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Psyche 
[Vol. 85 
thorax nylancieri (Forster). All our material also was collected in 
Istria, and in the Dalmatian island Krk\ Since the descriptions of all 
the three forms mentioned above are nearly identical, we assume 
that Myrmetaerus microcellatus and Myrmoxenus gordiagini men- 
ozzii are junior synonyms of Myrmoxenus gordiagini. We have been 
unable, however, to check the type material. 
Nothing has been known of the biology of Myrmoxenus! Myrme- 
taerus except the fact that they were always found living together 
with a host species belonging to the genus Leptothorax Mayr, sub- 
genus Myrafant Smith (1950), and thus apparently represent so- 
cially parasitic ants. W. Faber in 1972 recorded some observations 
on their colony foundation behavior. Recently we found out that M. 
gordiagini is a slave-making ant. The results of our experiments are 
presented in the following sections. 
Material and Methods 
W. Faber collected a total of three Myrmoxenus colonies on 25 
May 1972, on the slopes of a small valley NW of Baska, Krk. In the 
very same locality we found nine additional colonies between 
September 23 and 26, 1981. Another locality, where we gathered 
two colonies on 4 August 1976, and one colony on 22 September 
1981, is near the ruined town Dva grada, a few kilometers east of 
Rovinj in Istria, and just 35 km south of the type locality of M. 
gordiagini menozzii. Ten of these 15 colonies contained a Myr- 
moxenus queen; presumably the queens of the other five colonies 
were either lost during collecting or were missing prior to our col- 
lecting. Myrmoxenus workers were present in varying numbers up 
to about 40 (exact numbers cannot be given since all colonies were 
kept alive for several breeding seasons, and thus produced addi- 
tional workers). Two colonies contained only a queen and no 
workers; supposedly they were newly founded. 
Male and female as well as worker pupae were present in the 
colonies collected on August 4, 1976, and a few adult sexuals were 
found in field colonies on September 22 and 23, 1981. 
^Recently we found an additional population on the island Rab, south of Krk. Four 
colonies were collected on October 2, 1983. in an oak forest south of Suha Punta. 
They contained one queen each, and in one colony we found two additional females 
that were dCcUate but not inseminated. 
