Helgenema lamia, Smales, 2021

Durette-Desset, Marie-Claude & Digiani, María Celina, 2023, Revision of the genera of Heligmonellidae (Nematoda, Heligmosomoidea), parasitic in Muridae from New Guinea, Parasite (Paris, France) 30 (63), pp. 1-34 : 27-28

3.10.2.2 Helgenema lamia

Synlophe: in the proximal male section 10D, the large left ridge is interpreted as ridge 1’. This ridge numbering conforms that of the male section at midbody ( Fig. 10E ).

At midbody, the only clearly divergent ridges are 8 and 7’ (curved arrows, Fig. 10E’ ) rather than 7 and 8’ ( Fig. 10E ) as proposed in [ 44].

In the three sections, the axis of orientation is possibly oblique but its inclination is calculable only in the female section at midbody, the lateral cords being illustrated ( Fig. 10F’ ).

3.10.3 Conclusion

3.10.3.1 Synlophe

Even if the modifications proposed herein are right, it is not possible to know how the section 10A’ (proximal synlophe of H. keablei , female) is related to the midbody female section (10C’) or to the midbody male section (10B’). A large left ridge is present within the proximal female section (10A’) and it is found again in the midbody male section (10B’). On the contrary, the midbody female section (10C’) shows all ridges small and subequal and the large left ridge is absent. Sections A’ and B’ may then be assumed as corresponding to the same synlophe. This synlophe would be similar to that of Pogonomystrongylus , where a large left ridge is observed all along the body. On the contrary, there are no examples of large left ridges well-developed proximally and decreasing in size towards midbody. That is why it is difficult to assume sections 10A’ and 10C’ correspond to the same synlophe.

The original definition of the genus [ 43] indicated that the main character separating Helgenema from the remaining genera was the “ Cuticle with dilatation on left side supported anteriorly by large left dorso-lateral ridge ”. Some of the sections analyzed herein contradict this definition in several points: (1) the large ridge is actually left or left-ventral (ridge 1’) and not dorsal, (2) the midbody male section of H. keablei shows the dilatation supported by two ridges, (3) the proximal male section of H. lamia does not show an apparent cuticular dilatation, and (4) the midbody male section of H. lamia shows a large ridge 1’ which clearly is more developed than at proximal body. This latter condition cannot even be confirmed in the female of the same species, since the synlophe at proximal body is not provided.

We think that among the material concerned there are two types of synlophe: one with a large left ridge, more developed than the other ridges, all along the body (sections 10A’ and 10B’ of Helgenema keablei and 10D–10F of Helgenema lamia ). The other one, without large left ridge, with ridges small and subequal (section 10C of Helgenema keablei ).

3.10.3.2 Bursa

In both, Helgenema keablei and H. lamia , since rays 2 diverge first from the trunk 2-6, the bursal pattern is of type 1-4.

3.10.4 Conclusion

Without indication about the exact level of the sections, without the illustration of both sexes at the proximal part, and without precision on the material studied for the female sections (on same or different specimens), Helgenema keablei and Helgenema lamia are considered species inquirendae and Helgenema a genus inquirendum. It would be possible that under Helgenema there are two or three different taxa, with the two types of synlophe recognized distributed as follows: “ H. keablei ” (midbody male section and proximal female section); “ H. lamia ” (male and female); Nippostrongylinae i.s. 5 (midbody female section of H. keablei ).

Figures

Figure 10. Genus Helgenema Smales, 2020. Body sections. A–C’ Helgenema keablei. A, A’ within proximal body, female. B–C’ at midbody. B, B’, male. C, C’ female. D–F’ Helgenema lamia Smales, 2021. D within proximal body, male. E–F’ at midbody. E, E’ male, F, F’, female. Sources: A–C redrawn from [43]. D–F redrawn from [44]. A’–C’, E’, F’ modified sections: A’ reversed on its frontal axis with respect to the original, B’ reversed on frontal axis then rotated ca. 15° clockwise with respect to the original. C’, E’, F’ re-numbering of ridges.