Prosorhynchus luzonicus Velasquez, 1959

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 : 84-88

Prosorhynchus luzonicus Velasquez, 1959

( Fig. 1 .e)

Site. Pyloric ceca, intestine.

Locality. Ha Long (20°57'14"N, 107°18'23"E, July and August, 2013), Cat Ba (20°46'30"N, 107°04'38"E, August, 2013, July, 2014), Nghia Hung (19°59'18.5"N, 106°10'44.7"E, October, 2013, August, 2014), and Tinh Gia (19°24'31"N, 105°45'55"E, September, 2013).

Description. Measurement data based on 20 specimens ( Table 5). Body fusiform or elongate, widest at about mid of body, blunt at anterior end, tapering to rounded or pointed posterior end. Tegument spinous; spines squamous, tiny, reach to posterior extremity. Rhynchus large, muscular, conical, longer than wide. Mouth at level of ovary and/or anterior testis, always inside anterior half of body. Pharynx spherical, muscular, in anterior half of body. Cecum tubular or oval sac like, extends to anteriorly from pharynx.

Testes 2, subspherical, tandem, sometimes contiguous, slightly overlapping, dextral in about midbody. Cirrussac elongate, muscular, not thick-walled, more or less parallel-sided, normally reaching posterior testis, may reach to ceca or not reach to posterior testis. Seminal vesicle elongate-oval, dextral in proximal portion of cirrus-sac. Pars-prostatica long, in two distinct parts; proximal part narrow, curved proximally to form convoluted seminal duct, joins posterior-dorsal aspect of seminal vesicle; distal part wider, straighter, surrounded by dense layer of gland-cells, lining of filaments in chevron arrangement. Ejaculatory duct narrow, complex genital lobe inside genital atrium. Genital atrium large. Genital pore distinctly separated from posterior end.

Ovary oval, anterior to or overlapping anterior part of anterior testis. Uterus reaches anteriorly beyond ovarian region, almost to anterior extent of cecum (reaches in 1 of 45 specimens), and extends posteriorly to genital pore. Eggs tanned, numerous. Vitellarium with 25–28 follicles (13–15 follicles on long field and 11–13 on short field), consists of two lateral fields, usually symmetrical, long vitelline field dextral, anterior extremity close to posterior margin of rhynchus and always anterior to cecum, ovary and uterus; posterior extremity at about level of anterior testis. Excretory pore terminal; excretory vesicle not seen.

Species P. luzonicus P. maternus P. luzonicus P. maternus

Source This study This study Bray & Justine (2013) Bray & Justine (2006) Host(s) E. coioides E. coioides E.coioides E. malabaricus Location Ha Long, Cat Ba, Nghia Cat Ba New Caledonia New Caledonia

Hung and Tinh Gia

No of specimens 20 1 14 8

min max min max min max Length 824 1860 1852 792 1172 2052 2227 Width 225 462 352 129 288 392 476 Pre-vitelline distance 176 411 421 142 221 409 477 Pre-cecal distance 250 573 495 219 311 497 604 Pre-uterine distance 279 576 711 263 409 739 922 Pre-mouth distance 368 856 745 327 471 788 870 Pre-testicular distance 280 800 647 315 456 665 816 Pre-ovarian distance 310 743 594 276 407 633 762 Rhynchus length 201 357 306 126 170 280 360 Rhynchus width 147 256 192 99 170 189 243 Rhynchus to vitellarium distance 0 95 119 0 72 77 186 Rhynchus to uterus distance 61 259 410 133 272 386 641 Rhynchus to cecum distance 36 217 196 78 163 142 564 Long vitelline field 209 604 452 186 344 475 606 Short vitelline field 173 437 304 154 257 360 512 cecum length 94 235 204 80 125 202 231 cecum width 79 161 129 58 108 134 178 Pharynx length 53 91 82 42 66 58 101 Pharynx width 45 92 77 46 75 69 100 Ovary length 55 135 128 58 95 127 153 Ovary width 49 133 97 54 79 98 131 Ovary to anterior testis distance 0 0 0 0 0 0 12 Anterior testis length 66 175 162 69 99 152 188 Anterior testis Width 72 169 138 66 111 124 160 Distance between testes 0 29 0 0 39 0 114 Posterior testis Length 71 172 148 69 92 152 191 Posterior testis width 71 172 134 71 92 117 148 Posterior testis to cirrus-sac 0 131 407 0 0 230 363 Cirrus-sac length 287 601 394 230 360 468 541 Cirrus-sac width 81 186 115 70 124 91 116 Seminal vesicle length 81 170 188 101 165 198 275 Seminal vesicle width 28 57 79 37 63 61 88

......continued on the next page VN: Vietnam

NC: New Caledonia.

Remarks. We measured 20 specimens to create a visual key diagram for comparison with other species ( Fig. 5 ). It shows ten species without black squares that might be considered the same species. However, P. australis , P. crucibulum , P. longisaccatus and P. paracrucibulus differ in an arched vitellarium. Prosorhynchus scalpellus differs in its slender rhynchus. P. lafii differs in a clumped configuration of the vitelline follicles. The descriptions and illustrations of P. maternus are similar to our specimens but differ in several features. The anterior extent of the vitellarium allways is distinctly separated from the rhynchus, the rhynchus is slender and elongated, and the cirrus-sac never reaches to the testis level. In our specimens, the vitelline field is relatively closer to the rhynchus, the cirrus-sac overlaps or reaches the posterior testis, and the rhynchus is broad. In addition, the egg of P. maternus is

smaller (27–28 × 14–22 vs 29–36 × 20–23). The descriptions and illustrations of three further species, P. luzonicus , P. pacificus and P. atlanticus , are also similar to our specimens. The original description of P. pacificus from Mycteroperca olfax in Galapagos ( Manter 1940a) and P. atlanticus from M. bonaci in Florida ( Manter 1940b) differ from our specimens in the uterus not extending anteriorly beyond the ovary (pre-uterine distance % longer than pre-ovarian distance %). In contrast, the uterus of our specimens reaches anteriorly beyond the ovary (preuterine distance % often less than or equal to pre-ovarian distance %-see Table 5).

The measurement and features of our specimens are very similar to the original description of P. luzonicus from Lates calcarifer in The Philippines ( Velasquez 1959) and from E. coioides in New Caledonia ( Bray & Justine 2013). Therefore, we identified them as P. luzonicus . However, some opinions argue that P. luzonicus , P. pacificus and P. atlanticus are synonyms. For example, Hanson (1950) compared five Prosorhynchus specimens from the Yelloweye Rockfish Sebastes ruberrimus (Cramer) with both original descriptions of P. pacificus and P. atlanticus and found that they were similar to both of them. Hanson (1950) suggested P. pacificus as a synonym of P. atlanticus . Manter (1953) accepted P. atlanticus as a synonym of P. pacificus ( Manter 1953) . Winter (1960) and Overstreet (1969) also agreed with that when they found P. pacificus from the Spotted Grouper Epinephelus analogus Gill from off the Pacific coast of Mexico and Mycteroperca bonaci and M. microlepis , from off Florida, respectively. Madhavi (1974) found P. pacificus from the Greasy Grouper Epinephelus tauvina (Forsskål) and suggested P. luzonicus as a synonym of P. pacificus . The author also gave the range of egg size of this species as 24–36 × 12–24 µm ( Madhavi 1974). Nahhas & Cable (1964) did not agree that they are synonymous, but later Nahhas et al. (2006) accepted P. luzonicus and P. atlanticus as synonyms of P. pacificus when they found P. pacificus from E. tauvina and the Golden Trevally Gnathanodon speciosus (Forsskål) in the Arabian Gulf. However, some authors did not accept P. atlanticus as a synonym of P. pacificus such as Siddiqi & Cable (1960) who reported P. atlanticus from Mycteroperca sp. off Mona Island . Hafeezullah & Siddiqi (1970) also reported P. atlanticus from E. malabaricus at Karwar on the west coast of India. Bray & Justine (2006) restudied type specimens and found that the ‘synonymy of P. atlanticus and P. pacificus is not supported by our measurements in that in the former the vitellarium reaches to or close to the rhynchus, the rhynchus is relatively longer, the cirrus-sac is relatively shorter and the egg are larger’. Most recent researchers did not accept the synonymy of P. luzonicus with P. pacificus . Rückert (2006) reported P. luzonicus from E. coioides and E. fuscoguttatus in Lampung Bay , Indonesia ( Rückert 2006). It was again reported from E. coioides in Indonesian waters by Palm & Rückert (2009) and Rückert et al. (2009). Rückert et al. (2010) also reported P. luzonicus from E. fuscoguttatus in Lampung Bay , Indonesia. Bray & Justine (2013) reported P. luzonicus from E. coioides off New Caledonia.

In Vietnam, Vo (2010) and Vo et al. (2011; 2012) illustrated and described P. pacificus from some groupers E. bleekeri, E. coioides and E. malabaricus in Khanh Hoa province (Vo 2010; Vo et al. 2011; Vo et al. 2012). These authors accepted P. luzonicus as a synonym of P. pacificus. Although their descriptions are quite similar to our specimens and their specimens were collected from the same host E. coioides, we consider that the suite of characters from our specimens (see above) suggest that they belong in P. luzonicus.

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.

FIGURE 5. Visual comparison diagram for Prosorhynchus luzonicus from Vietnam.