ON THE METAPLEURAL GLAND OF ANTS 
By Bert HOlldobler and Hiltrud Engel-Siegel 
Department of Organismic and Evolutionary Biology, 
MCZ-Laboratories, Harvard University 
Cambridge, Massachusetts 
Introduction 
The metapleural gland (also called metasternal or metathoracic 
gland), a complex glandular structure located at the posterolateral 
corners of he alitrunk is peculiar to the ants. Although the gland was 
noted by Meinert (1860) and Lubbock (1877), it was Janet (1898) 
who conducted the first detailed anatomical study of this organ, as 
part of his classic work on Mvrmica rubra. Additional details have 
been added by Tulloch (1936) on Mvrmica laevinodis; by Whelden 
(1957a, b, 1960, 1963) on Amblvopone ( Stigmatomma ) pallipes, 
Rhvtidoponera convexa, R. metallica, Eciton burchelli, E. ham- 
atum; by Tulloch et al (1962) on Myrmecia nigrocincta; and by 
Kiirschner* (1970) on Formica pratensis. 
It is generally assumed that the metapleural gland is a universal 
and phylogenetically old character of the Formicidae. Even the 
extinct species Sphecomyrma freyi of Cretaceous age appears to 
have possessed a metapleural gland (Wilson et al 1967a, b) and the 
organ is well developed in the most primitive living ant species 
Nothomyrmecia macrops (Taylor 1978) (see Fig. 2). 
In the course of our current comparative study of the internal and 
external anatomy of exocrine glands in ants, we discovered that the 
metapleural gland is absent or significantly reduced in several ant 
genera where such reduction had not been previously suspected. In 
addition we observed a widespread absence of the metapleural gland 
in males among ant species. 
Our survey is far from complete, even at the generic and tribal 
levels. We think, however, that the pattern revealed by our 
observations is important enough to warrant a short publication at 
this time. 
*Kurschner apparently was not aware that the paired thorax gland near the petiole 
she described was the metapleural gland. 
Manuscript received by the editor March 16, 1984. 
201 
