1985] 
Wilson — Dominican amber ants. 3 
25 
7. In Azteca males the dorsal lobe (digitus) of the volsella is long 
and finger-like, extending posteriorly as far as the tips of the para- 
meres (see Fig. 6E). They are proportionately broader in Irido- 
myrmex and reach only partway along the length of the parameres. 
8. In most cases, the petiole of Azteca males is applied more 
broadly to the gaster than is the case in Iridomyrmex. 
Using the combination of traits above, it has been possible to 
establish beyond much doubt that the species of the Dominican 
amber divide cleanly into either Azteca or Iridomyrmex, that none 
falls between the two genera, and that none is especially primitive in 
overall aspect. The most abundant ant species in the amber is the 
Azteca to be described below. 
Azteca alpha, new species 
(Figs. 5-8) 
Diagnosis. A member of the alfari group, in which the worker 
caste is monomorphic or at most weakly polymorphic; alpha is also 
distinguished from the contemporary species belonging to this and 
other Azteca groups by the unique combination of traits in scape 
length, propodeal outline, and pilosity illustrated in Fig. 5. In 
particular, the worker appears especially close to A. fiebrigi. This 
Paraguayan species is distinguished from alpha by its slightly shor- 
ter scapes (which just reach the occipital corners in repose) and 
longer, denser body pilosity. 
The male of alpha (Fig. 6) is close to or identical with that of 
fiebrigi, including the distinctive conformation of the scape and first 
two funicular segments. Both forms differ from alfari, the other 
member of the species group for which I have seen males associated 
with workers, in that alfari has the scape and first funicular segment 
short and slender and the second (rather than first) funicular seg- 
ment conspicuously enlarged. 
The queen of alpha (Fig. 7), encountered singly in two amber 
pieces and hence only tentatively associated with the alpha worker 
caste (as opposed to that of eumeces, to be described subsequently), 
is closely similar to the fiebrigi queen. It differs in its somewhat 
thinner petiolar node viewed from the side. 
The name alpha alludes both to the early occurrence of the species 
in the geological record and to its numerical dominance in the 
Dominican amber. 
