Missimstrongylus oweni, Smales, 2018

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 : 22-23

3.8.1 Analysis of data and difficulties encountered Missimstrongylus oweni

3.8.1.1 Synlophe (number of worms studied not specified)

Section analyzed herein is at midbody, male ( Fig. 2 /8A). Lateral cords not illustrated; ridges numbered.

Careen absent. Fourteen ridges small, except ventral ridge 5’ medium sized, and ridges 8’-6’ minute. Two small gaps (arrowheads) on left-ventral left side between ridges 5’ and 4’ and on right-right ventral side between ridges 5 and 9’. Tips of ridges 1’ and 1 divergent (curved arrows). Ridges 1’ to 4’ oriented from dorsal to ventral, ridges 1 to 5 oriented from left to right, ridge 5’ oriented from right to left, remaining ventral ridges, oriented perpendicularly to body surface. Axis of orientation described as oblique in [ 41].

3.8.1.2 Bursa (number of worms studied not specified; illustrated in [ 41]: Figs. 4 and 7 )

Figure 4 , “left lateral view”, orientation not specified, rays 2-9 illustrated but no link between rays 6 and 8. Figure 7 , “right lateral view”, orientation not specified, only lateral and ventral rays illustrated. From diagnosis [ 41]: bursa dissymmetrical with right lobe larger and pattern of type 1-3-1; from the written description, bursa with left lobe larger.

3.8.2 Comments

3.8.2.1 Synlophe

The ridge arrangement illustrated in [ 41] does not match the usual orientation of the ridges in the Nippostrongylinae .

If the section is turned 90° clockwise ( Fig. 8A’ ), the largest ridge is placed on the left (a common arrangement in the Nippostrongylinae ). But, in doing so the divergent ridge tips are situated in the right dorsal-quadrant (never found in the Nippostrongylinae ). A further reversion of the section on its frontal axis ( Fig. 8A ”) keeps the largest ridge on the left and places the divergent ridges in the right-ventral quadrant. However, in doing so, the dorsal ridges become oriented rather anarchically (right-dorsal ones from left to right and left-dorsal ones perpendicular) and the largest ridge on the left is pointing to the ventral side, an orientation never found in the Nippostrongylinae . This synlophe does not actually match any other in the subfamily and no manipulation of the section (rotation and/or reversion) will make the synlophe to match the usual orientation observed in the Nippostrongylinae .

3.8.2.2 Bursa

The expressions “left lateral view” or “right lateral view” concerning the bursa are ambiguous since they may actually refer to either lateral lobe (left or right) on either of their two surfaces (dorsal or ventral). Anyway, we assume that Smales [ 41] intended to illustrate the left lobe in Figure 4 and the right lobe in Figure 7 . The right lobe is clearly longer than the left lobe. Judging from Figure 7 , the left and right lobes are in dorsal view. The pattern is 1-4 for both lobes; right lobe with ray 3 diverging at same level as ray 6, rays 4 and 5 parallel and joined to their extremities; left lobe with ray 3 diverging proximally to ray 6, rays 4-6 parallel and joined to their extremities.

3.8.3 Conclusion

In her Remarks, Smales [ 41] relates Missimstrongylus to Hasanuddinia , Melomystrongylus , Nugininema and Montistrongylus , all of which have synlophes with large ventral ridges. However, the data provided in the description of the type species of Missimstrongylus are insufficient to assert that the most developed ridge is indeed ventral in position. It could be also the left ridge. Under these conditions, Missimstrongylus oweni is considered a species inquirenda and, consequently, Missimstrongylus a genus inquirendum.

Figures

Figure 2. Genus Mawsonema Smales & Heinrich, 2010. Body sections. A–F’ Mawsonema mokwanense Smales & Heinrich, 2010. A, A’ within proximal body, male. B, C at midbody. B male, C female. D, E within distal body. D male, E female. F, F’ within proximal body, female. A–E synlophe of type I. F, F’ synlophe of type II. Source: A–F redrawn from [45]. A’, F’ modified figures: reversed on their frontal axes with respect to the originals. F’ axis of orientation reinterpreted as subfrontal.

Figure 4. Genus Pogonomystrongylus Smales, 2014. Body sections. A–D’ Pogonomystrongylus domaensis Smales, 2014. A–B’ within proximal body. A, A’ male, B, B’ female. C–D’ at midbody. C, C’ male, D, D’ female. Source: A–D redrawn from [36]. A’–D’, modified figures: A’–C’ reversed on their frontal axes with respect to the originals, then slightly rotated clockwise. D’ rotated 45° clockwise.

Figure 7. Genus Parvinema Smales, 2017. Midbody sections. A, B Parvinema bafunminense Smales, 2017. A male, B, B’ female. C, C’ Parvinema helgeni Smales, 2017, male. Source: A–C redrawn from [40]. B’, C’ modified figures with respect to the original: B’ numbering of ridges added. C’ reversed on its frontal axis, then rotated 30° clockwise.

Figure 8. Genus Missimstrongylus Smales, 2018. A-A” Missimstrongylus oweni Smales, 2018, section at midbody, male. Source: A redrawn from [41]. A’, A” modified figures: A’ rotated 90° clockwise with respect to the original, A” further reversion of A’ on its frontal axis.