Animal cytogenetics

Cytological studies on the Heteroptera date from Henking? s (1891) well-known discovery of a ? peculiar chromatin element? in Pyrrhocoris apterus (Pyrrhocoridae) which subsequently proved to be a sex-chromosome. Montgomery (1901a, 1906) and Wilson, in a series of publications spanning the period 1905-1912, made substantial contributions to Heteropteran cytology which provided the impetus for all subsequent studies. The work of the Schraders (Schrader 1940a, 1947a; Hughes-Schrader & Schrader 1961) established that the chromosomes of Heteropterans, like those of Homopterans, are holocentric and have no localised or individualised entromere. This, as we shall see, has important consequences for chromosome evolution within the group. Several taxonomic revisions of the Heteroptera have appeared since the earlier cytological studies so that some of the published work is now confounded by the use of incorrect specific names. In compiling this monograph I have taken the opportunity to correct these so that they conform with current usage.