Catenotaenia apodemi, Haukisalmi, Voitto, Hardman, Lotta M. & Henttonen, Heikki, 2010

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 : 13-15

Catenotaenia apodemi n. sp.

(Fig. 6)

Material examined: Five gravid specimens: four from the Korean field mouse Apodemus peninsulae (Thomas) from the Republic of Buryatia ( Russian Federation) and one from Apodemus uralensis (Pallas) from the Lower Tunguska River, North-Central Siberia ( Russian Federation). For the distribution and prevalence of C. apodemi (as Catenotaenia sp. 2) in Buryatia, see Haukisalmi et al. (2009).

Site: Small intestine.

Deposited specimens: Holotype, USNPC 102592 from A. peninsulae from Kamensk, Buryatia (51.58007o N, 106.35188o E). Paratypes (3 slides), USNPC 102593, other information as in the holotype. Voucher specimen, USNPC 102594 from Apodemus uralensis from near Podvoloseno, Russia (58.63955o N, 108.48993o E) and MSB Endo 158 from A. peninsulae from Kamensk, Buryatia.

Description: Length of fully gravid specimens 48–62 mm (n=4); maximum width 0.81–0.85 mm (n=4), attained in gravid proglottids. Number of proglottids 28–36 (n=4). Scolex 280–380 (345, n=5) wide, slightly flattened dorso-ventrally, sometimes with slight apical cone or bulge. Neck rather short (430–550, 486, n=5), of roughly uniform width, 185–300 (262, n=4) wide immediately posterior to scolex. Suckers 138–170 (153, n=5) in diameter, directed laterally or antero-laterally, embedded within scolex.

Proglottids acraspedote or "pseudocraspedote"; "velum" very short or absent. Mature proglottids longer than wide; of rather uniform width or widest in mid-region. Gravid proglottids of roughly uniform width, widest in mid-region or at genital pore. Length and length/width ratio of proglottids increase posteriad: immature proglottids 300–620 (454, n=8) long, with length/width ratio of 0.79–1.55 (1.08, n=8); mature proglottids 1.1–2.0 mm (1.54 mm, n=12) long, with length/width ratio of 1.62–3.20 (2.49, n=12); fully gravid proglottids 2.7–3.4 mm (n=3) long, with length/width ratio of 3.55–4.05 (n=3).

Genital pores irregularly and frequently alternating, with average of 60.8 changes per 100 proglottids or 1.65 (1–4) proglottids per unilateral set. Genital pores usually positioned roughly at border between anterior and middle thirds of proglottid margin; relative anterior distance of genital pore 0.30–0.34 (0.308, n=5).

FIGURE. 6. Catenotaenia apodemi n. sp. from Apodemus peninsulae (A–F, H) and A. uralensis (G). A, scolex and neck (scale bar 0.30 mm). B, immature proglottids (scale bar 1.0 mm). C, mature proglottids (scale bar 1.0 mm). D, E, uterus in pregravid proglottid (scale bars 0.50 mm). F, G, mature proglottid (scale bars 0.30 mm). H, egg (scale bar 0.020 mm).

Genital pores without marked marginal bulge.

Ventral longitudinal osmoregulatory canals 23–35 (23.5, n=8) wide; transverse connecting canals present in posterior margin of proglottid. Dorsal longitudinal osmoregulatory canals absent. Terminal genital ducts pass longitudinal canal dorsally.

Number of testes 70–90 (n=4), their diameter 65–103 (81, n=10). Testes situated posterior to female glands, confined by longitudinal canals, dorso-ventrally in 2–3 layers. Testicular field may be deeply divided longitudinally. Testes may slightly overlap ovary, antiporal testes sometimes reaching level of midvitellarium. Testicular field covers 44–54% (51, n=5) of proglottid length. Cirrus sac pyriform, with rather well-developed muscle layers; length in mature proglottids 120–150 (n=2). Cirrus sac does not usually overlap longitudinal canal. Internal seminal vesicle absent, although slightly expanded reservoir may be present in proximal cirrus sac. Distal vas deferens slightly twisted or looped, covered by thick continuous cell layer. Proximal vas deferens curved posteriad, sometimes slightly looped, not covered by cell layer. Ductus cirri provided with short spines; everted cirrus unarmed.

Ovary lobulated, asymmetrical, confined by longitudinal canals. Free space separating ovary from anterior margin of proglottid of variable length, usually short - 25–125 (76, n=5). Length of ovary 0.72–1.13 mm (0.97 mm, n=5), maximum width (in anterior part) 345–440 (407, n=5). Ovary extends significantly more posteriad than posterior edge of vitellarium, partly surrounding it. Ovary covers 55–63% (58%, n=5) of proglottid length. Vitellarium sparsely lobulated and irregularly shaped. Vitellarium usually longer than wide; length 230–300 (254, n=5) and width 190–230 (205, n=5). Vitellarium positioned usually slightly anterior to middle of proglottid; relative position 0.41–0.50 (n=9). Mehlis' gland ovoid or spherical, 90–120 (n=4) in diameter, median with respect to mid-line of vitellarium. Vagina opens postero-ventral to male pore. Proximal vagina strongly curved posteriad, merging seminal receptacle anteriorly or antero-medially. Vagina covered by thick cell layer. Length of vagina 190–210 (n=2) and maximum width ca. 50. Vaginal lumen with long delicate setae pointing distally. Seminal receptacle ovoid or round, with maximum diameter 120–150 (n=4) attained in postmature, pregravid or gravid proglottids. Uterus in pregravid proglottids with 29–34 (30.8, n=8) irregular primary branches on each side; secondary branches few. Anterior uterus usually without unbranched pocket. Branches disintegrate partly or totally in fully gravid proglottids. Eggs (outer membrane) ovoid, 35– 42 (37.1, n=20) long. Embryophore ovoid, 15–24 (19.0, n=20) long.

Remarks: Catenotaenia apodemi seems to be a host-specific parasite of Apodemus spp. with a wide distribution in Central Eurasia. The conspecificity of C. apodemi from Buryatia and Lower Tunguska River is confirmed by the present molecular data. The two sequences from Buryatia were identical and differed from the Siberian sequence by two nucleotides.

The most distinctive feature of C. apodemi is the long ovary that extends significantly posterior to the vitellarium, partly surrounding it. In this respect, is seems to differ from all other species of Catenotaenia . Catenotaenia apodemi is also characterized by a short and narrow strobila, short neck and elongated proglottids approaching acraspedote condition.