Key to the adult Silphidae of Texas

1 Elytra shorter, truncate, exposing 3 or 4 abdominal terga, usually with irregular red or orange maculae (Figs. 24–30); fifth abdominal tergum with stridulatory files; head with epistomal suture present (Fig. 1); second antennomere small, indistinct, hidden in tip of first antennomere (Fig. 2). ( Nicrophorinae: Nicrophorus)........................................ 7

- Elytra longer, usually not truncate, at most exposing 1 or 2 abdominal terga, usually without large colored maculae (Figs. 18– 23); fifth abdominal tergum lacking stridulatory files; head with epistomal suture absent (Fig. 3); second antennomere distinct, not hidden in tip of first antennomere (Fig. 4). ( Silphinae).................................................... 2

2(1-) Pronotum widest toward base (Fig. 6); elytra immaculate; hind femur of male not swollen and without spines............. 3

- Pronotum orbicular, widest toward middle (Fig. 5); elytra with small red maculae before apex; hind femur of male swollen, with one or two spines. Habitus: Fig. 19 ......................................... Necrodes surinamensis (Fabricius)

3(2) Head with a row of long erect hairs behind eyes; elytral disc with rugose to rugulose sculpturing, at least distally, and with dis- tinct costae (Figs. 18, 20–22)........................................................................... 4

- Head without a row of long erect hairs behind eyes; elytral disc smooth, without costae. Habitus: Fig. 23 .............................................................................................. Thanatophilus truncatus (Say)

4(3) Elytral epipleuron without aeneous luster or short golden hairs; pronotum entirely black, or with a black median macula and red-orange margins; elytral disc distally with weak rugulose sculpturing (Figs. 20–22). ( Oiceoptoma).................. 5

- Elytral epipleuron with aeneous luster and short golden hairs; pronotum with a black median macula and yellow margins; ely- tral disc uniformly rugose. Habitus: Fig. 18 ....................................... Necrophila americana (Linnaeus)

5(4) Pronotum entirely black (Figs. 20, 22).................................................................... 6

- Pronotum black with red-orange margins. Habitus: Fig. 21 ........................ Oiceoptoma noveboracense (Forster)

6(5) Elytral epipleuron wide in posterior half (Fig. 7), with upper oblique portion twice width of lower vertical portion; elytral inter- vals distally with weak rugulose sculpturing. Habitus: Fig. 20 ........................ Oiceoptoma inequale (Fabricius)

- Elytral epipleuron narrow in posterior half (Fig. 8), with upper oblique portion approximately equal in width to lower vertical portion; elytral intervals distally with weak to strong rugulose sculpturing. Habitus: Fig. 22 ...................................................................................................... Oiceoptoma rugulosum Portevin

7(1) Pronotum with anterior transverse impression, lateral margins not exceptionally narrow (Fig. 10); elytral epipleuron wide.. 8

- Pronotum without anterior transverse impression, lateral margins extremely narrow (Fig. 9); elytral epipleuron narrow. Habi- tus: Fig. 25 ................................................................ N icrophorus carolinus (Linnaeus)

8(7) Frons and pronotal disc black; tarsal empodium bisetose (Fig. 12).............................................. 9

- Frons and pronotal disc red (Fig. 10); tarsal empodium quadrisetose (Fig. 11). Habitus: Fig. 24 ..................................................................................................... Nicrophorus americanus Olivier

9(8) Pronotum glabrous, or with sparse hairs on anterior or lateral margins............................................ 10

- Pronotum with dense yellow pubescence. Habitus: Fig. 30 ............................ Nicrophorus tomentosus Weber

10(9) Posterior lobe of metepimeron glabrous or with dark hairs (or only a few yellow hairs) (Fig. 15); pronotum variable (Figs. 16– 17)............................................................................................... 11

- Posterior lobe of metepimeron covered with dense yellow pubescence (Fig. 13); pronotum cordate, widest anteriorly (Fig. 14). Habitus: Fig. 26 ............................................................ Nicrophorus marginatus Fabricius

11(10) Dorsal surface of elytra without long hairs (Fig. 13); epipleural ridge extended almost to humeral callus................ 12

- Dorsal surface of elytra with long fine hairs, especially laterally (Fig. 15); epipleural ridge obliterated well before humeral cal- lus. Habitus: Fig. 29 .............................................................. Nicrophorus orbicollis Say

12(11) Epipleuron entirely black; dorsal elytral maculation inconspicuous. Habitus: Fig. 28 ....... Nicrophorus pustulatus Herschel

- Epipleuron mostly orange with anterior black macula; dorsal elytral maculation conspicuous. Habitus: Fig. 27 ...................................................................................... Nicrophorus mexicanus Matthews