1968] 
Crozier — Chromosomes of Dacetine Ants 
89 
Variation in chromosome number within a genus has now been 
demonstrated for eight ant genera ( Iridomyrmex , Camponotus, 
LasiuSj Formica , Aphaenogaster , Pheidole, Leptothorax and Myrmica 
— see references), and it would be surprising in view of the diver- 
gence between the karyotypes reported here if such variation were 
not found in further work on the three dacetine genera. In the 
case of Epopostruma in particular, cytotaxonomy could prove a val- 
uable aid in a genus whose taxonomy is rendered difficult by the 
tendency of populations to mimic some other locally common ant 
species (Brown, pers. comm.). 
jOWWIliWMH 
Aii * bkbkXk iM* 
Figure 4. Diploid karyogram of Orectognathus clarki from cell in figure 
1. Line represents 10 microns. 
Interpopulation variation in chromosome morphology is indicated 
in Iridomyrmex of the (< detectus >> group (Crozier, 1968b), and 
populations of Rhytidoponera metallica vary in chromosome number 
(Crozier, unpub.), indicating that single-sample karyotype analyses 
in ants can be misleading, even though karyotypic stability does seem 
the rule in some ant groups. Unfortunately, few dacetine species 
are common enough to permit repeated sampling. 
Ant cytogenetics is still in a survey period, but this should not 
prevent the gathering of data on intraspecific karyotypic variation 
in suitable species. 
SUMMARY 
Two samples of Orectognathus clarki showed a haploid chromo- 
some number of I5 > comprising 9 me'tacentric to submetacentric and 
6 subacrocentric to acrocentric chromosomes. A sample of Colobos- 
truma alinodis had 1 1 metacentric chromosomes and one of a species 
of Epopostruma 10 metacentric chromosomes, as haploid numbers. 
