THE CHROMOSOMES OF 
THREE AUSTRALIAN DACETINE ANT SPECIES 
(HYMENOPTERA: FORMICIDAE) 
By R. H. Crozier* 
Genetics Department, University of Melbourne, 
and Department of Entomology and Limnology, 
Cornell University 
Although more species of Myrmicinae have been studied cytolog- 
ically than of any other ant subfamily (Imai, 1966; Hauschteck, 
1965), there have been no reports on the chromosomes of dacetines. 
The tribe Dacetini is a very distinct group whose members are mostly 
specialized feeders on Collembola and whose evolution has been 
traced in unusual depth for ants (Brown and Wilson, 1959)- The 
species treated here fall into three Australasian genera. 
Pharate pupae (prepupae), male pupae, and embryos were pre- 
treated with colcemid. Aceto-carmine-orcein squash preparations 
were made from Epopostruma and Orectognathus material, and an 
acetic acid dissociation, air drying technique with aceto-lactic orcein 
staining (Crozier, 1968a) was also used for Colobostruma and 
Orectognathus. The criteria used for chromosome classification are 
those of Levan, Fredga and Sandberg (1964). 
The nomenclature followed is that indicated by Brown and Wil- 
son (1959)- Identification of the ants was by W. L. Brown, and 
specimens will be deposited in the Australian National Insect Col- 
lection, C. S. I. R. O., Canberra. 
Orectognathus clarki (figures 1 & 4) 
2n = 30 
Material from Narbethong, Victoria, and Ferntree Gully State 
Park, Victoria, showed that the karyotype of this species comprises 
nine pairs of metacentric to submetacentric and six pairs of sub- 
acrocentric and acrocentric chromosomes; thus two chromosome 
groups are discernible (figure 4). 
Epopostruma sp. (figure 2) 
n ■ 10, 2n = 20 
Material from 5 miles W. of Hopetoun, Victoria, has a karyotype 
^Present address: Department of Entomology and Limnology, Cornell 
University, Ithaca, New York, 14850, U.S.A. 
Manuscript received by the editor February 12, 1968 
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