1965] 
Haskins and Whelden — Rhytidoponera 
91 
colony structure and toward the restriction of fertilized reproductives 
in the colony to a single or a few individuals, so evident in a great 
number of ant species, both evidently contribute to maintaining this 
maximal degree of relatedness within the community. 
Exceptions to both trends, to be sure, are known. On the one hand, 
they are well illustrated by the puzzling situations explored in species 
of the Formica obscuriventris group (King, 1949, 1955 j King and 
Sallee, 1951) and the Formica rufa group (Sturtevant, 1938; 
Chauvin, Courtois, and Lecompt, 1961) where it appears that young 
reproductives, even of different species, may be adopted by large 
colonies, thus prolonging the existence of the colony well beyond the 
second generation and introducing both multiple queens and what 
must be a remarkable degree of unrelatedness among the worker 
personnel of individual colonies. Exceptions to the second trend may 
be presented by the numerous pleometrotic species of ants, though it 
is still unclear, as in the Polybiine and Polistine wasps, how usually 
such multiple reproductives are in fact sisters, and how often or how 
elaborately special behavior patterns may be adapted to restricting 
reproduction in practice to a single dominant female, or to preventing 
non-sisters from coexisting in the colony. 
In this context, the course of social evolution in the genus Rhyti- 
doponera is of special interest, as is the probable degree of average 
relatedness among the workers of a single community of both normal 
and “queenless” forms. In the so-called “queenless” species, do 
workers in fact regularly give rise to workers? Is the same true of 
those species possessing functional typical queens? Is worker pro- 
duction accomplished in one or both groups through parthenogenetic 
thelytoky, so common among lower nonsocial Hymenoptera, and 
frequently reported in the Cape honey bee? Such thelytoky has been 
described in ants by several investigators over a long period of years, 
including Reichenbach (1902), Crawley (1912), and Comstock 
(1903) for Lasius niger, Haskins and Enzmann ( 1945) for Aphaeno- 
gaster picea and A. lamellidens, Soulie (i960) for Cremastog aster , 
and Otto (i960) for Formica polyctena, while Ledoux (1949, 1954) 
has reported extensively on a specialized social adaptation of thely- 
toky in the workers of Oecophylla. If such thelytoky obtains in 
Rhytidoponera the pattern of relatedness among colony members 
might be quite different than if laying workers possess developed 
spermatheca and are fertilized in the manner normal to ordinary 
ergatoid queens, by active low-flying males from other colonies. Such 
males are indeed characteristic of all species of Rhytidoponera , both 
those possessing and those lacking typical queens. Do laying workers 
