CHROMOSOME RELATIONSHIPS IN SOME NORTH AMERICAN SCARABAEOID BEETLES, WITH SPECIAL REFERENCE TOPLEOCOMAANDTROX

Publisher Website
Google Scholar
Abstract
The study comprises 18 scarabaeids and 1 lucanid. All scarabaeids have the karyotype 9II+Xyp characteristic of the family. Pleocoma species have metacentric autosomes and the highest known chiasma frequency in the family nearly 2 chiasmata per bivalent in P. simi Leach and P. minor Linsley, slightly fewer in two other species. The chiasmata form distally. In P. crinita Linsley, one arm of an autosomal bivalent tends to associate with the sex bivalent or its nucleolus. Of the 5 North American Trox species studied, the 2 belonging to the subgroup suberosus have acrocentric autosomes, whereas those of the 3 non-suberosus species are metacentric. The difference is presumably due to a series of pericentric inversion. Lichnanthe rathvoni Lec. has acrocentric autosomes, except for one pair that forms a ring bivalent. Other species have more usual relationships of scarabaeid chromosomes. Lichnanthe has the earliest and most rapid meiotic periode known in male beetles: it is usually completed before the pupal stage. Trox, on the contrary, has late adult beginning and long duration of the meiotic process. The lucanid Sinodendron rugosum Mann has 8II +Xyp, which is a new karyotype for the family.