Mawsonema mokwanense Smales & Heinrich 2010
Creators: name: Durette-Desset, Marie-Claude
name: Digiani, María Celina
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Chromadorea
Rhabditida
Heligmosomidae
Mawsonema
Mawsonema mokwanense

description: 3.2.1 Analysis of data and difficulties encountered Mawsonema mokwanense
3.2.1.1 Synlophe (based on sections from 10 worms, sex not specified)
Sections analyzed herein are within proximal body: male (Fig. 21/2A) and female (Fig. 23/2F), at midbody: male (Fig. 24/2B) and female (Fig. 27/2C), and within distal body: male (Fig. 28/2D) and female (Fig. 33/2E). Lateral cords illustrated in all figures and ridges numbered in Figures 21/2A and 23/ 2F. Axis of orientation described as subfrontal in [45] within proximal part, lacking orientation in middle and distal part.
Within proximal body (male): in Figure 2A, careen absent; 15 ridges small to minute, regularly spaced; presence of gap on right-dorsal quadrant (arrowhead). Most ventral ridges perpendicular to body surface; dorsal ridges oriented from right to left. Excretory glands observed in dorsal position.
At midbody (both sexes): in Figures 2B and 2C, careen absent; 15 minute ridges regularly spaced. In Figure 2B (male), on left-dorsal quadrant, small dilatation present supported by two ridges whose tips are slightly divergent (curved arrows). Remaining ridges perpendicular to body surface. Figure 2C (female), on dorsal, right-dorsal quadrant, presence of 2 minute ridges pointing to opposite directions (curved arrows); remaining ridges oriented mainly from right-dorsal to ventral side.
Within distal body (both sexes): in Figures 2D and 2E, careen absent; in Figure 2D (male) 14 ridges, in Figure 2E (female) 16 ridges minute and regularly spaced. Most ridges apparently perpendicular to body surface although in female, presence of small, mid-ventral dilatation supported by seven ridges including two with tips apparently divergent (curved arrows).
Within proximal body (female): in Figure 2F, careen present (curved arrows on the left), made up of two ridges of which dorsal one larger than ventral one; 13 ridges (including careen) medium-sized to minute, almost regularly spaced, except for large gap on left-ventral quadrant (arrowhead). Tips of ridges 8 and 4’ divergent (curved arrows on the right); tip of ridge 5’ perpendicular to body surface. Remaining ridges oriented from right to left on dorsal and ventral sides. Axis of orientation of ridges oriented few degrees above frontal axis on right side, below frontal axis on left side.
3.2.1.2 Bursa (based on 12 worms, illustrated in [45]: Figs. 32, 34 and 37)
Figure 32: entire bursa partially unfolded, orientation not specified. Figure 34: distal part of rays 8 and dorsal ray, orientation not specified; rays not illustrated up to base. Figure 37: entire bursa closed showing ventral rays.
From the written description [45]: bursa dissymmetrical with left lobe larger than right one and pattern of type 2-3 in both lobes.
3.2.2 Comments
3.2.2.1 Synlophe
Within the proximal part of the body, in the male section (Fig. 2A) the dorsal position of the excretory glands seems at first sight unlikely since these glands reach the excretory pore, which is ventral by definition. However, the position of the excretory glands may be dorsal if the level of the section is distant enough from the excretory pore. Based only on the position of these glands, and without information on the exact level of the section, we cannot know if the dorso-ventral orientation of the section is right or not. Nevertheless, if Fig. 2A is reversed on its frontal axis (Fig. 2A’), the gap becomes right-rightventral, as it is frequent in the Nippostrongylinae (arrowhead). Despite this reversion, there are still no groups of ridges oriented in opposite directions, and consequently it is not possible to determine an axis of orientation of the ridges.
At midbody and within distal part of body (Figs. 2B–2E), except for the presence of a pair of clearly divergent ridges in Figure 2C, the orientation of the ridges is rather disparate and it is likely that most ridges are in fact oriented perpendicularly to the body surface. The reason for the absence of an axis of orientation in these sections is the perpendicular orientation of the ridges, not a “loss of orientation” of these latter (as interpreted in [47].
Within the proximal part of another female (Fig. 2F), several elements allow us to suggest that the original orientation of the section is erroneous: (1) the axis of orientation of the ridges is oriented from right dorsal side from left ventral side; (2) the dorsal ridge of the careen is larger than the ventral one; (3) the largest ridges are dorsal in position; and (4) dorsal ridges are more numerous than the ventral ones.
Usually, in the Nippostrongylinae, (1) the axis of orientation of the ridges is oriented from the right-ventral to the left-dorsal quadrant or, at most, subfrontal; (2) when the ridges of the careen are unequal in size, the ventral ridge (1’) is always the largest; (3) other developed ridges are in mid-ventral or left-ventral position (never mid-dorsal); and (4) the ventral ridges are usually more (or as) numerous than the dorsal ridges.
For the orientation to be accurate, Figure 2F should be reversed on its frontal axis (Fig. 2F’). In the re-oriented section, the axis of orientation of the ridges becomes subfrontal, it is determined by ridges 4 and 8’ (divergent) on the right (ridge 5 being perpendicular to body surface) and 1 and 1’ (convergent) on the left (curved arrows).
Smales & Heinrich [45] stated in the “Remarks”: “ Mawsonema n. gen. has all the characteristics of the subfamily Nippostrongylinae except that the orientation of synlophe ridges exceeds the range given by Durette-Desset [4]”. We believe that the “range” to which the authors refer is the range of the inclination of the axis of orientation of the ridges which, following [4], in the Nippostrongylinae ranges between 45° and 67° to the sagittal axis. However, since 1983, the separation of subfamilies based only on the inclination of the axis of orientation has become less reliable since, based on more recent data, the inclination of the axis in the Nippostrongylinae actually ranges from 25° to 90° to the sagittal axis, a range which overlaps with that of the Pudicinae and the Brevistiatinae [1].
Nevertheless, we interpret the “exceptional” inclination (below the frontal axis) alleged by Smales & Heinrich [45] in Mawsonema as a misinterpretation of the orientation of the section 2F (treated above).
3.2.2.2 Bursa
In Figure 32, judging from the bursal shape and the position of the drawing strokes, the bursa is in ventral view. The ray bases are not illustrated. In Figure 37, only the divergence of rays 2 and 3 is illustrated.
Without description or illustration of the origin or level of divergence of rays 4-6 and 8, the bursal pattern cannot be confirmed.
3.2.3 Conclusion
3.2.3.1 Synlophe
Smales & Heinrich [45] studied the synlophe on 10 specimens but only 6 body sections were illustrated. It is not indicated if all body sections provided were taken from six different worms or made at different levels on one male and one female. Anyway, it is possible to state that the female synlophe illustrated on Figure 2F is very different from the others by having a well-developed careen, leading us to suggest that two different genera are present within the studied material. Based on the elements listed above, two types of synlophe could be described:
Type I: characterized by the absence of careen along whole body. With 15 ridges in male, 17 in female at mid-body, 15 in male, 16 in female within distal part. Ridges subequal, minute and regularly spaced. Within proximal part, ventral and left-ventral ridges oriented from right to left. At midbody and within distal part of body, no axis of orientation, most ridges being apparently perpendicular to body surface (Figs. 2A–2E).
Type II: Only represented by a female section within proximal part of body (Fig. 2F). Characterized by a careen supported by two small ridges. With 13 ridges including the careen. Gap present on left-dorsal quadrant. Ridges of right-ventral quadrant most developed, but not larger than the ridges of the careen. Axis of orientation probably subfrontal.
3.2.3.2 Bursa
From the illustrations and the written description, it is not possible to confirm the pattern of the bursa. Twelve worms were studied but only one is described and illustrated, whereas two types of synlophe have been highlighted. We have no data to attribute the described bursa to a given type of synlophe.
There seem to be two taxa concerned in the description of this species (each characterized by a different synlophe): “ M. mockwanense ” and a Nippostrongylinae i.s. 1. Since we do not know what type of synlophe the holotype corresponds to, Mawsonema mokwanense is considered a species inquirenda. Being the type species of the genus, it is impossible to give a precise definition of it. We thus consider Mawsonema a genus inquirendum.
description: Published as part of Durette-Desset, Marie-Claude & Digiani, María Celina, 2023, Revision of the genera of Heligmonellidae (Nematoda, Heligmosomoidea), parasitic in Muridae from New Guinea, pp. 1-34 in Parasite (Paris, France) (Paris, France) 30 (63) on pages 9-10, DOI: 10.1051/parasite/2023058, http://zenodo.org/record/12628842