4 
Psyche 
[Vol. 94 
mens measured), Head Width 0.52 mm (one specimen measured), 
Scape Length 1.56-1.66 mm (5 scapes in 3 specimens measured), 
Eye Length 0.14-0.16 mm (3 eyes on 3 specimens measured), Total 
Length 4.8-5. 5 mm (4 specimens measured). Three of those in piece 
number Do-4484-M possessed the following measurements: Head 
Length 1.20-1.36 mm, Head Width 0.72-0.84 mm, Scape Length 
2.40-2.48 mm, Eye Length 0.24-0.26 mm. These dimensions are at 
the extreme lower end of the variation showed by the extant Lepto- 
myrmex, represented by L. mjobergi of Queensland. Among other 
important character states of L. neotropicus with reference to the 
extant Leptomyrmex are the lack of hairs on the compound eyes, 
the almost completely hairless body surface, the narrowly con- 
stricted occiput, and the apparently light, uniform body color. 
The male that we have tentatively associated with Leptomyrmex 
neotropicus is illustrated in Figure 2. This specimen is similar to 
Leptomyrmex and Leptomyrmula in several important respects and 
is appropriately placed in the tribe Leptomyrmecini, whether it is 
really the male of L. neotropicus or not. The leptomyrmecine traits 
are as follows: exceptionally slender body form and overall habitus 
similar to Leptomyrmex and Leptomyrmula; antennae very long; 
venation reduced and the stigma vestigial or absent. The genitalia 
unfortunately cannot be studied. 
There are also some important differences. First, consider the 
venation (see Figure 3). Where extant Leptomyrmex species have a 
peculiarly narrow radial cell, Leptomyrmula maravignae has a 
wider and hence more “ordinary” radial cell, and L. neotropicus has 
no radial cell at all. Living Leptomyrmex, with the exception of L. 
fragilis, possess a stigmal appendage (“pterostigmal appendage” of 
Wheeler, 1934), a unique bladder-like structure extending from the 
position of the vestigial stigma out into the radial cell. This structure 
is absent in Leptomyrmula maravignae and the putative Lepto- 
myrmex neotropicus. In the extant Leptomyrmex, the antennae are 
about 0.7-0.9X as long as the body; in Leptomyrmula maravignae 
they are about 0.5X as long; and in Leptomyrmex neotropicus they 
are about equally long. 
The absence of the stigmal appendage and an exceptionally 
slender body form are shared by the male of Leptomyrmex neotro- 
picus with the male of the living L. fragilis, but there the resemb- 
lance ends. L. neotropicus is much smaller than L. fragilis, has a 
