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Psyche 
[Vol. 89 
smooth and shining. Pilosity as in the female. Coloration yellowish- 
brown with the head, the antennal club and the gastral tergites 
darker brown. 
The karyotype (fig. 5) was determined from 8 male pupae, follow- 
ing the method of Imai et al. (1977). In 68 metaphase plates a 
haploid number of 15 chromosomes was found, 13 of which are 
metacentric or submetacentric and two are subtelocentric. The 
second-largest chromosome exhibits a very characteristic banding. 
In 7 metaphase plates one additional, subtelocentric chromosome 
was found; this, however, may be an artefact. The host species, on 
the contrary, has a haploid chromosome number of 17 as does the 
second, smaller “L. muscorum ” from Jasper Park, and as occurs in 
European L. muscorum. 
Type locality: Jasper National Park, Alberta, Canada, a few 
meters above the road from 93A to Mt. Edith Cavill parking lot, in 
about 1500 m elevation. Numerous nests of the host species and also 
of a smaller kind of “L. muscorum” were found inhabiting the rot- 
ten sticks and logs lying on the ground of a rather open coniferous 
forest. 
Derivatio nominis: The ant is dedicated to my late friend, Dr. 
Walther Faber, from Vienna, Austria, whom I admired for his 
excellent studies in social parasitic ants. 
Differential diagnosis: The new species closely resembles the 
European inquiline ant Leptothorax kutteri, particularly with re- 
spect to size, coloration, and the ventral spines in petiole and post- 
petiole. It differs from that species through the lack of erect hairs in 
the antennal scapes and the tibiae. Also, the characteristic sculpture 
of the head of L. kutteri females is absent in L.faberi. The remarka- 
ble light coloration of the male’s scutellum and metanotum is, as far 
as I know, unique among leptothoracines belonging to the subgenus 
Leptothorax and their social parasites. 
The host species (fig. 1) and L.faberi are easily distinguished by 
the latter’s smaller size and lighter coloration (female). They also 
differ with respect to the karyotypes. L. faberi could only be con- 
fused with the second, smaller Leptothorax " muscorum ” form in 
Jasper Park (fig. 1), which is the host species of Doronomyrmex 
pocahontas. However, this species differs in the shape of petiole and 
postpetiole from L.faberi, and it has a karyotype which is identical 
to that of the large, black L. “ muscorum ”, host species of L.faberi. 
