1976] Holldobler, Stanton, and Engel — Exocrine Gland 
37 
cup structure is missing in this species. Furthermore we surveyed 32 
species of Aphaenogaster and 4 species of Stenamma, and in none 
of them could we find the cup structure (Tab. 1). An additional 
histological study of two Aphaenogaster species (A. texana, A. rudis) 
confirmed the absence of the tergal glands. It thus seems reasonable 
to suppose that the absence of the cup structure also indicates the 
absence of the tergal glands. 
Although none of the investigated forms of Aphaenogaster and 
Stenamma possess the cup structure, we found a very similar cutic- 
ular structure in Ocymyrmex picardi (tribe Ocymyrmecini). This 
came as a surprise, because the species is taxonomically not at all 
close to Novomessor . In Ocymyrmex the structure is also located 
on the dorsal surface of the fourth tergite (Fig. 5). 
The “cups” do not have the same approximate hexagonal shape 
and they appear to be not as deep as those of Novomessor. Since 
we could not obtain fixed specimens, we are unable to say if the 
structure is also associated with tergal glands. 
Discussion 
With the possible exception of Ocymyrmex picardi, where a simi- 
lar net-like structure was found at the fourth tergite, the newly dis- 
covered exocrine tergal glands seem to be restricted to the two species 
Novomessor albisetosus and N. cockerelli. They are absent in A. en- 
sifera ( = N. manni ) and in all other investigated species of Aphaeno- 
gaster. Our findings seem therefore to support Brown’s contention 
that N. manni should be reclassified as a species of Aphaenogaster. 
On the other hand, the existence of a large and rather complex exo- 
crine gland associated with a particular cuticular structure in N. albi- 
setosus and N. cockerelli (the type species of Novomessor) may argue 
against the assignment of the genus Novomessor to the synonymy of 
Aphaenogaster. It is clear that the repugnant odor, released by dis- 
turbed ants of N. albisetosus, originates from these tergal glands. We 
believe that the secretion’s function is defense, although our experi- 
ments have not yet identified the kind of enemies against which the 
substance is directed. Only little is known about the natural product 
chemistry of Novomessor. Vick et al. ( 1 969) found a series of hydro- 
carbons in Novomessor cockerelli, but they did not attempt to identi- 
fy the glandular source of these substances. However, they discuss 
rather vaguely the discovery of new abdominal glands: “A very large 
