Key to group 1 Heth spp.

1. With one continuous cervical collar of spines around circumference of neck, usually with interruption by lateral cervical spines.............................................................................................. 2

- With two continuous cervical collars around circumference of neck; rows of eight similar-sized spines extending from cervical collar to level of esophageal isthmus (Fig. 9E); lateral alae originating from posteriormost cervical spines and ending at base of tail; female length 1,326 –1,440 µm .................................................................. H. coyi

2. Lateral spines absent; cervical collar spines continuous, not interrupted laterally; numerous multi-cusped sensory papillae anterior and posterior to cervical collar (Fig. 9A); length of female 1,070 –1,210 µm .......................... H. albertoi

- Lateral spines present; cervical collar interrupted or deeply notched laterally, often by prominent cervical spines.......... 3

3. One or two pairs of lateral spines present, posterior lateral spines sometimes single................................. 4

- Numerous lateral spines (>8 pairs) extending half the length of the esophagus; lateral alae wing-like.................. 15

4. Single posterior lateral spine............................................................................ 5

- Posterior lateral spines paired or absent.................................................................... 7

5. Cervical collar interrupted laterally (Fig. 10G); length of female 1,550 –1,920 µm ...................... H. zeuglocantha

- Cervical collar notched or slightly produced laterally as two small, pointed lobes................................... 6

6. Cervical collar notched (Fig. 9I); female length 1,730 -2,240 µm ....................................... H. konoplevi

- Cervical collar slightly prolonged as two small, pointed lobes (Fig. 11D); females 1,420 –2,500 μm long....... H. hamatus

7. Lateral spine pairs broad, outer edges coarsely toothed....................................................... 8

- Lateral spine pairs slender, outer edges smooth............................................................. 9

8. Cervical collar with about 92 spines; two broad, strongly serrated pairs of lateral spines, their length and width about equal; length of female 2,600 –3,200 µm (Fig. 9F)......................................................... H. gordae

- Cervical collar with about 60 spines; anterior and posterior lateral spines much wider than long, posterior spines nearly encircling the body; female length 1,400 –1,700 µm (Fig. 10F)............................................. H. xarochae

9. With continuous anterior and posterior series of discontinuous spines around the circumference of the esophageal region (Fig. 9J); length of female 1,731 –2,482 µm ........................................................... H. maicuru

- Post-collar spines confined to lateral region............................................................... 10

10. Cervical collar densely serrated and expanded away from body; posterior spines apparently absent; length of female 1,820 – 2,070 µm (Fig. 9G)....................................................................... H. hexaspinosum

- Cervical collar not expanded away from body; posterior lateral spines present.................................... 11

11. Large multi-cusped papillae (2–4 per side) only present anterior to cervical collar................................. 12

- Papillae present both anteriorly and posteriorly to cervical collar; with transverse rows of small spines in cervical folds... 13

12. Cervical, anterior and posterior lateral spines narrow, about equal in size (Fig. 10B); length of holotype 2,800 µm ................................................................................................ H. perarmatum

- Cervical, anterior and posterior lateral spines progressively larger, broader and overlapping one another (Fig. 9B); lateral winglike alae extending from posterior region of esophagus to anus; female length 1,753 –1,973 µm .......... H. amazonensis

13. Collar interrupted by long, slender cervical spines nearly reaching base of anterior lateral spines; anterior and posterior lateral spines long and slender (Fig. 10E); female length 1,610 –1,990 µm .................................... H. spinosum

- Cervical collar interrupted by larger lateral spines not reaching base of anterior lateral spines........................ 14

14. Anterior and posterior spine pairs not sharing common bases (Figs. 1, 10A); female length 1,750 –1,830 µm .... H. mauriesi

- Anterior and posterior spine pairs with common bases....................................................... 15

15. Anterior lateral spines not reaching base of posterior spines (Fig. 9D); female length 2,960 –3,090 µm ........... H. clunyi

- Anterior pair of lateral spines overlapping base of posterior pair; (Fig. 9C); female length 1,880 –2,080 µm H. bifidispiculum

16. Prominent spines extending from posterior cervical collar to beginning of lateral alae (Fig. 10C, D); lateral alae extending from posterior esophagus to tail; length of female 1,155 –1,165 µm ........................................ H. pinnatum

- Somatic spines extending from cephalic extremity to isthmus with first three spines small and remaining spines long and curved (Fig. 9H); female length 1,740 –2,000 µm ...................................................... H. hispaniolae