1972] 
Miller & Kurczewski — Entomognathus 
75 
B. distinctus contains several beetle elytra firmly embedded at one 
end. 
The mature larvae of Entomognathus and Bothynostethus have 
been compared by Kurczewski and Evans (1972). They noted a 
pair of finger-like lobes on the prothorax, fewer head setae, and 
three- rather than four-toothed mandibles in B. distinctus. It should 
also be noted that both E. memorialis (Fig. 10) and E. brevis have 
in addition to the four teeth along the inner margin of the mandible 
a conspicuous rounded laminar protuberance ventrad of the second 
and third teeth. This protuberance is lacking in B. distinctus. 
The maxilla of B. distinctus is evenly rounded on the inner margin, 
whereas that of both E. memorialis (Fig. 11) and E. brevis (Grandi, 
1927) is strongly and broadly produced. 
The structural features of the maxilla and mandible of Ento- 
mognathus tentatively serve to distinguish this genus from all other 
genera of Sphecidae whose larvae have been described. Our con- 
fidence in these characters has been strengthened by comparing 
recently-collected mature larvae of crabronines in the genera Lin- 
denius, Crossocerus , and Anacrabro with the illustrations and 
descriptions of species in these genera prepared by Evans (1957, 
1959)- 
In summary, comparison of the European E. ( Entomognathus ) 
brevis with the North American E. ( Toncahua ) memorialis revealed 
few significant differences in nesting behavior and substantiated 
congenerity. Comparing the nesting ethology of the latter crabronine 
with the larrine Bothynostethus distinctus brought to light some 
striking similarities and rather significant differences. 
Differences in the morphology of the mature larvae of species of 
Entomognathus are even more subtle than differences in nesting 
behavior. Comparison of E. brevis , as depicted by Grandi (1927), 
with E. memorialis disclosed few, if any, real differences. The 
larvae of Entomognathus and Bothynostethus are, likewise, rather 
similar and support Evans’ (1958, 1959, 1964) belief that the 
sphecid subfamilies Crabroninae and Larrinae are much more closely 
related than is currently indicated in the Hymenoptera of America 
North of Mexico Synoptic Catalog (Muesebeck, et al., 1951; 
Krombein, 1958; Krombein and Burks, 1967). 
The cocoon of Bothynostethus is more crabronine than larrine 
and that of Entomognathus , the reverse, based upon comparisons 
with cocoons of Lyroda, Elenoculus, Tachytes, and Tachysphex in 
the Larrinae and Lindenius and certain Crabro in the Crabroninae. 
