A review of the Zoogonidae (Digenea: Microphalloidea) from fishes of the waters around New Caledonia, with the description of Overstreetia cribbi n. sp.

New and published reports of zoogonid digeneans from New Caledonian waters are recorded, including a description of Overstreetia cribbi n. sp. from Atherinomorus lacunosus. This species differs from its congeners in the detail of its circum-oral spination and some metrical features. Other new records are of: Diphterostomum plectorhynchi Machida, Kamegai & Kuramochi, 2006 in Diagramma pictum; Parvipyrum acanthuri (Pritchard, 1963) in Acanthurus dussumieri; Zoogonoides viviparus (Olsson, 1868) in Lagocephalus sceleratus; Deretrema ? combesorum (Bray & Justine, 2008a; Bray & Justine, 2008b) early ovigerous forms in Parupeneus pleurostigma; D? acutum (Pritchard, 1963) in P. barberinus; and an unidentified immature zoogonid in P. multifasciatus. The newly reported specimens are illustrated and measurements given. The distribution of New Caledonian zoogonids is listed.


Genus Zoogonoides Odhner, 1902
ZooBank: urn:lsid:zoobank.org:act:6CEFCB5C-4537-4C5D-A1F7-08901790BF65. Synonyms: see Bray & Gibson (1986). Discussion: Seven nominal species of Zoogonoides have been described from the Indo-Pacific region. Three of these can be distinguished from our specimen by the sucker ratio, with the ventral sucker smaller than, or of similar size to, the oral sucker (Table 1): Yamaguti, 1938, Z. kamegaii Toman, 1992and Z. anampses Toman, 1992(Yamaguti, 1938;Toman, 1992). Two others, Z. pyriformis Pritchard, 1963 andZ. synodi Yamaguti, 1970;(Pritchard, 1963;Yamaguti, 1970) can be distinguished by the lack of an atrial sac, a feature which is clear in the single specimen we have (Fig. 3). The two Indo-Pacific species that are described with this feature are the type-species, Z. viviparus (Olsson, 1868), and Z. yamagutii Kamegai, 1973. Z. viviparus is reported mainly in the North Atlantic Ocean, having been originally reported off Norway (Olsson, 1868;Bray & Gibson, 1986), but has been reported in the northern Pacific Ocean (Zhukov, 1960;Mamaev, Parukhin & Baeva, 1963;Machida et al., 1972;Tsimbalyuk, 1978;Machida, 1984;Shimazu, 1984) and the northern Indian Ocean (Sujatha & Madhavi, 1990). Z. yamagutii is known only from Plotosus lineatus (Thunberg, 1787) [as P. anguillaris] (Siluriformes: Plotosidae) from Nishidomari Bay, Tsushima Island, Japan (Kamegai, 1973). It was originally (Kamegai, 1973) compared only with Z. acanthogobii which was considered the 'only other representative in the genus possessing a saccular posterior diverticle of the genital atrium' . In fact, Z. viviparus is now known to exhibit this feature (see Bray & Gibson, 1986) and we cannot see any distinction between this species and our specimen. As far as we are aware this is the first record of Zoogonoides from the Southern Hemisphere apart, possibly, from the dubious report of Zoogonoides sp. from a freshwater fish in Lake Victoria, Uganda (Akoll et al., 2012). Aspects of the life-cycle of Z. viviparus are known from the northeastern Atlantic. The first intermediate host is the sorbeoconchan gastropod Buccinum undatum (Linnaeus, 1758), the second in intermediate host may be an ophiuroid or holothurian echinoderm, a polychaete, bivalve or gastropod, or possibly a mysid crustacean (Køie, 1976;Bray & Gibson, 1986). The most frequently reported definitive hosts are flatfish, with about 75% of records (pleuronectids 68%, soleids 6.6%, scophthalmids 0.9%). The only other group commonly reported as hosts are the callionymids (8.5%) and there are occasional reports from anarhichadids, blenniids, gobiids, liparids, lophiids, sillaginids, sticheaids and zeids, with one report from a cyprinid. Therefore, this appears to be the first report of Zoogonoides in a tetraodontiform fish. It is likely that Z. viviparus is a complex of species awaiting molecular elucidation.

Zoogonus pagrosomi Yamaguti, 1939
ZooBank: urn:lsid:zoobank.org:act:FE7F7E55-FD83-4021-A271-A9B5BA66F1DF. Discussion: We have recovered this species only from lethrinid fishes, but it was originally described from the sparid Chrysophrys auratus Forster 1801 (as Pagrosomus unicolor) from the Inland Sea of Japan (Yamaguti, 1939). Cribb, Bray & Barker (1992) reported it in Lethrinus atkinsoni off Heron Island in the southern Great Barrier Reef. The only other record of which we are aware is from the gadiform Merluccius gayi peruanus Ginsburg, 1954 (Merlucciidae) from off Callao, Peru (Rivera Terrones, 1992). This appears to be a poorly known species, therefore, with an unusual distribution, both geographical and in terms of its hosts. Nevertheless, several metric and ratio characters differ, e.g., size, width ratio, and the ratios of the suckers and the sizes of most gonads relative to body-length (Table 2). These ratios may represent allometric growth, or they may indicate that this is a distinct, but similar species. The information we have to hand is not sufficient to decide between these alternatives and is certainly not enough to warrant the erection of a new species.
Discussion: This species was originally reported in this host, from Okinawa, Japan (Machida & Kuramochi, 1999). Our record from New Caledonia is the only other report of this species. Pritchard, 1963 (Fig.  Discussion: The single specimen available appears indistinguishable (Table 2) from D. acutum as described by Pritchard (1963) apart from the vitellarium which is developed on one side of the body only. As only one specimen is available it is not possible to be certain that this is an anomalous condition. Both previous reports of this species, under this name, are from acanthurids of the genus Naso, from off Hawaii (Pritchard, 1963;Yamaguti, 1970). Bray (1987b) considered D. hawaiiense Yamaguti, 1970, D. sphyraenae Yamaguti, 1970, D. uku Yamaguti, 1970and Deretrema sp. of Yamaguti (1951 synonymous with D. acutum, following the discussion of Beverley- Burton & Early (1982) who pointed out that, according to Yamaguti (1970), they are distinguished by minor details of Laurer's canal. If these synonymies are accepted, then the host list is increased to include   Etymology: This species is named after our colleague Dr. Tom Cribb, of the University of Queensland, who has contributed immeasurably to our understanding of the taxonomy and biology of digeneans.
Ovary oval, entire, contiguous with ventral sucker and close to anterior testis. Proximal female system obscured by eggs. Uterus runs posteriorly from ovary passes ventrally over testes, fills bulk of body posterior to anterior testis, presumably reaches extracaecally, but caeca obscured by eggs. Metraterm short, muscular, with narrow sheath of gland-cells. Eggs numerous, operculate, tanned. Vitellarium forms 2 lateral fields of few (8-9 aporal, 11 poral) irregularly oval follicles between levels of ventral sucker and posterior testis.
Excretory pore terminal. Excretory vesicle anterior extent and shape obscured by eggs.
Only six ovigerous specimens of Overstreetia spp. have been reported. The genus was erected based on two specimens of the type species O. sodwanaensis Bray, 1985 from Pranesus pinguis (Lacepède, 1803) off Sodwana, Natal, South Africa (Bray, 1985). Subsequently, two ovigerous specimens and one immature specimen of O. olsoni Bray & Cribb, 2006 were described from the Capricorn silverside Atherinomorus capricornensis (Woodland, 1961) off Heron Island, Queensland, Australia (Bray & Cribb, 2006). Now we have discovered two ovigerous specimens from Atherinomorus lacunosus off New Caledonia. We have re-measured the holotype of O. sodwanaensis (BMNH 1983.8.3.1) and the paratype of O. olsoni (BMNH 2005.3.11.6) and included the data in Table 3. These two specimens appear to represent a new species. They differ from the described species most obviously in the oral spination. In O. cribbi the enlarged spines form an arc beside the aperture of the oral sucker and pass dorsally around the oral sucker region. This contrasts with the condition in O. sodwanaensis where the oral spine rows are limited to the anterior part of the oral sucker region (Fig. 8), and the condition in O. olsoni where there are no noticeably enlarged circum-oral spines (Fig. 9).
In O. sodwanaensis the cirrus-sac is recurved, with a long internal seminal vesicle. The body is narrower, the ventral sucker is relatively larger, the oesophagus, vitelline    field and ovary to anterior testis distances are relatively greater and the oral sucker size, post-testicular distance and post-vitelline distance are relatively smaller (Table 3).
In O. olsoni the body is narrower, the forebody, oesophagus, vitelline field and ovary to anterior testis distances are relatively greater and the oral and ventral sucker sizes, post-testicular distance and post-vitelline distance are relatively smaller (Table 3).
In our discussion of the hosts of Overstreetia above we have used the names given in the original papers, but recently Kimura et al. (2007) have reviewed and restudied Indo-Pacific Atherinomorus [syn: Pranesus] spp. and synonymised A. capricornensis with A. lacunosus and recognised A. pinguis. Presuming that the host identifications are correct, then the Overstreetia from the Great Barrier Reef and New Caledonia are from the same host species, but differ distinctly. The host of the South African species may also be conspecific, as Kimura et al. (2007) considered some of the subspecies of A. pinguis as well as some specimens referred to A. pinguis by various authors to be synonymous with A. lacunosus.

New Caledonian host: Triodon macropterus.
Discussion: This species was originally reported in this host, from off Okinawa, Japan (Machida & Kuramochi, 1999). Our record from off New Caledonia is the only other report of this species.
• Jean-Lou Justine conceived and designed the experiments, performed the experiments, contributed reagents/materials/analysis tools, wrote the paper, reviewed drafts of the paper, collected parasites.

New Species Registration
The following information was supplied regarding the registration of a newly described species: The new species is entered in ZooBank and its LSID: urn:lsid:zoobank.org:act: FC32CC29-F6DD-46DC-B2F2-84F3953B2991.