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 : 509-510

Key to group 3 female Heth spp.

1. Cervical collar with discontinuous spines; lateral spines present................................................ 2

- Cervical collar spines absent; base of most posterior fold in neck with small, single posteriorly curved spine ( Fig. 14C ); females 1,140 –1,189 µm long......................................................................... H. spoliatus

2. Multiple somatic papillae present in anterior region; three pairs of lateral spines (cervical, anterior, posterior)............ 3

- Somatic papillae usually absent, rarely one or two in anterior region............................................ 5

3. Head about same width as anterior portion of body; each side of body with approximately 12 multi-cusped papillae flanking the cervical and lateral spines; cervical spines joined, with long, smooth sublateral extensions; lateral alae present ( Fig. 13E ); females 1,800 –2,500 µm long..................................................................... H. imias

- Head narrower than anterior portion of body............................................................... 4

4. Sublateral cervical spine extensions short, smooth; anterior and posterior lateral spines fused at their bases; ( Fig 13C ); females 1,640 –2,720 µm long......................................................................... H. baracoa

- Sublateral cervical spine extensions long, serrated; anterior and posterior spines slender, not fused at their bases ( Fig. 13D ).......................................................................................... H. duvidosum

5. Head wide, about 1.5× width of anterior portion of body; cervical collar with about 12 small, well-separated spines of various sizes; one pair of lateral spines ( Fig. 13F ); females 1,312 –1,600 µm long........................... H. macrocephala

- Head not enlarged, about same width as anterior portion of body............................................... 6

6. With cervical collar.................................................................................... 7

- With cervical collar of separate spines and a similar ring of spines posterior to collar ( Fig. 14A ); females 2,142 –3,004 µm long..................................................................................... H. sinediscus

7. Four pairs of fused lateral spines on each side of body, increasing in length from anterior to posterior, approximately 10, 16, 23 and 32 µm long, respectively ( Fig. 14D ); females 1,685 –1,890 µm .................................... H. travassosi

- Fewer than four pairs of lateral spines on each side.......................................................... 8

8. Cervical collar with more than 40 non-contiguous spines of similar length around circumference of neck; posterior to cervical collar ( Fig. 14F ); females 2,400 –3,090 µm long..................................................... H. tuzetae

- Cervical collar with fewer than 40 discontinuous spines....................................................... 9

9. Transverse rows of minute cuticular spines encompassing anterior esophageal region; two pairs of lateral spines, their bases separate, 11-12 µm long ( Fig. 14B ); females 1,831 –2,126 µm long................................... H. spinalatum

- Esophageal region minute cuticular spines................................................................ 10

10. Lateral spines separate; cervical collar with 8 spines around circumference of neck, interrupted by two lateral spines in the same plane as cervical spines; ( Fig. 14E ); females 1,550 –1,830 µm long................................... H. travofilhoi

- Lateral spine bases touching or clearly fused............................................................... 11

11. Cervical collar formed by 10 large spines around circumference of neck; one pair of lateral spines ( Fig. 13G ); female length 2,062 –2,186 µm ............................................................................ H. multiplus

- Lateral collar region plate-like with strong spine at each end.................................................. 12

12. One pair of lateral spines posterior to collar, broadly fused at base ( Figs. 13A, B ); females 1,550 –1,830 µm long. H. artigasi

- Posterior lateral spines not broadly fused, bases meeting at a point............................................. 13

13. Vulva with overlapping anterior flap; area rugosa absent....................................... H. magnavulvaris

- Vulva without an anterior vulval flap; area rugosa present anterior to vulva ( Fig. 13H )................... H. parartigasi

Figures

FIGURE 13. Worldwide Heth spp., discontinuous collar, no shield (Group 3). A) H. artigasi (after Dollfus 1952). B) H. artigasi (after Adamson 1983). C) H. baracoa (after Spiridonov 1989). D) H. duvidosum (after Artigas 1929). E) H. imias (after Spridonov 1989). F) H. macrocephala (after Kloss 1965). G) H. multiplus (after Kloss 1965). H) H. parartigasi (after Adamson 1985).

FIGURE 14. Worldwide Heth spp. Group 3 (continued). A) H. sinediscus (after Kloss 1965). B) H. spinalatum (after Kloss 1965). C) H. spoliatus (after García & Coy 1995). D) H. travassosi (Dollfus 1952). E) H. travfilhoi (after Adamson 1983). F) H. tuzetae (after Adamson 1983).