Key to group 2 Heth spp.

1. Multiple cuticular knob–like papillae in anterior esophageal region............................................. 2

- Knob-like papillae absent near head region, rarely one or two close to the cervical collar............................ 9

2. Lateral cervical collar spines reaching or overlapping proximal base of anterior lateral spines........................ 3

- Lateral cervical collar spines not reaching anterior lateral spines................................................ 6

3. Anterior and posterior lateral spines about equal in length..................................................... 4

- Posterior lateral spines much longer than anterior spines (Fig. 11G); anterior anal lip normal, without large lobe; female 2,340 – 3,230 μm long............................................................................... H. initiensis

4. Anterior anal lip with large lobe extending over anus; female 2,610 –4,225 μm long (Fig. 11E)............ H. impalutiensis

- Anterior anal lip not swollen into large lobe................................................................ 5

5. Shield length and width about equal (Fig. 11M); female 1,365 –2,075 μm long.......................... H. taynguyeni

- Shield longer than wide (Fig. 12C); females 2,550 –2,640 μm long................................. H. vietnamensis

6. Shield width twice that of its length; female 2,190 –4,483 µm long (Figs. 2A, B, D, 6A)................. H. pivari n. sp.

- Shield length and width about equal, or length much longer than width.......................................... 7

7. Shield tapering, up to 3 times longer than wide (Fig. 12A); females 2,180 –2,370 μm long................ H. tonkinensis

- Shield width and length similar, rounded or trapezoidal in shape................................................ 8

8. Shield rounded or ovoid; lateral spines less than 20 µm long (Fig. 11A); female 1,105 –1,440 μm long.......... H. baudini

- Shield trapezoidal; lateral spines 28–30 μm long (Fig. 11L); female 1,905 –2,575 μm long.................... H. taybaci

9. Cervical collar overlapping proximal base of anterior lateral spines............................................ 10

- Lateral cervical spines not overlapping anterior lateral spines................................................. 12

10. Eight longitudinal ridges extending from base of posterior lateral spines to vulva (Fig. 11B); female 2,160 –2,600 μm long.............................................................................................. H. costata

- Longitudinal ridges absent............................................................................ 11

11. Anterior and posterior lateral spine pairs fused, 26–33 μm long; shield a semicircle, about twice as wide as long (Fig. 11I); females 2,700 –3,024 μm long................................................................. H. orthopori

- Anterior lateral spines widely separated, 50 μm long; posterior lateral spines 55 μm long, bases closer but not touching (Fig. 11K); females 2,010 –2,360 μm long........................................................... H. sutherlandi

12. Lappets continuous, not separated laterally................................................................ 13

- Lappets separated................................................................................... 15

13 Length of cervical spines along lappet edges irregular, some spines forked; anterior and posterior lateral spines with fused bases (Fig. 12B); females 1,700 –2,800 μm long........................................................ H. tuxtlensis

- Cervical spines along lappet edges about the same size...................................................... 14

14. Shield forming a W-shape, length and width equal (Fig. 11H)............................................. H. juli

- Shield entire, not bilobed, well anterior to base of anterior lateral spines (Fig. 11C)..................... H. dimorphum

15. Wing-like lateral alae present; each pseudolabial plate with three conspicuous spines; cuticular collar with more than 100 spines; shield tapering, (Figs. 12D); female length 2,400 –2,960 μm................................. H. xaniophora

- Lateral alae absent................................................................................... 16

16. Anterior lateral spines widely separated; shield of typical size (Fig. 11J); females 1,970 –2,630 μm long.. H. ortonwilliamsi

- Anterior lateral spines fused basally; shield trapezoidal, small (Fig. 11F); females 1,764 –1,962 μm long....... H. insularis