Parasciurotaenia

Haukisalmi, Voitto, 2009, A taxonomic revision of the genus Anoplocephaloides Baer, 1923 sensu Rausch (1976), with the description of four new genera (Cestoda: Anoplocephalidae), Zootaxa 2057, pp. 1-31 : 18-19

Parasciurotaenia n. g.

(Fig. 9)

Etymology: The genus is named after the definitive hosts ( Marmota spp., Sciuridae ) of P. r y j i k o v i and its superficial resemblance to Sciurotaenia .

Diagnosis: Strobila long and very wide. Suckers directed laterally. Neck (unsegmented region) present. Proglottides craspedote, much wider than long. Genitalia single. Genital pores irregularly and very frequently alternating, genital pores positioned in middle of proglottis margin. Genital atrium strong, capable of forming prominent genital papilla. Genital ducts cross osmoregulatory canals dorsally. Internal and external seminal vesicles present. Cirrus sac short, overlapping or not reaching ventral longitudinal canal. Retractor muscle of cirrus sac present. Testes numerous, arranged in single transverse group in antiporal part of proglottis; prominent gap separates testicular field from antiporal ventral longitudinal canal. Ovary small relative to proglottis size, rounded, poral, very densely lobed. Vagina long and very thin, extending markedly across ventral longitudinal canal, with conspicuously distended distal part; enters genital atrium posterior to cirrus sac. Early uterus transverse tube in middle of proglottis (longitudinally and dorso-ventrally), not overlapping longitudinal osmoregulatory canals; poral end curved, terminating posterior to external seminal vesicle. Fully developed (pregravid) uterus arborescent, with separate anterior and posterior sacculi; transverse median trunk present. Female reproductive organs mature slightly earlier than male organs; testes persist after resorption of female glands overlapping developing uterus. Pyriform apparatus present. Parasitic in sciurid rodents (marmots). Type species: P. r y j i k o v i (Spasskii, 1950) n. comb. (syn. Paranoplocephala ryjikovi Spasskii, 1950 ) from the gray marmot Marmota baibacina Kastschenko ; holotype not assigned.

Remarks. Parasciurotaenia is compared with three genera that resemble it in having a median early uterus (in longitudinal direction) that does not overlap the ventral longitudinal canals. Parasciurotaenia can be differentiated from these genera by its larger body ( Afrobaeria , Equinia ), irregularly and very frequently alternating genital pores ( Equinia ), number of testes ( Equinia ), presence of a distinct gap between the testicular field and the antiporal ventral longitudinal canal ( Afrobaeria , Equinia ), type of cirrus sac ( Equinia ) and presence of a cirrus retractor muscle ( Afrobaeria ). The vagina of P. r y j i k o v i is very long and thin and has a characteristic distal dilatation, which also differentiates it from all the other species of Anoplocephaloides sensu Rausch (1976) . Parasciurotaenia differs from Sciurotaenia in the presence of a cirrus retractor muscle, length and structure of the vagina, longitudinal position of the early uterus and position of the poral end of the early uterus with respect to the external seminal vesicle (posterior in Parasciurotaenia , anterior in Sciurotaenia ). For detailed descriptions of P. ryjikovi , see Spasskii (1950, 1951).

The microhabitat of P. r y j i k o v i was not specified.

FIGURE. 9. Parasciurotaenia ryjikovi from Marmota himalayana . A. Scolex and anterior strobila (scale-bar 0.50 mm). B. Mature proglottis (scale-bar 0.50 mm). C. Uterus in a pregravid proglottis (scale-bar 1.0 mm).