Neoechinorhynchus, Stiles & Hassall, 1905

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 : 436-437

Key to the South American species of Neoechinorhynchus :

1a. Eggs with concentric membranes, without polar prolongations of the fertilization membrane; subgenus Neoechinorhynchus Stiles & Hassall, 1905 ....................................................... 2

1b. Eggs with polar prolongations of the fertilization membrane; subgenus Hebesoma Van Cleave, 1928 ..................................... 9

2a. Trunk ovoid, elliptical or fusiform, swollen equatorially; proboscis without apical organ............................................ 3

2b. Trunk elongated, swollen anteriorly; proboscis with or without apical organ....................................................... 6

3a. Lemnisci much longer than proboscis receptacle (twice or more); male reproductive system occupies about 50% of trunk..................... 4

3b. Lemnisci longer than proboscis receptacle; male reproductive system occupies more than 60% of trunk.................................. 5

4a. Sexual dimorphisms present; neck twice longer than the proboscis; lemnisci subequal, overlapping anterior testes; eggs drop-shaped............................... N. (N.) pimelodi Brasil-Sato & Pavanelli, 1998

4b. Sexual dimorphisms absent; neck short; lenmisci unequal, reaching level of testes, but not overlapping them; eggs elongate......................................... N. (N.) prochilodorum Nickol & Thatcher, 1971

5a. Neck short; lemnisci slightly longer than proboscis receptacle; cement gland almost same size than testes. N. (N.) paraguayensis Machado Filho, 1959

5b. Neck long; lemnisci much longer than proboscis receptacle; cement gland bigger than testes................ N. (N.) pterodoridis Thatcher, 1981

6a. Proboscis with apical organ not observed; tegument with 1–2 dorsally and 1–3 ventral giant nuclei............... N. (N.) villoldoi Vizcaíno, 1992

6b. Probosis with apical organ; tegument with 5 dorsally and 1–2 ventral giant nuclei.................................................. 7

7a. Dorsal tegument with 4 prominent pre-equatorial giant nuclei and the fifth post-equatorial.......... N. (N.) macronucleatus Machado Filho, 1954

7b. Dorsal tegument with giant nuclei not clustered in pre-equatorial region.... 8

8a. Apical organ about half length than proboscis; elongated cement gland, separated for a distance of testes. Coiled vagina associated to paravaginal muscles........................ N. (N.) buttnerae Golvan, 1956

8b. Apical organ large, almost same length than proboscis; elongated cement gland overlaps testes. Proboscis with two lateral hooks larger than other in first circle........................... N. (N.) curemai Noronha, 1973

9a. Proboscis with prominent apical organ; neck relatively long, trunk elongated, swollen anteriorly; male reproductive system 79%, female reproductive system 32%......................... N. (H.) colastinense sp. n.