Prosorhynchus

Truong, Thuong Van, Palm, Harry W., Bui, Te Quang, Ngo, Huong Thi Thuy & Bray, Rodney A., 2016, Prosorhynchus Odhner, 1905 (Digenea: Bucephalidae) from the orange-spotted grouper Epinephelus coioides (Hamilton, 1822) (Epinephelidae), including Prosorhynchus tonkinensis n. sp., from the Gulf of Tonkin, Vietnam, Zootaxa 4170 (1), pp. 71-92 : 82-84

Prosorhynchus sp. B (VN)

( Fig. 1 .d)

Site. Intestine.

Locality. Cat Ba, Hai Phong, Vietnam (20°46'30"N, 107°04'38"E, August 2014).

Description. Based on one specimen ( Table 1). Body elongate, widest at vitelline region. Tegument spinous; spines squamous, tiny, reach to posterior extremity. Rhynchus conical, muscular, longer than wide, blunt at posterior end. Mouth near mid body, just anterior to posterior testis, inside anterior half of body. Pharynx globular, anterior-dextral to posterior testis. Cecum oval, sac-like, extends anteriorly from pharynx.

Testes 2, sub-spherical, oblique, anterior testis sinistral to ovary. Cirrus–sac elongate, not thick walled, not reaching to posterior testis, located in posterior half of body. Seminal vesicle tubular, extending about half-length of cirrus-sac. Pars-prostatica relatively narrow, with dorsal-ventral loop near middle of cirrus-sac. Ejaculatory duct narrow, complex genital lobe inside genital atrium. Genital atrium large. Genital pore distinctly separated from posterior end.

Ovary oval, dextral to anterior testis. Uterus reaches anteriorly as far as anterior testis, extending posteriorly to posterior margin of cirrus-sac. Eggs tanned, numerous. Vitellarium forming an arch of 24 follicles, beginning at posterior testis level and covering cecum and gonads. Excretory pore terminal. Excretory vesicle not seen.

Remarks. As only a single specimen with clear features could be observed, which differs from all other known species, we herewith record it as Prosorhynchus sp. B ( VN) due to the lack of further material.

The comparison diagram visual key of Prosorhynchus sp. B ( VN) ( Fig. 4) demonstrates that Prosorhynchus sp. B ( VN) does not differ from P. lafii , P. maternus and P. pacificus in the visual key. However, it still can be distinguished by its arched vitellarium. In P. lafii from the Brown-marbled Grouper Epinephelus fuscoguttatus (Forsskål) off Queensland, Australia ( Bott & Cribb 2009), P. maternus from E. malabaricus off New Caledonia ( Bray & Justine 2006) and P. pacificus from M. olfax off Galapagos Islands waters ( Ecuador)( Manter 1940a), the vitelline follicles are in two lateral fields.

Figure 4 illustrates that two species have one black square against their name, namely P. caudovatus and P. luzonicus . However, P. caudovatus from Epinephelus sp. from off Suez (Red Sea, Egypt) ( Eckmann 1932) differs from Prosorhynchus sp. B ( VN) in its filamented eggs. Further, it also differs in one major (Rhynchus %) and three minor distinguishing features in the visual keys ( Table 4 ). Prosorhynchus sp. B ( VN) is clearly distinguished from P. luzonicus from L. calcarifer in Philippine waters ( Velasquez 1959) by its arched vitellarium. In the visual keys, Prosorhynchus sp. B ( VN) also is distinguished from P. luzonicus in PTR % ( Table 4 ) but it does not differ in this feature considering the new data on P. luzonicus from Bray & Justine (2013) and the present study (see Table 4 ).

The visual key demonstrates that P. atlanticus , P. jexi , P. jupe , P. promicropsi and P. serrani have two black squares against their name. Prosorhynchus atlanticus from the Gag Mycteroperca microlepis (Goode & Bean) and M. bonaci off Florida ( Manter 1940b) is distinguished from Prosorhynchus sp. B ( VN) in its vitellarium in two follicles fields, whereas in Prosorhynchus sp. B ( VN), the vitellarium is an arched form. Prosorhynchus jexi from the Longfin Grouper Epinephelus quoyanus (Valenciennes) off Australia ( Bott & Cribb 2009) differs from Prosorhynchus sp. B ( VN) in two clustered lateral vitelline fields. Prosorhynchus jupe from ‘ Promicrops ’ guttatus (presumably the Red Hind Epinephelus guttatus [Linnaeus]) in Brazilian waters ( Kohn 1967) is distinguished from Prosorhynchus sp. B ( VN) in its tandem vitelline fields, and P. promicropsi from Promicrops itaiara off Florida ( Manter 1940b) is distinguished from Prosorhynchus sp. B ( VN) in its vitellarium in two fields and the cecum extended anteriorly beyond the vitellarium. Prosorhynchus serrani from Variola louti off New Caledonia ( Durio & Manter 1968) is distinguished from Prosorhynchus sp. B ( VN) in its thick walled cirrus-sac. Furthermore, Prosorhynchus sp. B ( VN) differs from all of the above species in some major and minor distinguishing features as seen in table 3.

Figures

FIGURE 1. Prosorhynchus spp. from groupers. a, b Prosorhynchus tonkinensis n. sp., note the spermatophore (a) and intended posterior extremity (b); c Prosorhynchus sp. A (VN); d Prosorhynchus sp. B (VN); e P. luzonicus; f Prosorhynchus maternus. Uterus in bold outline and treated as transparent. Scale bars: a, b, c, d = 100 µm; e, f = 200 µm.

Tables

TABLE 4. Ratio comparison of Prosorhynchus sp. B (VN), yellow shading shows major distinctions.

Length	Width %	Rhynchus %	PreVRt %	PreUR %
Prosorhynchus sp. B (VN) 1597	20	18	20	37
P. luzonicus 824–1860	20–34	18–25	15–28	29–44
P. lafii 1040 –1184	15–22	18	26	34
P. maternus 2052 –2227	19–21	13–17	19–23	34–41
P. pacificus 1206 –1444	25–27	18–19	26–31	41–46
P. luzonicus 1060 –2020	22–25	10–19	20	42
P. caudovatus 2000 –4000	18–20	10–12	18–31	25–46
P. atlanticus 705–1677	27–33	24–26	23–25	36–49
P. jexi 1104 –1424	19–25	15	20	32
P. jupe 1520 –2530	13–21	6–11	15–24	29–42
P. promicropsi 1498 –1957	18–20	13–15	35	44
P. serrani 1027 –2245	22	12–18	20	17
continued.