Hymenolepis sp.

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 : 213-214

Hymenolepis sp.

Site of infection: Small intestine

Host species: Heteromys gaumeri

Locality: Hobonil ranch (Yucatan)

Specimens deposited: CNHE 11975

GenBank accession numbers: OR271652‒ OR271654

Comments: The morphological characteristics observed in our specimens agreed with those established for the genus Hymenolepis (sensu stricto) ( Czapliski & Vaucher 1994), i.e., scolex with unarmed rostellum ( Figure 3B ); three testes separated in two groups by female gonads; ovary wide, median, lobed, fan shaped, and ventral to male genital organs; vitelline gland compact and median; cirrus-sac short, not reaching middle of proglottid; uterus labyrinthine. In North America, 11 species of Hymenolepis occur in sciurid, arvicoline, geomyid, and neotomine rodents ( Rowan et al. 2023): Hymenolepis diminuta (Rudolphi) , Hymenolepis citelli (McLeod) , Hymenolepis scalopi Schultz , Hymenolepis pitymi Yarinsky , Hymenolepis tualatinensis Gardner , Hymenolepis weldensis Gardner & Schmidt , Hymenolepis geomydis Gardner & Schmidt , Hymenolepis robertrauschi Gardner, Luedders & Duszinski , Hymenolepis folkertsi Makarikov, Nims, Galbreath & Hoberg , Hymenolepis crateogeomyos Gardner, Dursahinan, Campbell & Rácz , and Hymenolepis ackerti Rowan, Hope & Jiménez. The species found in H. gaumeri has a scolex with rostrum-like projection, which allows us to differentiate it from Hy. diminuta , Hy. citelli , Hy. crateogeomyos , Hy. ackerti , Hy. weldensis , Hy. geomydis , Hy. scalopi , and Hy. robertrauschi . Our specimens can be differentiated from the other three species that posse a scolex with rostrum-like projection, Hy. tualatinensis , Hy. folkertsi and Hy. pitymi , by several characteristics, such as a wider scolex (255‒330 vs 92‒167 in Hy. tualatinensis , 168 in Hy. folkertsi , and 159 in Hy. pitymi ), a longer rostellar pouch (70‒115 vs 51‒61 in Hy. tualatinensis and 67 in Hy. folkertsi ), and larger suckers (120‒140 x 90‒130 vs 93‒102 x 70‒86 in Hy. folkertsi and 66‒92 x 37‒45 in Hy. pitymi ). Moreover, Hy. tualatinensi and Hy. pitymi parasitize geomyid and cricetid rodents, respectively. Phylogenetic analysis showed that Hymenolepis from H. gaumeri and Hy. folkertsi were sister species (see results below). Considering the above mentioned, the specimens found in H. gaumeri likely represent a new, undescribed Hymenolepis species.

In Mexico, unidentified species of Hymenolepis have been reported from other heteromyid rodents such as H. irroratus in Puebla and Queretaro ( García-Prieto et al. 2012) and Dipodomys merriami Mearns in Zacatecas ( Martínez-Salazar et al. 2016). This is the first record of Hymenolepis in H. g aumeri.

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.