Flannerystrongylus chisholmae, Smales, 2020

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 : 23-25

3.9.1.2 Flannerystrongylus chisholmae ( Figs. 9D–9 E’)

3.9.1.2.1 Synlophe (based on sections from two males and five females). Sections analyzed herein are at midbody: male ( Fig. 2C /9D) and female ( Fig. 2E /9E). In both sections lateral cords illustrated, and ridges numbered in Figure 2C /9D.

In both sections careen absent; 15 minute ridges regularly spaced and subequal in size; axis of orientation described as subfrontal by Smales [ 43] but no arrow indicating its direction. In the original figures, the external lining of cuticle that connects the ridges to each other is not drawn.

Figure 9D (male): on dorsal surface, non-numbered ridge between ridges 6 and 7; some ridges pointing to left, some others to right and remaining oriented perpendicularly to body surface in rather disparate arrangement.

Figure 9E (female): ridges mostly oriented perpendicularly to body surface.

3.9.1.2.2 Bursa (number of worms studied not specified, illustrated in [ 43]: Figs. 2G, 2L and 2N ). Figure 2G , left lobe, view not specified, rays 2-6 numbered, only distal part of rays illustrated. Figure 2L , dorsal lobe, view not specified, only distal extremity of dorsal ray and rays 8 illustrated. Figure 2N , right lobe, view not specified, ray 6 smaller and separated from rays 4-5. From the written description [ 43]: bursa dissymmetrical with left lobe larger, lateral rays 4-6 about same length, reaching margin of bursa, pattern of type 2-3.

3.9.2 Comments

3.9.2.1 Synlophe

Flannerystrongylus abulus : within the proximal part of the body, the female section ( Fig. 9A ) should be slightly rotated clockwise to align the left lateral cord horizontally and to have the accurate orientation of the section ( Fig. 9A’ ). We propose a slight modification on the numbering of the ridges, so that ridge 8’ in [ 42] becomes ridge 8. Figure 9B can be similarly rotated clockwise ( Fig. 9B’ ). This re-arrangement would make all three synlophes (A’, B’, C) more or less consistent, with an oblique axis of orientation separating 8 right-dorsal and 7 left-ventral ridges although passing between incorrectly oriented ridges.

Flannerystrongylus chisholmae : on the male section ( Fig. 9D ) ridge 7 in [ 43] is in fact ridge 8, and ridge 8 in [ 43] becomes ridge 9 ( Fig. 9D’ ). In both sections the external lining of the cuticle must be added ( Figs. 9D’ and 9E’).

In both species, at midbody, an axis of orientation of the ridges cannot be identified in any of the sections because most ridges are oriented perpendicularly to the body surface.

In her comments, Smales [ 42] gives a rather detailed differential diagnosis against 41 genera from the Sahul region and Malaysia pointing that Flannerystrongylus is characterized by the absence of a gradient in ridge size and by a regular spacing of the ridges, this latter character being relatively rare in this group of Australasian genera. Both elements, subequal ridges and spaced regularly are found in the genus Equilophos , considered by Smales [ 42] as the most related morphologically, differing mainly from Flannerystrongylus by the number of ridges (more than 30 in Equilophos vs. 15 in Flannerystrongylus ).

3.9.2.2 Bursa

Flannerystrongylus abulus : the positions of Figures 12 and 15 in [ 42] do not follow the rules generally agreed in Zoology, i.e., that the animal should be drawn with the proximal part to the top of the page, which makes the comparison with other species easier. 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). It is based on the curvature of the lateral rays that we deduce that Figure 12 corresponds to the left lobe in ventral view and Figure 15 to the right lobe also in ventral view. From the written description, Figure 14 in [ 42] is in dorsal view since the left ray 8 is said to be larger than the right one.

Judging from the figures, there are three different arrangements of rays 8 with respect to the dorsal ray and the lateral lobes: (1) that on Figure 12, with left ray 8 diverging from the common trunk of rays 2-6; (2) that on Figure 14, with left ray 8 curved diverging from the dorsal ray just above the division of this latter and completely separated from ray 6, right ray 8 strongly curved, touching distally the right branch of the dorsal ray; (3) that on Figure 15, with right ray 8 not strongly curved, distant from the right branch of the dorsal ray.

Figure 14 matches the written description, whereas Figures 12 and 15, for different reasons, do not. We are not able to know if Figure 12 corresponds to another type of bursa, because the description provided is insufficient. The same observation applies to Figure 15, in which, for instance, the divergence of rays 2 and 3 is not observed. This may imply the presence of two or three different species among the type material. These bursae have a pattern of type 2-2-1.

Flannerystrongylus chisholmae : despite the incomplete description of the bursa, the pattern is clearly 1-4 on both lobes. On the left lobe, ray 3 diverges proximally to ray 6, this latter being joined to rays 4 and 5 up to their extremities. On the right lobe, rays 3 and 6 diverge at the same level from the common trunk of rays 3-6 and rays 4 and 5 are joined up to their extremities. In [ 43], Figure N shows the right ray 6 much shorter than right rays 4 and 5, in contradiction with the written description. Figures G and L match the written description, whereas Figure N does not.

3.9.3 Conclusion

In view of the very brief written description, the many problems with the illustrations of the synlophe, and the contradictory illustrations of the bursa, Flannerystrongylus abulus is considered a species inquirenda and, consequently, Flannerystrongylus a genus inquirendum. Flannerystrongylus chisholmae is also considered a species inquirenda due to its insufficient description.

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 9. Genus Flannerystrongylus Smales, 2019. Body sections. A–C Flannerystrongylus abulus Smales, 2019. A, A’ within proximal body, female. B, C at midbody. B male, C female. D–E’ Flannerystrongylus chisholmae Smales, 2020. D–E’ at midbody. D, D’ male. E, E’ female. Abbreviation: cu, cuticle. Sources: A–C redrawn from [42]; D, E redrawn from [43]. A’, B’, D’, E’: modified figures: A’ rotation clockwise, re-numbering of ridges with respect to the original. B’ rotation clockwise. D’, E’ addition of external cuticular lining. D’ re-numbering of ridges.