Key to the species of Limnocoris of North America

1. Embolium with lateral margin prolonged into a long and curved spine; hemelytral membrane distinctly reduced (Fig. 11A).......................................................................... Limnocoris moapensis (La Rivers)

1’. Embolium with lateral margin convex, not prolonged into a long and curved spine; hemelytral membrane developed (e.g., Figs. 3A, C).............................................................................................. 2

2. Posterior margin of propleuron shallowly convex at mid-length (Figs. 1 B–D); mesosternum with longitudinal row of golden setae (Fig. 2C); abdominal sterna with dispersed elongate golden setae (Fig. 2H); lateral margin of female subgenital plate with elongate golden setae (Fig. 2H).......................................................................... 3

2’. Posterior margin of propleuron straight (Fig. 1A); mesosternum without longitudinal row of golden setae (Fig. 2D); abdominal sterna without dispersed elongate setae (e.g, Fig. 2G); lateral margin of female subgenital plate without elongate golden setae (e.g., Fig. 2G)....................................................................................... 10

3. Posterolateral corners of abdominal segments III–V produced posteriorly, spinose (Fig. 2E); body length ≥ 9.20 mm ...... 4

3’. Posterolateral corners of abdominal segments III–V not produced posteriorly, narrowly rounded to right angled, not spinose (Fig. 2F); body length <9.20 mm ........................................................................ 5

4. Pubescent area of propleuron extended posteriorly to approximately halfway along lateral margin (Fig. 1C); fossa of mesosternal carina shallow (Fig. 17D).................................................. Limnocoris virescens Montandon

4’. Pubescent area of propleuron not extended posteriorly along lateral margin (as in Fig. 1D); fossa of mesosternal carina deep (Fig. 9D).......................................................................... Limnocoris major n. sp.

5. Mesosternal carina with elongate golden setae on lateral margin; fossa shallow, elongate, and narrow (Figs. 3D, F).................................................................................. Limnocoris chaetocarinatus n. sp.

5’. Mesosternal carina without elongate setae on lateral margin; fossa not as above (e.g., Figs. 4C, 4E, 13C, 13E)............ 6

6. Pubescent area of propleuron not extended posteriorly on lateral margin (as in Fig. 1D); fossa of mesosternal carina deep, elliptical, sometimes with subtle angles at greatest width (Figs. 13C, E); female subgenital plate with posterior margin evenly convex (Fig. 13D)........................................................... Limnocoris panamensis La Rivers

6’. Pubescent area of propleuron distinctly extended posteriorly on lateral margin (Fig. 1B); fossa of mesosternal carina shallow and semicircular (Fig. 4C) or fossa obscured by lateral margins touching at midline (Figs. 5C, 15D, 16 D–E); female subgenital plate with posterior margin tapering posteriorly (Figs. 4D, 5D, 15E, 16G)......................................... 7

7. Distal margin of labrum bluntly pointed (Fig. 16F); mesosternal carina without excavation posterior to fossa in lateral view (Figs. 16H)................................................................. Limnocoris signoreti Montandon

7’. Distal margin of labrum distinctly acuminate (Figs. 4C, 5C, 15D); mesosternal carina with small excavation posterior to fossa in lateral view (Figs. 2A, 4E, 5E)......................................................................... 8

8. Fossa of mesosternal carina with lateral margins generally touching each other at middle, leaving a wide, circular or subtriangular posterior opening and small separation anteriorly (Fig. 4C); lateral lobe of male tergum VIII with lateral margin shallowly concave in anterior half (Fig. 6D); posterior margin of male sternum VIII with medial notch (as in Fig. 18B).......................................................................................... Limnocoris hintoni La Rivers

8’. Fossa of mesosternal carina with lateral margins touching each other along most of its length, leaving only a small opening at anterior and posterior ends (Figs. 5C, 15D); lateral lobe of male tergum VIII with lateral margin straight in anterior half (Figs. 6F, 19B); posterior margin of male sternum VIII without medial notch........................................... 9

9. Body color usually brown to dark brown; hemelytral membrane without pale spot medially (Fig. 5A)............................................................................................ Limnocoris inornatus Montandon

9’. Body color usually light brown to yellowish; hemelytral membrane with pale spot medially (Figs. 15A, C)......................................................................................... Limnocoris pygmaeus La Rivers

10. Mesosternal carina with median projection (Figs. 2B, 18E); fossa with small aperture anteriorly (Figs. 2D, 18C); posterior margin of male sternum VIII with medial notch (Fig. 18B).................................. Limnocoris zacki n. sp.

10’. Mesosternal carina without median projection (Figs. 7 F–G, 8E, 12E); fossa without anterior aperture (Figs. 7D, 8C, 12C); posterior margin of male sternum VIII without medial notch.................................................. 11

11. Mesosternal carina with anterior projection well-developed, almost at same level of fossa (Fig. 12E); fossa elongate, with lateral margins convergent and meeting posteriorly but open ended anteriorly; anterior ridge entering open anterior end of fossa; ridge with fine longitudinal sulcus on midline (Fig. 12E).................................... Limnocoris nanus n. sp.

11’. Mesosternal carina with anterior projection lower than fossa (Figs. 7 F–G, 8E); fossa not open anteriorly, ranging from rounded to subtriangular; ridge without sulcus (Figs. 7D, 8C)........................................................ 12

12. Region between anterior projection and fossa of mesosternal carina almost straight or slightly sinuate in lateral view, and angled dorsoventrally ~20 degrees from the long body axis (Figs. 7 F–G); antennal flagellomeres not partially fused; apex of left medial lobe of male tergum VIII distinctly angled laterally (Fig. 10B).......................... Limnocoris insularis Champion

12’ Region between anterior projection and fossa of mesosternal carina concave in lateral view, and angled dorsoventrally ~70 degrees from the long body axis (Fig. 8E); antennal flagellomeres partially fused; apex of left medial lobe of male tergum VIII slightly angled laterally (Fig. 10D)................................................... Limnocoris lutzi La Rivers