Prosorhynchus platycephali ( Yamaguti, 1934 ) Srivastava, 1938

Bray, Rodney A & Palm, Harry W, 2009, Bucephalids (Digenea: Bucephalidae) from marine fishes off the south-western coast of Java, Indonesia, including the description of two new species of Rhipidocotyle and comments on the marine fish digenean fauna of Indonesia, Zootaxa 2223, pp. 1-24 : 15-19

Prosorhynchus platycephali ( Yamaguti, 1934) Srivastava, 1938

Syns. Gotonius platycephali Yamaguti, 1934 ; Prosorhynchus tsengi of Hafeezullah & Siddiqi (1970) ( Figure 6 )

Host: Sunagocia otaitensis (Cuvier) , Platycephalidae , fringelip flathead.

Site: intestine.

Locality: Pelabuhan Ratu, Java, Indonesia (06°59S, 106°32’E, March 2008).

Deposition of specimens: vouchers ZMB Generalkatalog Entozoa, E.7457, BMNH 2009.5.22.4–5, NBC MZBTr 206.

Taxonomic comparison: Using a similar visual key to that developed for Rhipidocotyle spp. (see above) we discovered that this form, illustrated in Figure 6 , cannot, on the basis of these 9 parameters, be distinguished from two described species, Prosorhynchus eleutheronemae Wang, 1985 and P. platycephali ( Yamaguti, 1934) , and only one parameter distinguishes this form from P. apertus McFarlane, 1936 , P. caballeroi Gupta & Ahmad, 1976 , P. caudovatus Manter, 1940 , P. fujianensis Wang, 1985 , P. indicum Madhavi, 1974 , P. jupe ( Kohn, 1967) and P. synanceiae Wang, 1985 (see comparison diagram – Figure 7). We believe that our specimens belong to P. platycephali .

Prosorhynchus platycephali has been considered the synonym of P. f a c i l i s ( Ozaki, 1924) by Nagaty (1937) and of P. tsengi Tsin, 1933 by Hafeezullah & Siddiqi (1970). Bilqees (1977) rejected both synonymies, although she considered that the specimens illustrated by Hafeezullah & Siddiqi (1970) and designated P. tsengi were, in fact, P. platycephali . Our observations confirm Bilqees’ view and according to our visual key, based on the observations of Yamaguti (1934), Hafeezullah & Siddiqi (1970), Bilqees (1977) and our own, P. facilis has a much larger rhynchus (over 10% of body-length vs 3–6% of body-length) and eggs 35–40 long (vs 22–30 long). P. tsengi differs in length (1,500–1,800 vs 2,430–5,900), width (24–25% of body-length vs 8–16%) and cirrus-sac reach (about 41% of body-length vs about 15–27%). In addition, as pointed out by Bilqees (1977) the testes in P. tsengi overlap, whereas in P. platycephali they are always distinctly separated. All parameters of ‘ P. t s e n g i ’ of Hafeezullah & Siddiqi (1970) as far as they can be ascertained from their illustration fit within the variation we have found for P. platycephali . The position of Mehlis’ gland posterior to the anterior testis also appears to be a distinguishing feature of P. platycephali .

Prosorhynchus platycephali has been reported from the bartail flathead Platycephalus indicus (Linnaeus) (Platycephalidae) from Japan ( Yamaguti 1934), the rough flathead Grammoplites scaber (Linnaeus) (Platycephalidae) from off Cochin, India ( Hafeezullah & Siddiqi 1970) and Pakistan ( Bilqees 1977) and now from a flathead off Java. It has also been reported, but not described or illustrated from the white-edged lyretail Variola albimarginata Baissac (Serranidae) and the yellow-edged lyretail V. louti (Forsskål) from off Okinawa, Japan ( Dyer et al. 1988).

Prosorhynchus eleutheronemae described from the fourfinger threadfin Eleutheronema tetradactylum (Shaw) (Polynemidae) from off Fujian Province, China (Wang 1985) appears to resemble P. platycephalus closely, but is possibly distinguished by the slight separation between the ovary and anterior testis.

Prosorhynchus apertus from Ophiodon elongatus off British Columbia, Canada ( McFarlane 1936) differs from our specimens, according to the visual key, in its post-testicular distance (about 12% of body-length vs 24–36 (30)%). According to the illustration the gap between the ovary and the anterior testis is greater than that between the testes and the cirrus-sac reaches the anterior testis. The pre-vitelline distance (about 36% of body-length vs 16–27 (20)%) is probably also a distinguishing feature.

Prosorhynchus caballeroi from the shrimp scad Alepes djedaba (Forsskål) (as Caranx kalla Cuvier ) ( Carangidae ) from the Bay of Bengal ( Gupta & Ahmad 1976) differs from our specimens, according to the visual key, in its pre-vitelline distance (about 42% of body-length vs 16–27 (20)%). The testes are contiguous and the cirrus-sac reaches to the middle of the anterior testis. The pre-uterine distance (about 36% of bodylength vs 13–30 (18)%) and post-testicular distance (about 18% of body-length vs 24–36 (30)%) are probably also distinguishing features.

Prosorhynchus caudovatus from Epinephelus spp. in the waters around Africa ( Bray 1984; Eckmann 1932) differs, according to the visual key, in its rhynchus length (about 9–12% of body-length vs 3–6%). It can also easily be distinguished by the filamentous eggs.

Prosorhynchus fujianensis was described from the eel Anguilla mauritiana (now considered the giant mottled eel Anguilla marmorata ) from off Fujian Province, China (Wang 1985) and was distinguished from P. platycephali in the visual key by its shape (width about 21–27% of length vs 8–16%). In addition the spaces between the three gonads are short and more or less equal and the uterus appears to reach significantly anteriorly to the vitellarium.

Prosorhynchus indicum from the barred queenfish Scomberoides tala (Cuvier) (Carangidae) in the Bay of Bengal ( Madhavi 1974) differs from our specimens, according to the visual key, in its pre-vitelline distance (about 50% of body-length vs 16–27 (20)%). The cirrus-sac reaches to the posterior testis. The pre-uterine distance (about 37% of body-length vs 13–30 (18)%) and post-testicular distance (about 16% of body-length vs 24–36 (30)%) are probably also distinguishing features.

Prosorhynchus jupe from the red hind Epinephelus (as Promicrops ) guttatus (Linnaeus) ( Serranidae ) off Espírito Santo State, Brazil ( Kohn 1967) differs from our specimens, according to the visual key, in its premouth distance (about 31–34% of body-length vs 45–56 (50)%). The vitelline distribution is unusual in that one of the two fields lies at about the level of the ovary and the other lies between the testes. The posttesticular distance (about 42–43% of body-length vs 24–36 (30)%) is probably also a distinguishing feature.

Prosorhynchus synanceiae from the estuarine stonefish Synanceia horrida (Linnaeus) (Synanceiidae) off Fujian Province, China (Wang 1985) differs from our specimens, according to the visual key, in the relative length of the rhynchus (8–9% of body-length vs 4-5%). It also probably differs in pre-vitelline distance (about 33% of body-length vs 16–27 (20)%) and post-testicular distance (about 18% of body-length vs 24–36 (30)%). In the illustration the cirrus-sac just overlaps the posterior testis, a condition we did not find in our specimens.

Prosorhynchus tsengi is also a parasite of flatheads ( Platycephalidae ) having been described and illustrated in Platycephalus indicus from off China (Shen & Qiu 1995; Tsin 1933). Other records, without descriptive matter, are from P. indicus off China ( Li et al. 1989; Shen 1989), the orange-freckled flathead Ratabulus diversidens (McCulloch) [as Suggrundus diversidens ] ( Platycephalidae ) off eastern Australia ( Hooper 1983) and the soldierbream Argyrops filamentosus (Valenciennes) (Sparidae) in the Gulf of Mannar off India ( Parukhin 1976). Hooper (1983) accepts the synonymy of P. platycephali and P. t s e n g i and may, therefore be referring to the former. The original illustration of P. tsengi by Tsin (1933, fig. 8) shows a lobed rhynchus, apparently with an aperture, and a straight pars prostatica, indicating that the species may in fact belong to the genus Rhipidocotyle . The illustration in Shen & Qiu (1995, fig. 16) similarly indicates that the generic status of this species is questionable.

Figures

FIGURE 6. Prosorhynchus platycephali (Yamaguti, 1934). Ventral view. Scale-bar = 500 μm.