Cytogenetic mapping of the 5S (red) and 18S (green) rDNA clusters in four species of Scarabaeinae belonging to the (a) Oniticellini, (b) Onthophagini, and (c, d) Coprini tribes. (a) Eurysternus caribaeus, (b) Digitonthophagus gazella, (c) Ontherus apendiculatus and (d) O. sulcator. The arrows indicate the sex bivalents. Note the co-localization of the two gene clusters in (a) and (b). Bar = 5 μm.