Due to limited knowledge regarding the diversity of parasitic helminths of the common gundi (Ctenodactylus gundi), we have undertaken a helminthological survey of the gundi in Southern Tunisia. A total of 125 gundis were analysed with the main objective of providing more complete descriptions of their parasitic helminths. Among them, two nematodes, namely Ctenodactylina tunetae Bernard, 1969 (Pharyngodonidae) and Hilgertia hilgerti (Seurat, 1915) (Oxyuridae), were recovered from the large intestine and caecum. Morphological and morphometric analyses of both species were carried out using light microscopy and, for the first time, scanning electron microscopy. These nematodes were found in the large intestine and caecum with prevalences of 28.80% for C. tunetae and 55.20% for H. hilgerti. Moreover, both nematodes usually coinfect gundis, with 22.40% of hosts harbouring both species simultaneously. Our morphological and morphometric results are compared with those of previous studies. One of the most interesting results concerns the sexual dimorphism at a buccal level observed in C. tunetae, related to cephalic papillae (rounded in males; rectangular in females), lip lobes (bilobed in males; trilobed in females), and oesophageal teeth (semiarc-shaped in males; double semiarc-shaped in females). In conclusion, this study provides further knowledge of these two nematodes, as well as novel data regarding the sexual dimorphism present at the oral level.

Psammomys obesus is a diurnal herbivorous rodent widely distributed across the arid regions of North Africa and the Arabian Peninsula. Although it has ecological, agricultural, public-health, and biomedical importance, its helminth fauna remains poorly known. This study provides the first inventory of helminth parasites infecting P. obesus in southern Tunisia and examines variations in parasitism according to host sex, age, body condition and sampling region. A total of 152 specimens of P. obesus were captured between September 2023 and March 2026 in Tamaghza and Djebel Dahar regions. Parasitological examination revealed four helminth species: three cestodes, Sudarikovina aegyptica, Gerbillitaenia psammomi and Mesocestoides sp. larvae, and one nematode, Syphacia sp. Their respective prevalences were 63.82%, 12.50%, 0.66% and 16.45%. The findings of Mesocestoides and Syphacia species represent new records for P. obesus. Furthermore, S. aegyptica constitutes a new record for Tunisia. Host age and sampling region significantly influenced the occurrence and abundance of G. psammomi, as adults were more likely to be infected and harbored a significantly higher parasite burden than juveniles. In contrast, host sex and body condition had no significant effect. For S. aegyptica and Syphacia sp. no significant association was found between parasite occurrence or abundance and the host’s sex, age or body condition.

In this study, the ultrastructural characteristics of the mature spermatozoon of the cestode Gerbillitaenia psammomi, a parasite of the fat sand rat (Psammomys obesus) in the south of Tunisia, were examined by means of transmission electron microscopy. The spermatozoon is of Levron et al.’s type VI. This type of sperm cell is mainly characterized by the presence of a single axoneme of the 9 + ‘1’ pattern typical of the trepaxonematan Platyhelminthes, crest-like bodies, a periaxonemal sheath, twisted cortical microtubules, and a spiraled nucleus. The spermatozoon of G. psammomi possesses two crest-like bodies of different length. The results obtained in the present study suggest certain similarities with the remaining analyzed catenotaeniids; namely, Catenotaenia pusilla, Skrjabinotaenia (Meggittina) gerbilli, and Spasskijela lobata. The results are compared and discussed according to several characteristics found in the catenotaeniids and other studied cestodes, particularly those of the order Cyclophyllidea.

Psammomys obesus is a diurnal herbivorous rodent widely distributed across the arid regions of North Africa and the Arabian Peninsula. Although it has ecological, agricultural, public health, and biomedical importance, its helminth fauna remains poorly known. This study provides a comprehensive inventory of helminth parasites infecting P. obesus in southern Tunisia and examines variations in parasitism according to host sex, age, body condition, and sampling region. A total of 152 specimens of P. obesus were captured between September 2023 and March 2026 in the Tamaghza and Djebel Dahar regions. Parasitological examination revealed four helminth species: three cestodes, Gerbillitaenia psammomi, Sudarikovina aegyptica, and Mesocestoides sp. larvae, and one nematode, Syphacia sp. Their respective prevalences were 63.8%, 12.5%, 0.7%, and 16.4%. The species are morphologically described, and genetic data and a phylogenetic tree are provided for Syphacia sp. The findings of Mesocestoides and Syphacia species represent new records for P. obesus. Furthermore, S. aegyptica constitutes a new record for Tunisia. Host age and sampling region significantly influenced the occurrence and abundance of G. psammomi, as adults were more likely to be infected and harbored a significantly higher parasite burden than juveniles. In contrast, neither host sex nor body condition was significantly associated with parasite occurrence or abundance. No significant association between parasite occurrence or abundance and the host’s sex, age, or body condition was found for S. aegyptica and Syphacia sp.