Key to males of Platyceroides Benesh

1. Flightless. Mesotibiae and metatibiae robust (Fig. 17)................................... Platyceroides keeni (Casey)

- Fully winged. Mesotibiae and metatibiae long and narrow (Fig. 18)............................................ 2

2. Head wider across genae than across eyes, anterior margin of head distinctly emarginate (Fig. 19)...... P. laticollis (Casey)

- Head width across genae and eyes subequal, or genae narrower than eyes; anterior margin of head weakly emarginate, almost truncate (Fig 20)..................................................................................... 3

3. Clypeus thickened, tumid anteriorly, strongly declivous before labrum (Fig. 21).......................... P. latus (Fall)

- Clypeus normal, not raised medially, descending to labrum (Fig. 22)............................................ 4

4. Elytra shagreened (microsculptured), appearing dull.........................................................5

- Elytra shiny or glossy, lacking microsculpture............................................................. 10

5. Antennal club small, shorter than funicle, or subequal in length (Fig. 23).........................................6

- Antennal club distinctly larger, longer than funicle to subequal to scape (Fig. 24)...................................8

6. Elytral striae distinctly impressed and serially punctate; Coastal mountains........... P. pampinatus Paulsen, new species

- Elytral striae obsolete, longitudinal cracks (if present) not punctate; Sierra Nevadas................................ 7

7. Labrum large, as long as width of terminal maxillary palp; Klamath Mountains, Oregon .............. P. marshalli Paulsen

- Labrum small, shorter than width of terminal maxillary palp; northern Sierra Nevadas, California ........ P. potax Paulsen

8. Elytra lacking impressed, serially punctate striae................................................. P. opacus (Fall)

- Elytra with feebly to distinctly impressed, punctate striae..................................................... 9

9. Elytra short (about 2x pronotal length); Sierra Nevadas............................... P. barrae Paulsen, new species

- Elytra elongate (almost 3x pronotal length); coastal mountains........................ P. infernus Paulsen, new species

10. Form robust, elytra short, about 2x pronotal length.......................................................... 11

- Form elongate, elytra longer, almost 3x pronotal length...................................................... 13

11. Mesotibiae and metatibiae with external margin subserrate with 3–4 similarly sized teeth; northeastern Oregon............................................................................................. P. viriditinctus (Benesh)

- Mesotibiae and metatibiae with external margin usually with 1 larger tooth and proximal teeth when present distinctly smaller; northern California.................................................................................. 12

12. Antennal club unusually small, as short as funicle............................................ P. agassii (LeConte)

- Antennal club larger, distinctly longer than funicle........................................... P. pacificus (Casey)

13. Elytral color light brown or rufous with pronotal disc darker.................................................. 14

- Color uniformly darker piceous. If lighter (teneral), dorsum is unicolorous...................................... 15

14. Antennal club large, subequal to scape; posterior angles of pronotum greater than 90°; Washington south to northern Oregon.................................................................................... P. aeneus (Van Dyke)

- Antennal club smaller, distinctly shorter than scape; posterior angles of pronotum ~ 90°; known only from Humboldt County, California.......................................................................... P. californicus (Casey)

15. Antennal club large, distinctly longer than funicle; San Francisco Bay area........................ P. thoracicus (Casey)

- Antennal club smaller, subequal to funicle; southwestern Oregon ...................... P. umpquus Paulsen, new species