Metrocoris lituratus

Chen, Zhen Ye Ping-Ping & Bu, Wen-Jun, 2016, Notes on the Metrocoris lituratus group (Heteroptera: Gerridae: Metrocoris) with descriptions of four new species in Sichuan Basin from China, Zootaxa 4117 (3), pp. 359-374 : 373

Key to the Metrocoris lituratus group species (based on apterous males)

1. Fore femur with a constriction in the middle, basal half slightly thicker than apical half.............................. 2

- No constriction in the middle of fore femur but with a subapical indentation and a single apical tooth................... 6

2. Constriction in middle of fore femur marked by a tooth-like edge; basal edge of subapical indentation also tooth-like...... 3

- Neither the edge of median constriction of fore femur nor the edge of subapical indentation tooth-like................................................................................................ M. constrictus Chen & Nieser

3. Paramere with hooked tip............................................................................... 4

- Paramere with blunt tip................................................................................. 5

4. Paramere apically with a small hook curved upward............................................ M. lituratus (Stål)

- Paramere apically birdhead-shaped............................................................... M. xiei Chen

5. Apex of paramere truncate........................................................... M. esakii Chen & Nieser

- Outer edge of paramere with a distinct sharp turn, apex truncate........................ .. M. cantonensis Chen & Nieser

6. Blade of paramere laterally with angular projection in the middle ( Figs. 63–66 )....................................7

- Blade of paramere laterally without projection in the middle ( Figs. 59–62 )....................................... 10

7. Body size relatively small (5.85–6.05); male proctiger laterally without a pair of blackish dots ( Fig. 55 ).. M. astictus sp. nov.

- Body size relatively large (more than 6.62); male proctiger laterally with a pair of blackish dots ( Fig. 56–58 )............. 8

8. Paramere stout and triangularly curved upwards ( Figs. 66 , 83 ); accessory lateral sclerites of endosoma relatively thick in dorsal view ( Figs. 71 , 81 )....................................................................... M. zhengi sp. nov.

- Paramere laterally not triangle-shaped; accessory lateral sclerites of endosoma relatively thin in dorsal view.............. 9

9. Paramere laterally with distinctly angular projection, apex slightly curved upward ( Figs. 64 , 77 )...... M. falciformis sp. nov.

- Paramere with small projection, apex without curving ( Figs. 65 , 80 ).......................... M. guizhouensis sp. nov.

10. Abdominal tergite VII strongly developed, paramere apically tapering......................... M. heineri Chen & Zettel

- Abdominal tergite VII slightly developed, paramere apically slightly extended.................................... 11

11. Paramere comparatively smaller.................................................. M. sichuanensis Chen & Nieser

- Paramere comparatively large...........................................................................12

12. Apex of paramere round, without projection................................................. M. cylindricus Chen

- Apex of paramere blunt, inner side with a small hook-like projection.............................. M. hubeiensis Chen

Figures

FIGURES 59 – 66. Paramere of Metrocoris spp. (males) in external view. 59 – 62. M. sichuanensis Chen & Nieser, 1993 (59: Qingchen mountain; 60: Laojun mountain; 61: Xinmin village; 62: Hubaoxia Forest Park); 63. M. astictus sp. nov.; 64. M. falciformis sp. nov.; 65. M. guizhouensis sp. nov.; 66. M. zhengi sp. nov.. Scale 0.2 mm.

FIGURES 44 – 58. Photographs of abdominal segment VIII, pygophore and proctiger of Metrocoris spp. (males). 44, 49, 54. M. sichuanensis Chen & Nieser, 1993; 45, 50, 55. M. astictus sp. nov.; 46, 51, 56. M. falciformis sp. nov.; 47, 52, 57. M. guizhouensis sp. nov.; 48, 53, 58. M. zhengi sp. nov.. Scale 0.4 mm.

FIGURES 72 – 83. Illustrations of endosoma sclerites (dorsal and lateral views) and paramere of Metrocoris spp. (males). 72 – 74. M. astictus sp. nov.; 75 – 77. M. falciformis sp. nov.; 78 – 80. M. guizhouensis sp. nov.; 81 – 83. M. zhengi sp. nov.. Scale 0.1 mm.

FIGURES 67 – 71. Endosoma of Metrocoris spp. (males) in dorsal view. 67. M. sichuanensis Chen & Nieser, 1993; 68. M. astictus sp. nov.; 69. M. falciformis sp. nov.; 70. M. guizhouensis sp. nov.; 71. M. zhengi sp. nov.. Scale 0.1 mm.