Ditestolepis, SOLTYS, 1952

DITESTOLEPIS SOLTYS, 1952

Amended diagnosis (modified after Spassky, 1954): Small cestodes with serial homonomous maturation. Strobila may consist of one to four series of proglottides. Premature and mature proglottides acraspedote, pregravid slightly craspedote. Scolex with rudimentary rostellum; suckers elongate, inside dorsal and ventral bothrium-like depressions. Osmoregulatory canals without transverse anastomoses. Genital pores dextral. Cirrus-sac crosses midline of proglottis. Cirrus armed, spines small, decreasing in size towards end of cirrus. Internal seminal vesicle absent. External seminal vesicle elongate. Testes three, in a triangle, one poral and two antiporal, one aporal testis very small, dorsal to external seminal vesicle. Ovary slightly bilobed. Vitellarium entire, postovarian. Seminal receptacle small, thin-walled. Uterus initially horseshoe-shaped,

SYSTEMATICS OF PARASITIC CESTODES 975

then ring-shaped, in gravid proglottides sacciform. Uteri of gravid proglottides within a series merge to form syncapsule. Palaearctic.

Ty p e a n d o n ly s p e c i e s: D i t e s t o l e p i s d i a p h a n a (Cholodkowsky, 1906) Soltys, 1952 (syn: Hymenolepis diaphana Cholodkowsky, 1906 ; Dicranothaenia diaphana (Cholodkowsky, 1906) Skrjabin & Mathevossian, 1948 ; Neoskrjabinolepis diaphana (Cholodkowsky, 1906) Kobulej, 1953 ; Soricinia diaphana (Cholodkowsky, 1906) Zarnowski, 1955 ; Sinuterilepis spasskyi ( Sadovskaya, 1965) .

Remarks: The scolex of D. diaphana is trapezoid in lateral view ( Fig. 4A). Its strobila contains varying number of series of proglottides at different stages of development, which may be quite different in appearance ( Fig. 3A). Uterine development in Ditestolepis is particularly unusual. Initially the uterus is horseshoe-shaped, but in the process of maturation the posterior ends of the uterus merge to form a ring. Then the internal walls of ring-shaped uterus coalesce and the uterus becomes sac-like ( Fig. 4E). Finally, the uteri of neighbouring gravid proglottides fuse and form a syncapsule uniting all gravid proglottides in a series. Eggs are embedded in a thick layer of matrix secreted by the uterine epithelium ( Korneva et al., 2010). Although some previous descriptions reported an internal seminal vesicle in D. diaphana ( Vaucher, 1971) , the internal seminal vesicle is actually absent. Instead, there is a winding internal vas deferens forming a sac-like expansion filled with sperm, in the proximal part of the cirrus-sac ( Fig. 4D).

At different times Ditestolepis included several species, namely Ditestolepis secunda Schaldybin, 1964 , Ditestolepis quarta Karpenko, 1983 , Ditestolepis longicirrosa Sawada & Harada, 1990 , Ditestolepis ezoensis Sawada & Koyasu, 1991 , Ditestolepis cyclocephala Sawada & Koyasu, 1991 , Ditestolepis m i n u t a S awa d a & K o y a s u, 1 9 9 1, D i t e s t o l e p i s crassisaccata Sawada & Asakawa, 1992 , Ditestolepis grandiovarium Sawada et al., 1992 ( Schaldybin, 1964; Karpenko, 1983; Sawada & Harada, 1990; Sawada & Koyasu, 1991a, b; Sawada & Asakawa, 1992; Sawada et al., 1992). However, some of these species were transferred to other genera, e.g. D. quarta and D. secunda were moved into Soricinia , D. ezoensis – into Diorchilepis , D. crassisaccata – into Spalania ( Czaplinski & Vaucher, 1994; Karpenko, 1999; Karpenko & Chechulin, 2000; Lykova et al., 2006), while D. longicirrosa was synonymized with Ecrinolepis longibursata ( Morozov, 1957) . Ditestolepis cyclocephala , D. minuta and D. grandiovarium from Japanese shrews do not conform to the generic diagnosis of Ditestolepis or any other known genera and, therefore, their taxonomical position requires further clarification.