Untangling convoluted taxonomy of Chambriella Rego, Chubb & Pavanelli, 1999 (Cestoda: Proteocephalidae), with erection of Riggenbachiella n. g. and the description of a new species from pimelodid catfishes in the Neotropical Region Author Philippe Vieira Alves Author Alain de Chambrier Author José Luis Luque Author Tomáš Scholz text Syst Parasitol 2017 2017-02-20 94 367 389 journal article 10.1007/s11230-017-9700-1 7c324801-2c22-439d-87c8-1bdb83e11827 925123 Chambriella Rego, Chubb & Pavanelli, 1999 Syns Lenhataenia de Chambrier & Scholz, 2008 ; Robertiella Rego, 1999 ( nomen nudum ) Amended diagnosis Proteocephalidae , Monticelliinae . Small-sized worms. Testes, ovary, vitelline follicles and uterus cortical. Strobila acraspedote, with proglottides variable in shape and size. Scolex quadrilobed, almost rectangular in apical view, with rounded to slightly conical apex; metascolex absent. Suckers large, bi-loculate, pear-shaped, with free posterior margin overlapping narrow proliferation zone, well delimited from scolex. Proliferation zone (neck) present. Internal longitudinal musculature formed by small bundles of muscle fibres, variable in number. Testes in one field. Cirrus-sac subovate, thick-walled; internal sperm duct thickwalled, strongly coiled in proximal half of cirrus-sac. Genital pores pre-equatorial, irregularly alternating. Genital atrium present. Ovary bi-lobed, slightly follicular. Vagina anterior and/or posterior to cirrussac, surrounded by ring-like vaginal sphincter. Vitelline follicles form two lateral bands, reaching to anterior margin of proglottides also on poral side, i.e. preporally. Uterine development type 2 according to de Chambrier et al. (2004) . Parasites of pimelodid catfishes ( Siluriformes : Pimelodidae ) in the Neotropical Region. Type- and only known species : Chambriella agostinhoi ( Pavanelli & Santos, 1992 ) [syn. of Chambriella megacephala (Woodland, 193 4) n. comb.] Remarks The taxonomic history of Chambriella has been convoluted and two of the present authors (AC and TS) also contributed to the confusion by providing an incorrect diagnosis of this poorly described genus. The key problem was that they could not examine typespecimens of both species of Chambriella at the time and that the original descriptions of both species and the original generic diagnosis were not detailed enough to recognise the actual morphology of the cirrus-sac. However, recent evaluation of the type-material of Chambriella agostinhoi (type-species) and C. paranaensis deposited in CHIOC revealed that these species differ markedly in the structure of the cirrussac. In C. agostinhoi , the cirrus-sac is relatively large and wide, subovate and contains a convoluted, thickwalled internal sperm duct (vas deferens) and a cirrus with a simple ejaculatory duct, i.e. identical with that of L . megacephala , type- and only species of Lenhataenia , which was redescribed by de Chambrier & Scholz (2008; see their figure 42) . This re-examination also revealed that C . agostinhoi and L . megacephala are indistinguishable from each other in all morphological characteristics, even though they occur in different fish hosts (but of the same family, the Pimelodidae ). Conversely, the cirrus-sac of C . paranaensis is sigmoid, composed of three parts: a large, chambered internal seminal vesicle, a middle muscular part with a sinuous ejaculatory duct followed by a straight, short cirrus with an inverted T-shaped ejaculatory duct in its proximal part, i.e. markedly different from that of C . agostinhoi and L . megacephala . These findings lead us to synonymise Lenhataenia with Chambriella , but the type-species of the latter genus, Chambriella agostinhoi , becomes a junior synonym of Chambriella megacephala n. comb. , and to transfer C . paranaensis to Riggenbachiella n. g. as Riggenbachiella paranaense n. comb. Rego (1999) transferred both nominal species of Chambriella , i.e. the genus that he and two co-authors erected in the same year ( Rego et al., 1999 ), to an allegedly new, but never formally defined genus, Robertiella , as ‘‘ Robertiella agostinhoi n. comb. ’’ and ‘‘ R . paranaensis n. comb. ’’. Therefore, Robertiella is considered a nomen nudum in accordance with the International Code of Zoological Nomenclature ( ICZN, 1999 ).