Heth, Cobb, 1898

Phillips, Gary, Moulton, John K. & Bernard, Ernest C., 2020, Heth pivari n. sp. (Nematoda: Ransomnematoidea: Hethidae) from the indigenous North American millipede Narceus gordanus (Spirobolida: Spirobolidae), with keys for worldwide Heth spp., Zootaxa 4861 (4), pp. 486-514 : 506-507

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

Figures

FIGURE 1. Heth mauriesi female, terminology used to describe the anterior ornamentation of Heth spp. A) Drawings of H. mauriesi from Adamson (1982), courtesy of Dr. Martin Adamson. B) SEM of H. mauriesi, previously unpublished image courtesy of Dr. Ramon Carreno. Scale bars 50 µm.

FIGURE 9. Worldwide Heth spp., continuous collar and no shield (Group 1). A) H. albertoi (after García & Fontana 2004). B) H. amazonensis (after Kloss 1965). C) H. bifidispiculum (after Adamson 1982). D) H. clunyi (after Adamson 1985). E) H. coyi (after García et al. 1997). F) H.gordae (after Mejía-Madrid 2014). G) H.hexaspinosum (after Chitwood 1935).H) H. hispaniolae (after García et al. 2001). I) H. konoplevi (after Malysheva & Sumaya 2017). J) H. maicuru (after Adamson 1983).

FIGURE 10. Worldwide Heth spp. Group 1 (continued). A) H. mauriesi (after Adamson 1982). B) H. perarmatum (after Dollfus 1952). C, D) H. pinnatum, head end and neck region (after García & Coy 1995). E) H. spinosum (after Adamson 1983). F) H. xarochae (after Mejía-Madrid 2014). G) H. zeuglocantha (after Hunt 1994).

FIGURE 11. Worldwide Heth spp., continuous collar with cervical shield (Group 2). A) H. baudini (after Malysheva & Cribb 2012). B) H. costata (after Hunt 1994). C. H. dimorphum (after Chitwood 1935). D) H. hamatus (after Bowie 1985). E) H. impalutiensis (after Malysheva et al. 2012). F) H. insularis (after Kloss 1965). G) H. initiensis (after Malysheva & Sumaya 2017). H) H. juli (after Cobb 1898). I) H. orthopori (after Adamson 1987). J) H. ortonwilliamsi (after Hunt 1994). K) H. sutherlandi (after Hunt 1994). L) H. taybaci (after Malysheva & Spiridonov 2010). M) H. taynguyeni (after Malysheva & Spiridonov 2010).