Mesocestoididae

Dumendiak, S., Halajian, A., Mekonnen, Y. T., Aschenborn, O., Camacho, G. J., Schuster, R. K., Mackenstedt, U., Romig, T. & Wassermann, M., 2024, Hidden diversity of cestodes in wild African carnivores: I. Non-taeniid cyclophyllideans, International Journal for Parasitology: Parasites and Wildlife 24, pp. 100929-100929 : 100929-

3.1.2. Mesocestoididae - Mesocestoides spp .

Three distinct sequences could be assigned to the family of Mesocestoididae : Mesocestoides sp. I was found in a serval ( Leptailurus serval ) from South Africa, Mesocestoides sp. II in two servals from South Africa, and Mesocestoides sp. III in two domestic cats from Ethiopia.

The complete nad1 (888 bp) and cox1 (1599 bp) genes were obtained from specimens of Mesocestoides spp . II and III, and of a European M. litteratus for comparative purposes, whereas only a 1006 bp long fragment of cox1 could be obtained from Mesocestoides sp. I . For the construction of a concatenated sequence tree including data from the NCBI data base, the nad1 and cox1 sequence lengths were reduced to 258 (plus one codon gap) bp and 373 bp, respectively ( Fig. 4 ). The reference species were M. litteratus (sequences obtained in this study), M. lineatus , M. corti and Mesocestoides spp . M1, M2 and M3 ( Varcasia et al., 2018) retrieved from GenBank. It should be noted that nad1 and cox1 sequences of M. lineatus are not derived from the same specimen, because the nad1 sequence corresponding to the cox1 isolate was too short (202 bp) (MH463537). However, this sequence and the nad1 sequence included in the phylogenetic tree, which was 261 bp, were 100% identical and both originated from V. vulpes in Slovakia (Hrˇckova et al., 2011). In the phylogenetic tree, which is based on the complete genes and allows for gaps and missing data, these two sequences of M. lineatus were included as separate isolates ( Fig. S3 ). Accepting missing data in the tree calculation also enabled the inclusion of Mesocestoides sp. I , whose close relationship with the Mediterranean M1 and M2 was confirmed, and the distinctness of the new Mesocestoides species II and III was emphasized.

Parts of the 12S rRNA (283 bp) and cob (479 bp) genes could only be sequenced from Mesocestoides sp. II and did not match closely with any Mesocestoides sequence in the NCBI GenBank. Fragments of the 18S rRNA gene were sequenced from both Mesocestoides sp. I (506 bp) and II (509 bp), both sequences are identical and because of its highly conserved nature, the comparison with GenBank entries remained inconclusive; the sequences matched several Mesocestoides species by> 99%.

The morphological description of Mesocestoides sp. I is based on early proglottids of a single incomplete specimen. Seven specimens of Mesocestoides sp. II and eight of Mesocestoides sp. III were available for examination. In all three species, the testes are located in the space between the longitudinal excretory vessels and are separated into two flanks by the female sexual organs. The testes may meet in the midline at the anterior end of the proglottid. Testes numbers varied depending on

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the maturity level of the segments. Between 24 and 30 testes per proglottid were counted in Mesocestoides sp. I , 40–57 for Mesocestoides sp. II and 28–34 in Mesocestoides sp. III. Cirrus sacks of all three species are round. Ovaries and vitellaria may reach the posterior margins of the craspedote segments in all three species. Worms of species II have short and stout gravid proglottids, reaching 1.4 mm width and 2 mm length. Those of species III are in comparison more slender, flatter and elongated in shape, with up to 1 mm width and 5 mm length. Mesocestoides sp. II tends to have distinctly serpentine uteri, those of Mesocestoides sp. III are mostly narrowly twisted around a linear axis in a corkscrew manner. A typical shape of the uterus of Mesocestoides sp. I could not be determined due to the singularity and prematurity of the material at hand.

Figures

Fig. 4. Maximum likelihood (GTR + G + I) phylogenetic tree based on 634 bp long concatenated sequences of nad1 (261 bp) and cox1 (373 bp). Eight lineages of Mesocestoides are included. The canine genotype of Dipylidium caninum is used as an outgroup. Respective GenBank accession numbers are added after the species name. Novel lineages are written in bold and colour. Bootstrap values> 50 (%) are included. The scale bar represents the estimated number of substitutions per site. Mesocestoides sp. I was omitted, as no nad1 sequence could be obtained.

Fig. 3. Morphological illustrations of Pseudandrya cf. mkuzii. A: Dorsal view of a mature proglottid. O = ovary, V = vitellarium, T = testes, SR = coiled seminal receptacle, C = cirrus sack, VS = internal vesicula seminalis. B: Egg with three thin envelopes around the oncosphere.