Pomphorhynchus tereticollis (Rudolphi, 1809)

Reier, Susanne, Sattmann, Helmut, Schwaha, Thomas, Harl, Josef, Konecny, Robert & Haring, Elisabeth, 2019, An integrative taxonomic approach to reveal the status of the genus Pomphorhynchus Monticelli, 1905 (Acanthocephala: Pomphorhynchidae) in Austria, International Journal for Parasitology: Parasites and Wildlife 8, pp. 145-155 : 149-150

3.1.2. Pomphorhynchus tereticollis

Eight juvenile specimens obtained from different fish species in Styria ( Table 1) were assigned to the species P. tereticollis . Since Špakulová et al. (2011) provided data of juvenile specimens of the subadults differed only in trunk size, the remaining measurements were combined for both life stages. Averaged measurements are given in parentheses .

Measurements are in µm unless otherwise stated.

*not present in every specimen.

original Rudolphi type material in their re-description of P. tereticollis , we were able to compare our results even though we only had juvenile material at hand. The assignment was not possible with conventional light microscopy as the extensions on the basal hooks of the proboscis were not visible after fixation. Subsequently, confocal laser scans were performed, which visualized the species-specific extensions on the basal hooks and showed the posterior branching of the basal hook roots ( Fig. 2 A , Fig. S1 ). Remarkably, this species was the only representative of the genus whose hooks were autofluorescent. Therefore, for a better comparability with the other two species, we performed a 3- D reconstruction of a hook row of the sectioned proboscis ( Fig. 2 D ). This method also showed the extensions on the basal hooks with exception of basal hook no. 10 for which it was not possible to depict the extension in the general view ( Fig. 2 D ). However, the extensions of these last hooks are visible in Fig. 2 A and Fig. S1 . The examined specimen had 16 longitudinal rows of hooks on the proboscis. The proboscis had an ovoid shape armed with ten hooks per row. The five anterior hooks were stout while the four basal hooks were smaller. Last circle of basal hooks was located on the anterior part of the bulb, a species-specific trait known for P. tereticollis ( Špakulová et al., 2011) .

Figures

Fig. 2. Proboscis and longitudinal row of hook roots of the three determined Pomphorhynchus species. All images are volume rendering of the 3-D stacks. In volume rendering each grayscale value is assigned a color according to an arbitrary colormap. The depiction depends on which values and how transparent they are displayed. In the present images a glow color map is used, which assigns graded colors from black (background) to shades of red-orange-yellow. A. Volume rendering of a confocal laser scan image stack of the proboscis of P. tereticollis. B. Volume rendering of the sectioned proboscis of P. bosniacus including reconstructed hooks as surface rendering. C. Volume rendering of the sectioned proboscis of P. laevis including reconstructed hooks as surface rendering. D-F. Internal view of the sectioned proboscids including a single longitudinal row of hooks. D. P. tereticollis. E. P. bosniacus. F. P. laevis. Legend: Red arrow = last circle of hooks; green arrow = extensions on basal hook roots of P. tereticollis; blue arrow = basal hooks attached in the middle of hook roots of P. bosniacus; yellow arrow: lack of extensions on basal hook roots of P. laevis. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 1. Map showing European rivers relevant for the present study. The study area in Austria is highlighted in grey. Localities of P. bosniacus are indicated as circle, the one of P. tereticollis as asterisk and the one of P. laevis as square. Different sizes are indicating higher or lower abundances.