排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
Angela M. Zanata Willian M. Ohara Osvaldo T. Oyakawa Fernando C. P. Dagosta 《Journal of fish biology》2020,97(5):1343-1353
Characidium iaquira, a new species from the upper rio Juruena, rio Tapajós basin, Brazil, is described. The new species can be promptly distinguished from all congeners by having a unique v-shaped dark mark lying along the caudal-fin extension, in medium- and large-sized specimens, and a remarkable iridescent green colouration in life. Characidium iaquira is closely related to Characidium crandellii and Characidium declivirostre by sharing unambiguous synapomorphies such as branchiostegal membranes united to each other across the isthmus, a scaleless area extending from the isthmus to the pectoral girdle, and dermal flaps surrounding anterior and posterior naris independent, but touching each other distally. Morphological specializations of the paired fins in the three riffle-dwellers species are discussed, including the wing-like shape, robustness, and inclination of the pectoral fin. 相似文献
2.
Individuals of two populations of the fish Characidium cf. fasciatum were cytogenetically studied and showed a basic diploid
number of 50 chromosomes. Some fishes were found to have 51 to 54 chromosomes due to the presence of one to four small subtelocentric/acrocentric
supernumerary chromosomes. When analyzed by conventional Giemsa staining, male and female specimens of C. cf. fasciatum from
the Quinta stream and Pardo River presented the same basic karyotypic macro- and microstructure, consisting of 32 metacentric
and 18 submetacentric chromosomes. Ag-NORs were terminally located on the long arms of two submetacentric chromosome pairs.
Constitutive heterochromatin was identified by C-banding as small pericentromeric blocks in the majority of the chromosomes,
and B-chromosomes were found to be heterochromatic. The occurrence of one totally heterochromatic submetacentric chromosome
restricted to females and considered as an unusual feature in fish karyotypes led to the identification of a ZZ/ZW sex-chromosome
system. The implications of chromosomic differentiation observed in the genus Characidium are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
R. B. Noleto A. P. Amorim M. R. Vicari R. F. Artoni M. M. Cestari 《Journal of fish biology》2009,75(2):448-453
Characidium fishes with a sex chromosome system form a monophyletic group. This work presents data of Characidium lanei from the South Atlantic basin (Brazil), including an unknown type of ZW sex chromosome system for the groups including the presence of rDNA sites on sex chromosomes. 相似文献
1