Monoctenus, Dahlbom, 1835

Hara, Hideho & Nagase, Hirohiko, 2023, The Japanese species of Monoctenus (Hymenoptera: Diprionidae), Zootaxa 5380 (6), pp. 541-561 : 542-545

Key to Japanese species of Monoctenus

1 Female ............................................................................................. 2

- Male................................................................................................ 8

2(1) Mesonotum entirely black ( Fig. 2A 1). Femora mostly black ( Fig. 2B 1). Valvula 3 in dorsal view not tapering, apically slightly concave ( Fig. 2C 1), in lateral view apically truncate ( Fig. 2D 1) (condition in M. kondoi unknown)..................... 3

- Mesonotum widely red yellow anteriorly ( Fig. 2A2 ). Femora entirely yellow ( Fig. 2B2 ). Valvula 3 in dorsal view tapering, apically pointed or narrowly rounded ( Fig. 2C2 ), in lateral view narrowly rounded ( Fig. 2D2 )......................... 5

3(2) Abdomen with middle laterotergites yellow ( Fig. 3A 1 ). Pronotum with posterodorsal corner widely yellow ( Fig. 3B 1 ). Trochanters and their surroundings yellow ( Fig. 3A 1 ). Lancet with rounded apex ( Fig. 3C 1 )...................... M. kondoi

- Abdomen with laterotergites black, at most basal laterotergites partly yellow ( Fig. 3A 2 ). Pronotum with posterodorsal corner narrowly yellow or brown ( Fig. 3B 2a ), or entirely black ( Fig. 3B 2b ). Trochanters and their surroundings mostly black ( Fig. 3A 2 ). Lancet with acute apex ( Fig. 3C 2 )................................................................... 4

4(3) Antenna with 19–20 antennomeres; serration deep and flagellomere 6 in lateral view with breadth including serration 1.5–1.8 × dorsal length ( Fig. 4A 1 ).................................................................... M. nipponicus

- Antenna with 18 antennomeres; serration relatively shallow and flagellomere 6 in lateral view with breadth including serration 1.1–1.4 × dorsal length ( Fig. 4A 2 )................................................... M. obscuratus hokkaidonis

5(2) Abdomen with laterotergites mostly yellow ( Fig. 5A 1 ). Mesepisternum entirely black ( Fig. 5A 1 ). Lancet with ctenidia of annuli 1and 2 parallel and inclined anteriorly ( Fig. 5B ).................................................... M. decoratus

- Abdomen with laterotergites black ( Fig. 5A 2a, A2b ), sometimes some laterotergites partly yellow ( Fig. 5A 2c ). Mesepisternum entirely black ( Fig. 5A 2a ) or partly pale ( Fig. 5A 2b, A2c ). Lancet with ctenidia of annuli 1and 2 as above or not as above. .. 6

6(5) Mesepisternum centrally with one or two small brown spots ( Fig. 6A 1 ). Lancet with ctenidia of annuli 1and 2 parallel and inclined anteriorly ( Fig. 6B 1 )................................................................ M. cryptomeriae

- Mesepisternum entirely black ( Fig. 6A 2a ) or ventrally red yellow ( Fig. 6A 2b ). Lancet with ctenidia of annuli 1and 2 converging dorsally ( Fig. 6B 2a ) or parallel and inclined posteriorly ( Fig. 6B 2b )............................................. 7

7(6) Antenna with 19–21 antennomeres ( Fig. 7A 1 ); flagellomere 6 with breadth including serration 1.8–2.1 × dorsal length. Lancet with ctenidia of annuli 1 and 2 converging dorsally and ctenidium of annulus 2 inclined anteriorly ( Fig. 7B 1 )........ M. itoi

- Antenna with 15–17 antennomeres ( Fig. 7A 2 ); flagellomere 6 with breadth including serration 1.1–1.5 × dorsal length. Lancet with ctenidia of annuli 1 and 2 parallel and ctenidium of annulus 2 inclined posteriorly ( Fig. 7B 2 )............ M. fujisanus

8(1) Trochanters and femora mostly black ( Fig. 8A 1 ). Penis valve with paravalva nearly straight on ventral edge, and inner sclerite broad and broadest near middle ( Fig. 8B 1 )................................................................. 9

- Trochanters and femora yellow ( Fig. 8A 2 ). Penis valve with paravalva roundly convex on ventral edge, and inner sclerite narrow and broadest near apex ( Fig. 8B 2 ).................................................................... 10

9(8) Antenna with 24–26 rami (27–29 antennomeres). Penis valve with valviceps 2.5–2.7 × as long as broad ( Fig. 9A 1 )...................................................................................... M. kondoi or M. nipponicus

- Antenna with 23–24 rami (26–27 antennomeres). Penis valve with valviceps 3.2–3.5 × as long as broad ( Fig. 9A 2 )....................................................................................... M. obscuratus hokkaidonis

10(8) Labrum yellow brown or brown ( Fig. 10A 1 ). Pronotum yellow posterolaterally. Antenna with 23–25 rami (26–28 antennomeres)................................................................................. M. cryptomeriae

- Labrum dark brown or black ( Fig. 10A 2a, b ). Pronotum and antenna often not as above............................. 11

11(10) Pronotum entirely black ( Fig. 11A 1a ), often narrowly brown posterolaterally ( Fig. 11A 1b ). Antenna with 25–30 rami (28–33 antennomeres)................................................................................... M. itoi

- Pronotum narrowly or widely yellow posterolaterally ( Fig. 11A 2a, b ). Antenna with 25–27 rami (27–30 antennomeres)................................................................................. M. decoratus or M. fujisanus

Figures

FIGURE 1. A, Fore wing of Monoctenus kondoi, male. B, Male antenna of M. nipponicus.

FIGURE 2. A1, 2, Female body, dorsal; B1, 2, ditto, ventral; C1, 2, valvula 3, dorsal; D1, 2, ditto, lateral. A1, B1, C1, D1, Monoctenus nipponicus; A2, B2, M. cryptomeriae; C2, D2, M. itoi.

FIGURE 3. A1, 2, Female body, ventrolateral; B1, 2a, b, female pronotum, lateral (posterodorsal corner arrowed); C1, 2, apex of lancet. A1, B1, C1, Monoctenus kondoi; A2, B2a, M. obscuratus hokkaidonis; B2b, C2, M. nipponicus.

FIGURE 4. Antenna, lateral (f6 = flagellomere 6). A1, Monoctenus nipponicus; A2, M. obscuratus hokkaidonis.

FIGURE 5. A1, 2a, b, c, Female body, ventrolateral; B, lancet (an = annulus).A1, B, Monoctenus decoratus; A2a, M. itoi; A2b, M. fujisanus; A2c, M. cryptomeriae.

FIGURE 6. A1, 2a, b, Female body, ventrolateral; B1, 2a, b, lancet (an = annulus). A1, B1, Monoctenus cryptomeriae; A2a, B2a, M. itoi; A2b, B2b, M. fujisanus.

FIGURE 7. A1, 2, Female antenna, lateral (f6 = flagellomere 6); B1, 2, lancet (an = annulus). A1, B1, Monoctenus itoi; A2, B2, M. fujisanus.

FIGURE 8. A1, 2, Male body, ventrolateral; B1, 2, penis valve, lateral.A1, B1, Monoctenus nipponicus; A2, M. itoi; B2, M. cryptomeriae.

FIGURE 9. Penis valve. A1, Monoctenus nipponicus; A2, M. obscuratus hokkaidonis.

FIGURE 10. Male head, anteroventral. A1, Monoctenus cryptomeriae; A2a, b, M. itoi.

FIGURE 11. Male pronotum, lateral. A1a, b, Monoctenus itoi; A2a, b, M. spp.