1961] 
Brown — Strumigenys 
65 
clasmospongia was only a larger, relatively narrow-headed variant of 
unidentata. The unique type of S. fusca was more puzzling, being a 
rather large louisianae- like worker with fairly broad head and longish 
mandibles, but having the posterior half of the first gastric tergite 
nearly completely smooth and definitely shining. Var. brevicornis 
turned out as expected: a large louisianae female fitting fairly well 
with the largest worker forms from South American samples of the 
species, so that my earlier synonymy was confirmed. 
In addition to these types, I have been able during the last few years 
to examine an increasing accumulation of louisianae- related forms from 
southeastern Brazil and northern Argentina, and scattered specimens 
have even come in from central Brazil and Surinam, previously blanks 
on the map. These samples are due mostly to the kindness of Father 
Borgmeier and Father Kempf. Study of this new material has com- 
pletely changed my ideas on relationships of the species within the 
louisianae complex. First, the relatively slender, long-mandibulate 
forms with shining gastric dorsum were shown to be common in 
southeastern Brazil; it is these forms to which the names unidentata 
and clasmospongia have been applied. Taken in combination, the dis- 
tinctive <( unidentata characters” give the impression of a distinct 
species inhabiting southeastern Brazil, but all attempts to define a 
species with these characters have failed. The reason for this failure 
is that the new material clearly shows that each of the characters go- 
ing to make up the unidentata in its “typical” manifestation actually 
has its own independent pattern of geographical and individual varia- 
tion within louisianae. The long mandibles (MI up to 67) of the 
southeastern Brazilian samples are approached by samples from Bo- 
livia (MI 60-63), and some series from southeastern Brazil have 
much shorter mandibles (MI as low as 56, and perhaps even lower in 
some samples seen but not measured), in this respect being not far 
from average for the species louisianae taken as a whole. The gastric 
sculpture of the unidentata pattern, in which basigastric costulae of 
moderate length are followed by a smooth or nearly smooth, shining 
surface (though this surface may be obscured by secretion or other 
foreign matter), is not confined to southeastern Brazilian specimens 
with long mandibles; in fact, it is found in series with much shorter 
mandibles from localities as far away as Tucuman, in northern Ar- 
gentina; Goias, Amazonas and Surinam in the northwest and north; 
and even in southern Mexico (Veracruz, Puebla). Furthermore, cer- 
tain series even in southeastern Brazil contain workers with shorter 
mandibles, some individuals of which have the reticulate, opaque 
" louisianae sculpture”, while others from the same nest sample have 
