Hydatigera Lamarck, 1816

Sasaki, Mizuki, Anders, Jason Lee & Nakao, Minoru, 2021, Cestode fauna of murid and cricetid rodents in Hokkaido, Japan, with assignment of DNA barcodes, Species Diversity 26, pp. 255-272 : 266

Genus Hydatigera Lamarck, 1816 9. Hydatigera taeniaeformis ( Batsch, 1786)

The bladder cysts of Hydatigera taeniaeformis , each containing a strobilocercus larva, were found from the liver of My. rufocanus in Asahikawa and Ra. norvegicus in Nayoro and Kushiro ( Fig. 9B ). The morphometric feature of the strobilocercus is as follows: Whole body 3.6–5.4 long by 2.8–3.6 wide (n=3). Scolex armed with 36 hooks. Large hooks 0.444 –0.450 long (n=10), 19 in number. Small hooks 0.268 –0.271 long (n=10), 19 in number. The cox 1 sequences of the strobilocerci (nos. Ces05 and O22) showed 99.2% similarity (923 out of 930 nucleotides identical) to that of Hyd. taeniaeformis from China (accession no. FJ597547 ) (Liu et al. 2011).

The former Hyd. taeniaeformis sensu lato is a cryptic species complex, including Hyd. taeniaeformis and Hydatigera kamiyai Iwaki, 2016 ( Galimberti et al. 2012; Jia et al. 2012; Nakao et al. 2013; Lavikainen et al. 2016). Both species prevail in Hokkaido, using domestic cats and rodents as definitive and intermediate hosts, respectively ( Iwaki et al. 1993; Asakawa and Fukumoto 1997; Okamoto et al. 2007). In general, the host specificity of both species is strict in selecting intermediate hosts, namely, murids (e.g., R. norvegicus ) for Hyd. taeniaeformis and cricetids (e.g., My. rufocanus ) for Hyd. kamiyai ( Nonaka et al. 1994; Iwaki et al. 1994a; Lavikainen et al. 2016). However, in this study, fully developed strobilocerci of Hyd. taeniaeformis were found from cricetids.

In Japan, the adult tapeworms of Hyd. taeniaeformis sensu lato have been found from the following carnivores: the cat, Felis catus Linnaeus, 1758 ; the dog Canis lupus familiaris Linnaeus, 1758 ; the Tsushima leopard cat, Prionailurus bengalensis euptilurus (Elliot, 1871) ; the raccoon, Procyon lotor ( Linnaeus, 1758) ( Oishi and Kume 1973; Yagisawa 1978; Uga et al. 1983; Matoba et al. 2003; Yasuda et al. 2005). A special attention should be paid to the raccoon, an invasive species from North America, because it is now increasing in number in Hokkaido ( Ikeda et al. 2004). Both Hyd. taeniaeformis and Hyd. kamiyai are also alien species probably due to the anthropogenic movement of domestic cats or commensal rodents into Japan ( Lavikainen et al. 2016).

Figures

Fig. 9. Larvae of the family Taeniidae. A, The proliferated cysticerci of Taenia crassiceps in the subcutaneous tissue of Myodes rufocanus; B, the strobilocercus of Hydatigera taeniaeformis from the liver of Rattus norvegicus; C, the disseminated alveolar hydatid of Echinococcus multilocularis in peritoneal organs of My. rufocanus. Scale bars: 20mm.