1981] 
Holldobler, Moglich, & Maschwitz — Pella 
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different results. Pella laticollis , when irritated mechanically dis- 
charges a pungent smelling brownish secretion from its tergal gland 
that shows acidic reactions. Only when the beetles were severely 
attacked and firmly grasped on their appendages by the ants, could 
we smell the tergal gland secretion. We never observed the beetles 
employing tergal gland secretion when they were attacking ants. 
Ants contaminated with tergal gland secretion usually exhibited a 
repellent reaction, releasing the grip on the beetles and grooming 
and wiping their mouth parts and antennae on the substrate. But the 
beetles had to escape quickly, because other ants close by became 
alerted and were rapidly approaching the scene, apparently alarmed 
by the ants’ alarm pheromone. We noticed that beetles that were 
attacked by L. fuliginosus workers often smelled somewhat like the 
ants’ mandibular secretions, but the beetles’ tergal gland secretions 
clearly smelled differently. Conceivably, some of the attacked 
beetles were contaminated with the ants’ strongly smelling mandib- 
ular gland secretions. 
Our chemical analysis of the tergal gland secretions of P. laticollis 
did not reveal a resemblance to the mandibular gland secretions of 
L. fulginosus, whose major compounds are farnesal, 6-methyl-5- 
hepten-2-one; perillene and dendrolasin, a furan (Quilico et al 1957; 
Bernardi et al 1967). When we treated the tergal gland section with 
2,4 — dinitrophenyl-hydrazine, we obtained an orange-yellowish pre- 
cipitate. This was subjected to thinlayer chromatography in two 
separate systems. In each system we obtained two spots. The Rf 
values and the color reaction, when treated with ammonia vapour, 
identified them as dinitrophenylhydrazones of p-benzoquinone and 
p-toluquinone. Furthermore, the chromatography of the hydro- 
quinones obtained from the secretion by reduction with SO 2 also 
demonstrated the presence of p-benzo- and p-toluquinone in the 
tergal gland secretion. 
For comparison we used thinlayer chromatography to analyze the 
dinitrophenylhydrazones of the tergal gland secretion of several 
other aleocharine staphylinds found near the nests of L. fuliginosus. 
Pella humeralis, A theta fungi and Sipalia cireellaris also produce 
benzo- and toluquinone; in Oxypoda vittata we found only tolu- 
quinone. 
In addition Kolbe and Proske (1973) identified isovaleric acid in 
the tergal gland secretion of P. humeralis , and with the aid of gas 
chromatography we detected saturated hydrocarbons and short 
