Eurotaenia

Eurotaenia n. g.

(Fig. 15)

Etymology. The name of the new genus refers to the geographical distribution of E. gracilis (Europe). “ Eurotaenia ” is feminine.

Diagnosis. Strobila moderately long and wide. Scolex globular, merging rather abruptly with neck. Neck usually long. In well-relaxed specimens anterior strobila (posterior to neck) prominently elongated, thread-like, in its anterior part often slightly narrower than neck. Suckers embedded within scolex, directed laterally or anterolaterally. Proglottids distinctly craspedote, velum prominent. Length/width ratio of mature proglottids relatively high (33–38%). Genital pores either unilateral or infrequently (and irregularly) alternating. Genital ducts pass dorsal to longitudinal osmoregulatory canals. Testes rather large (relative to proglottid size), antiporal and anterior to ovary. Antiporal testes overlap or slightly extend across antiporal ventral longitudinal canal; poral testes reach or overlap corresponding poral canal, rarely extending across it. Testes slightly overlap ovary, being occasionally in contact with vitellarium. Cirrus-sac rather wide, overlapping or slightly extending across poral longitudinal canals. Vagina tubiform, slightly curved, covered with prominent, intensely stained cell-layer throughout its length. Vagina reaching or overlapping ventral longitudinal canal; slightly shorter than or as long as cirrus sac. Seminal receptacle large, spherical, subspherical or ovoid, depending on degree of relaxation. Ovary median or slightly antiporal, large, often filling whole space between ventral longitudinal canals. Vitellarium relatively large, median or slightly poral with respect to ovary. Early uterus densely reticulated, anterior, lateral parts widened posteriorly. In arvicoline rodents (Cricetidae) in western Eurasia.

Type species: E. gracilis (Tenora & Murai, 1980) n. comb.

Paranoplocephala gracilis Tenora & Murai, 1980 Holotype of E. gracilis: HNHM 3/1.

Remarks. Among the genera in the group 3.1. (also including Douthittia, Rauschoides, Arctocestus and Lemminia), Eurotaenia is best distinguished by its prominently elongated anterior strobila and long vagina with a very thick, intensely stained cell layer. Also, it can be distinguished from other related genera except Rauschoides by the wide transverse distribution of testes in the poral part of the proglottid (overlapping or extending slightly beyond poral ventral canal in Eurotaenia) and from Rauschoides and Arctocestus by more numerous testes lateral to the antiporal ventral canal in the latter. Eurotaenia (gracilis) can also be separated from Rauschoides by the morphology of the early uterus; in Eurotaenia the early uterus is anterior with lateral “wings”, whereas in Rauschoides it covers most of the proglottid without distinct “wings”.

Eurotaenia gracilis appeared as an unresolved basal lineage in all mitochondrial data sets. The concatenated cox1 and 28S data of Wickström et al. (2005) suggest that E. gracilis may be the sister group for the rest of the “arvicoline clade” of cestodes, although that analysis lacked several Paranoplocephala -like species included in the present analysis.