have no a stable direction even in lower taxa that have been resulted in the appearance of sufficient différencies between congeneric species and between species of closed genera on such characteristic as the arm chromosome number. The problem of ancestral karyotypic structure and some karyotaxonomical problems are discussed.

ISSN:0008-7114    

DOI:10.1080/00087114.1990.10797009

出版商:Taylor & Francis    

年代:1990

数据来源: Taylor

摘要:

The taxonomic situation of the genusLeptothorax(sensu stricto = subgenusLeptothoraxsensu Smith 1950) appears particularly puzzling in North America when using morphological characters alone. This paper analyses the taxonomic impact of the complex variations observed in the chromosome numbers of the presently recognized species. The method of Imai modified for some details was applied to specimens obtained from colonies reared in laboratory. These were collected between 1978 and 1984, in different regions of Québec and in Alberta for Canada, in New Hampshire and Utah for USA. Over 250 slides of testes (male pupae) or brain (female prepupae) were prepared. Results for the nearctic species are compared to European data. For the traditionalmuscorumtaxon as applied in North America the haploid numbers varied from 15 to 23 including supernumerary chromosomes. At least four distinct species can be extracted from these results. Male diploidy is documented. Different tendencies are stressed between the actual subgeneraLeptothoraxandMyrafant.

ISSN:0008-7114    

DOI:10.1080/00087114.1990.10797010

出版商:Taylor & Francis    

年代:1990

数据来源: Taylor

摘要:

Species of theParamecium aureliacomplex, characterized by inbreeding, show differences in the number of chromosomes, not only between species, but also within species. It seemed interesting to study the karyologic differentiation inParamecium jenningsi, a taxonomic species of the genusParameciummorphologically similar to theP. aureliaspecies complex, but characterized by outbreeding. Applying the method of semi-thin sections it was found thatP. jenninpistrains from India, Uganda, and Madagascar differ karyologically from each other.

ISSN:0008-7114    

DOI:10.1080/00087114.1990.10797011

出版商:Taylor & Francis    

年代:1990

数据来源: Taylor

摘要:

Karyotypical analysis ofCrocus vernus(L.) Hill subsp.vernus(2n= 16 + 2B) and ofCrocus etruscusPari. (2n= 8) is reported. B-chromosomes inCrocus vernus(L.) Hill subsp.vemusare found for the first time. The karyological comparative analysis points out a true micromorphic differentiation between the two species considered.

ISSN:0008-7114    

DOI:10.1080/00087114.1990.10797012

出版商:Taylor & Francis    

年代:1990

数据来源: Taylor