Raphidascaris (Sprentascaris) saltaensis , Ailán-Choke, Lorena Gisela, Ramallo, Geraldine & Davies, Dora, 2017

Ailán-Choke, Lorena Gisela, Ramallo, Geraldine & Davies, Dora, 2017, New species of Raphidascaris (Sprentascaris) (Nematoda: Anisakidae) in Rineloricaria steinbachi (Actinopterygii: Loricariidae) from Northwest Argentina, Zootaxa 4231 (1), pp. 129-136: 130-135

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Raphidascaris (Sprentascaris) saltaensis

sp. nov.

Raphidascaris (Sprentascaris) saltaensis  sp. nov.

( Figs 1–2View FIGURE 1View FIGURE 2)

Type material. Holotype: female CH-FML # 07663; paratypes: eight males and five females, of which nine specimens were used for SEM, CH-FML # 0 7665.

Type host. Rineloricaria steinbachi Regan  , ( Siluriformes  : Loricariidae  ) (IBIGEO-I # 355–422).

Type locality. La Caldera River (24°35´40.07”S; 65°22´11”W), La Caldera Department, province of Salta, Northwest Argentina.GoogleMaps 

Etymology. The new species is named for its geographical location in the province of Salta.

Site of infection. Intestine.

Infection parameters. Prevalence: 11.94% (8/67); media intensity: 2.63 per fish.

Measurements. Table 1.

General description. Medium sized nematodes. Cuticle bearing transverse striations. Mouth aperture triangular, two ventrolateral lips and one dorsal lip. Lips well-developed and oval-shaped; dorsal lip slightly smaller than the two ventrolateral ones. Dorsal lip bearing two double papillae, ventrolateral lips with one double papilla, one single papilla and one amphid. Lips with lateral membranous margins forming finger-shaped protrusions at each side. Membranous extensions at base of lips. Interlabia absent ( Figs. 1View FIGURE 1 A –C; 2A –C). Excretory pore slightly posterior to nerve ring level. Lateral alae present in both sexes, beginning in lateral region below lips and reaching almost to tail tip. Muscular oesophagus short with expanded posterior half. Caudal alae absent in both sexes. Ventriculus shorter than wide, ventricular appendix longer than wide. Both sexes with conical tail, its distal tip slender and sharply pointed.

Adult males (eight specimens): Spicules equal, simple with pointed distal tips. Twenty pairs of caudal papillae. Preanal papillae: Sixteen subventral pairs; counting from cloaca opening, the first until the seventh pair are closer to each other than the remaining pairs. Adanal papillae: only one subventral pair. Postanal papillae: three small subventral pairs. Lateral alae present, without the partition in the caudal region. Caudal alae absent. Conical tail ( Fig. 1View FIGURE 1 G).

Adult female (six specimens): Vulva preequatorial, posterior to oesophagus end level ( Fig. 1View FIGURE 1 E). Eggs ovalshaped, with thick and rough shell provided with membranous striations, mature eggs larvated ( Figs. 1View FIGURE 1 D). Conical tail ( Figs. 1View FIGURE 1 F; 2D).

Remarks. Raphidascaris (Sprentascaris) saltaensis  sp. nov. is distinguished from their congeners, by possessing 16 pairs of preanal papillae, membranous elevations below the lips, mature eggs with striated shell and the size of spicules (0.24 mm). For more detailed description of morphometric differences between the new species and other species of Raphidascaris  ( Sprentascaris  ) see Table 2.

Raphidascaris (S.) saltaensis  sp. nov. differs from R. (S.) mahnerti  and R. (S.) lanfrediae  by the absence of caudal alae in the males; but shares this feature with R. (S.) pimelodi  , R. (S.) hypostomi  and R. (S.) marano  . The new species presents lateral alae, which begins in the base of ventrolateral lips and extends almost to tail tip; no partition of this structure is observed, hence caudal alae are not present. Raphidascaris (S.) saltaensis  sp. nov differs from R. (S.) pimelodi  and R. (S.) hypostomi  by the presence of lateral alae, and by the number of postanal papillae pairs; R. (S.) saltaensis  possess three pairs, while R. (S.) pimelodi  and R. (S.) hypostomi  present five pairs and lack lateral alae ( Moravec 1998).

Raphidascaris (S.) saltaensis  sp. nov. resembles R. (S.) marano  , both species have lateral alae and three pairs of postanal papillae; but can readily be distinguished by the number of preanal papillae (16 vs. 22), the shape and size of lips (smaller and different lips with protrusions vs. longer, symmetrical, simple and equal lips), shape of eggs (rough-shelled vs. thin-shelled) and the spicule length (0.24 vs. 0.27) ( Moravec 1998; Ramallo 2009).

Discussion. Five genera of Anisakidae  have been reported from the intestine of Neotropical freshwater fishes: Goezia (Zeder, 1800)  , Hysterothylacium (Ward and Magath, 1917)  , Terranova (Leiper and Atkinson, 1914)  , Raphidascaroides (Yamaguti, 1941)  and Raphidascaris (Railliet and Henry, 1915)  . Goezia  , Hysterothylacium  and Raphidascaris  show a broad geographical distribution including Mexico, Guyana, Venezuela, Brazil, Paraguay, Peru and Argentina; in contrast Raphidascaroides  and Terranova  were only recorded in Brazil and Venezuela ( Moravec 1998). Raphidascaris  has two subgenera: Raphidascaris  (not in the Neotropical region ), and Sprentascaris  whose members are restricted to South America and were only reported in freshwater fishes ( Ramallo 2009). Species of Raphidascaris  ( Sprentascaris  ) are characterized by possessing a cuticular ring without spines, the presence of small postlabial or interlabial cuticular elevations, absence of true interlabia; the excretory pore slightly posterior to nerve ring level, a muscular oesophagus with ventriculus and ventricular appendix; and no intestinal caecum ( Moravec 1998). 

All species of Raphidascaris  ( Sprentascaris  ), except R. (S.) lanfrediae  , have Siluriformes  fishes as hosts. Raphidascaris (S.) hypostomi  was isolated from specimens of the subfamilies: Hypostominae and Ancistrinae  (all Loricariidae  ) ( Moravec 1998). Eiras et al. (2010) found nematodes identified as R. (S.) hypostomi  and R. (S.) mahnerti  in Metynnis lippincottianus Cope  ( Characiformes  , Serrasalmidae  ) from Brazil. Raphidascaris (S.) mahnerti  was also reported in Loricariidae  fishes; moreover Moravec et al. (1993) recorded the third larval stage of Raphidascaris  ( Sprentascaris  ) in the intestine of the cichlid Geophagus brasiliensis Quoy & Gaimard  , ( Perciformes  , Cichlidae  ). The larva is probably conspecific with R. (S.) mahnerti  and G. brasiliensis  could be a paratenic host ( Moravec 1998). This is not the only time Raphidascaris  ( Sprentascaris  ) was detected in cichlids; Melo et al. (2011) reported the adults of R. (S.) lanfrediae  in Satanoperca jurupari  . Possibly, this species share the host spectrum with R. (S.) mahnerti  . Both species might be closely related but they can be differentiated by morphological features and their geographical distribution (Melo et al. 2011). Raphidascaris (S.) pimelodi  is distinguished from other known species of the subgenus, because it was only detected in a pimelodid species.

Although R. (S.) marano  and Raphidascaris (S.) saltaensis  sp. nov. have both been recorded in Northwest of Argentina, they inhabit different fluvial systems; R. (S.) marano in Marapa River  (basin of Sali River, provinces of Tucumán and Catamarca), and R. (S.) saltaensis  sp. nov. in La Caldera River (basin of the Bermejo River , province of Salta)  . Ramallo (2009) proposed that R. (S.) marano  would be an endemic species in Argentina, following the endemic character of its host, H. cordovae  ( Loricariidae  ). However, H. cordovae  is synonymous of H. paranensis  , thus the geographical distribution was extended to include Paraguay (Paraguay River basin, the main tributary of Paraná River) ( Ferraris 2007). The new parasite species was found from Rineloricaria steinbachi  ( Loricariidae  ), whose geographical distribution is limited to southern Bolivia and northwestern Argentina , including the basins of the Bermejo (Rivers Bermejo, San Andrés, La Caldera, Mojotoro and Vaqueros and streams Gallinato and Pucheta), Juramento (Rivers Salado, Piedras, Arias Arenales, Rosario, Aguas Negras and Calchaquí), Pilcomayo River , and also the Dorado River basin (La Sala stream and Popayan River ). 

In this paper, we propose the erection of the sixth species of Raphidascaris  ( Sprentascaris  ) from the Neotropical region and the second from Argentina. Raphidascaris (S.) saltaensis  sp. nov. differs from all congeners in the number of preanal papillae, the shape and size of lips, the egg’s shell and the spicules length. The new identification key presented in the article incorporates R. (S.) lanfrediae  , R. (S.) marano  and R. (S.) saltaensis  sp. nov.

TABLE 1. Measurements of Raphidascaris (Sprentascaris) saltaensis sp. nov. Given in mm, mean ± SD (range). (* measurements with a unique value).

6.59±1.37 (5.62–7.56) 5.65±0.32 (5.12–5.92)
0.58±0.06 (0.54–0.63) 0.46±0.15 (0.28–0.67)
0.02±0.02 (0.01–0.04)
0.05±0.02 (0.04–0.06) 0.06±0.00 (0.06–0.07)
0.92±0.25 (0.71–1.27) 0.79±0.09 (0.63–0.88)
0.36±0.06 (0.30–0.43) 0.22±0.06 (0.14–0.34)
0.37±0.08 (0.32–0.43) 0.34±0.03 (0.29–0.37)
0.45±0.02 (0.44–0.47) 0.40±0.05 (0.32–0.47)
0.06±0.01 (0.06–0.07)
0.19±0.06 (0.15–0.24)
0.14±0.06 (0.10–0.19)
0.05±0.00 (0.04–0.05)
Ventricular appendix/ oesophagus length ratio
0.24±0.02 (0.22–0.27)
0.30±0.13 (0.15–0.39) 0.25±0.02 (0.22–0.27)
0.06±0.02 (0.04–0.09)
0.03±0.01 (0.03–0.04)