Paracamallanus cyathopharynx (Baylis, 1923) Syns.

Nofal, Ashlee P., Dos Santos, Quinton M., Jirsa, Franz & Avenant-Oldewage, Annemari`e, 2022, Camallanid nematodes from Clarias gariepinus (Burchell, 1822) in the Crocodile River, Gauteng, South Africa: Exploring diversity and divergence in an acid-mine drainage impacted environment, International Journal for Parasitology: Parasites and Wildlife 19, pp. 196-210 : 204-205

3.3. Paracamallanus cyathopharynx morphological re-evaluation

Based on the CO1 mtDNA genetic variation observed for Paracamallanus samples, their morphometry was revisited using statistical analyses to identify distinguishable traits between specimens to differentiate between the two lineages. Two suspected morphotypes were observed pertaining to the buccal capsules of Paracamallanus specimens (supplementary file G). In Fig. 8 , the isolated buccal capsules of the two suspected morphotypes can be seen using both LM (brightfield and fluorescence) and SEM. The most distinct trait is the shape of the anterior and posterior capsules ( Fig. 8A (iii), 8 B(iii)), which are elliptical (wider than long) in morphotype A and more rectangular (longer than wide) in morphotype B. Further, morphotype A has large tridents which extend past the anterior part of the posterior capsule, reaching the posterior part ( Fig. 8A (ii)). In comparison, in morphotype B, the tridents extend approximately three-quarters down the anterior part of the posterior capsule and do not reach the posterior part ( Fig. 8B (ii)). Nine

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ridges were observed in both morphotypes. However, the central ridge of morphotype A was less conspicuous and shorter than in morphotype B. Both morphotypes were observed in males and females. Most female specimens with morphotype A (elliptical buccal capsules) were ovigerous (subgravid) and morphotype B (rectangular buccal capsules) females were larvigerous (gravid). Similarly, the differences in buccal capsules are suspected to be related to maturity in males, but this could not be distinguished.

By overlaying the PCA plot generated using all morphometric ratios with suspected buccal capsule morphotypes and CO1 lineages, definite separation is seen between males and females due to sexual dimorphism ( Fig. 9A ). Eigenvalues were high as the plot explains 82.55% of the total variation with 20.42% on the x-axis and 62.13% on the y-axis. However, only a few specimens could be accurately traced back to their respective lineages. There was no clear indication of a relationship between buccal capsule morphotype and CO1 lineages, with all females sharing morphotype A but representing both lineages. Notably, F13 appears to be a morphological outlier but shares the same lineage as F12 and F15. Similarly, the PCA plot in Fig. 9B , based on only buccal capsule ratios overlayed with morphotype and lineage data, does not show any consistent pattern or grouping. Unlike in the first plot, data is randomly scattered with no specific morphometric drivers. Eigenvalues were lower as the plot explains 70.83% of the total variation with 19.34% on the x-axis and 51.49% on the y-axis. Again, no clear relationship between buccal capsule morphotype and CO1 lineages was observed.

Figures

Fig. 8. Lateral view of isolated buccal capsules of Paracamallanus specimens, morphotypes A and B. (i). Brightfield. (ii). Epifluorescence [Filter-set 09 (Ex. 470/40)]. (iii). SEM. 1 = anterior part of posterior capsule; 2 = posterior part of posterior capsule; t = trident; ellipse = elliptical shape of capsule; rectangle = rectangular shape of capsule.

Fig. 9. Principal Component Analyses (PCA) of Paracamallanus morphometry collected from Clarias gariepinus (Burchell, 1822). A- PCA using morphometric ratios for both males and females. B- PCA using buccal capsule ratios for both males and females. Each parasite is indicated as a dot, with the fill, shape and colour corresponding to morphotype and lineage (refer to key). F = female; M = male.