Hamacreadium morgani Baz, 1946

Martin, Storm B., Cutmore, Scott C., Ward, Selina & Cribb, Thomas H., 2017, An updated concept and revised composition for Hamacreadium Linton, 1910 (Opecoelidae: Plagioporinae) clarifies a previously obscured pattern of host-specificity among species, Zootaxa 4254 (2), pp. 151-187 : 167-169

Hamacreadium morgani Baz, 1946

( Figure 5 a)

Synonyms: Hamacreadium lethrini Nagaty & Abdel Aal, 1962 nec Yamaguti, 1934; Hamacreadium balistesi Nagaty & Abdel Aal, 1962 n. syn.; Hamacreadium nebulosae Nagaty & Abdel Aal, 1962 n. syn.; Hamacreadium nagatyi Lamothe- Argumedo, 1962 n. syn.; Hamacreadium lenthrium Manter, 1963 (misapplied) n. syn.; Hamacreadium egyptia Abdou, Heckmann, Beltagy & Ashour, 2001 n . syn.; Hamacreadium agyptia Abdou, Heckmann, Beltagy & Ashour, 2001 (misspelling).

Records. From the red porgy, Pagrus pagrus (Linnaeus) (Sparidae) [as P. vulgaris Valenciennes ], from a fishery in Alexandria, Egypt by Baz (1946). From the pink ear emperor, L. lentjan [as “ L. mehsenoides ”], in the Red Sea by Nagaty & Abdel Aal (1962c) as H. lethrini . From the Picasso triggerfish, Rhinecanthus aculeatus (Linnaeus) (Tetradontiformes: Balistidae ) [as Balistes aculeatus Linnaeus ] and two specimens from the spangled emperor, Lethrinus nebulosus (Forsskål) , as H. balistesi , in the Red Sea by Nagaty & Abdel Aal (1962a). From L. nebulosus in the Red Sea by Nagaty & Abdel Aal (1962a) as H. nebulosae . From the sky emperor, Lethrinus mahsena (Forsskål) , and L. nebulosus in the Red Sea by Abdou et al. (2001) as H. egyptia and as Pseudoplagioporus interruptus Durio & Manter, 1968 .

Remarks. The description provided by Baz (1946), based on ten specimens from a single fish, is consistent with the concept of Hamacreadium , although the excretory vesicle was not described. This poses a problem because the fish was presumably sourced from the Mediterranean, but sparids of the Mediterranean, including P. pagrus , are particularly well examined, and there are no other reports of Hamacreadium species from any Mediterranean fishes. Sasal et al. (1999) and Bartoli et al. (2005) examined 19 and 59 P. pagrus respectively, collected off Corsica, and both found three opecoelid species: Allopodocotyle jaffensis ( Fischthal, 1980) Bray, 1987 , Macvicaria crassigula ( Linton, 1910) Bartoli, Bray & Gibson, 1989 and Pachycreadium carnosum ( Rudolphi, 1819) Cortini & Ferretti, 1959 . Likewise, M. crassigula was the only opecoelid recovered from a further 50 P. pagrus examined from off the coast of Tunisia by Gargouri Ben Abdallah & Maamouri (2008). It seems unlikely that the specimens reported by Baz (1946) could represent any of these three species. His specimens were 5,700–7,300 µm in length, much larger than recorded for either A. jaffensis (1,890–2,910 µm, Bartoli et al. 1989b), M. crassigula (1,700–3,422 µm, Bartoli et al. 1989a) or P. carnosum (2975–5,313, Bartoli et al. 1988). Further, all three have an entire ovary, among other distinguishing characters. Two further opecoelids, Cainocreadium dentecis Jousson & Bartoli, 2001 and Peracreadium characis ( Stossich, 1886) Bartoli, Gibson & Bray, 1989 (2,910–4,780 and 2,080–4,250 µm long, Bartoli et al. 1989), infect Mediterranean sparids, but both have a medial genital pore and are apparently restricted to the common dentex, Dentex dentex (Linnaeus), and the sharpsnout seabream, Diplodus puntazzo (Walbaum) , respectively (Bartoli et al. 1989c; Sasal et al. 1999). Thus, H. morgani is concluded to represent a genuine Hamacreadium species, but neither the host nor the locality is considered convincing.

The descriptions of H. balistesi , H. nagatyi [as H. lethrini nec Yamaguti] and H. nebulosae are based on three, one and two specimens respectively. None was compared with H. morgani and neither H. balistesi nor H. nebulosae was compared with H. nagatyi . These species are indistinguishable from one-another and cannot justifiably be considered distinct. Bray & Cribb (1989) synonymised H. balistesi , H. nagatyi (and its other names, H. lethrini nec Yamaguti and H. lenthrium ) and H. nebulosae with H. mutabile , but this view is not accepted here because of the new biogeographical arguments made earlier for H. mutabile , because H. morgani and all of its synonyms are largely known from lethrinids rather than lutjanids, and also because of morphological distinctions; H. mutabile is comparatively smaller, has more ovarian lobes and consistently pre-bifurcal vitelline follicles, whereas H. morgani , H. balistesi , H. nagatyi and H. nebulosae were all described with a four-lobed ovary and vitelline follicles terminating at the level of the intestinal bifurcation. The descriptions of H. morgani , H. balistesi and H. nagatyi did not detail the excretory vesicle, but for H. nebulosae it was described as reaching to the midlevel of the ventral sucker, unusual, but similar to that of Cainocreadium alanwilliamsi Bray, 1990 .

Bray & Justine (2016) noted that the description of H. egyptia by Abdou et al. (2001) was based upon an immature specimen, and on this basis considered the species unrecognisable. However, Abdou et al. (2001) also reported P. interruptus from the same fish, and it is likely that H. egyptia represents the immature form of those worms. To further complicate the matter, the adult specimens identified as P. interruptus by Abdou et al. (2001) do not represent that species, but are more consistent with H. morgani ; the ovary is lobed rather than entire and is anterior to the testes rather than between them, and the worms were 6,000–7,000 µm long, comparable to H. morgani (5,700–7,300 µm), but much larger than Durio & Manter (1968) reported for P. interruptus (2,204–4,389 µm). Thus H. egyptia is synonymised here with H. morgani .

The report of H. balistesi from a balistid is not convincing. Nagaty & Abdel Aal (1962a) based their description on three specimens from one balistid and one L. nebulosus , but only two were mature. Although not explicit, the description suggests that it was the specimen from the balistid which was immature. One might assume that the name given to this species suggests the description was based on the specimen from the balistid, but Nagaty & Abdel Aal (1962a) also proposed H. nebulosae and so could not name both species after L. nebulosus .

Hamacreadium interruptum has been considered a senior synonym of H. balistesi by Ramadan (1983) and of H. nagatyi by Fischthal & Kuntz (1965) but that species is considered morphologically distinct here (see H. interruptum above).

Figures

FIGURE 5. Reproduction with modification of type illustration for (a) Hamacreadium morgani Baz, 1946 and (b) Hamacreadium phyllorchis (Bilqees, 1976) Cribb, 2005. Abbreviations: C, caecum; Cs, cirrus-sac; Ep, excretory pore; Ev, excretory vesicle; Gp, genital pore; O, ovary; Oes, oesophagus; Os, oral sucker; P, pharynx; T, testis; U, uterus; Vf, vitelline follicles; Vs, ventral sucker. Scale: 1000 µm, 1000 µm.