Acanthocephalus lucidus Van Cleave, 1925

Nagasawa, Kazuya, 2014, An Amphibian Acanthocephalan, Acanthocephalus lucidus (Echinorhynchida: Echinorhynchidae), Infecting a Fish, Salvelinus leucomaenis leucomaenis (Salmoniformes: Salmonidae), Species Diversity 19, pp. 151-156 : 153-154

Acanthocephalus lucidus Van Cleave, 1925 ( Fig. 1 )

Acanthocephalus lucidus Van Cleave, 1925: 151 , fig. 1 (type locality: Province Shimosa [now Chiba Prefecture], Japan); Harada 1935: 16–18, fig. 6; Yamaguti 1939: 321– 322; Yamaguti 1954: 391–392; Kobayashi 1954: 15–16, unnumbered fig.; Petrochenko 1956: 308–309, fig. 124; Yamaguti 1963: 48; Golvan 1969: 270, fig. 205; Uchida 1975: 64–68, 73–74; Wang 1980: 119; Hasegawa 1981: 387–389, figs 1–4; Nagasawa and Egusa 1981a: 1153– 1156, figs 1–3; Amin 1985: 42; Golvan 1994: 137; Telford 1997a: 95–96, 101–103; Telford 1997b: 41–46, fig. 12-9; Goldberg et al. 1997: 46, table 1; Araki 1999: 150; Goldberg and Bursey 2002: 165–166, 170; Araki 2003: 149; Goldberg and Bursey 2003: 167–168, table 1; Goldberg et al. 2004: 55.

Acanthocephalus artatus Van Cleave, 1925: 151–152 , fig. 4 (type locality: Province Shinano [now Nagano Prefecture], Japan); Yamaguti 1935: 252–253; Joyeux and Baer 1935: 14; Houdemer 1938: 149; Uchida 1975: 68, 73; Golvan 1994: 136; Araki 1999: 149; Araki 2003; 149.

Acanthocephalus aratus: Amin 1985: 42 .

Acanthocephalus atratus: Amin 2013: 285 .

Not Acanthocephalus lucidus: Gupta and Lata 1967: 337 , figs 19–21.

Description of male. Trunk cylindrical, unarmed, 4.38 × 0.76 in mounted condition. Proboscis slightly rounded anteriorly, 0.55 × 0.30; armed with 16 longitudinal rows of four or five (mostly four) hooks per row. Hook blade longer than root, without modifications. Hook blade increasing in length from apex of proboscis towards its base: 91, 98, 105, and 110 µm long. Neck short, conical, 0.13 × 0.40 at junction with trunk. Proboscis receptacle double-walled, 0.41 × 0.27, with cerebral ganglion at its posterior end. Lemnisci flat, broad, longer than proboscis receptacle, 0.55–0.66 × 0.20. Testes oval, tandem; anterior testis 0.42 × 0.36; posterior testis 0.49 × 0.34. Cement glands in compact cluster, club-shaped, four in number, 0.52–0.67 long. Saefftigen’s pouch 0.53 × 0.16. Bursa with papillae, 0.32 × 0.48. Genital pore subterminal.

Host. Whitespotted char Salvelinus leucomaenis leucomaenis ( Salmoniformes : Salmonidae ).

Locality. Ushirogata Stream, tributary of Rokumaibashi River, Ushirogata, Aomori Prefecture, Honshu, Japan.

Site of infection. Intestine.

Prevalence and intensity. One (8.3%, 252 mm TL) of 12 fish examined (133–268 [mean 210] mm TL) had one male of Acanthocephalus lucidus . All (100%) of these fish, on the other hand, were individually infected with 1–94 (mean 23.9) individuals of Echinorhynchus cotti .

Remarks. The morphology of the present specimen corresponds to the original description of Acanthocephalus lucidus by Van Cleave (1925) and the subsequent descriptions by Harada (1935), Yamaguti (1935, 1939), Hasegawa (1981), and Nagasawa and Egusa (1981a), therefore, it is identified as belonging to this species. In particular, the possession of hook blades that increase in size from anterior to posterior, and of club-shaped cement glands in a compact cluster is diagnostic.

Acanthocephalus lucidus and A. artatus were originally described in the same paper by Van Cleave (1925) based on specimens from the Japanese brown frog, Rana japonica Günther, 1858 that had been captured in “Province Shimosa” and “Province Shinano”, Japan, respectively. Later, Harada (1935) collected specimens of A. lucidus from R. japonica in “Province Musasi”, Japan, and synonymized A. artatus with A. lucidus , because the hook arrangement is quite similar in these two acanthocephalans and the mature eggs of his specimens were intermediate in size between the mature eggs of A. lucidus and A. artatus reported by Van Cleave (1925). Harada’s (1935) proposal was supported by subsequent researchers including Yamaguti (1939, 1963), Petrochenko (1956), Golvan (1969), and Amin (1985; who misspelled the specific name as “ aratus ”). Most recently, however, Amin (2013) reversed the synonymy, regarding A. lucidus as a junior synonym of A. artatus (misspelled as “ atratus ”), supposedly on Harada (1935) and Yamaguti (1939). As was noted above, the latter two authors actually used A. lucidus as valid, and Harada (1935), acting as first reviser, had already fixed the relative priority of the two names. In other words, A. lucidu s is still valid and should be treated as a senior synonym of A. artatus .

In addition to the records of A. lucidus in East Asia ( Table 1), there is a record of this species from Rana temporaria Linnaeus, 1758 in London, U.K. ( Gupta and Lata 1967). However, the two female specimens collected in London had a much shorter maximal hook blade length (44 µm vs 105 µm; see Hasegawa 1981) and much larger eggs (196 µm long vs 100 µm long; see Hasegawa 1981) than females of A. lucidus from Japan, and are not identifiable with this species (see Nagasawa and Egusa 1981a).

Among the aquatic arthropods collected from Ushirogata Stream, amphipods were found, but no isopods. The amphipods were identified as Sternomoera japonica (Tattersall, 1922) , previously known as Paramoera japonica (Gammaridea: Pontogeneiidae ; see Kuriyabashi et al. 1996). No larval infection of A. lucidus was detected in these amphipods (n =62), although some of them harbored cystacanths of E. cotti in the hemocoel. The latter acanthocephalan is known to parasitize salmonids as adults and amphipods as cystacanths in the Kanita River near the sampling site ( Nagasawa and Egusa 1981b).

Figures

Fig. 1. Acanthocephalus lucidus Van Cleave, 1925, male (NSMT–As 4040), from the intestine of Salvelinus leucomaenis leucomanis (Pallas, 1814). A, entire body; B, proboscis. Scale bars: A, 0.5mm; B, 0.2mm.