LARVAL TAXONOMY OF THE TROGINAE IN NORTH AMERICA 21 

 KEY TO THE KNOWN THIRD STAGE LARVAE OF OMORGUS 



1. Dorsal lobe 1 of first 4 abdominal segments with transverse row 



of spinules only, very rarely with 1 long seta per segment (fig. 



33) 2 



Dorsal lobe 1 of first 4 abdominal segments with at least 6 setae in 

 addition to transverse row of spinules 3 



2. Frons with posterior frontal setae (fig. 24) monachus 



Frons without posterior frontal setae fuliginosus 



3. Cranium with large concavity on median border of eyespot. Con- 



cavity with single seta. Concavity about same size as eyespot; 



anterior border declivous; posterior border vertical (fig. 25) . 4 



Cranium smooth mediad of eyespot, or with at most a very shallow 



depression with a single seta 5 



4. Galea with at least 4 setae on dorsal surface in addition to whorl of 



5 setae at base of terminal uncus (fig. 49) texanus 



Galea without setae on dorsal surface, only with whorl of 5 setae 

 at base of terminal uncus (fig. 26) rubricans 



5. Epipharynx with group of phobae mediad of right fused phobal 



mass (fig. 11) suberosus 



Epipharynx without group of phobae mediad of right fused phobal 

 mass (fig. 9) 6 



6. Lacinia with 1 or more exterior setae (fig. 26) injlatus 



Lacinia without exterior setae 7 



7. Head capsule width greater than 5.0 mm. Each tibiotarsus with 



average of 2 1 to 26 setae. Epipharynx as in figure 1 1 . scutellaris 



Head capsule width less than 4.5 mm. Each tibiotarsus with 



average of 15 to 21 setae .... punctatus, asper, and carinatus 



Generic Description of Trox Larvae 



Larvae of this genus may be characterized as follows: Cranium 

 (fig. 1) light orange or light orange brown, red brown, or dark red 

 brown to black. Cranium usually slightly reticulate posterior to posterior 

 frontal setae, with prominent elevated and depressed areas anterior 

 to posterior frontal setae. Cranium strongly pitted in T. fascifer, T. 

 aequalis, and T. scaber; pits very small or lacking in other species. 

 With 1 dorsal epicranial seta and 1 median epicranial seta on each 

 side (median epicranial seta very short or absent in above three 

 species). With about 5 to 12 long setae near each antenna and with 

 small, slightly raised, nonpigmented eyespot at base of each antenna. 

 Frons with paired posterior, median, exterior, and anterior setae. 

 Each anterior angle of frons with 1 seta. Frontoclypeal suture indistinct. 



