Validation of Christianella Guiart, 1931 (Cestoda: Trypanorhyncha) and its taxonomic relationship with Grillotia Guiart, 1927

Christianella Guiart, 1931 (Cestoda: Trypanorhyncha) is redefined as a subgenus of Grillotia Guiart, 1927 based on the type-species, G. (C.) minuta (van Beneden, 1849), from the elasmobranch Squatina squatina (Linnaeus). Grillotia smarisgora (Wagener, 1854) is treated as a synonym of G. (C.) minuta, as are G. angeli Dollfus, 1969 and G. bothridiopunctata Dollfus, 1969. Other species included in the subgenus are G. (C.) carvajalregorum Menoret & Ivanov, 2009 (formerly Progrillotia dollfusi Carvajal & Rego, 1983), G. (C.) australis Beveridge & Campbell, 2001, G. (C.) longispinis (Linton, 1890) n. comb. (formerly Rhynchobothrium longispine Linton, 1890) and G. (C.) yuniariae Palm, 2004. The subgenus is similar to Grillotia Guiart, 1927 (sensu stricto), having two bothria and an atypical heteroacanthous armature, but differs in having a single row of intercalary hooks, fewer, elongate segments with testes often in longitudinal columns, a distinctive basal armature, an internal seminal vesicle which extends beyond the cirrus or hermaphroditic sac and no uterine pore. The adults of three species are known, all parasitising members of Squatina Dumeril.