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3’. Head may have short setae, but not with
stout setae in a distinct row behind eye . . . 5
4. Humerus with small tooth (Figs. 27-30)
or acute angle. Elytra without reticulate
sculpturing . . . . . . . . . . . . . . . . Oiceoptoma
A. Pronotum entirely black . . . . . . . .
. . . . . . . . . . . . . . . O. inaequale (Fabr.)
A’. Pronotum black with reddish orange
margins . . . . O. novaboracense (Forster)
4’. Humerus rounded, lacking tooth. Elytra
with reticulate sculpturing . . Heterosilpha
5. Humerus with small tooth (Figs. 31-33).
Labrum shallowly emarginate. Mesocoxae
widely separated (by about width of mesocoxa)
. . . . . . . . . . . . . . . . Thanatophilus
A. Elytra smooth, lacking costae
(Figs 33, 64) . . . . T. truncatus (Say)
A’. Elytra tuberculate, with costae (Figs.
31, 32, 62) . . . . T. lapponicus (herbst)
5’. Humerus rounded. Labrum deeply
emarginate. Mesocoxae narrowly separated
(by about half or less width of mesocoxa) . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . Aclypea
THE CARRION BEETLES OF NEBRASKA 21
Key TO The GeNeRA AND SPe-
CIeS OF ThIRD INSTAR lARVAe
OF SIlPhINAe IN NeBRASKA
(modified from Anderson and Peck 1985)
1. Urogomphi distinctly longer than 10th
abdominal segment (by at least half their
length) (Figs. 34-35). Sternum of 2nd abdominal
segment with 3 large sclerites . . 2
1’. Urogomphi equal to or slightly longer
than 10th abdominal segment (Figs. 36-39).
Sternum of 2nd abdominal segment with 1
large sclerite . . . . . . . . . . . . . . . . . . . . . . . 3
2. Basal segment of urogomphus up to
twice as long as 10th abdominal segment
(Fig. 35). Dorsal color dark brown to black . .
. . . . . . . . . . . . . . . . . . . . . Thanatophilus
2’. Basal segment of urogomphus more
than twice as long as 10th abdominal segment
(Fig. 34). Dorsal color reddish brown
. . . . . . . Necrodes surinamensis (Fabr.)
3. Second segment of antenna with 1 large
sensory cone (Fig. 40). Prothoracic tergite
Fi g s. 34-39. Abdominal apex of larval silphine (dorsal view): 34, Necrodes surinamensis; 35, Thanatophilus truncatus;
36, Necrophila americana; 37, Oiceoptoma novaboracense; 38, Aclypea bituberosa; 39, Heterosilpha ramosa (Figs.
38-39 after Anderson and Peck 1985).