Taenia rileyi Loewen, 1929

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, Zootaxa 5357 (2), pp. 205-240 : 214

Taenia rileyi Loewen

(= Taenia lyncis Skinker )

Site of infection: Liver

Host species: Sigmodon toltecus

Locality: Kuncheil ranch (Yucatan)

Specimens deposited: CNHE 11977

Comments: Each cyst contained one small, poorly developed metacestode 1.5‒2.8 mm long (without bladder). The metacestodes examined in this study showed characters which agreed with descriptions given by Mollhagen (1979) from S. hispidus, Rausch (1981) from Myodes rutilus (Pallas) and Tamiasciurus hudsonicus (Erxleben) , and the updated revision of the genus Taenia ( Loos-Frank 2000) , i.e., invaginated scolex with four suckers 140 long by 160 wide and rostellum with 2 crowns of 19‒20 hooks each ( Figure 3E ), longer hooks 240 in length and smaller hooks 190‒205 in length ( Figure 3F ).

While some studies have reported strobilocercus larvae for T. rileyi ( Grundmann 1958; Mollhagen 1979), other studies refer to it as cysticercus ( Mahrt & Soo-Jeet 1972; Mollhagen 1978). There is considerable confusion on the form of larval T. rileyi due to the different levels of development of the strobilization. Since strobilization might easily interpret an evaginated cysticercus of T. rileyi, Mollhagen (1979) suggested not considering it as the sole diagnostic criterion. In Mexico, metacestodes of Hyd. taeniaeformis have also been reported in the liver of cricetid and murid rodents ( Preisser & Falcón-Ordaz 2019; Panti-May et al. 2021). However, the length of large hooks of Hyd. taeniaeformis is larger than those of T. rileyi .

The only record of T. rileyi in Mexico was reported by Flores-Barroeta (1966) in Canis familiaris Linnaeus from Mexico City. Our study reports T. rileyi for the first time in rodents from Mexico.

Figures

FIGURE 3. A. Scolex of Raillietina sp. (1) from Sigmodon toltecus, apical view. B. Scolex of Hymenolepis sp. from Heteromys gaumeri, dorsoventral view. C. SEM micrograph of scolex of the metacestode of Hydatigera taeniaeformis from Sigmodon toltecus, apical view. D. Large and small rostellar hooks of the metacestode of Hydatigera taeniaeformis from Sigmodon toltecus, lateral view. E. SEM micrograph of scolex of the metacestode of Taenia rileyi from Sigmodon toltecus, apical view. F. Large and small rostellar hooks of the metacestode of Taenia rileyi from Sigmodon toltecus, lateral view.