Dipylidiidae, Stiles, 1896

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-

3.1.3. Dipylidiidae - Dipylidium sp.

From the Dipylidium specimen found in an aardwolf ( Proteles cristata ) from South Africa, a cox1 (1647 bp) and nad1 (894 bp) sequence as well as the front part of cob (472 bp) and a fragment of the 18S rRNA gene (468 bp) were obtained. The novel sequence represents the earliest branching lineage within the Dipylidium clade in all the phylogenetic trees ( Figs. 1 and 6 , Supplementary Figs. S1 , S 4 , and S5). Based on the phylogenetic tree constructed with concatenated mitochondrial sequences, the novel Dipylidium sp. and D. caninum (canine and feline genotypes) form a sister clade to two Joyeuxiella spp . (q.v. 3.1.4.) which is, however, not strongly supported ( Fig. 6 and S 4 ). This sister-clade relationship cannot be seen when only cox1 is analysed ( Fig. 1 and

S1), nor in the 18S rRNA tree ( Fig. S5 ).

Two gravid proglottids of a single poorly conserved worm were available for morphological examination. No scolex was found. Width of the gravid proglottids is between 1.8 and 2.1 mm, length up to 5 mm. The two genital openings are equatorial, the cirrus sack (about 130 μm long within gravid proglottids) is positioned anterior to the female genital opening. Seminal receptacles are regressed but still visible in the gravid proglottids. The eggs fill the complete proglottid, crossing the longitudinal excretory ducts. However, in contrast to Dipylidium caninum , they are not clearly sorted into multi-ovular packets. Hexacanth embryos are 15–18 μm in diameter and are encapsulated in two visible envelopes. The inner membrane surrounding the embryo measures 18–22 μm in diameter. The very thin and oval outer membrane (egg capsule) ranges 26–37 μm by 24–28 μm. Apart from being more oval and slightly smaller in size, the egg capsules are similar to those found in Joyeuxiella spp . ( Fig. 5 ).

Figures

Fig. 1. Maximum likelihood (GTR + G + I) phylogenetic tree based on a 355 bp long fragment of cox1. 28 species of cyclophyllidean cestodes are included, Spirometra theileri 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> 70 (%) are included. The scale bar represents the estimated number of substitutions per site.

Fig. 6. Maximum likelihood (GTR + G + I) phylogenetic tree based on 2768 positions of concatenated sequences of cob (469 bp), cox1 (1560 bp) and nad1 (739 bp). 13 species of cyclophyllidean cestodes are included, Spirometra theileri 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.

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. 5. Morphological illustrations of different ovarious structures in gravid proglottids of Dipylidium caninum, Dipylidium sp. and Joyeuxiella sp. III. P = egg packet, C = egg capsule, M = oncospheral membrane, H = hexacanth embryo.