Key to the species of Plochionocerus

1. Abdominal tergites red or metallic golden; abdominal sternites metallic blue-greenish......................... 2

1’. Abdominal tergites and sternites metallic blue and/or green................................................................... 3

2(1). Head rectangular (Fig. 2), dorsally and ventrally flat in lateral view; antennomeres 4–8 almost trans- verse, 9 and 10 subquadrate (Fig. 30); aedeagus pear-shaped (Fig. 92) ................................. P. splendens

2’. Head rounded (as in Fig. 19), dorsally and ventrally convex in lateral view; antennomeres 4–10 trans-

verse (Fig. 26); aedeagus ovate (Fig. 82) ..................................................................................... P. igneus 3(1’). Head elongate, narrowed caudally; pronotal hypomeron with fine, scarce setae on anterior third; anterior margin of labrum with pair of pointed and long central teeth (Fig. 34); aedeagus elongate (Fig. 85) .................................................................................................................................................. P. marquezi

3’. Head not elongate, not narrowed caudally (Figs. 1, 2); pronotal hypomeron lacking setae (Fig. 63); anterior margin of labrum with pair of lateral teeth, variable in length, and a pair of central teeth, longer than the lateral (Figs. 35, 36); aedeagus not elongate (Figs. 77–84, 86–93) ........................................... 4

4(3’). Body slender; apical labial palpomere elongate, with truncate apex (Fig. 44) .......................... P. gracilis

4’. Body robust; apical labial palpomere strongly widened toward obliquely truncate apex (Fig. 43, 46, 47) .................................................................................................................................................................. 5

5(4’). Head rounded or ovate (Figs. 1, 19) ........................................................................................................ 6

5’. Head rectangular or subquadrate (as Fig. 2) .......................................................................................... 13

6(5). Dorsal surface of head slightly to strongly convex (Figs. 11, 14, 19) ..................................................... 7

6’. Dorsal surface of head flat (Figs. 12, 13)............................................................................................... 11

7(6). Ventral surface of head convex (Fig. 12)................................................................................................. 8

7’. Ventral surface of head flat (Figs. 11, 13, 14) ........................................................................................ 10

8(7). Apical antennomere in males shorter than 9+10 combined (0.75–0.88 times; as in Figs. 27, 28); head wider than pronotum (1.31 times) ......................................................................... P. impressipennis (part)

8’. Apical antennomere in males as long as 9+10 combined (0.90–1.07 times; Figs. 25, 26); head as wide as or slightly wider than pronotum (1.05–1.23 times) ............................................................................. 9

9(8’). Head slightly oblong (length/width: 1.13–1.31) and slightly wider than pronotum (1.13–1.35 times); apical antennomere in males moderately longer than wide (1.36–1.54 times); ventral surface of head with dense, umbilicate punctures (20–29 on each half of head; Fig. 50); aedeagus ovate, parameres moderately long (0.35–0.47 times length of median lobe), apical area of median lobe 0.28–0.41 times its length and internal sac moderately visible (Fig. 91) .......................................... P. simplicicollis (part)

9’. Head oblong (length/width: 1.22–1.54) and almost as wide as pronotum (0.86–1.11 times); apical antennomere in males conspicuously longer than wide (1.40–1.74 times); ventral surface of head with less dense, umbilicate punctures (10–19 on each half of head; similar to Fig. 52); aedeagus pear-shaped, parameres short (0.24–0.28 times length of median lobe), apical area of median lobe 0.29–0.35 times its length, internal sac clearly visible (Fig. 79) ...................................................................... P. fulgens (part)

10(7’). Mandibular channel present (Fig. 63); ventral surface of head with very dense, umbilicate punctures (>30 on each half of head; similar to Fig. 53); pronotum slightly longer than wide (1.30–1.41 times); parameres of aedeagus long (0.58–0.61 times length of median lobe; Fig. 78) ..................... P. discedens

10’. Mandibular channel absent or poorly developed; ventral surface of head with less dense, umbilicate punctures (10–19 on each half of head; similar to Fig. 52); pronotum ca. 1.5 times longer than wide (1.48–1.49 times); parameres of aedeagus moderately long (0.37–0.38 times length of median lobe; Fig. 77) .................................................................................................................................................. P. ashei

11(6’). Ventral surface of head moderately convex, without expanded, umbilicate punctures (Fig. 52); apical antennomere in males shorter than antennomeres 9+10 combined (0.83 times their length; similar to Figs. 27, 28); head wider than pronotum (1.34 times); aedeagus ovate (Fig. 80) ..................... P. hermani

11’. Ventral surface of head flat, with expanded, umbilicate punctures (Figs. 50, 51, 53); apical antennomere in males almost as long as antennomeres 9+10 combined (0.88–1.07 times; Figs. 25, 26); head as wide as pronotum (1.03–1.07 times); aedeagus pear-shaped (Figs. 87, 93)................................................... 12

12(11’). Mandibular channel present (Fig. 63); antennomeres 4–10 moderately transverse (similar to Figs. 24, 26); prosternum slightly transverse (length/width: 0.72–0.80); parameres of aedeagus moderately long (0.35 times length of median lobe), internal sac clearly visible (Fig. 87) .......................... P. newtonorum

12’. Mandibular channel absent; prosternum transverse (length/width: 0.61); antennomeres 4–10 strongly

transverse (Fig. 31); parameres of aedeagus short (0.29 times length of median lobe), internal sac moderately visible (Fig. 93) ...................................................................................................... P. transversalis 13(5’). Lateroposterior half of pronotum lacking obliquely depressed areas; pronotum almost as long as elytra (1.05 times length of elytra) ................................................................................................... P. pronotalis

13’. Lateroposterior half of pronotum with two obliquely depressed areas (Figs. 56, 57); pronotum shorter than elytra (<0.89 times length of elytra).............................................................................................. 14

14(13’). Apical antennomere in males shorter than antennomeres 9+10 combined (0.83–0.93 times; Figs. 27, 28); pronotum longer than wide (1.59–1.66 times)................................................................................ 15

14’. Apical antennomere in males as long as or longer that antennomeres 9+10 combined (> 0.96 times; Figs. 24–26); pronotum slightly oblong or ca. 1.5 times longer than wide (1.34–1.52 times).............. 17

15(14). Head slightly oblong (length/width: 1.19–1.25); ventral surface of head with very dense, umbilicate punctures (>30 on each half of head; Fig. 53); lateroposterior half of pronotum with two shallow, obliquely depressed areas ...................................................................................................... P . puncticeps

15’. Head oblong (length/width: 1.34–1.40); ventral surface of head with less dense, umbilicate punctures (10–19 on each half of head; similar to Fig. 52); lateroposterior half of pronotum with two clearly visible, obliquely depressed areas (Fig. 56)................................................................................................. 16

16(15’). Head slightly wider than pronotum (1.15–1.29 times); aedeagus with basal half curved (in lateral view), slightly longer, with internal sac moderately visible (Fig. 84) .................................... P. janthinus

16’. Head wider than pronotum (1.31–1.48 times); aedeagus with basal half straight (in lateral view), slightly shorter, with internal sac conspicuously visible (Fig. 83) ........................ P. impressipennis (part)

17(14’). Apical antennomere in males longer than antennomeres 9+10 combined (1.21 times; Fig. 29); first antennomere almost twice as long as 2+3 combined (1.88 times; Fig. 29) ........................... P. reticularis

17’. Apical antennomere in males almost as long as antennomeres 9+10 combined (0.96–1.06 times; Figs. 27, 30, 31); first antennomere 1.63–1.68 times the length of antennomeres 2+3 combined................. 18

18(17’). Head oblong (length/width: 1.26–1.50); apical antennomere in males conspicuously longer than wide (1.52–1.80 times); aedeagus pear-shaped, with apical area of median lobe 0.26–0.31 times its total length (Figs. 79, 81) ............................................................................................................................... 19

18’. Head slightly oblong (length/width: 1.22–1.24); apical antennomere in males moderately longer than wide (1.42–1.45 times); aedeagus ovate, with apex of median lobe 0.39–0.41 times its total length (Figs. 86, 91) .......................................................................................................................................... 20

19(18). Antennomere 9 in males shorter than antennomere 10 (0.85 times; Fig. 25); ventral surface of head with dense, umbilicate punctures (20–29 on each half of head; similar to Fig. 51); pronotum ca. 1.5 times longer than wide (length/width: 1.47–1.58); head wider than pronotum (1.05–1.16 times); aedeagus with parameres moderately long (0.30–0.32 times length of median lobe) and internal sac moderately visible; head dorsally and ventrally flat (Fig. 81) ......................................................... P. humeralis

19’. Antennomere 9 in males almost as long as antennomere 10 (0.95 times); ventral surface of head with less dense, umbilicate punctures (10–19 on each half of head; similar to Fig. 52); pronotum slightly oblong (length/width: 1.16–1.40); head almost as wide as pronotum (0.86–1.05 times); aedeagus with parameres short (0.24–0.28 times length of median lobe) and internal sac conspicuously visible; head dorsally and ventrally convex (Fig. 79) ............................................................................ P. fulgens (part)

20(18’). Ventral surface of head with moderately dense, umbilicate punctures (10–19 on each half of head; similar to Fig. 52); pronotum slightly oblong (length/width: 1.34); mandibular channel absent; second antennomere 3/4 the length of third antennomere (0.75 times their length) ........................... P. modestus

20’. Ventral surface of head with dense, umbilicate punctures (20–29 on each half of head; Fig. 50); pronotum ca. 1.5 times longer than wide (length/width: 1.47); mandibular channel present (Fig. 63); second antennomere ca. 1/2 the length of third antennomere (0.52–0.68 times its length)... P. simplicicollis (part)