Rhinoxenus arietinus Kritsky, Boeger & Thatcher, 1988

Domingues, Marcus V. & Boeger, Walter A., 2005, Neotropical Monogenoidea. 47. Phylogeny and coevolution of species of Rhinoxenus (Platyhelminthes, Monogenoidea, Dactylogyridae) and their Characiformes hosts (Teleostei, Ostariophysi) with description of four new species, Zoosystema 27 (3), pp. 441-467 : 448-450

Rhinoxenus arietinus Kritsky, Boeger & Thatcher, 1988

( Fig. 1F )

Rhinoxenus arietinus Kritsky, Boeger & Thatcher, 1988: 88-92 , figs 9-17.

TYPE HOST AND LOCALITY. — Nasal cavity of Schizodon fasciatus (Anostomidae) , Ilha Marchantaria, Rio Solimões, near Manaus, Amazonas, Brazil, 25.XI.1983 ( Kritsky et al. 1988).

MATERIAL EXAMINED. — Brazil. Rio Capucapu, Cachoeira das Garças, Manaus, Amazonas, from Leporinus agassizii (Anostomidae) , 30.X.1989, voucher specimens ( CHIOC 36282 a-b). — Rio Paraná, Porto Rico, Paraná, from Leporinus elongatus (Anostomidae) , 1992, voucher specimens ( CHIOC 36283 a-b; INPA 429; MNHN HG-T 1 205-205 bis); same locality, from Leporinus obtusidens (Anostomidae) , 1992, voucher specimens ( INPA 428 a-c; MNHN HG-T 1 204-240 bis; USNPC 95231). — Rio Paraná, Ressaco do pau véio, Porto Rico, Paraná, from Leporinus elongatus (Anostomidae) , 1992, voucher specimens ( INPA 430 a-c); from Leporinus elongatus (Anostomidae) , 17. VI.1996, voucher specimens ( USNPC 95232). — Rio Tibagi, near Jataizinho, Paraná, from Leporinus elongatus (Anostomidae) , 28-29. V.1997, voucher specimens ( CHIOC 35284 a-c; INPA 431 a-c; USNPC 95233); same locality, from Leporinus obtusidens , 28- 29. V.1997, voucher specimens ( CHIOC 36307 a-d; MNHN 164 HG-T 1 206-206 bis). — Reservatório de Itaipu, Foz do Iguassu, Paraná, from Leporinus friderici friderici (Anostomidae) , 15.XI.1996, voucher specimens ( CHIOC 36286 a-b; INPA 432; USNPC 95234); same locality, from Schizodon sp. (Anostomidae) , 15.XI.1996, voucher specimens ( CHIOC 36291 a-c; INPA 426 a-b; MNHN 161 HG-T 1 203- 203 bis; USNPC 95229). — Rio Paraná, near Porto Rico, Paraná, from Leporinus friderici friderici (Anostomidae) , 1993, voucher specimens ( CHIOC 36285 a-b; MNHN 165 HG-T 1 207); same locality, from Leporinus lacustris (Anostomidae) , 1993, vouch- er specimens ( CHIOC 36287 a-b; INPA 427; USNPC 95230); same locality, from Schizodon altoparanae (Anostomidae) , 1993, voucher specimens ( CHIOC 36288 a-c; INPA 424 a-b; MNHN 158 HG-T 1 201-201 bis; USNPC 95227); same locality, from Schizodon borelli (Anostomidae) , 1992, voucher specimens ( CHIOC 36289 a-b; INPA 422; USNPC 95224-95226); same locality, from Schizodon borelli (Anostomidae) , 1993, voucher specimens ( CHIOC 36290 a-c; INPA 423 a-c; MNHN 156 HG-T 1 198 bis-199-199 bis, 157 HG-T 1 200-200 bis); same locality, from S. knerii (Steindachner, 1875) (Anostomidae) , 1993, voucher specimens ( USNPC 95228).

PREVIOUS RECORD. — Aquarium INPA, Manaus, Amazonas, Brazil from Rhytiodus argenteofuscus (Anostomidae) , 8.II.1984 ( Kritsky et al. 1988).

COMPARATIVE MEASUREMENTS. — See Tables 3 and 4.

REMARKS

Rhinoxenus arietinus is known from nine species of Leporinus , Schizodon , and Rhytiodus . Leporinus elongatus and L. obtusidens are reported as hosts in two different localities (both in the Rio Paraná and Rio Tibagi, PR, Brazil). Kritsky et al. (1988) considered the occurrence of Rhinoxenus arietinus in Rhytiodus argenteofuscus as accidental. However, this parasite occurs in other anostomids, and thus, it seems to represent a parasite specific to this family.

The specimens analyzed herein do not differ significantly from those described by Kritsky et al. (1988). However, the proximal projection of the accessory piece, that surrounds the first ring of the MCO ( Kritsky et al. 1988: figs 11, 12), was not observed herein, and the two tandem b r i m s a s s o c i a t e d t o t h e b a s e o f t h e M C O ( Fig. 1F ) were not described by Kritsky et al. (1988). The measurements of the sclerotized structures of the present material do not differ from those presented in the original description. Rhinoxenus arietinus differs from the other species of the genus by possessing two posterior muscular lobes on the haptor and a ventral anchor with a conspicuous superficial and deep root.

Figures

FIG. 1. — Sclerotized structures of selected Rhinoxenus species; A, R. piranhus Kritsky, Boeger & Thatcher, 1988, male copulatory organ (MCO); B, R. piranhus, vagina; C, R. nyttus Kritsky, Boeger & Thatcher, 1988, MCO; D, R. nyttus, detail of the base of the MCO (distal portion of MCO not shown); E, R. nyttus, ventral anchor; F, R. arietinus Kritsky, Boeger & Thatcher, 1988, MCO. Arrow indicates the circular tandem sclerotized brims. Scale bars: A-D, F, 20 μm; E, 50 μm.