ISSN:
1432-0886
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract Five species of the subfamily Thericleinae from East Africa show various types of “cryptochiasmatic” meiosis in the male, in which the chiasmata are not visible in prophase and are only revealed in the course of first metaphase. Several of these species have very large chromosomes. Two species belonging to the subfamily Miraculinae, from Madagascar have 2 n♂=25 acrocentric chromosomes, the highest number known in the Eumastacidae. Their meiosis is of the normal type. — Eighteen species of the subfamily Pseudoschmidtiinae, also from Madagascar have, for the most part, small chromosomes and a very uniform karyotype, of 2 n♂=21 acrocentrics. A species of Xenomastax has acquired an X1X2Y sex chromosome mechanism as a result of two successive chromosomal fusions. A fusion beween autosomes has reduced the chromosome number to 2 n♂=19 in the genus Tetefortina. The male meiosis of the Pseudoschmidtiinae is quite orthodox. — Two species of Eumastacids belonging to the subfamily Mastacideinae, from South India, show 2 n♂=21 acrocentrics. The male meiosis is quite orthodox, with a rather high chiasma frequency. — Three South American species of Eumastacidae, belonging to the subfamilies Paramastacinae, Parepisactinae and Eumastacinae respectively, have karyotypes which seem to be very different from those of the Old World subfamilies that have been studied. Meiosis is normal. The cytological evidence thus confirms the view of systematists that the evolutionary divergence of the subfamilies of Eumastacidae is very considerable, and presumably ancient. As far as we can tell, each subfamily may be characterized by a typical or primitive karyotype. There have been fewer evolutionary fusions of chromosomes in the Thericleinae and Pseudoschmidtiinae than in the Morabinae and no chromosomal dissociations are known to have occurred in the two former subfamilies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00293910
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