1982] Buschinger — Leptothorax faberi 205 
< i t »**««• «* 
(JtKU JtUn i « » 
* 
IfCltlM***** * * 
Fig. 5. Karyotype of Leptothorax faberi n.sp. The normal karyotype has n = 15 
chromosomes, but 2 of 18 individuals had n = 16 in 2 out of 25 and 5 out of 18 
metaphase plates respectively (center line). 
3. Biological observations 
All observations were made under laboratory conditions, and, 
due to the restricted material, they must be fragmentary. However, a 
few interesting facts could be recorded, particularly with respect to 
reproductive behavior. Sexuals of L. faberi were observed to leave 
the nest and to become sexually active in the morning, about 3 to 4 
hours after the morning rise in temperature in our artificial 15/25°C 
temperature rhythm. Copulation was seen twice, the behavior being 
identical to that of Leptothorax kutteri, Doronomyrmex pads and 
other social parasites of this group (Buschinger, 1971, 1974, 1975). 
A distinct sexual-calling behavior, resembling that of L. kutteri, was 
not seen, but poison gland secretion seems to serve as sexual 
pheromone as in the species mentioned above. The poison gland of 
one female was squeezed onto a small piece of filter paper, and the 
paper then put into a nest with L. faberi males. The males suddenly 
became excited, and a few began to mount the host species workers. 
