Chambriella megacephala ( Woodland, 1934 ) Philippe Vieira Alves & Alain de Chambrier & José Luis Luque & Tomáš Scholz, 2017

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 : 370-371

Chambriella megacephala ( Woodland, 1934) n. comb.

Syns Monticellia megacephala Woodland, 1934 ;

Goezeella agostinhoi Pavanelli & Santos, 1992 ;

Chambriella agostinhoi ( Pavanelli & Santos, 1992) ; Lenhataenia megacephala de Chambrier & Scholz, 2008

Type-host: Sorubimichthys planiceps (Spix & Agassiz) ( Siluriformes : Pimelodidae ), originally reported erroneously by Woodland (1934) as Platystomatichthys sturio (Kner) (see de Chambrier & Scholz, 2008).

Other hosts: Zungaro jahu (Ihering) , Zungaro zungaro (Humboldt) and Pseudoplatystoma fasciatum (Linnaeus) (all Siluriformes : Pimelodidae ).

Type-locality: River Amazon (lower reaches), 50 miles downstream of Santarém, State of Pará, Brazil . Other localities: River Paraná (upper reaches), Porto Rico ( State of Paraná , Brazil; 22 43 0S, 53 10 0W); River Amazon, Itacoatiara (State of Amazonas, Brazil; 3 0 9 0S, 5 8 26 0W) and Iquitos (Region of Loreto, Peru; 3 47 0S, 7 3 20 0W).

Prevalence: 38% (6/16) and 50% (11/22) in Z. jahu (syn. Paulicea luetkeni ) from River Paraná ( Brazil) and in S. planiceps from River Amazon ( Peru), respectively ( Pavanelli & Santos, 1991; de Chambrier et al., 2015b).

Site in host: Anterior intestine.

Material studied: (i) Goezeella agostinhoi ex Paulicea luetkeni (= Zungaro jahu ): holotype (entire specimen, CHIOC 3 2.8 2 0a); 3 paratypes (entire specimens, CHIOC 3 2.8 2 0b-d); (ii) Chambriella agostinhoi ex Z. jahu : vouchers (2 entire specimens, 1 fragment and 1 slide with serial crosssections), River Cuiabá, Cuiabá, State of Mato Grosso (River Paraná basin, Brazil), collected by A. A. Rego on 3 1.vii. 1 9 9 3 (MHNG-PLAT 1 9 5 4 6, 2 2 4 9 7, host field nos. BR 4 0 7, BR 4 0 8); ex Z. zungaro : vouchers (4 entire specimens and 3 fragments mixed with Riggenbachiella amazonense ), River Amazon, Itacoatiara, State of Amazonas (Brazil), collected by A. A. Rego and A. de Chambrier on 8.x. 1 9 9 5, and 1 entire specimen from River Amazon, Iquitos (Peru) collected by T. Scholz and R. Kuchta on 1 6.ix. 2 0 0 6 (MHNG- PLAT 2 7 9 9 0, CHIOC 3 8 4 8 4, host field Nos. BR 6 3 4, PI 4 4 5a); (iii) Lenhataenia megacephala ex Sorubimichthys planiceps : vouchers (2 entire specimens, 1 mixed with R. amazonense ), River Amazon, Itacoatiara, State of Amazonas (Brazil), collected by A. A. Rego and A. de Chambrier on 2.x. 1 9 9 5 (MHNG-PLAT 2 0 7 6 8, host field No. BR 4 6 7); (iv) Chambriella sp. ex Pseudoplatystoma fasciatum : vouchers (2 entire specimens and fragments), River Amazon, Iquitos, Region of Loreto (Peru) collected by T. Scholz and R. Kuchta on 5.ix. 2 0 0 6 (MHNG-PLAT 6 0 0 2 6, host field no. PI 3 0 4a).

Representative DNA sequences: Seven isolates of ‘ L. megacephala ’ from S. planiceps in the River Amazon had identical sequences of 1,4 9 1 bp long of the lsr DNA (D1-D3 domains) (GenBank KY2 0 7 4 4 9). Two isolates of ‘ C. agostinhoi ’, one from Z. jahu (type-host) in the River Paraná and one from Z. zungaro in the River Amazon, also had identical sequences with those of the seven isolates of ‘ L. megacephala ’ (GenBank KY2 0 7 4 4 7, KY2 0 7 4 4 8).

Remarks

Comparison of voucher specimens of Lenhataenia megacephala ex S. planiceps with those of Goezeella agostinhoi ex Z. jahu (type and newly collected material; Figs. 2A–D, G , 3 ) revealed that these two taxa are indistinguishable from each other in their morphology, except for the position of the vagina in relation to the cirrus-sac (either anterior or posterior; see Table 2). This feature has been broadly used to distinguish congeneric species (Gil de Pertierra, 2003; Arredondo & Gil de Pertierra, 2010; Gil de Pertierra & de Chambrier, 2013), but its taxonomic value seems to be questionable for the above-mentioned species because their conspecificity has also been confirmed by molecular data (sequences of both taxa are identical, Fig. 1 ). Since no but one morphological differences were found among the studied specimens, the description of de Chambrier & Scholz (2008) is not repeated herein.

These results thus show that C. megacephala , which possesses both an anterior and a posterior vagina in relation to the cirrus-sac, is widely distributed in South America, with records from the Amazon and Paraná River basins. It occurs in species of as many as three genera of big pimelodid catfishes ( Pseudoplatystoma Bleeker , Sorubimichthys Bleeker and Zungaro Bleeker ), which is unusual among Neotropical proteocephalids ( Rego et al., 1999; de Chambrier et al., 2015b).

Figures

Fig. 1 Tree resulting from Bayesian Inference (BI) analysis of partial (D 1 - D 3 domains) of lsr DNA data for selected members of the Proteocephalidae, including Riggenbachiella amazonense n. sp. and Chambriella megacephala (Woodland, 1934) n. comb. Bayesian inference posterior probabilities / Maximum likelihood (ML) bootstrap support values are shown at the nodes. Branches with posterior probability support \ 0.90 (BI) are collapsed and support values \ 70 (ML) are not shown. The scale-bar indicates the number of substitutions per site

Fig. 2 Scanning electron micrographs of representatives of c monticelliine proteocephalideans. Chambriella megacephala (Woodland, 1934) ex Sorubimichthys planiceps (MHNG-PLAT 54608): A, B, Scoleces, dorsoventral and apical views, respectively; C, D, G, Microtriches on the apex of the scolex, external upper surface of the suckers and between suckers, respectively. Riggenbachiella amazonense n. sp. ex S. planiceps (MHNG-PLAT 54609): E, F, Scoleces, dorsoventral and apical views, respectively; H, K, L, Microtriches on the apex of the scolex, external upper surface of the suckers and between suckers, respectively. Riggenbachiella paranaense (Pavanelli & Rego, 1989) ex Hemisorubim platyrhynchos (MHNG-PLAT 36430): I, J, Scoleces, dorsoventral and apical views, respectively; M – O, Microtriches on the apex of the scolex, external upper surface of the suckers and between suckers, respectively. Scale-bars: A, B, E, F, I, J, 100 l m; C, D, G, H, K – O, 1 l m

Fig. 3 Chambriella megacephala (Woodland, 1934) ex Zungaro jahu. A, Scolex, apical view (paratype of C. agostinhoi, CHIOC 32820 c); B, Terminal genitalia, ventral view (holotype of C. agostinhoi, CHIOC 32820 a); C, Terminal genitalia, dorsal view (MHNH- PLAT 22025); D, E, Cross-sections at anterior and cirrus-sac level of proglottides, respectively (MHNH-PLAT 19546); F, Eggs drawn in distilled water (MHNH-PLAT 20768). Abbreviations: al, anterior sucker loculus; ci, cirrus; cs, cirrus-sac; do, dorsal osmoregulatory canal; ed, ejaculatory duct; em, bi-layered embryophore; lm, internal longitudinal musculature; oe, outer envelope; on, oncosphere; pl, posterior sucker loculus; st, subtegumental muscle fibres; su, subtegumental cells; te, testes; tg, tegument; ut, uterus; va, vas deferens; vi, vitelline follicles; vo, ventral osmoregulatory canal; vs, vaginal sphincter. Scale-bars: A, D, E, 200 l m; B, C, 100 l m; F, 20 l m