Syphacia sp. (2) Site of infection: Caecum and large intestine Host species: Reithrodontomys gracilis Localities: Kuncheil cattle ranch (Yucatan) Specimens deposited: CNHE 12029‒30 Comments: The specimens found in R. gracilis had a cuticle with fine transverse striations, fields between transverse striations with shallow longitudinal depressions; a cephalic plate laterally-elongated in females; deirids present in females; cervical alae poorly developed (Figure 5H); lateral alae absent; male spicule 60 long; female tail 315‒550 long; females with not prominent vulva; and eggs 85‒108 long by 25‒ 35 wide (Figure 5I). Among the eight species of Syphacia with cervical alae (Sy. carlitosi, Sy. alata, Sy. obvelata, Sy. peromysci, Sy. samorodini, Sy. p. rauschi, Sy. sigmodoni, and Sy. hodarae), our specimens can be differentiated from Sy. carlitosi, Sy. alata, Sy. obvelata, Sy. samorodini, and Sy. hodarae by having deirids. In addition, the species from R. gracilis has a longer spicule than that of Sy. peromysci (57‒70), Sy. p. rauschi (56) and Sy. sigmodoni (64). Based on these findings, we consider that our specimens likely represent a new, undescribed Syphacia species. This is the first helminthological record for R. gracilis.

Published as part of Panti-May, Jesús Alonso, Moguel-Chin, Wilson Isaias, Hernández-Mena, David Iván, Cárdenas-Vargas, Miguel Humberto, Torres-Castro, Marco, García-Prieto, Luis, Digiani, Maria Celina, Hernández-Betancourt, Silvia F. & Vidal-Martínez, Víctor Manuel, 2023, Helminths of small rodents (Heteromyidae and Cricetidae) in the Yucatan Peninsula, Mexico: an integrative taxonomic approach to their inventory, pp. 205-240 in Zootaxa 5357 (2) on page 224, DOI: 10.11646/zootaxa.5357.2.3, http://zenodo.org/record/10017978