36 
Psyche 
[March 
tergal segment. From these results we hypothesized that a gland 
might exist between the third and fourth tergite, and which ap- 
parently cannot be spotted under a dissecting microscope. We 
therefore conducted a series of histological investigations which 
finally confirmed our suspicion. Workers of N. albisetosus and 
N. cockerelli possess two large glandular complexes, located bi- 
laterally under the third tergite (Fig. 1). One complex consists of 
approximately 50 single glandular cells, each of which sends an 
individual channel through the intersegmental membrane between 
the third and fourth tergite (Fig. 2). The external openings of these 
channels are closely associated with a series of cuticular “cups”, 
which are located at the apical end of the dorsal surface of the fourth 
segment. Under the dissecting microscope the arrangement of the 
series of cups looks like a netlike structure, but the SEM pictures 
clearly reveal the hexagonal shape of the individual cups which are 
arranged like the cells of a honeybee comb (Fig. 3). Normally 
this part of the fourth tergite is tightly overlapped by the third ter- 
gite, and only by pulling the segments apart is the structure exposed. 
We assume that the cups serve as repositories for the glandular 
secretions. When the substance is needed the ant exposes this area 
and the chemical evaporates. Indeed, the odor can be released sim- 
ply by pulling the third and fourth tergite slightly apart. These tergal 
glands with the associated cuticular cup structure are found not 
only in the worker caste but also in queens and males (Fig. 4). In 
addition males of N. albisetosus and N. cockerelli were found to 
possess a similar glandular complex located bilaterally under the 
fourth tergite. The glandular channels open through the inter- 
segmental membrane between the fourth and fifth segment. The 
cuticular cup structure at the fifth segment is, however, much less 
conspicuous than that at the fourth segment.* 
In general, there appear to be no distinct differences in the tergal 
glands and the cup structures of N. albisetosus as opposed to N. 
cockerelli. Although we did not have fixed specimens of A. ensifera 
( = N. manni), the investigation of dried specimens in the systematic 
collection of the Museum of Comparative Zoology revealed that the 
♦Another, previously undescribed exocrine glandular complex was found in 
workers and queens of N. albisetosus and N. cockerelli ventrally at the fourth seg- 
ment. The glandular channels open through the membrane near the cloaca. We 
are currently investigating the function of this gland. 
