Anisakid nematodes (Nematoda: Anisakidae)from the marine fishes Plectropomus laevis Lacepede(Serranidae) and Sphyraena qenie Klunzinger(Sphyraenidae) off New Caledonia, including two newspecies of Hysterothylacium Ward & Magath, 1917

Frantisek Moravec . Jean-Lou Justine

Received: 26 June 2015 / Accepted: 2 August 2015

� Springer Science+Business Media Dordrecht 2015

Abstract Based on light and scanning electron

microscopical studies, two new species ofHysterothy-

lacium Ward & Magath, 1917 (Nematoda: Anisaki-

dae) are described from the digestive tract of

perciform fishes off New Caledonia: H. alatum n. sp.

from Plectropomus laevis (Lacepede) (Serranidae)

and H. sphyraenae n. sp. from Sphyraena qenie

Klunzinger (Sphyraenidae). The former species

(H. alatum) is mainly characterised by its large body

(male 42.05 mm, gravid females 51.18–87.38 mm

long), the shape of the dorsal lip, conspicuously broad

cervical alae, a short caecum and a long ventricular

appendix, the length of the spicules (925 lm), the

number (25 pairs) and distribution of the genital

papillae and the tail tip bearing numerous minute

cuticular protuberances. The other species

(H. sphyraenae) is mainly characterised by the

presence of narrow lateral alae, a short caecum and a

long ventricular appendix, the length (762–830 lm)

and shape of the spicules, the number (37–38 pairs)

and arrangement of the genital papillae, and by the tail

tip which lacks any distinct cuticular projections

visible under the light microscope. In addition, and

unidentifiable at the species level, conspicuously large

(45.71–66.10 mm long) larvae of Contracaecum

Railliet & Henry, 1912, were found in the body cavity

of P. laevis, which serves as a paratenic host for this

parasite.

Introduction

Our knowledge of the species diversity of anisakid

nematodes (Anisakidae) which parasitise marine

fishes and elasmobranchs in New Caledonian waters

remains incomplete, since only four nominal species

of these parasites have previously been recorded in

this region: Terranova scoliodontis (Baylis, 1931)

from the shark Galeocerdo cuvier (Peron & Lesueur)

(Carcharhinidae),Hysterothylacium cenaticum (Bruce

& Cannon, 1989) from Tetrapturus audax (Philippi)

(Istiophoridae), Raphidascaris (Ichthyascaris) ne-

mipteri Moravec & Justine, 2005 from Nemipterus

furcosus (Valenciennes) (Nemipteridae), and

R. (Ichthyascaris) etelidis Moravec & Justine, 2012

from Etelis coruscans Valenciennes and Pristipo-

moides filamentosus (Valenciennes) (both Lutjanidae)

F. Moravec (&)

Institute of Parasitology, Biology Centre of the Czech

Academy of Sciences, Branisovska 31,

370 05 Ceske Budejovice, Czech Republic

e-mail: moravec@paru.cas.cz

J.-L. Justine

Institut Systematique, Evolution, Biodiversite, ISYEB,

UMR7205 CNRS, EPHE, MNHN, UPMC, Museum

National d’Histoire Naturelle, Sorbonne Universites,

CP51, 57 rue Cuvier, 75231 Paris cedex 05, France

123

Syst Parasitol (2015) 92:181–195

DOI 10.1007/s11230-015-9597-5

(Moravec & Justine, 2005, 2006, 2012). Anisakid

nematodes unidentified to species or genera, mostly as

larval stages, have also been reported from fishes

belonging to different families by Justine et al. (2010a,

b, 2012) and Shamsi et al. (2015).

Recent examinations of anisakid nematodes col-

lected from two species of perciform fishes, the

blacksaddled coralgrouper Plectropomus laevis

(Lacepede) (Serranidae) and the blackfin barracuda

Sphyraena qenieKlunzinger (Sphyraenidae), revealed

that they represent two new species of Hysterothy-

lacium Ward & Magath, 1917 plus one species of

larval Contracaecum Railliet & Henry, 1912, which

are described herein.

The blacksaddled coralgrouper P. laevis (maximum

body length 125 cm, weight 24.2 kg) and the blackfin

barracuda S. qenie (maximum body length 200 cm,

weight up to 50 kg) are both tropical marine, reef-

associated fishes. The former has an Indo-Pacific

distribution, whereas the latter is distributed in the

Indo-Pacific from the Red Sea and East Africa to the

central Indian Ocean, French Polynesia and the eastern

Pacific (Mexico, Panama). Both species are targeted

by commercial and recreational fishermen (Froese &

Pauly, 2015).

Materials and methods

Fish were caught off New Caledonia by various

means. The nematodes intended for morphological

studies were fixed in hot 70 % ethanol. For light

microscopical examination (LM), the specimens were

cleared with glycerine. Drawings were made with the

aid of a Zeiss drawing attachment. Specimens used for

scanning electron microscopical examination (SEM)

were postfixed in 1 % osmium tetroxide (in phosphate

buffer), dehydrated through a graded acetone series,

critical-point-dried and sputter-coated with gold; they

were examined using a JEOL JSM-7401F scanning

electron microscope at an accelerating voltage of 4 kV

(GB low mode). All measurements are in micrometres

unless otherwise indicated. The classification system

of the Ascaridoidea adopted follows Keys to the

Nematode Parasites of Vertebrates (Anderson et al.,

2009; Gibbons, 2010). The fish nomenclature follows

FishBase (Froese & Pauly, 2015).

Family Anisakidae Railliet & Henry, 1912

Hysterothylacium alatum n. sp.

Type-host: Blacksaddled colargrouper Plectropomus

laevis (Lacepede) (Perciformes: Serranidae); fork

length 550 mm.

Site in host: Digestive tract (pyloric caecum).

Type-locality: Off New Caledonia, Passe de Teramba

off La Foa (collected 27.iii.2003).

Prevalence and intensity: 1 of 6 fish infected; 6

nematode specimens.

Type-material: Holotype and allotype (anterior and

posterior body ends mounted on SEM stub and

remaining parts of bodies preserved in 70 % ethanol)

plus 2 paratypes in the Helminthological Collection of

the Institute of Parasitology, Biology Centre of the

Czech Academy of Sciences, Ceske Budejovice (Cat.

No. N–1090); 2 paratypes in the Museum National

d’Histoire Naturelle, Paris (MNHN JNC357A).

Etymology: The specific name alatum (=winged) is a

Latin adjective relating to a characteristic feature of

this nematode, i.e. the presence of conspicuously

broad cervical alae.

Description (Figs. 1–3)

General. Body large, elongate, yellowish in colour.

Anterior part of body slender. Broad asymmetrical

cervical alae, widest in region of c. 1/3 of oesophageal

length, extend posteriorly to about level of middle of

oesophagus (Figs. 1D, 2A); from there they continue

posteriorly to tail as narrow cuticular ridges (Figs. 2E,

F, 3A). Deirids not observed. Anterior end with 3 large

lips provided with broad lateral flanges; each lip has

narrow base. Posterior part of dorsal lip roughly

rectangular, broad, with margins of lateral flanges

almost parallel, bears 2 lateral double papillae;

anterior part of dorsal lip much narrower, anteriorly

rounded, separated from posterior part of lip by 2

fairly deep lateral depressions (Figs. 1B, 2B–D).

Subventral lips with 1 double, 1 single papilla and

amphid. Interlabia well developed, conical, reaching

anteriorly to about level of labial papillae (Figs. 1C,

2B–D). Oesophagus cylindrical, long, ending in small

spherical ventriculus; ventricular appendix narrow,

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Fig. 1 Hysterothylacium alatum n. sp. ex Plectropomus laevis. A, Anterior end of young female, lateral view; B, Dorsal lip; C,

Cephalic end of gravid female, sublateral view; D, Anterior body end of largest female, ventral view; E, Tail of largest female, lateral

view; F, Tail tip of largest female, ventral view; G, Tail of male, ventral view; H, Egg; I, Vulva, lateral view; J, Posterior end of male,

ventral view; K, Tail of male, lateral view; L, Posterior end of male, lateral view

Syst Parasitol (2015) 92:181–195 183

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very long. Anterior intestinal caecum short, slightly

longer than length of ventriculus (Fig. 1A, D). Cae-

cum to ventricular appendix length ratio 1:8–18.

Nerve-ring encircles oesophagus at about 1/6 of its

length. Excretory pore at level of nerve-ring or just

posterior to it (Fig. 1A, D). Tail conical; its tip with

numerous minute but distinct protuberances.

Male [Based on 1 specimen, holotype.] Length of

body 42.05 mm, maximum width 558. Lips 105 long;

length of interlabia 45. Length of oesophagus

1.90 mm, representing 4.5 % of body length;

maximum width 190. Nerve-ring and excretory pore

653 and 680, respectively, from anterior extremity.

Ventriculus 109 9 136; ventricular appendix

5.30 mm long, maximum width 204. Intestinal cae-

cum 299 long, with maximum width 82. Caecum to

ventricular appendix length ratio 1:18. Posterior end of

body curved ventrally. Spicules equal, alate, 925 mm

long, representing 2.2 % of body length (Fig. 1L).

Total of 25 pairs of genital papillae present, 17 being

pre-anals, 1 adanal, and 7 postanals; papillae of several

posteriormost pre-anal pairs, adanal pair and of

postanal pairs very small; no double papillae present

Fig. 2 Hysterothylacium alatum n. sp., SEM micrographs. A, Anterior end of female, ventral view; B–D, Cephalic end, apical, dorsal

and subdorsal views, respectively; E, F, Posterior end of male, lateral and ventral views, respectively. Abbreviations: a, double cephalic

papilla; b, single cephalic papilla; c, amphid; d, dorsal lip; i, interlabium

184 Syst Parasitol (2015) 92:181–195

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(Figs. 1G, J–L, 2E, F, 3A). One papilla-like ventro-

median organ located on anterior cloacal lip present

(Figs. 1G,J, L, 2E, F, 3A). Tail conical, 136 long; tail

tip bearing numerous minute protuberances (Figs. 1G,

J–L, 2E, F, 3A, B).

Gravid female [Based on 2 complete and 1 incomplete

ovigerous specimens; measurements of allotype in

parentheses.] Length of body 51.18–87.38 (87.38) mm,

maximum width 598–789 (789). Length of asymmet-

rical cervical alae in allotype (3.67/2.72) mm, maxi-

mum width (299). Lips 136–190 (190) long; length of

interlabia 68–99 (99). Length of oesophagus 3.33–5.30

(5.30) mm, representing 6.0–6.5 (6.0) % of body

length; maximum width 204 (204). Nerve-ring and

excretory pore 612–843 (843) mm and 680–925,

respectively, from anterior extremity. Ventriculus

109–136 9 122–136 (136 9 122); ventricular

appendix 4.64–5.85 (4.64) mm long, maximum width

136 (136). Intestinal caecum 320–571 (571) long,

maximum width 82–95 (95). Caecum to ventricular

appendix length ratio 1:8–18 (1:8). Vulva pre-equato-

rial, 26.38–46.44 (46.44) mm from anterior end of

body, at 52–53 % (53 %) of body length; posterior

vulval lip protrudes distinctly (Fig. 1I). Vagina long (in

allotype 3.40 mm long, 163 wide), directed posteriorly

from vulva. Uterus forms numerous coils, contains

numerous almost spherical eggs 48–51 in diameter in

allotype (Fig. 1H); only immature eggs present in

paratype. Tail conical, 231–680 long (Fig. 1E); tip

rounded, bears numerous small cuticular protuberances

(Fig. 1E, F).

Non-gravid female [Based on 2 specimens.] Length of

body 11.48–14.21 mm, maximum width 258–299.

Maximum width of cervical alae 27–41. Lips 75–78

long; length of interlabia 33–36. Length of oesophagus

1.71–1.90 mm, representing 13.4–14.9 % of body

length; maximum width 82–109. Nerve-ring and

excretory pore 354–367 and 405–408, respectively,

from anterior extremity. Ventriculus 68–109 9 82–95;

ventricular appendix 1.67–1.85 mm long, maximum

width 41. Intestinal caecum 190–204 long, maximum

width 54–68. Caecum to ventricular appendix length

ratio 1:9. Vulva in larger specimen pre-equatorial,

5.98 mm from anterior end of body, at 42 % of body

length; vulval lips not protruding. Uterus empty. Tail

204–218 long; tip rounded, bears numerous small

cuticular protuberances.

Remarks

According to Moravec et al. (2012), a total of 67 valid

species of Hysterothylacium have been reported from

marine, estuarine and freshwater fishes. However, an

additional three species have since been described:

H. gibsoni Xu, Li & Zhang, 2014, H. simile Li, Zhang

& Liu, 2013 and H. zhoushanense Li, Liu & Zhang,

2012 (emend.) (see Li et al., 2012, 2013; Xu et al.,

2014). Consequently, at present this genus contains 70

recognised species.

Of these, as in the new species, the following ten

species possess a markedly short caecum and a long

ventricular appendix, spicules of about 1 mm in length

and the tail tip bearing numerous small cuticular

protuberances or spines: H. amoyense (Hsu, 1933),

H. anguillae Moravec, Taraschewski, Appelhoff &

Fig. 3 Hysterothylacium alatum n. sp., SEM micrographs. A,

Tail of male, ventrolateral view; B, Tail tip of male, lateral view

Syst Parasitol (2015) 92:181–195 185

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Weyl, 2012, H. arnoglossi Petter & Maillard, 1987,

H. fabri (Rudolphi, 1819), H. pelagicum Deardorff &

Overstreet, 1982, H. reliquens (Norris & Overstreet,

1975), H. rhacodes Deardorff & Overstreet, 1978,

H. scomberoideiBruce&Cannon, 1989,H. scombero-

mori Bruce, 1990 and H. zhoushanense (see Norris &

Overstreet, 1975; Deardorff & Overstreet, 1978, 1981,

1982; Petter & Maillard, 1987; Bruce & Cannon,

1989; Bruce, 1990; Li et al., 2008, 2012, 2013;

Moravec et al., 2012; Xu et al., 2014).

Of these ten species, only H. scomberoidei, a

parasite of Scomberoides commersonianus Lacepede

(Carangidae) off Australia, possesses lateral alae

conspicuously expanded in the cervical region, as in

the new species. In all of the other nine species, the

lateral alae are absent (H. amoyense), strongly reduced

(H. anguillae, H. reliquens, H. fabri) or very narrow

(H. arnoglossi, H. pelagicum, H. rhacodes,

H. scomberomori, H. zhoushanense). Hysterothy-

lacium scomberoidei differs from the new species

mainly in the shape of the dorsal lip (lateral flanges of

the posterior part of lip with straight rims vs rims

rounded), a conspicuously shorter ventricular appen-

dix (1.79–2.16 mm in males, 1.74–2.71 mm in

females vs 5.30 mm in male, 4.64–5.85 mm in

females), a non-elevated vulva (vs vulval lips

markedly elevated), a shorter body in gravid females

(23.5–52.5 mm long vs 51.2–87.4 mm) and by larger

eggs (53–60 lm vs 48–51 lm in diameter) (see Bruce

& Cannon, 1989).

Conspicuously broad lateral alae in the cervical

region are also present in H. fortalezae (Klein, 1973),

H. nipponense Moravec & Nagasawa, 1998 (syn.

H. japonicum Moravec & Nagasawa, 1998) and

H. tetrapteri (Bruce & Cannon, 1989) (Klein, 1973;

Deardorff &Overstreet, 1981; Bruce &Cannon, 1989;

Moravec & Nagasawa, 1998a, b; Xu et al., 2014).

However, H. nipponense and H. tetrapteri differ

markedly from the new species in having a very long

caecum, whereas the caecum of H. fortalezae is short,

resembling thus that of H. alatum n. sp. Hysterothy-

lacium fortalezae is a parasite of Scomberomorus spp.

(Scombridae) and allegedly also a carangid and a

serranid in the West Atlantic region (off Brazil and the

USA) (Klein, 1973; Deardorff & Overstreet, 1981).

However, in contrast to the new species, the body size

of H. fortalezae is much smaller (males

12.0–23.4 mm, females 10.0–15.4 mm long vs male

42.1 mm, females 51.2–87.4 mm), the spicules are

shorter (560–680 lm vs 925 lm), the medioventral

precloacal organ is absent (vs present), the ventricular

appendix is much shorter (506–835 lm long in males,

556–661 lm in females vs 5,300 lm in male,

4,638–5,848 lm in females), the length ratio of the

caeca and ventricular appendix is different (1:5.0–6.5

in males, 1:3.4–5.4 in females vs 1:18 in male, 1:8–18

in females), the vulval lips are not protruding (vs

protruding) and the female tail tip bears rather large

cuticular spines (vs numerous small protuberances)

(see Deardorff & Overstreet, 1981). Both species also

differ in the type-host family (Scombridae vs Ser-

ranidae) and geographical regions (Atlantic vs

Pacific).

Fairly broad lateral alae are typical also of

H. aduncum (Rudolphi, 1802), H. auctum (Rudolphi,

1802),H. sinense Li, An& Zhang, 2007 andH. spirale

Rossin, Datri, Incorvaia & Timi, 2011, but all of these

species have a relatively long caecum (Hartwich,

1975; Moravec et al., 1985; Moravec & Nagasawa,

2000; Rossin et al., 2011; Li et al., 2007, 2013).

Hysterothylacium alatum n. sp. has previously been

reported from P. laevis off New Caledonia as

Hysterothylacium sp. by Justine et al. (2010a). Figus

et al. (2005) recorded adultHysterothylacium sp. from

the serranid fish Serranus cabrilla (Linnaeus) in the

southwestern Mediterranean, which, as visible from

photos provided, seems to be morphologically similar

to H. alatum n. sp. However, judging from the

different host genera and remote geographical regions,

both these forms probably belong to different species.

From off New Caledonia, two other nematode

species were recently described from a congeneric

host, Plectropomus leopardus (Lacepede), namely the

trichosomoidid Huffmanela plectropomi Justine, 2011

and the capillariid Capillaria plectropomiMoravec &

Justine, 2014 (Justine, 2011; Moravec & Justine,

2014). It is likely that these two species can also

parasitise both Plectropomus leopardus and P. laevis

in the shared environment, as suggested by the finding

of unidentified capillariids in both species by Justine

et al. (2010a).

Hysterothylacium sphyraenae n. sp.

Type-host: Blackfin barracuda Sphyraena qenie Klun-

zinger (Perciformes: Sphyraenidae); fork length

630 mm, weight 1.5 kg

186 Syst Parasitol (2015) 92:181–195

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Site in host: Stomach.

Type-locality: Fish caught by trolling, off Noumea,

New Caledonia (collected 14.iv.2003).

Prevalence and intensity: Single fish examined; 3

nematode specimens.

Type-material: Holotype and allotype in the Museum

National d’Histoire Naturelle, Paris (MNHN

JNC394E).

Etymology: The specific name of this nematode relates

to the genitive form of the generic name of the host.

Description (Figs. 4–6)

General. Medium-sized nematodes with transversely

striated cuticle (Figs. 5A–G, 6B), green when alive,

whitish in ethanol. Maximum width near middle of

body. Lips almost equal in size (dorsal lip slightly

smaller than ventrolateral lips), slightly shorter than

wide, with narrow bases; their lateral flanges widest

just posterior to middle of lips; pulp with 2 anteriorly

protruding lobes. Dorsal lip with 2 subdorsal double

papillae; each subventral lip with 1 double subventral

papilla, 1 small single papilla and amphid situated

laterally (Figs. 4B, C, 5A, B, D). Interlabia well

developed, low, about 1/3 length of lips (Figs. 4C, 5A,

B, D). Cervical alae very narrow, starting about level

of lip bases, extending posteriorly in both sexes as

cordons almost to end of tail (Figs. 4E, 5C, E–G).

Deirids just posterior to level of nerve-ring (Fig. 4B).

Oesophagus long, slightly broader posteriorly than

anteriorly. Nerve-ring encircles oesophagus at about

one sixth of its length. Ventriculus small, almost

spherical; ventricular appendix long, narrow. Intesti-

nal caecum markedly short. Excretory pore just

posterior to nerve-ring (Fig. 4A). Tail of both sexes

conical; tip lacks distinct cuticular outgrowths visible

under LM.

Male [Based on 2 specimens; holotype; measurements

of paratype in parentheses.] Length of body 18.39

(18.71), maximum width 558 (544). Deirids slightly

asymmetrical, 544/589 (544/571) from anterior

extremity. Width of cervical alae 27(27). Lips 96

(93) long; length of interlabia 39 (45). Length of

oesophagus 2.51 (2.46) mm, representing 13.7

(13.2) % of body length; maximum width 122 (109).

Nerve-ring 517 (503) from anterior extremity; excre-

tory pore just posterior to nerve-ring. Ventriculus

95 9 105 (136 9 150); ventricular appendix 1.41

(1.52) mm long, maximum width 136 (109). Intestinal

caecum 204 (150) long, with maximum width 109

(109). Caecum to ventricular appendix length ratio 1:7

(1:10). Posterior end of body curved ventrally.

Spicules equal, alate, 762 (830) long, representing

4.1 (4.4) % of body length; fairly broad ventral

spicular ala forms distinct spike somewhat anterior

to mid-length of spicule (Fig. 4G). Total of 38 (37)

pairs of small subventral papillae present, 28 (27)

being pre-anals and 10 (10) postanals; papillae of

several posteriormost pre-anal and postanal pairs very

small; papillae of 4th subventral postanal pair doubled.

One papilla-like ventromedian organ located on

anterior cloacal lip present (Figs. 4D, E, G, 5C, E–

G, 6B). Posterior cloacal lip with granular surface

(Figs. 4E, 5F, G). Tail conical, 150 (150) long,

markedly narrowed at its distal third; tip obtusely

pointed, without caudal projections visible under LM,

but with few poorly developed protuberances visible

under SEM (Figs. 4D, E, G, 5C, E–G, 6A).

Female [Based on 1 specimen containing immature

eggs, allotype.] Length of body 19.11 mm, maximum

width 571. Lips 93 long. Length of interlabia 39.

Length of oesophagus 2.56 mm, representing 13.4 %

of body length; maximum width 272. Nerve-ring and

excretory pore 490 and 558, respectively, from

anterior extremity. Ventriculus 109 9 109; ventricu-

lar appendix 1.32 mm long, maximum width 95.

Intestinal caecum 245 long, maximum width 68.

Caecum to ventricular appendix length ratio 1:5.

Vulva pre-equatorial, 7.11 mm from anterior end of

body, at 37 % of body length. Vagina about 1.63 mm

long, directed posteriorly from vulva. Uterus forms

numerous coils and contains only immature eggs. Tail

conical, 340 long; tip obtusely pointed, without any

caudal projections visible under LM (Fig. 4F).

Remarks

Of the 70 previously described, recognised species of

Hysterothylacium (see above), 19 are characterised by

the presence of a markedly short intestinal caecum and

a long ventricular appendix; these features also typical

of H. alatum n. sp. and H. sphyraenae n. sp. However,

in contrast to H. sphyraenae n. sp., some of these

species possess conspicuously broad cervical alae

(H. alatum,H. fortalezae andH. scomberoidei) or their

spicules are much shorter, i.e. not exceeding 0.5 mm

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Fig. 4 Hysterothylacium sphyraenae n. sp. ex Sphyraena genie. A, Anterior body end of female, lateral view; B, Cephalic end of male,

dorsal view; C, Same, enlarged; D, Posterior end of male, ventral view; E, Tail of male, ventral view; F, Tail of female, lateral view; G,

Posterior end of male, lateral view

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Fig. 5 Hysterothylacium sphyraenae n. sp., SEM micrographs. A, Dorsal lip, dorsal view; B, Ventrolateral lip, ventrolateral view; C;

Posterior end of male, lateral view; D, Cephalic end, lateral view; E, Posterior end of male, ventral view; F, G, Tail of male, ventrolateral

and lateral views, respectively (arrow indicates postanal double papilla). Abbreviations: a, double cephalic papilla; b, single cephalic

papilla; c, amphid; e, precloacal median organ; g, cloacal aperture; i, interlabium

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(H. gibsoni, H. physiculi Moravec & Nagasawa, 2000

and H. winteri Torres & Soto, 2004) or much longer,

i.e. not less than 1.3 mm [H. bifidalatum Petter &

Maillard, 1987, H. chaunaxi (Olsen, 1952), H. pelag-

icum and H. reliquens] (see e.g. Deardorff & Over-

street, 1981; Petter & Maillard, 1987; Bruce &

Cannon, 1989; Moravec & Nagasawa, 2000; Torres

& Soto, 2004; Xu et al., 2014).

Although most of the remaining 11 species have

narrow lateral alae, resembling H. sphyraenae, almost

all of these species are characterised by the presence of

numerous, distinct cuticular spines or protuberances

on the tail tip, which are readily visible under the LM

(H. amoyense, H. anguillae, H. arnoglossi, H. fabri,

H. rhacodes,H. scomberomori andH. zhoushanensis).

In contrast, three species, H. cornutum (Stossich,

1904), H. dollfusi (Schmidt, Leiby & Kritsky, 1974)

and H. ogcocephali (Olsen, 1952), were described as

lacking such ornamentation on the tip of the tail (e.g.

Schmidt et al., 1974; Deardorff & Overstreet, 1981;

Bruce & Cannon, 1989; Moravec & Nagasawa, 2000).

However, it is worth noting that two of them,

H. dollfusi and H. ogcocephali, were studied only

under the LM and the tail tip of H. cornutum was

observed by SEM only under low magnification

(Bruce & Cannon, 1989). The tail tip of all specimens

of H. sphyraenae studied under the LM appeared to

lack any cuticular ornamentation, resembling that in

H. cornutum, H. dollfusi and H. ogcocephali; only at a

very high magnification did the tail tip reveal the

presence of a few minute protuberances (Fig. 6A).

Hysterothylacium sphyraenae differs from H. cor-

nutum, a parasite of Thunnus spp., mainly in the absence

of ventral, precloacal, cuticular ornamentation, the

presence of a pair of double postanal papillae, the shape

of the female tail (markedly elongate inH. cornutum) and

its somewhat shorter spicules (Deardorff & Overstreet,

1982; Bruce & Cannon, 1989; Moravec & Nagasawa,

2000). It differs mainly from H. dollfusi, a specific

parasite of the freshwater paddlefish Polyodon spathula

(Walbaum) in North America, by the presence of lateral

alae, more numerous pairs of pre-anal papillae (27–28 vs

19–20) and somewhat shorter spicules (0.76–0.83 mm vs

1.07–1.45 mm) (Schmidt et al., 1974). From H. ogco-

cephali, a specific parasite of Ogcocephalus radiatus

(Mitchill) in theNorthAtlantic region, by the shape of the

lips (conspicuously elongate in H. ogcocephali), more

numerous pairs of postanal papillae (10 vs 3–4) and

somewhat longer spicules (762–830 vs 330–660 lm)

(Deardorff & Overstreet, 1981). A characteristic feature

of the new species, not reported in other Hysterothy-

lacium spp., is the presence of a distinct ventral spike

formed by each spicular ala (Fig. 4G).

Hysterothylacium sphyraenae is the first valid

nominal species of this genus described from fishes

of the family Sphyraenidae. Williams & Williams

(1996) listed ‘‘H.marinum’’ from Sphyraena barracu-

da (Walbaum) in the Pacific Ocean, but this informa-

tion is based on evident species misidentification. The

taxonomic status of the anisakid originally established

as Gordius marinus Linnaeus, 1767 remains uncertain

and the records of Contracaecum orHysterothylacium

marinum reported by Yamaguti (1935), Deardorff &

Overstreet (1981) and Moravec & Nagasawa (2000)

relate, in fact, to H. rigidum (Rudolphi, 1809). In

contrast to H. sphyraenae, H. rigidum is a specific

Fig. 6 Hysterothylacium sphyraenae n. sp., SEMmicrographs.

A, Tail tip of male, lateral view; B; Postanal double and single

papillae

190 Syst Parasitol (2015) 92:181–195

123

parasite of the Lophiidae in Europe, reported also off

Japan, and it is characterised by a very long caecum

extending anteriorly nearly to the level of the nerve-

ring, spicules usually longer than 1 mm and by the

presence of distinct numerous cuticular spines at the

tail tip in both sexes (Yamaguti, 1935; Hartwich,

1975; Deardorff & Overstreet, 1981; Moravec &

Nagasawa, 2000).

Unidentifiable ascaridoid larvae were inadequately

described as Ascaris sphyranurae Linstow, 1907 from

the body cavity of Sphyraena barracuda (reported as

Sphyranura barracuda) off Tasmania, Australia by

Linstow (1907a); apparently, S. barracuda only served

as a paratenic host. Adults or larvae of Hysterothy-

lacium, not identified to species, have frequently been

reported from other species of congeneric hosts

throughout the world (e.g. Petter & Sey, 1997;

Williams & Williams, 1996; Al-Zubaidy et al., 2012).

Contracaecum sp. third-stage larvae

Host: Blacksaddled colargrouper Plectropomus laevis

(Lacepede) (Perciformes: Serranidae); fork length

860 mm, weight 13.2 kg.

Site in host: Ensheated around intestine; bodies of

some specimens ensheathed by thin-walled capsule.

Locality: Off Noumea, New Caledonia, Recif Abore

(collected 2 July 2006).

Prevalence and intensity: 1 of 6 fish examined; 5

nematode specimens.

Voucher specimens: Museum National d’Histoire

Naturelle, Paris (MNHN JNC1887).

Description (Figs. 7, 8)

[Based on 5 specimens.] Body robust, whitish,

45.71–66.10 mm long and 1.22–1.59 mm wide. Cuticle

finely transversely striated (Fig. 8A–D), lateral alae

absent. Cephalic end rounded, with anteriormost part

somewhat elevated, separated from rest of body by

groove (Figs. 7B, C, 8A–C). Oral aperture demarcated

by2broad, lobular elevations (anlagenof lips) protruding

out of mouth, 12–41 high, 1 dorsal and 1 U-shaped

ventral; latter bearing small ventral cuticular tooth

(Figs. 7B, C, 8A–C). Four submedian cephalic papillae

surround oral aperture (Figs. 7B, C, 8A–C). Excretory

pore situated immediately posterior to ventral cephalic

tooth (Figs. 7B, E, 8A–C). Oesophagus narrow,

1.80–2.19 mm long, 163–204 wide. Ventriculus small,

rounded, size 136–204 9 122–190; posterior ventricular

appendix conspicuously large, 5.17–5.83 mm long,

326–490 wide. Nerve-ring 313–488 from anterior

extremity. Intestinal caecum short, extends only short

distance anterior to ventriculus; length 408–558, maxi-

mum width 204–218 (Fig. 7A). Length ratio of caecum

and ventricular appendix 1:10–14. Genital primordium

indistinct. Tail conical, 190–218 long, with few minute

terminal cuticular spines not visible in all specimens

(Figs. 7D, 8D).

Fig. 7 Contracaecum sp. third-stage larva ex Plectropomus

laevis. A, Anterior end of body, lateral view; B, Cephalic end,

apical view; C, Cephalic end, lateral view; D, Tail, lateral view;

E, Cephalic end, lateral view

Syst Parasitol (2015) 92:181–195 191

123

Remarks

The general morphology of these larvae, especially the

structure of the digestive tract and the location of the

excretory pore, indicates that they belong to Contra-

caecum. Species of this genus are parasites of fish-

eating birds and marine (rarely freshwater) mammals,

except sirenians (Anderson et al., 2009). However, as

compared with the known third-stage larvae of other

congeneric species, these larvae are considerably

larger (up to c.60 mm vs at most about 26 mm in

other congeners) (e.g. Anderson, 2000; Moravec et al.,

1993;Moravec &Van As, 2015) and their tail tip bears

a few minute cuticular spines, not reported for larvae

of other Contracaecum spp.

On the other hand, they are rather similar to adults

of the genus Paraheterotyphlum Johnston & Mawson,

1948, parasites of sea snakes in the Pacific region

(Johnston & Mawson, 1948; Schmidt & Kuntz, 1973;

Sprent, 1978), particularly in having a very long

ventricular appendix and a short caecum, the presence

of minute cuticular spines on the tail tip (found in

Paraheterotyphlum fourth-stage larvae; Sprent, 1978)

and in the large body measurements. However, adults

of Paraheterotyphlum spp. are 61–158 mm long

(Sprent, 1978), whereas those of Contracaecum spp.

are at most 90 mm long in C. osculatum (Rudolphi,

1802) (see e.g. Baylis, 1937; Mozgovoy, 1953;

Hartwich, 1975). However, according to Sprent

(1978), the excretory pore of P. australe Johnston &

Mawson, 1948 (the type-species of Paraheteroty-

phlum) is located slightly posterior to the nerve-ring,

whereas that in the present larvae is found just

posterior to the cephalic larval tooth (Fig. 8A–C).

Therefore, these larvae appear to belong to Contra-

caecum. In having minute cuticular spines at the tail

tip, they also resemble fourth-stage larvae of some

Hysterothylacium spp., but differ distinctly from them

by the location of the excretory pore, the much less

developed anlagen of lips and the markedly larger

body measurements.

Third-stage larvae of Contracaecum have fre-

quently been reported from the internal organs of

many species of freshwater, brackish-water andmarine

Fig. 8 Contracaecum sp. third-stage larva ex Plectropomus laevis, SEM micrographs. A, Cephalic end, lateral and apical views; B,

Cephalic end, apical view (arrow indicates ventral tooth); C, Cephalic end, apical view (another specimen) (arrow indicates ventral

tooth); D, Tail, ventral view. Abbreviations: a, cephalic papilla; c, cloacal aperture; e, excretory pore; o, oral aperture

192 Syst Parasitol (2015) 92:181–195

123

fishes, which serve as paratenic hosts (Anderson, 2000;

Moravec, 2009, 2013). Unfortunately, the species

identification of Contracaecum larvae from fishes

based on morphometrical features is practically

impossible. Judging by the structure of the digestive

tract, and especially the markedly short caecum and

long ventricular appendix, the present larvae tend to

resemble the adults ofC. rectangulum (Linstow, 1907),

as illustrated by Linstow (1907b) (see also Mozgovoy,

1953). This parasite of Antarctic seals was later

considered a junior synonym of C. osculatum (Rudol-

phi, 1802) by Baylis (1937), although Mozgovoy

(1953) did not agreewith this synonymy (the caecum is

much longer than the ventricular appendix in C. oscu-

latum). However, according to Linstow (1907b), the

body lengths of C. rectangulum is only 40 mm and

55–60 mm, respectively, for the male and females,

which is not comparable with the present third-stage

larvae. Apparently, these larvae belong to another,

perhaps undescribed species of Contracaecum.

Acknowledgements We thank Claude Chauvet (UNC,

Noumea) for providing fish, and Ronald Fricke (Staatliches

Museum fur Naturkunde, Stuttgart, Germany) for identifying the

barracuda (from photographs). Thanks are also due to the staff of

the Laboratory of Electron Microscopy, Institute of Parasitology,

BCCAS, in Ceske Budejovice for their technical assistance, and to

Blanka Skorıkova of the same Institute for help with the

illustrations. The authors also thank two anonymous reviewers

for their helpful suggestions, and to David Gibson, Natural History

Museum, London, for the linguistic revision of the MS.

Funding This study was partly supported by the Institute of

Parasitology (with institutional support RVO 60077344) and the

Czech Science Foundation (Project No. P505/12/G112).

Compliance with ethical standards

Conflict of interest The authors declare that they have no

conflict of interest.

Ethical approval All applicable institutional, national and

international guidelines for the care and use of animals were

followed.

References

Al-Zubaidy, A. B., Mhaisen, F. T., & Abker, M. A. M. (2012).

Occurrence of five nematode species from some Red Sea

fishes, Yemen. Mesopotamian Journal of Marine Science,

27, 140–156.

Anderson, R. C. (2000). Nematode parasites of vertebrates.

Their development and transmission. Second edition.

Wallingford and New York: CABI Publishing, 650 pp.

Anderson, R. C., Chabaud, A. G., & Willmott, S. (Eds) (2009).

Keys to the nematode parasites of vertebrates. Archival

volume. Wallingford: CAB International, 463 pp.

Baylis, H. A. (1937). On the ascarids parasitic in seals, with

special reference to the genus Contracaecum. Parasitol-

ogy, 29, 121–128.

Bruce, N. L. (1990). Redescription of the ascaridoid nematode

Hysterothylacium scomberomori (Yamaguti) from Aus-

tralian Spanish mackerel Scomberomorus commerson

(Lacepede). Memoirs of the Queensland Museum, 28,

427–434.

Bruce, N. L., & Cannon, L. R. G. (1989). Hysterothylacium,

Iheringascaris and Maricostula new genus, nematodes

(Ascaridoidea) from Australian pelagic marine fishes.

Journal of Natural History, 23, 1397–1441.

Deardorff, T. L., & Overstreet, R. M. (1978). Thynnascaris

rhacodes sp. n. (Nematoda: Ascaridoidea) in fishes from

the Israeli Mediterranean coast. Annales de Parasitologie

Humaine et Comparee, 53, 519–525.

Deardorff, T. L., & Overstreet, R. M. (1981). Review of Hys-

terothylacium and Iheringascaris (both previ-

ously = Thynnascaris) (Nematoda: Anisakidae) from the

northern Gulf of Mexico. Proceedings of the Biological

Society of Washington, 93(1980), 1035–1079.

Deardorff, T. L., & Overstreet, R. M. (1982). Hysterothylacium

pelagicum sp. n. and H. cornutum (Stossich, 1904) (Ne-

matoda: Anisakidae) from marine fishes. Proceedings of

the Helminthological Society of Washington, 49, 246–251.

Figus, V., D’Amico, V., Loddo, S. L., Siddu, N. L., & Canestri

Trotti, G. (2005). Elminti parassiti di Serranus cabrilla (L.)

(Osteichthyes, Serranidae) del Golfo di Cagliari, Mediter-

raneo sud-occidentale. Ittiopatologia, 2, 207–215.

Froese, R., & Pauly, D. (Eds) (2015). FishBase. World Wide

Web electronic publication. http://www.fishbase.org, ver-

sion 04/2015.

Gibbons, L. M. (2010). Keys to the nematode parasites of ver-

tebrates. Supplementary volume. Wallingford: CABI, 416

pp.

Hartwich, G. (1975). Schlauchwurmer, Nemathelminthes Rund-

oder Fadenwurmer, Nematoda Parasitische Rundwurmer

von Wirbeltieren I. Rhabditida und Ascaridida. Die Tier-

welt Deutschlands 62. Jena: VEB Gustav Fischer Verlag,

256 pp.

Johnston, T. H., & Mawson, P. M. (1948). Some new records of

nematodes from Australian snakes. Records of the South

Australian Museum, 9, 101–106.

Justine, J.-L. (2011). Huffmanela plectropomi (Nematoda: Tri-

chosomoididae: Huffmanelinae) from the coralgrouper

Plectropomus leopardus (Lacepede) off New Caledonia.

Systematic Parasitology, 79, 139–143.

Justine, J.-L., Beveridge, I., Boxshall, G. A., Bray, R. A.,

Moravec, F., Trilles, J.-P., &Whittington, I. D. (2010a). An

annotated list of parasites (Isopoda, Copepoda, Monoge-

nea, Digenea, Cestoda and Nematoda) collected in group-

ers (Serranidae, Epinephelinae) in New Caledonia

emphasizes parasite biodiversity in coral reef fish. Folia

Parasitologica, 57, 237–262.

Syst Parasitol (2015) 92:181–195 193

123

Justine, J.-L., Beveridge, I., Boxshall, G. A., Bray, R. A.,

Moravec, F., & Whittington, I. D. (2010b). An annotated

list of fish parasites (Copepoda, Monogenea, Digenea,

Cestoda and Nematoda) collected from Emperors and

Emperor Bream (Lethrinidae) in New Caledonia further

highlights parasite biodiversity estimates on coral reef fish.

Zootaxa, 2691, 1–40.

Justine, J.-L., Beveridge, I., Boxshall, G. A., Bray, R. A., Miller,

T. L., Moravec, F., Trilles, J.-P., & Whittington, I. D.

(2012). An annotated list of fish parasites (Isopoda,

Copepoda, Monogenea, Digenea, Cestoda, Nematoda)

collected from Snappers and Bream (Lutjanidae,

Nemipteridae, Caesionidae) in New Caledonia confirms

high parasite biodiversity on coral reef fish. Aquatic

Biosystems, 8, 22.

Klein, V. L. M. (1973). Helmintos parasitos das especies

Scomberomorus cavalla (Cuvier) e Scomberomorus mac-

ulatus (Mitchill) do litoral Cearense: Contracaecum fort-

alezae sp. n. (Nematoda: Ascaridoidea). Memorias do

Instituto Oswaldo Cruz, 71, 199–202.

Li, L., An, R., & Zhang, L. (2007). A new species of Hys-

terothylacium (Nematoda: Anisakidae) from marine fishes

from Yellow Sea, China, with a key to the species of the

genus Hysterothylacium. Zootaxa, 1614, 43–52.

Li, L., Liu, Y.-Y., & Zhang, L.-P. (2012). Morphological and

genetic characterization of Hysterothylacium zhousha-

nensis sp. nov. (Ascaridida: Anisakidae) from the flatfish

Pseudorhombus oligodon (Bleeker) (Pleurinectiformes:

Paralichthyidae) in the East China Sea. Parasitology

Research, 111, 2393–2401.

Li, L., Xu, Z., & Zhang, L. (2008). Redescription of three spe-

cies of Hysterothylacium (Nematoda: Anisakidae) from

marine fishes from the Yellow Sea, China, with the syn-

onymy of Hysterothylacium muraenesoxin (Luo, 1999).

Zootaxa, 1878, 55–67.

Li, L., Zhang, L.-P., & Liu, Y.-Y. (2013). Hysterothylacium

simile n. sp. andH. aduncum (Rudolphi, 1802) (Nematoda:

Raphidascarididae) from marine fishes in the Bohai and

Yellow Sea, China, with comments on the record of

H. paralichthydis (Yamaguti, 1941) from Chinese waters.

Systematic Parasitology, 84, 57–69.

Linstow, O. (1907a). Neue und bekannte Helminthen. Zoolo-

gische Jahrbucher, 24, 1–20 ? Pl. 1.

Linstow, O. (1907b). Nematodes of the Scottish National

Antarctic Expedition, 1902–1904. Proceedings of Royal

Society of Edinburgh, 26, 464–472 ? Plts. 1, 2.

Moravec, F. (2009). Experimental studies on the development of

Contracaecum rudolphii (Nematoda: Anisakidae) in

copepod and fish paratenic hosts. Folia Parasitologica, 56,

185–193.

Moravec, F. (2013). Parasitic nematodes of freshwater fishes of

Europe, 2nd Edition. Prague: Academia, 601 pp.

Moravec, F., & Justine, J.-L. (2005). Two anisakid nematodes

from marine fishes off New Caledonia, including Raphi-

dascaris (Ichtyascaris) nemipteri n. sp. from Nemipterus

furcosus. Systematic Parasitology, 62, 101–110.

Moravec, F., & Justine, J.-L. (2006). Three nematode species

from elasmobranchs off New Caledonia. Systematic Par-

asitology, 64, 131–145.

Moravec, F., & Justine, J.-L. (2012). Raphidascaris (Ichthyas-

caris) etelidis n. sp. (Nematoda, Anisakidae), a new

ascaridoid nematode from lutjanid fishes off New Cale-

donia. Zoosystema, 34, 113–121.

Moravec, F., & Justine, J.-L. (2014). Capillaria plectropomi n.

sp. (Nematoda: Capillariidae), a new intestinal parasite of

the leopard coral grouper Plectropomus leopardus (Ser-

ranidae) off New Caledonia. Parasite, 21, 76.

Moravec, F., Kohn, A., & Fernandes, B. M. M. (1993). Nema-

tode parasites of fishes of the Parana River, Brazil. Part 2.

Seuratoidea, Ascaridoidea. Habronematoidea and Acuar-

ioidea. Folia Parasitologica, 40, 115–134.

Moravec, F., & Nagasawa, K. (1998a). Hysterothylacium

japonicum sp. n. (Nematoda, Anisakidae) from the rare

marine fish Trachipterus ishikawai in Japan. Acta Para-

sitologica, 43, 39–42.

Moravec, F., & Nagasawa, K. (1998b). Hysterothylacium nip-

ponense nom. n. (Nematoda: Anisakidae) forH. japonicum

Moravec et Nagasawa, 1998 preoccupied by Hysterothy-

lacium japonicum Rajyalakshmi, 1996. Folia Parasito-

logica, 45, 328.

Moravec, F., & Nagasawa, K. (2000). Some anisakid nematodes

from marine fishes of Japan and the North Pacific Ocean.

Journal of Natural History, 34, 1555–1574.

Moravec, F., Nagasawa, K., & Urawa, S. (1985). Some fish

nematodes from fresh waters in Hokkaido, Japan. Folia

Parasitologica, 32, 305–316.

Moravec, F., Taraschewski, H., Appelhoff, D., & Weyl, O.

(2012). A new species of Hysterothylacium (Nematoda:

Anisakidae) from the giant mottled eel Anguilla mar-

morata in South Africa. Helminthologia, 49, 174–180.

Moravec, F., &VanAs, L. L. (2015). Studies on ascaridid, oxyurid

and enoplid nematodes (Nematoda) from fishes of the Oka-

vango River, Botswana. Folia Parasitologica, 62, 039.

Mozgovoy, A. A. (1953). [Ascaridata of animals and man and

the diseases caused by them, Part 2.] Osnovy Nematodo-

logii 2. Moscow: Publishing House of the USSR Academy

of Sciences, 616 pp (In Russian).

Norris, D. E., & Overstreet, R. M. (1975). Thynnascaris reli-

quens sp. n. and T. habena (Linton, 1900) (Nematoda:

Ascaridoidea) from fishes in the northern Gulf of Mexico

and eastern U. S. seaboard. Journal of Parasitology, 61,

330–336.

Petter, A. J., & Maillard, C. (1987). Ascarides de Poissons de

Mediterranee occidentale. Bulletin du Museum National

d’Histoire Naturelle, 4e Serie, 9, section A,No. 4, 773–798.

Petter, A. J., & Sey, O. (1997). Nematode parasites of marine

fishes with a description of Cucullanus trachinoti n. sp.

from Trachinotus blochi. Zoosystema, 19, 35–59.

Rossin, M. A., Datri, L. L., Incorvaia, I. S., & Timi, J. T. (2011).

A new species of Hysterothylacium (Ascaridoidea,

Anisakidae) parasitic in Zenopsis conchifer (Zeiformes,

Zeidae) from Argentinean waters. Acta Parasitologica, 56,

310–314.

Schmidt, G. D., & Kuntz, R. E. (1973). Nematode parasites of

Oceana. XX. Paraheterotyphlum ophiophagos n. sp. (Hete-

rocheilidae), from the banded yellow-lip sea snake, Latciauda

colubrina. American Midland Naturalist, 89, 481–484.

Schmidt, G. D., Leiby, P. D., &Kritsky, D. C. (1974). Studies on

helminths of North Dakota. VIII. Nematodes from the

paddlefish, Polyodon spathula (Walbaum), including

Thynnascaris dollfusi sp. n. (Nematoda: Stomachidae).

Canadian Journal of Zoology, 52, 261–263.

194 Syst Parasitol (2015) 92:181–195

123

Shamsi, S., Poupa, A., & Justine, J.-L. (2015). Characterisation

of ascaridoid larvae from marine fish off New Caledonia,

with description of newHysterothylacium larval types XIII

and XIV. Parasitology International, 64, 396–404.

Sprent, J. F. A. (1978). Ascaridoid nematodes of amphibia and

reptiles: Paraheterotyphlum. Journal of Helminthology,

52, 163–170.

Torres, P., & Soto, M. S. (2004).Hysterothylacium winteri sp. n.

(Nematoda: Anisakidae), a parasite of Chilean rock cod,

Eleginops maclovinus (Perciformes: Eleginopidae), from

South Chile. Folia Parasitologica, 51, 55–60.

Williams, E. H., &Williams, L. B. (1996). Parasites of offshore

big game fishes of Puerto Rico and the western Atlantic.

Mayaguez, Puerto Rico: Puerto Rico Department of Nat-

ural and Environmental Resources, San Juan and the

University of Puerto Rico, 382 pp.

Xu, Z., Li, L., & Zhang, L.-P. (2014). Hysterothylacium gibsoni

sp. nov. and H. tetrapteri (Bruce et Cannon, 1989) (Ne-

matoda: Ascaridida) from the Chinese marine fishes. Acta

Parasitologica, 59, 323–330.

Yamaguti, S. (1935). Studies on the helminth fauna of Japan.

Part 9. Nematodes of fishes, 1. Japanese Journal of Zool-

ogy, 6, 337–386.

Syst Parasitol (2015) 92:181–195 195

123