Riggenbachiella, Alves, de Chambrier, Luque & Scholz in Press, 1999

Philippe Vieira Alves, Alain de Chambrier, José Luis Luque & Tomáš Scholz, 2017, 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, Syst Parasitol 94, pp. 367-389: 372-373

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http://doi.org/ 10.1007/s11230-017-9700-1

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Riggenbachiella   n. g.

Syn. Chambriella Rego, Chubb & Pavanelli, 1999   (pro parte)


Proteocephalidae   , Monticelliinae   . Small-sized worms. Testes, ovary, vitelline follicles and uterus cortical.

Strobila acraspedote, with proglottides variable in shape and size. Scolex quadrilobed, quadrangular in apical view, wider than proliferative zone, with rounded to conical apex; metascolex absent. Suckers large, bi-loculate, with free posterior margin overlapping narrow proliferation zone, well delimited from scolex proper; loculi variable in shape and size.

Internal longitudinal musculature formed by small, sparsely distributed bundles of muscle fibres. Testes in one field. Cirrus-sac sigmoid, composed of three parts: large, chambered internal seminal vesicle, middle muscular part with sinuous ejaculatory duct followed by straight, short cirrus with inverted T-shaped ejaculatory duct in its proximal part. Genital pore pre-equatorial, irregularly alternating. Genital atrium present. Ovary bi-lobed, slightly follicular. Vagina anterior, exceptionally posterior to cirrus-sac, with short thickened portion surrounded by ring-like vaginal sphincter. Vitelline follicles arranged in two lateral bands. Uterine development type 2 according to de Chambrier et al. (2004). Parasites of pimelodid catfishes ( Siluriformes   : Pimelodidae   ) in the Neotropical Region. Type-species: Riggenbachiella amazonense   n. sp.

Etymology: This name is given in honour of the late Emil E. Riggenbach, University of Basel, Switzerland, for his contribution to the systematics of proteocephalid cestodes at the end of the 19th Century. The name should be treated as femininum.


The new genus is placed in the Monticelliinae   because of the cortical position of the testes, ovary, vitelline follicles and uterus ( Rego, 1994). To date, the subfamily includes nine genera parasitising freshwater fishes in the Neotropical region, namely Ageneiella de Chambrier & Vaucher, 1999   ; Chambriella Rego, Chubb & Pavanelli, 1999   ; Choanoscolex La Rue, 1911   ; Goezeella Fuhrmann, 1916   ; Manaosia Woodland, 1935   ; Monticellia La Rue, 1911   ; Regoella Arredondo, de Chambrier & Gil de Pertierra, 2013   ; Spasskyellina Freze, 1965   ; and Spatulifer Woodland, 1934   .

Riggenbachiella   n. g. can be readily distinguished from all the above-mentioned taxa by the unique morphology of the cirrus-sac, which is sigmoid and composed of three parts: a voluminous, chambered internal seminal vesicle, a muscular middle part with a sinuous ejaculatory duct, and a straight, short cirrus with an inverted T-shaped ejaculatory duct in its proximal part (see Figs. 4B –F View b , 5B –D).

The new genus can be further differentiated from all but three monticelliine genera by having biloculate suckers instead of uni-loculate ones present in Choanoscolex   , Manaosia   , Monticellia   , Regoella   , Spasskyellina   and Spatulifer   . Riggenbachiella   n. g. differs from Ageneiella   and Goezeella   , which also have bi-loculate suckers, in several features, such as the absence of a metascolex (present in Goezeella   ), the different development of the inner longitudinal musculature (well-developed in Goezeella   and Ageneiella   ) and unequal extension of the uterine diverticula (branches penetrate into the medulla, sometimes reaching the dorsal cortex in Ageneiella   ).

Another genus with bi-loculate suckers, Chambriella   (syn. Lenhataenia   , see above), differs from Riggenbachiella   n. g. by the morphology of the cirrussac (it has a ‘typical’ structure with a simple internal sperm duct forming several coils, not being enlarged to form an internal seminal vesicle; see Fig. 3B, C View Fig. 3 in the present paper and figure 42 in de Chambrier & Scholz, 2008).













Philippe Vieira Alves, Alain de Chambrier, José Luis Luque & Tomáš Scholz 2017


Rego, Chubb & Pavanelli 1999