4 
Psyche 
[March 
Table 2. Numbers of workers responding to the poison gland secretion in the artificial test. Number 
of replications in parentheses. 9 
Test Species 
Cyphomyrmex Trachymyrmex 
rimosus septentrionalis 
A cromyrmex 
octospinosus 
Atta 
cephalotes 
Atta 
texana 
Source Species 
Cyphomyrmex rimosus 
74 ( 8 ) 
70(8) 
— 
— 
56(8) 
T rachymyrmex 
septentrionalis 
52(6) 
64(7) 
3 °( 4 ) 
26( 4) 
66(8) 
Acromyrmex octospinosus 
— 
48(6) 
69 ( 8) 
3 1 ( 4 ) 
27(4) 
Atta cephalotes 
— 
16(2) 
77(10) 
87(10) 
50(6) 
Atta texana 
63 ( 8 ) 
54 ( 6 ) , 
34 ( 4 ) 
— 
33 - 4 ) 
Acromyrmex sometimes produced a greater trail following response 
among all four genera than those obtained with Trachymyrmex and 
Cyphomyrmex extracts, no definite conclusions can be drawn from 
these results. The glands dissected out of Atta and Acromyrmex 
workers were generally larger than those obtained from the other two 
genera and conceivably they contained more odor trail substance. 
Even if all of the poison glands from all four genera were the same 
size, there would be no way of determining whether they all contained 
equal concentrations of the trail substances. Reliable quantitative 
experiments on the cross-generic activities of the attine odor trail 
substances must await isolation and identification of the pure phe- 
romone ( s ) . 
The odor trail substances of the attines did not release trail follow- 
ing behavior in any non-attine species which were examined. Thus, 
no response was obtained with the odor trail laying ponerine Termi- 
topone laevigata (Fr. Smith) 8 , the dorylines Eciton burchelli (West- 
wood) 7 and E. hamatum Forel. 7 , the myrmicines Crematogaster line- 
olata (Say) 5 , Monomorium minimum (Buckley) 5 , and Solenopsis 
saevissima (Fr. Smith) 5 or the dolichoderines Conomyrma pyramica 
(Roger) 5 and Iridomyrmex pruinosus (Roger) 5 . 
DISCUSSION AND CONCLUSIONS 
Based on external morphological features, the genera of the tribe 
Attini have the most easily recognized phylogenetic relationships of 
any of the myrmicine tribes (Creighton, 1950). Thus Trachymyrmex 
can be shown to grade into Atta and into the genus Cyphomyrmex 
through the transitional genus Mycetosoritis. The interrelationships 
of the attine genera are further supported by ethological evidence 
which largely parallels the morphological conclusions (Weber, 1958). 
