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Introduction

Early systematic studies of the marine digenean fauna of New Caledonia were by Durio & Manter (1968a), Durio & Manter (1968b) and Durio & Manter (1969). More recently we have added to the knowledge of this fauna, including summary papers on the Lepocreadiidae Odhner, 1905 (Bray & Justine, 2012) and the Bucephalidae Poche, 1907 (Bray & Justine, 2013). Here we present a similar paper summarising our knowledge of the family Zoogonidae Odhner, 1902. This family is one of the major families of marine fish digeneans, with a few species in freshwater (Bray, 2008). It contains 159 species in 33 genera. Molecular analyses of a few species (Hall, Cribb & Barker, 1999; Cribb et al., 2001; Olson et al., 2003; Bray et al., 2005; new data) shows that the family is a member of the superfamily Microphalloidea Ward, 1901, close to, and probably paraphyletic to the family Faustulidae Poche, 1926. There are two distinct subfamilies in the Zoogonidae, the Zoogoninae Odhner, 1902, whose members produce eggs without a tanned shell, and therefore have a reduced vitellarium (Bray, 1987a), and the Lepidophyllinae Stossich, 1903, whose members produce tanned eggs and have a vitellarium consisting of paired fields of follicles (Bray, 1987b). Molecular phylogeny (Olson et al., 2003; Bray et al., 2005) indicates that the Zoogoninae, based on two species, is monophyletic and sister to the monophyletic Faustulidae, based on three species. The two species of lepidophyllines in the analysis are paraphyletic, with the Deretrema species sister to the Zoogoninae + Faustulidae, and Lepidophyllum species sister to that assemblage. As can be seen the sample size is small and, although the support for this arrangement is statistically good, the findings are clearly provisional and preliminary. The known zoogonid fauna of waters around New Caledonia is small, but will probably be found to be larger when explorations of the deep-sea are undertaken. In this paper we list all the known species, including a new species of the genus Overstreetia (Bray, 1985), and attempt to place them in the context of their endemicity.

Materials and Methods

Digeneans were collected live, immediately fixed in nearly boiling saline (Cribb & Bray, 2010; Justine, Briand & Bray, 2012) and then transferred to 80% ethanol. Whole-mounts were stained with Mayer’s paracarmine, cleared in beechwood creosote and mounted in Canada balsam. Measurements were made through a drawing tube on an Olympus BH-2 microscope, using a Digicad Plus digitising tablet and Carl Zeiss KS100 software adapted by Imaging Associates, and are quoted in micrometres. The following abbreviations are used: BMNH, British Museum (Natural History) Collection at the Natural History Museum, London, UK; MNHN JNC, Muséum National d’Histoire Naturelle, Paris, France.

The electronic version of this article in Portable Document Format (PDF) will represent a published work according to the International Commission on Zoological Nomenclature (ICZN), and hence the new names contained in the electronic version are effectively published under that Code from the electronic edition alone. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix “http://zoobank.org/”. The LSID for this publication is: urn:lsid:zoobank.org:act:FC32CC29-F6DD-46DC-B2F2-84F3953B2991. The online version of this work is archived and available from the following digital repositories: PeerJ, PubMed Central and CLOCKSS.

Family Zoogonidae Odhner, 1902

Subfamily Zoogoninae Odhner, 1902

Genus Diphterostomum Stossich, 1903

ZooBank: urn:lsid:zoobank.org:act:D56035F2-141C-4607-8AFE-7AEFED0AE0B3.

Diphterostomum tropicum Durio & Manter, 1968

ZooBank: urn:lsid:zoobank.org:act:71827EC5-F9EA-44A4-888D-12BF3E1FE770.

Syn: Diphtherostomum tropicum Durio & Manter, 1968

Record from off New Caledonia: Durio & Manter (1968a)

New Caledonian host: as Lethrinus sp., ‘bec de cane’; ‘can be safely identified as’ Lethrinus nebulosus (Forsskål, 1775) (Justine, 2007).

Discussion: Durio & Manter (1968a) also reported this species in the pink-ear emperor Lethrinus lentjan (Lacepède, 1802) (as L. glyphodon Günther, 1859) from Green Island, on the Great Barrier Reef. The only other report is from the sparid Chrysophrys auratus (Forster, 1801) from off New Zealand by Korotaeva (1975).

Diphterostomum plectorhynchi Machida, Kamegai & Kuramochi, 2006 (Fig. 1)


            Diphterostomum plectorhynchi.

Figure 1: Diphterostomum plectorhynchi.

Diphterostomum plectorhynchi Machida, Kamegai & Kuramochi 2006. Ventral view with ventral sucker twisted. Scale bar 200 µm.

ZooBank: urn:lsid:zoobank.org:act:3949FC49-247A-49CB-85E3-208E7FF8551C.

Host: Diagramma pictum (Thunberg, 1792), Perciformes, Haemulidae, painted sweetlips.

Site: digestive tract.

Locality: Between Larégnière and Récif Crouy (22°20′702S, 166°19′295E, 05/05/2008); Interior Lagoon near Récif Toombo (22°32′536S, 166°29′069E, 25/08/2009).

Specimens: MNHN JNC2511, JNC2512, JNC3023, BMNH 2014.1.31.2-3.

Previous New Caledonian records: none.

Discussion: This species was originally reported from this host and two Plectorhinchus spp. from off Japan (Machida, Kamegai & Kuramochi, 2006). The specimens originally described were flattened at fixation, so some features appear distinct, but the major distinguishing feature of this species is the large ‘elongate conical’ pharynx. Taking into consideration the different fixation methods used, our specimens do not appear to be distinguishable from D. plectorhinchi (Table 1).

Table 1:
Measurements and ratios of three zoogonine species.
Species Diphterostomum plectorhynchi Parvipyrum acanthuri Zoogonoides viviparus
Host Diagramma pictum Acanthurus dussumieri Lagocephalus sceleratus
n 10 2 1
min max mean
Length 880 1,395 1,120 511 592 561
Width 213 333 275 Lateral Lateral 233
Forebody length 545 929 699 183 150 219
Oral sucker length 62 212 147 68 58 97
Oral sucker width 89 198 151 Lateral Lateral 92
Prepharynx length 0 0 0 11 10 0
Pharynx length 53 198 113 28 28 35
Pharynx width 38 121 85 Lateral Lateral 43
Oesophagus length 295 508 416 81 77 50
Intestinal bifurcation to ventral sucker 18 82 62 0 0 53
Pre-vitelline distance 729 1,059 860 ? 404 382
Vitelline mass length 40 74 56 ? 31 43
Vitelline mass width 42 61 53 ? 32 44
Ventral sucker length 153 269 223 224 279 155
Ventral sucker width 159 209 186 Lateral Lateral 175
Cirrus-sac length 211 424 320 159 187 97
Cirrus-sac width 59 78 67 51 50 43
Ovary length 78 112 95 93 103 105
Ovary width 75 143 106 76 70 61
Testis length 61 128 97 80 91 ?
Testis width 52 120 79 81 77 ?
Post-testicular distance 75 171 136 77 78 ?
Post-vitelline distance 83 219 165 112 136 140
Post-uterine distance 14 69 34 25 20 21
Post caecal distance 227 449 361 246 291 196
Egg length 31 41 36 29 46 42
Egg width 11 22 15 19 18 23
Width %* 20.9 28.1 24.5 Lateral Lateral 41.5
Forebody %* 57.6 66.6 62.3 35.8 25.3 39.0
Sucker length ratio 1.06 2.88 1.65 3.31 4.84 1.59
Sucker width ratio 0.95 1.94 1.39 Lateral Lateral 1.90
Pharynx: oral sucker width ratio 0.43 0.65 0.55 Lateral Lateral 0.46
Oral sucker length %* 6.10 15.9 13.0 13.2 9.7 17.4
Pharynx length %* 5.46 14.2 9.88 5.53 4.80 6.17
Ventral sucker length %* 16.1 24.7 20.0 43.8 47.1 27.7
Oesophagus length %* 24.7 48.4 35.8 15.9 13.0 8.92
Pre-vitelline distance %* 76.5 84.4 80.0 ? 68.24 68.1
Ovary length %* 6.55 9.80 8.56 18.2 17.4 7.70
Testis length %* 6.74 10.8 8.71 15.6 15.4 18.7
Post-testicular distance %* 8.32 13.7 11.8 15.1 13.2 ?
Post-vitelline distance %* 9.27 18.5 14.5 21.8 22.9 24.9
Post-uterine distance %* 1.35 5.76 3.06 4.90 3.45 3.67
Postcaecal distance %* 18.7 35.6 29.0 24.1 24.6 36.9
Cirrus-sac length %* 17.6 41.7 29.4 31.1 31.6 17.3
Intestinal bifurcation to ventral sucker %** 3.18 10.36 7.96 ? ? 24.1
DOI: 10.7717/peerj.292/table-1

Notes:

% of body-length.
% of forebody.

Two other species of Diphterostomum have been reported in haemulid fishes, D. anisotremi (Nahhas & Cable, 1964) and D. indicum (Madhavi, 1980). The former is an Atlantic species with a tiny pharynx and is easily distinguishable from D. plectorhynchi (see Nahhas & Cable, 1964) and has been considered synonymous with D. brusinae (Stossich, 1888) (Bray, 1987a). D. indicum, reported from the silver grunt Pomadasys argenteus (Forsskål, 1775) (as P. hasta), the banded grunter P. furcatus (Bloch & Schneider, 1801) (as Rhonciscus furcatus) and the saddle grunt P. maculatus (Bloch, 1793) from the Bay of Bengal (Madhavi, 1980), is said to have both dextral and sinistral genital pores, and has a fairly small pharynx. This seems the most similar species to D. plectorhynchi.

There are about 13 recognised Diphterostomum spp. (depending on the validity of some synonymies) with, according to our records, over 200 reports of various life-cycle stages. More than 130 of these (66%) refer to the species D. brusinae. About 5% of these records are from the Indo-West Pacific Region, but no reports are from haemulids. Members of this genus are all similar with few distinguishing features.

Genus Parvipyrum Pritchard, 1963

ZooBank: urn:lsid:zoobank.org:act:7C176519-62E1-401E-BDDE-F19F8B2CBA7D.

Parvipyrum acanthuri Pritchard, 1963 (Fig. 2)


            Parvipyrum acanthuri.

Figure 2: Parvipyrum acanthuri.

Parvipyrum acanthuri Pritchard, 1963. Lateral view. Scale bar 200 µm.

ZooBank: urn:lsid:zoobank.org:act:CC2194F2-9241-43D4-9E17-0E5EFCA3C9A3.

Hosts: Acanthurus blochii Valenciennes, 1835, Perciformes, Acanthuridae, ringtail surgeonfish; A. dussumieri Valenciennes, 1835, Perciformes, Acanthuridae, eyestripe surgeonfish.

Site: Digestive tract.

Localities: ex A. blochii, Nouméa Fish Market (23/06/2007); ex A. dussumieri, Nouméa Fish Market (08/04/2011), Récif Snark (22°26′S, 166°25E, 15/05/2008).

Specimens: ex A. blochii, MNHN JNC2213, BMNH 2007.11.14.51; ex A. dussumieri, MNHN JNC2545, JNC3374, BMNH 2014.1.31.6.

Previous New Caledonian record: Bray & Justine (2008a).

Previously reported New Caledonian host: Acanthurus blochii.

Discussion: This tiny worm (Table 1) is known only from members of the genus Acanthurus, and has been reported only from Hawaii (Pritchard, 1963; Yamaguti, 1970) and New Caledonia.

Genus Zoogonoides Odhner, 1902

ZooBank: urn:lsid:zoobank.org:act:6CEFCB5C-4537-4C5D-A1F7-08901790BF65.

Zoogonoides viviparus (Olsson, 1868) Odhner, 1902 (Fig. 3)


            Zoogonoides viviparus.

Figure 3: Zoogonoides viviparus.

Zoogonoides viviparus (Olsson, 1868). Ventral view. Scale bar 200 µm.

ZooBank: urn:lsid:zoobank.org:act:A1FAB647-C92F-4E1B-8528-333DA6931E3E.

Synonyms: see Bray & Gibson (1986).

Host: Lagocephalus sceleratus (Gmelin, 1789), Tetraodontiformes, Tetraodontidae, silver-cheeked toadfish.

Site: digestive tract.

Locality: near Îlot Pandanus (22°15′585S, 166°17′513E, 18/06/2009).

Specimens: MNHN JNC2982.

Previous New Caledonian records: none.

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): Z. acanthogobii Yamaguti, 1938, Z. kamegaii Toman, 1992 and Z. anampses Toman, 1992; (Yamaguti, 1938; Toman, 1992). Two others, Z. pyriformis Pritchard, 1963 and Z. 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.

Genus Zoogonus Looss, 1901

ZooBank: urn:lsid:zoobank.org:act:A7BE318D-98F2-49C3-975E-5ED3D691ACEF.

Zoogonus pagrosomi Yamaguti, 1939

ZooBank: urn:lsid:zoobank.org:act:FE7F7E55-FD83-4021-A271-A9B5BA66F1DF.

Hosts: Gymnocranius euanus (Günther, 1879), Perciformes, Lethrinidae, Japanese large-eye bream; Lethrinus atkinsoni Seale, 1910, Perciformes, Lethrinidae, Pacific yellowtail emperor; L. genivittatus Valenciennes, 1830, Perciformes, Lethrinidae, longspine emperor:

Site: intestine, digestive tract.

Localities: ex G. euanus, Inside Lagoon, facing Récif Toombo (22°32′361S, 166°26′992E, 06/11/2007), Off Récif Kué (22°36′S, 166°31′E, 07/10/2008); ex L. atkinsoni, Off Ever Prosperity (22°27′S, 166°21′E, 26/04/2006); ex L. genivittatus, Off Baie des Citrons, Nouméa (22°17′55″S, 166°25′20″E, 21/07/2007), Baie Maa (22°12′809S, 166°19′666E, 30/08/2007).

Specimens: ex G. euanus, MNHN JNC2388, BMNH 2014.1.31.4; ex L. atkinsoni, MNHN JNC1789, BMNH 2007.11.14.52; ex L. genivittatus, MNHN JNC2293, BMNH 2007.11.14.52.

Previous New Caledonian records: 1. Bray & Justine (2008a), 2. Justine et al. (2010).

Previously reported New Caledonian host: G. euanus (2, as Zoogonus sp.), L. atkinsoni (1, 2), L. genivittatus (1, 2).

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.

Subfamily Lepidophyllinae Stossich, 1903

Genus Deretrema Linton, 1910

ZooBank: urn:lsid:zoobank.org:act:17B66089-6C3B-4FF8-A89A-526FBC4C00E0.

Deretrema combesae Bray & Justine, 2008

ZooBank: urn:lsid:zoobank.org:act:9BAE2C81-2145-4704-9AD9-E1FFEAD06603.

Record from off New Caledonia: Bray & Justine (2008b).

New Caledonian host: Parupeneus multifasciatus (Quoy & Gaimard, 1825), Perciformes, Mullidae, manybar goatfish.

Deretrema combesorum Bray & Justine, 2008

ZooBank: urn:lsid:zoobank.org:act:CE93F29C-4B9E-4E39-B986-BBB772DA8016.

Record from off New Caledonia: Bray & Justine (2008b).

New Caledonian host: Parupeneus multifasciatus (Quoy & Gaimard 1825), Perciformes, Mullidae, manybar goatfish.

Deretrema ? combesorum Bray & Justine, 2008, early ovigerous forms (Fig. 4)


            Deretrema ? combesorum.

Figure 4: Deretrema ? combesorum.

Deretrema ? combesorum Bray & Justine, 2008, early ovigerous form. Scale bar 200 µm.

Host: Parupeneus pleurostigma (Bennett, 1831), Perciformes, Mullidae, sidespot goatfish.

Site: digestive tract

Locality: West of Passe de Dumbéa (precise coordinates not available, 22/11/2007).

Specimens: MNHN JNC2416, BMNH 2014.1.31.5.

Discussion: Three small worms, two of them with a few eggs, may be early mature members of C. combesorum. They show all the diagnostic characters listed in Bray & Justine (2008b, table 2), differentiating D. combesae and C. combesorum. 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.

Table 2:
Measurements and ratios of Deretrema spp.
Species Deretrema ? acutum Deretrema ? combesorum
Host Parupeneus barberinus Parupeneus pleurostigma
n 1 min max mean
Length 2,035 721 935 794
Width 487 214 278 245
Forebody length 674 351 489 412
Oral sucker length 203 78 96 89
Oral sucker width 206 85 91 88
Prepharynx length 7 0 0 0
Pharynx length 101 47 53 50
Pharynx width 91 45 50 47
Oesophagus length 173 71 113 93
Intestinal bifurcation to ventral sucker 180 154 246 195
Pre-vitelline distance 560 303 382 333
Vitelline field length 363 120 148 136
Ventral sucker length 298 83 92 88
Ventral sucker width 375 90 94 93
Cirrus-sac length 345 112 145 127
Cirrus-sac width 69 39 50 46
Ovary length 161 53 104 86
Ovary width 149 74 92 85
Testis length 191–219 96 112 106
Testis width 142–166 83 141 111
Post-testicular distance 789 61 144 101
Post-vitelline distance 1,098 277 393 323
Post-uterine distance 114 40 44 42
Post caecal distance 777 175 249 204
Egg length 42 28 41 34
Egg width 22 14 23 19
Width %* 23.94 25.9 38.5 31.3
Forebody %* 33.13 48.7 54.5 51.9
Sucker length ratio 1.47 0.89 1.18 1.00
Sucker width ratio 1.81 1.03 1.06 1.05
Pharynx: oral sucker width ratio 0.44 0.50 0.56 0.53
Oral sucker length %* 9.97 10.26 12.95 11.30
Pharynx length %* 4.96 5.27 7.31 6.35
Ventral sucker length %* 14.7 9.59 12.66 11.24
Oesophagus length %* 8.52 9.79 13.29 11.73
Pre-vitelline distance %* 27.5 40.90 43.27 42.09
Vitelline field length%* 17.8 15.86 19.15 17.20
Ovary length %* 7.89 7.38 14.36 10.79
Testis length %* 9.40 11.96 14.65 13.65
Post-testicular distance %* 38.8 8.33 15.39 12.47
Post-vitelline distance %* 54.0 38.06 42.06 40.59
Post-uterine distance %* 5.62 4.69 5.48 5.09
Postcaecal distance %* 34.7 22.94 27.72 25.33
Cirrus-sac length %* 17.0 15.46 17.26 16.09
Intestinal bifurcation to ventral sucker %** 26.7 43.75 50.24 46.84
DOI: 10.7717/peerj.292/table-2

Notes:

% of body-length.
% of forebody.

Deretrema triodontis Machida & Kuramochi, 1999

ZooBank: urn:lsid:zoobank.org:act:58F09856-2B9D-45E3-90A1-9501B76CC397

Record from off New Caledonia: Bray, Cribb & Justine (2010).

New Caledonian host: Triodon macropterus Lesson, 1831, Tetraodontidae, Triodontidae, threetooth puffer.

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.

Deretrema ? acutum Pritchard, 1963 (Fig. 5)

Deretrema? acutum.

Figure 5: Deretrema? acutum.

Deretrema? acutum Pritchard, 1963. Ventral view. Scale bar 500 µm.

ZooBank: urn:lsid:zoobank.org:act:CC7B648A-0BF1-400C-BFF6-B4852742B4E9.

Host: Parupeneus barberinus (Lacepède, 1801), Perciformes, Mullidae, dash-and-dot goatfish.

Site: digestive tract.

Locality: West of Îlot Goëland (22°22′246S, 166°22′934E, 26/10/2007).

Specimens: MNHN JNC2346.

Previous New Caledonian records: none.

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, 1970 and 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 cheilodactylids, carangids, lutjanids and sphyraenids, and the distribution is widened to include Japanese waters.

Genus Dupliciporia Reimer, 1985

ZooBank: urn:lsid:zoobank.org:act:78C451F6-4544-4FB1-89F4-95CD079874FF.

Dupliciporia lanterna Bray & Justine, 2008

ZooBank: urn:lsid:zoobank.org:act:29BD2E10-7E06-4F86-90EA-C8840F1A5432.

Record from off New Caledonia: Bray & Justine (2008a).

New Caledonian host: Priacanthus hamrur (Forsskål, 1775), Perciformes, Priacanthidae, moontail bullseye.

Genus Lecithostaphylus Odhner, 1911

ZooBank: urn:lsid:zoobank.org:act:431229B4-A8F9-4107-B3A4-779055CD30F4.

Lecithostaphylus nitens (Linton, 1898) Linton, 1940

ZooBank: urn:lsid:zoobank.org:act:EDDA9CF7-19AA-4386-AAE2-BEBF6ABC566D.

Record from off New Caledonia: Bray & Justine (2008a).

New Caledonian host: Tylosurus crocodilus (Péron & Lesueur, 1821), Beloniformes, Belonidae, hound needlefish.

Discussion: This species is reported only from belonids of the genera Tylosurus, Platybelone and Ablennes, mostly from the former. It was originally reported in ‘Tylosurus caribbaeus’ [? T. acus] from off Woods Hole, Massachusetts in the Northwestern Atlantic Ocean. Most reports are from the northwestern Atlantic or Gulf of Mexico, including one from T. crocodilus (see Overstreet, 1969). Machida & Kuramochi (2000) reported this species from the Pacific Ocean off Japan and the Philippines.

Genus Overstreetia Bray 1985

ZooBank: urn:lsid:zoobank.org:act:DE25FCA5-450F-448E-9523-78F12BDB65A5.

Overstreetia cribbi sp. n.

ZooBank: urn:lsid:zoobank.org:act:2047A8D5-A5AE-49E9-B521-7EF17CA9F9EA.

Host: Atherinomorus lacunosus (Forster, 1801), Atheriniformes, Atherinidae, hardyhead silverside.

Site: digestive tract.

Locality: Anse Vata, Nouméa (22°18′30″S, 166°25′50″E, 03/10/2008).

Specimens: Holotype MNHN JNC2656, Paratype BMNH 2014.1.31.1.

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.

Based on 2 ovigerous specimens. Measurements on Table 3. Body elongate, narrow fusiform (Fig. 6). Tegument spinous posteriorly as far as anterior hindbody. Enlarged circum-oral spines present around oral sucker and reaching posteriorly forming arc alongside aperture (Fig. 7), up to 36 long. Oral sucker subglobular, with narrow ventro-terminal aperture. Ventral sucker circular, in anterior half of body, slightly wider than oral sucker. Forebody long. Prepharynx long thick-walled. Pharynx oval. Oesophagus shorter than prepharynx. Intestinal bifurcation in posterior forebody. Caeca pass into uterine area, terminations obscured by eggs.

Overstreetia cribbi n. sp.

Figure 6: Overstreetia cribbi n. sp.

Overstreetia cribbi n. sp., ventral view of holotype, uterus in outline. Scale bar 500 µm.
Overstreetia cribbi n. sp.

Figure 7: Overstreetia cribbi n. sp.

Overstreetia cribbi n. sp., photographs. (A) Anterior end of paratype showing spination. (B) Anterior end of holotype showing spination in ventral plane. (C) Anterior end of holotype showing spination in plane slightly dorsal to figure 7B, also showing ventral aperture of oral sucker. (D) Anterior end of holotype showing spination in dorsal plane.
Table 3:
Original measurements of Overstreetia spp.
Bold figures indicate distinctions from O. cribbi.
Species O. cribbi n. sp. O. sodwanaensis O. olsoni
Host Atherinomorus lacunosus Pranesus pinguis Atherinomorus capricornensis
n 2 1 1
Holotype Paratype Holotype Paratype
Length 1,313 1,250 1,947 1,030
Width 255 237 305 134
Forebody length 478 420 736 421
Oral sucker length 163 142 136 78
Oral sucker width 115 104 116 73
Prepharynx length 59 34 173 103
Pharynx length 84 72 111 49
Pharynx width 90 73 98 50
Oesophagus length 57 102 210 116
Intestinal bifurcation to ventral sucker 110 63 64 66
Pre-vitelline distance 584 538 889 491
Long vitelline field 256 248 522 252
Short vitelline field 214 210 530 233
Ventral sucker length 121 155 191 67
Ventral sucker width 141 121 206 73
Cirrus-sac length 258 ? 274 142
Cirrus-sac width 57 ? 83 52
Ventral sucker to ovary distance 0 0 21 4
Ovary length 114 98 136 72
Ovary width 94 82 77 64
Ovary to anterior testis distance 0 0 93 48
Anterior testis length 101 92 156 75
Anterior testis width 84 73 184 57
Distance between testes 0 0 0 0
Posterior testis length 97 101 173 69
Posterior testis width 87 90 153 53
Post-testicular distance 378 404 461 274
Post-vitelline distance 472 458 496 297
Post-uterine distance 13 33 64 61
Post caecal distance ? ? 178 153
Egg length 35–40 (38) 31–39 (36) 35–40 (37) 33–42 (38)
Egg width 14–23 (20) 18–24 (21) 19–26 (23) 17–24 (20)
Width %* 19.4 18.9 15.6 13.0
Forebody %* 36.4 33.6 37.8 40.9
Sucker length ratio 0.74 1.09 1.41 0.86
Sucker width ratio 1.23 1.17 1.78 1.00
Pharynx: oral sucker width ratio 0.78 0.70 0.85 0.68
Oral sucker length %* 12.4 11.4 6.96 7.55
Pharynx length %* 6.36 5.73 5.68 4.73
Ventral sucker length %* 9.20 12.4 9.82 6.53
Oesophagus length %* 4.32 8.20 10.8 11.3
Pre-vitelline distance %* 44.5 43.0 45.6 47.6
Long vitelline field %* 19.5 19.8 26.8 24.5
Ovary length %* 8.69 7.81 6.98 6.97
Ovary to anterior testis distance %* 0 0 4.76 4.69
Anterior testis length %* 7.70 7.37 8.02 7.25
Posterior testis length %* 7.39 8.09 8.88 6.67
Post-testicular distance %* 28.8 32.4 23.7 26.6
Post-vitelline distance %* 35.9 36.6 25.5 28.8
Post-uterine distance %* 0.96 2.61 3.31 5.91
Postcaecal distance %* ? ? 4.57 16.0
Cirrus-sac length %* 19.7 ? 14.1 13.7
Intestinal bifurcation to ventral sucker %** 23.1 15.1 8.71 15.6
DOI: 10.7717/peerj.292/table-3

Notes:

% of body-length.
% of forebody.

Testes 2, oval, entire to slightly irregular, tandem, contiguous, in anterior half of hindbody. Cirrus-sac broadly claviform, posterior end overlaps anterior edge of ventral sucker. Seminal vesicle allantoid, undivided, surrounded by gland-cells, in proximal region of cirrus-sac. Pars prostatica vesicular. Ejaculatory duct short, thick-walled. Genital atrium small. Genital pore submarginal, sinistral, bifurcal.

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.

Discussion

According to the key in Bray (2008) only members of two zoogonid genera have tandem testes, namely Overstreetia and Pseudopalaeorchis Kamegai, 1970. Since the key was produced two further zoogonid genera have been described with tandem testes, Whitegonimus Jeżewski, Zdzitowiecki & Laskowski, 2009 and Oesophagotrema Chaari, Derbel & Neifar, 2011 (Jeżewski, Zdzitowiecki & Laskowski, 2009; Chaari, Derbel & Neifar, 2011). Only Overstreetia is known to exhibit enlarged circum-oral spines.

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).


            Overstreetia sodwanaensis.

Figure 8: Overstreetia sodwanaensis.

Overstreetia sodwanaensis Bray, 1985, photographs. (A) Anterior end of holotype (BMNH 1983.8.3.1) showing spination in ventrolateral plane, also showing ventral aperture of oral sucker. (B) Anterior end of holotype showing spination in dorsolateral plane.

            Overstreetia olsoni.

Figure 9: Overstreetia olsoni.

Overstreetia olsoni Bray & Cribb, 2006, photographs. (A) Anterior end of paratype (BMNH 2005.3.11.6) showing spination in ventral plane, also showing ventral aperture of oral sucker. (B) Anterior end of paratype showing spination in dorsal plane.

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.

Genus Sacculoacetabulum Machida & Kuramochi, 1999

ZooBank: urn:lsid:zoobank.org:act:9115FED3-87BC-44C7-A310-8C9638F18C98.

Sacculoacetabulum ohjibah Machida & Kuramochi, 1999

ZooBank: urn:lsid:zoobank.org:act:37EC1F47-C1B4-43C2-96F4-223DC92CCB0F.

Record from off New Caledonia: Bray, Cribb & Justine (2010).

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.

Zoogonidae immature

Host: Parupeneus multifasciatus (Quoy & Gaimard, 1825), Perciformes, Mullidae, manybar goatfish.

Site: digestive tract.

Locality: Off Récif Kué, Middle of Reef (22°36′30″S, 166°32′E, 09/12/2008).

Specimens: JNC2827.

Zoogeography

The zoogonid fauna of New Caledonian waters as described here is small, and probably represent a low proportion of the complete fauna as the Zoogonidae (and particularly the Lepidophyllinae) is one of the relatively few digenean families with a good representation in the deep-sea, i.e., off the continental shelf (Bray, 2004). Nevertheless, we will list the distribution of the 13 species which have been reported from New Caledonian waters, bearing in mind that these results are preliminary.

Four species (31% of the fauna) are endemic: Deretrema combesae, Deretrema combesorum, Dupliciporia lanterna and Overstreetia cribbi n. sp.

One species (8%) is restricted to South Western Pacific close to New Caledonia (FAO Major Fishing Area 71): Diphterostomum tropicum.

Four species (31%) are found in the northern and southern Western Pacific (FAO 61 & 71): Diphterostomum plectorhynchi, Parvipyrum acanthuri, Deretrema triodontis and Sacculoacetabulum ohjibah.

One species (8%) is reported in the Western and Central Pacific (FAO 61, 71 & 77): Deretrema acutum.

One species is reported from sites across the Pacific Ocean (FAO 61, 71 and 87): Zoogonus pagrosomi.

Two species (15%) are cosmopolitan (FAO 21, 27, 31, 37, 57, 61, 67 & 71): Zoogonoides viviparus, Lecithostaphylus nitens. These are probably cryptic complexes.