Catenotaenia pusilla ( Goeze, 1782 )

Haukisalmi, Voitto, Hardman, Lotta M. & Henttonen, Heikki, 2010, Taxonomic review of cestodes of the genus Catenotaenia Janicki, 1904 in Eurasia and molecular phylogeny of the Catenotaeniidae (Cyclophyllidea), Zootaxa 2489, pp. 1-33 : 8

Catenotaenia pusilla ( Goeze, 1782)

(Fig. 2)

Material examined: Three whole-mount specimens and sections from the house mouse Mus musculus (Muridae) ( MHNG 40381, 44883, 44886). Additional data for the relative positions of the genital pore and vitellarium and the number of uterine branches were extracted from the illustrations of Janicki (1906), Joyeux & Baer (1945) and Genov (1984), all of which were made from cestodes found in M. musculus .

Description (main features): Proglottids slightly craspedote; velum short. Mature and subsequent proglottids usually with convex margins, widest in mid-region or at genital pore. Genital pores positioned somewhat posterior to border between anterior and middle thirds of proglottid margin; relative anterior distance of genital pore 0.39–0.46 (0.42, n=5). Distinct marginal bulge associated with genital pore absent.

Longitudinal division of testicular field absent. Antiporal testes reaching level of mid-vitellarium, usually not overlapping ovary. When cirrus withdrawn, cirrus sac usually overlaps longitudinal canal but does not seem to extend across it.

Ovary asymmetrical, short relative to its width. Posterior part of ovary reaches level of mid-vitellarium. Free space separating ovary from anterior margin of proglottid of variable length (up to 376). Vitellarium shorter than wide. Midpoint of vitellarium positioned somewhat posterior to midline of proglottid; relative longitudinal position 0.58–0.63 (0.60, n=5). Vagina slightly curved, almost straight, merging seminal receptacle antero-porally. Uterus in pregravid proglottids with 9–17 (12.9, n=12) primary branches on each side; secondary and tertiary branches frequent. Outer egg membrane elongate.

Remarks: Tenora & Murai (1975) and Genov (1984) have suggested that C. pusilla is a host-specific parasite of M. musculus , rejecting the long-standing view of this species being a host-generalist. The hostspecific view is supported by the present study. The geographic distribution (based on the host-generalist view) included Eurasia, North America, Africa and Japan ( Spasskii 1951, Tenora 1959, Genov 1984). However, the occurrence of C. pusilla s. str. outside Europe and the former USSR has not been confirmed.

In the past, C. pusilla has been identified primarily on the basis of a low number of uterine branches and the “semioval” shape of its gravid proglottids. These features, combined with the characteristic shape of mature proglottids, enable a rather straightforward identification of C. pusilla . Catenotaenia gracilae Asakawa, Tenora, Kamiya, Harada & Borkovcova, 1992 has 13–25 uterine branches, which overlaps the corresponding range of C. pusilla (9–17), but the former species has distinctly craspedote mature proglottids that are widest posteriorly (vs. convex margins widest in the middle of the proglottid in C. pusilla ).

The present study revealed additional features that characterize C. pusilla . These are the lack of a marginal bulge of the genital pore (characteristic for most Catenotaenia ), the ovary is short compared to its width, the vitellarium is positioned rather posteriorly and the vagina is almost straight and merges with the seminal receptacle antero-porally. In most of the other species, the proximal vagina is strongly curved posteriad and merges with the seminal receptacle antero-medially or anteriorly.