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).