Neoechinorhynchus (Neoechinorhynchus) pimelodi Brasil-Sato & Pavanelli, 1998

Arredondo, Nathalia J. & Gil de Pertierra, Alicia A., 2012, A new species of Neoechinorhynchus (Eoacanthocephala: Neoechinorhynchidae) from Pachyurus bonariensis (Perciformes: Sciaenidae) from the Paraná River basin in Argentina, with comments on two other species of the genus, Revue suisse de Zoologie 119 (4), pp. 425-439 : 433

Neoechinorhynchus (Neoechinorhynchus) pimelodi Brasil-Sato & Pavanelli, 1998

Figs 9, 12, 15, 18, 20, 21

MATERIAL STUDIED: MANC-Pa No. 519/1 (3 males and 5 females) from P. albicans ; MANC-Pa No. 519/2 (2 females) from P. argenteus ; and MANC-Pa No. 519/3 (6 males and 7 females) from P. maculatus ; Colastiné River , Sante Fe Province, Argentina .

REMARKS: This species was originally described by Brasil-Sato & Pavanelli (1998) from Pimelodus maculatu s and later from Franciscodoras marmoratus (Lütken, 1874) ( Siluriformes : Doradidae ) by Santos & Brasil-Sato (2004), both from São Francisco River in Brazil. In Argentina, this species was found in the type host P. maculatus and also in two previously unrecorded hosts, P. albicans and P. argenteus ; all of the hosts belong to the Pimelodidae . This is also the first record of this species from the Paraná River basin. The SEM studies on this species made by Brasil-Sato & Pavanelli (1998) showed only the copulatory bursa, but herein we include the proboscis, anterior trunk extremity, and the porous tegumental surface (Figs 15, 18, 20, 21).

The specimens from Argentina are larger than those from Brazil. Some of the differences recorded in males and females are, for example, length of trunk (2.8-6.3 mm and 2.2-6.8 mm, respectively), proboscis dimensions (115-175 long, 120-195 wide and 135-175 long, 130-200 wide, respectively), proboscis receptacle length (450-635 and 450-630, respectively) (Fig. 12), andlemniscilength (980-2500 and 1020-2220, respectively). Brasil-Sato & Pavanelli (1998) measured only the outer membrane of the eggs, now the size of each component of the eggs was determined: outer membrane 22–25 (24; n = 4) long, 15-17 (16) wideversus 15-22 (18) long, 12-15 (14) wideinthe Brazilian specimens; fertilization membrane 21-23 (22; n = 4) long, 13-15 (14) wide; acanthor 18-21 (19; n = 4) long, 10-12 (11) wide; larval hooks 2-4 (3; n = 5) long (Fig. 9). The eggs of the new material are slightly larger than those from Brazil. This difference could be because the eggs measured by Brasil-Sato & Pavanelli (1998) are not completely mature (intrauterine or free in trunk cavity) versus spontaneously laid eggs in this work. However, the similarities in the shape of the trunk (elliptic), the shape of the proboscis (spherical), the apparent absence of the apical organ, the distribution and size of the proboscis hooks, the percentage of the trunk occupied by the reproductive system and the position of the genital pore in males and females, and particularly in the morphology of the eggs (drop-shaped) allowed assigning the specimens from Argentina to Neoechinorhynchus (N.) pimelodi . Thus, size differences could be due to differential growth rates from different hosts (see Amin & Muzzall, 2009). The low indices of infection (prevalence, mean intensity and mean abundance) recorded in all the hosts collected in the Paraná River basin do not allow establishing which the principal host is. Brasil-Sato & Pavanelli (1999) studied the prevalence and mean intensity of infection of N. (N.) pimelodi from P. maculatus in the São Francisco River ( Brazil) during the drought and flooding period; its prevalence is much higher than that in Colastiné River (42-51% and 30-34% versus 2.9% in the present paper), whereas the mean intensity of infection is very similar (4.8-4.9 and 3.5-4.9 versus 4.4 in the present paper).