Neoechinorhynchus (Neoechinorhynchus) macronucleatus Machado Filho, 1954

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 : 432

Neoechinorhynchus (Neoechinorhynchus) macronucleatus Machado Filho, 1954

Figs 11, 14, 17

MATERIAL STUDIED: MANC-Pa No. 518/1-2 (2 females) from Lycengraulis grossidens ; Paraná-Guazú River , Entre Ríos Province, Argentina.

REMARKS: Machado Filho (1954) briefly described this species from the intestine of Licengraulis sp. from Brazil. Later, Fabio (1983) recorded one male specimen from Hoplias malabaricus (Bloch, 1794) also from Brazil. In Argentina, only five juvenile females were recovered from L. grossidens . The specimens are easily recognized because they have a cylindrical proboscis, the hooks of the anterior circle larger and stouter than the hooks in the middle and posterior circles, four prominent giant nuclei pre-equatorially situated in the dorsal body wall and lemnisci much longer than the proboscis receptacle.

In addition, minor differences were recorded in the measures of some characters while others were recorded for the first time: proboscis 110-135 (n = 2) long, 95- 110 wide; length of hooks in anterior circle 40-50 (45; n = 4), in middle circle 25-35 (30; n = 4), in posterior circle 15-25 (20; n = 4); length of hook roots in anterior circle 40-50 (45; n = 4), in middle circle 5-15 (10; n = 3), in posterior circle 5 (n = 3); apical organ 65-75 (n = 2) long, 25 wide; proboscis receptacle 435-560 (n = 2) long, 110-125 wide; cerebral ganglion oval-shaped, situated near posterior end of receptacle 105-130 (n = 2) long, 50-65 wide (Figs 11, 14, 17). The presence of an apical organ, cerebral ganglion and roots of hooks in middle and posterior circle are recorded for the first time, and this is the first study of N. (N.) macronucleatus using SEM.