Pierre Bartoli

Rodney A Bray

David I Gibson

Three poorly known and rarely reported Bucephalid species (Digenea) in fishes from the Western Mediterranean fishes

Keywords: Seriola dumerili (Risso), Carangidae. Locality: Off Scandola Nature Reserve, Corsica, France (41°25¢N; 8°38¢E). Sites: Pyloric caeca (preferred site), stomach and duodenum. Number of fish examined:9 . Prevalence: 22.2%. Intensity: 41.5. Abundance: 9.2 Material studied: Thirty-five adult specimens. In most specimens, the rhynchus

scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

This is second of a series of papers dealing with the Bucephalidae from fish from the Scandola Nature Reserve, Corsica (Western Mediterranean) [START_REF] Bartoli | Two species of the fish digenean genus Rhipidocotyle Diesing, 1858 (Bucephalidae) reported for the first time from European seas[END_REF].

Materials and methods

Fish were collected live off the Natural Reserve of Scandola, Corsica (Western Mediterranean) and autopsied immediately after death. The digeneans collected were studied while still living and later in permanent preparations. Individuals were fixed in Bouin's fluid between a slide and a cover-glass under a light pressure, stained in acetic carmine and mounted in Canada balsam. Studies were conducted using a microscope with DIC optics and illustrations were made with the aid of a drawing apparatus. Measurements are given as the range in micrometres, with the mean in parentheses. Only ovigerous specimens were taken into account for measurements. Voucher specimens have been deposited in the Natural History Museum, London.

Family Bucephalidae Poche, 1907Subfamily Bucephalinae Poche, 1907 Genus Bucephalus von Baer, 1827

Bucephalus gorgon (Linton, 1905) [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF] Syns Gasterostomum gorgon Linton, 1905; Nannoenterum gorgon (Linton, 1905) Linton, 1940;Bucephalus introversus Manter, 1940 Description Specimens with rhynchus not retracted (Figures 1234; Table 1) General morphology (Figure 1A-B). Body elongate, with parallel margins; anterior extremity truncate; posterior extremity rounded.

Tegument. Entire body surface spined, densely anteriorly, less dense posteriorly. Spines thin, scale-like, with transversely elongate bases; appearing sharp at body margin.

Rhynchus. Rhynchus sucker-like, muscular, oval, with terminal aperture, crowned by series of fleshy retractable tentacles. Twenty-eight of 30 specimens studied had tentacles retracted (retracted tentacles resemble papillae). Three categories of extension can be seen (Figure 2A-C) which are, according to terminology of [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephalus Baer, 1827[END_REF]:

-2 conspicuous primary tentacles, emanating from each anterior corner of ventral aperture of rhynchus; -5 smaller secondary tentacles, 1 on mid-dorsal line, 2 latero-dorsal and 2 latero-ventral; -11-14 small papillae, at bases of 7 tentacles (see above), often retracted; number difficult to estimate.

Digestive system. Mouth on ventral surface, slightly posterior to middle of body. Prepharynx not seen. Pharynx subspherical, usually anterior to ovary (81.5%; n = 27) [contiguous with ovary (68.2%) or separated by caecum (31.8%)]; more rarely (18.5%), posterior to ovary [contiguous with ovary (100%)]. Oesophagus short. Caecum usually oriented anteriorly (74.1%), sometimes posteriorly (25.9%). Oral and oesophageal glands not detected.

Male reproductive system. Testes 2, oval, entire, posterior to middle of body, dextral (100%), often contiguous (72.4%) or slightly separated by uterine loops (27.6%); anterior testis contiguous with ovary (55.2%) or slightly separated (44.8%). Cirrus-sac thin-walled, cylindrical, rectilinear (Figure 3), sinistral (100%); its proximal extremity at level of posterior testis (24.2%), anterior testis (72.4%) or ovary (3.4%). Seminal vesicle elongate, more than twice as long as wide. Seminal duct absent. Pars prostatica cylindrical, rectilinear, lined by thick layer of anuclear structures, surrounded by prostatic cells. Ejaculatory duct passes through distal extremity of cirrus-sac and genital lobe. Genital lobe with irregular expansions, projects into genital atrium. Genital atrium thin-walled, wide, devoid of surrounding glandcells. Genital pore ventral, subterminal, wide.

Female reproductive system. Ovary spherical to oval, entire, just posterior to middle of body, dextral (100%), in contact with posterior margin of caecum (100%). Oo¨capt swollen, emerges from posterior margin of ovary (Figure 4). Oviduct tubular, thick-walled, ciliated, directed posteriorly. Laurer's canal thin-walled, devoid of external gland-cells, rectilinear, oriented transversely, post-ovarian, opens dorsally just posterior to ovary. Oo¨type and Mehlis' gland poorly developed. Proximal part of uterus contains sperm, acts as uterine seminal receptacle. Uterine loops extend well into pre-vitelline field. Distal part of uterus differentiated as weakly developed metraterm; opens into genital atrium near distal extremity of cirrus-sac. Eggs thin-shelled, operculate. Vitelline follicles in 2 longitudinal fields of subglobular follicles; dextral field 12-14 (13) (80% have 13); sinistral field 16-20 (19) (75% have 19) (n = 20), almost twice length of dextral. Vitelline ducts in dorsal parenchyma of body; sinistral much longer than dextral, forming conspicuous loop before joining vitelline reservoir (Figure 1A). Vitelline reservoir inconspicuous. Vitelline duct joins oviduct just before oo¨type.

Excretory system. Excretory vesicle I-shaped, reaches anterior level of ovary (Figure 1B). Excretory pore terminal.

Specimens with retracted rhynchus (Figure 5AB; Table 1) In the stomach and the pyloric caeca of 1 fish, 6 specimens exhibiting a rhynchus withdrawn into the anterior extremity of the body were found along with 'normal' specimens. These 6 specimens have the anterior part of their body enlarged and truncate. The retracted rhynchus, abutted against the anterior uterine loops, retains its usual structure with 7 retracted tentacles. Some characters of these 6 specimens are similar to those of specimens having their rhynchus located terminally: the size of the rhynchus and eggs; the relative arrangement of the gonads; and the extent of the uterine loops, cirrus-sac and excretory vesicle. Some other 5), South China Sea (6).

Discussion

In describing Gasterostomum gorgon, Linton (1905, p. 364) mentioned ''an anterior sucker [i.e. a rhynchus] surrounded by a crown of about eighteen tentacles''; in most cases, the anterior end of his specimens was withdrawn (his figure 241; incorrectly oriented). [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF] placed this species in Bucephalus von Baer, 1827. Linton (1940) redescribed the species with an anterior sucker provided with about 20 tentacles, the specimens being ''all macerated'' (p. 37) and moved the species to Nannoenterum Ozaki, 1924. Velasquez (1959, p. 138) examined the material of Linton (1940) and replaced this species in Bucephalus as B. gorgon (Linton, 1940 [sic]), either assuming that the species described by Linton in 1905 andin 1940 were different or as a lapsus. [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephalus Baer, 1827[END_REF], as well as [START_REF] Nahhas | Digenetic trematodes of marine fishes from the Floridian Northern Gulf of Mexico[END_REF], [START_REF] Fischthal | Additional records of digenetic trematodes of marine fishes from Israel's Mediterranean coast[END_REF] and [START_REF] Fischthal | Comparative allometry of size of the digenetic trematode Bucephalus gorgon (Linton, 1905) Eckmann, 1932 (Bucephalidae) in two sites of infection in the marine fish Seriola dumerili (Risso)[END_REF], retained the name of B. gorgon (Linton, 1905).

The original description of Linton (1905) is fragmentary while the 'somewhat diagrammatic' figures are probably of macerated worms and worms with the rhynchus withdrawn. The redescription of Linton (1940) is slightly more detailed, but with schematic figures exclusively of the rhynchus with its tentacles. The first useful figures of the body and rhynchus were provided by [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephalus Baer, 1827[END_REF], but details of the structure of the genital and excretory systems, as well as metrical data, are still missing. Nevertheless, the description of the specimens from Corsica fits well with those of Linton (1940) and of [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephalus Baer, 1827[END_REF] (see Table 2).

The rhynchus of B. gorgon consists of seven large retractile tentacles, each of them provided with one or two small basal processes. The small distal prongs observed in the tentacles of some species, such as Bucephalus varicus [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF], are absent in B. gorgon. Seven large tentacles appear to be the basic number among Bucephalus species. The retraction of the rhynchus observed in some specimens may be an indicator of a moribund condition. In our material, all specimens with a non-retracted rhynchus were clearly alive and moving, whereas the six large (old?) specimens with a retracted rhynchus were motionless. Three of these six specimens had a disorganised, lacunar parenchyma, the tegument was shedding its spines and the vitelline follicles were more or less disintegrated. The retracted rhynchus could be observed in macerated specimens.

The first report of B. gorgon from S. dumerili in Mediterranean waters was by [START_REF] Fischthal | Additional records of digenetic trematodes of marine fishes from Israel's Mediterranean coast[END_REF] and [START_REF] Fischthal | Comparative allometry of size of the digenetic trematode Bucephalus gorgon (Linton, 1905) Eckmann, 1932 (Bucephalidae) in two sites of infection in the marine fish Seriola dumerili (Risso)[END_REF] from off the Mediterranean coast of Israel. Recently, [START_REF] Montero | Parasite fauna in cultured greater amberjacks (Seriola dumerili) from the Spanish Mediterranean[END_REF] listed this species from S. dumerili in the Balearic Sea. It is probable that the bucephalid species collected by [START_REF] Grau | Some protozoan and metazoan parasites of the amberjack from the Balearic Sea (western Mediterranean)[END_REF] from the digestive tract of S. dumerili in the Balearic Sea and [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF]; and (2) B. paraheterotentaculatus [START_REF] Velasquez | Studies on the family Bucephalidae Poche, 1907 from Philippine food fishes[END_REF] from Seriolina (as Seriola) nigrofasciata (Ru¨ppell) off the Philippines [START_REF] Velasquez | Studies on the family Bucephalidae Poche, 1907 from Philippine food fishes[END_REF].

B. introversus was described by Manter (1940) on the basis of two kinds of specimens. This author stated that in ''... almost all specimens the anterior end was introverted into the anterior part of the body ...'' and gave some measurements of four specimens with the anterior end everted. Comparison of the description of B. introversus of [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF] with that reported in here for B. gorgon, shows them to be very similar (Table 3). Strangely, [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF] never made reference to B. gorgon as described by Linton (1905) from the same host fish species. It is our opinion that B. introversus is a synonym of B. gorgon. Most other records appear to be of the same species, but that of Caballero y C. et al. (1956), from the centropomid Centropomus pectinatus Poey, is not considered conspecific here and should be further investigated.

B. paraheterotentaculatus differs from B. gorgon in that the mouth is located more posteriorly (at about the level of the anterior end of the cirrussac), and it has a posteriorly oriented caecum, overlapping gonads, a much smaller rhynchus, confluent vitelline follicles forming an arch anteriorly with a larger dextral field, and a long excretory vesicle extending to the rhynchus. when fixed; maximum width at level of ovary or anterior testis.

Genus

Tegument. Entire surface of body spinose and finely folded (transverse rows of thin furrows), between anterior extremity and ovarian level, and particularly in anterior part of this region; spines very dense, strongly developed, acuminate, flattened, with transversely enlarged bases; posterior to ovarian level, spines smaller, less dense, and absent posterior to level of cirrus-sac.

Rhynchus. Rhynchus sucker-like, round, ventroterminal, devoid of special spines, lobes and glandcells.

Digestive system. Mouth on ventral surface, usually near middle of body; anterior lip with prom- inent conical outgrowth (oral papilla) protruding over oral opening, with oral gland-cell ducts opening on tip (Figures 7,8). Pharynx spherical.

Oesophagus distinct, thin-walled. Caecum cylindrical, posteriorly oriented, reach posteriorly as far as level of middle of ovary or further; wall thick and transversely folded; gastrodermis with large non-chromophilic convex cells (Figure 7). Oesophageal and oral gland-cells numerous, very small, not easily detected. 7A); in 11.1% of specimens, genital atrium is everted and genital lobe is protruded through genital pore (Figure 7B). Genital lobe with 2 pointed, irregular lobes. Genital atrium thin-walled, wide, devoid of surrounding gland-cells. Genital pore ventral, subterminal.

Female reproductive system. Ovary spherical to oval, entire, in middle of body, dextral (88.9%)o r median (11.1%), contiguous with right side of caecum (89.5%) or its distal extremity (10.5%).

Oo¨capt swollen, emerging from right side of ovary (Figure 10). Oviduct tubular, thick-walled, lined with posteriorly directed cilia. Laurer's canal thinwalled, devoid of external glandular cells, rectilinear, transversely oriented, post-ovarian, opens dorsally just posterior to ovary. Oo¨type thickwalled; Mehlis' gland poorly developed. Proximal part of uterus containing sperm, acts as uterine seminal receptacle. Uterine loops exclusively postovarian, fill most of post-ovarian part of body; distal part not differentiated as metraterm, opens into genital atrium near distal extremity of cirrussac. Eggs thin-shelled, operculate; abnormal eggs coexisting with normal ones in 33.3% of specimens. Vitelline follicles in 2 regular longitudinal rows, on either sides of pharynx, 13-18 (15) in dextral field, 16-19 (17) in sinistral field; total number 30-34 (32); sinistral field longer than dextral. Vitelline ducts run in dorsal parenchyma; sinistral duct longer than dextral, describes conspicuous loop before joining vitelline reservoir (Figure 6A-B). Vitelline reservoir posterior to ovary with unusually straight common vitelline duct joining oviduct just proximal to oo¨type.

Excretory system. Excretory vesicle I-shaped, sometimes with irregular bulges, very long, reaching to near rhynchus. Excretory pore terminal

Type-host and locality: Sarda sarda, off Woods Hole, Massachusetts, USA.

Discussion

Historical review Gasterostomum arcuatum was originally described by [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF] from the Atlantic bonito Sarda sarda off Woods Hole, Massachusetts, USA and later (Linton, 1901) from the dusky shark Carcharhinus obscurus (Lesueur) ('almost certainly' an accidental host according to [START_REF] Bray | The digeneans of elasmobranchs -distribution and evolutionary significance[END_REF]) from the same area. Linton (1905) then reported this species from off Beaufort, North Carolina, USA from two other fish hosts, the cero Scomberomorus regalis (Bloch) (with a figure) and the crevalle jack Caranx hippos (L.). [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF] placed the species in Bucephalopsis as B. arcuata

[sic] [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF]. Nagaty (1937 p. 45) listed the synonyms of B. arcuatus. Unaware of Eckmann's new combination, Linton (1940) retained this species in Gasterostomum and added three new host fishes for it, the mackerel Scomber scombrus L., the largehead hairtail Trichiurus lepturus L. and the cod Gadus morhua L. from off Woods Hole. The same year, [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF] pointed out that the species reported by Linton (1905) (1963) pointed out that the specimens from the barracuda that he found earlier [START_REF] Manter | Digenetic trematodes of fishes from the Galapagos Islands and the neighboring Pacific[END_REF], and those reported by [START_REF] Siddiqi | Digenetic trematodes of marine fishes of Puerto Rico[END_REF], had an excretory vesicle ending at the level of the pharynx, whereas it extends almost to the rhynchus in B. arcuatus (see [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF], figure 86), more widely separated vitelline fields, and a longer cirrus-sac. Manter (1963, p.229) considered the specimens from Sphyraena barracuda to be Bucephaloides longicirrus Nagaty, 1937, a parasite of Sphyraena agam from the Red Sea, basing his opinion on the truncate rhynchus, the location of the gonads, the extent of the vitellarium and uterus and the egg-size. [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF] described and figured Bucephalopsis arcuatus from the striped bonito Sarda orientalis (Temminck & Schlegel) from off Hawaii. Bray (1984) transferred Bucephaloides arcuatus to Prosorhynchoides unaware that this action had been taken the year earlier by [START_REF] Love | A checklist of parasites of California, Oregon, and Washington marine and estuarine fishes[END_REF]. Bray (1984) also synonymised Bucephalopsis callicotyle Kohn, 1962, from the bluefish Pomatomus saltatrix (L.) off Brazil, with P. arcuatus.

Identification of the Mediterranean specimens Surprisingly, despite many reports of Prosorhynchoides arcuatus around the world, the morphological and metrical data available for this species are extremely fragmentary, apart from those given by [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF] for specimens from Sarda orientalis off Hawaii.

The description and the measurements of [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF] agree with the data from the present study except for the number of vitelline follicles and the side of the body where the U-shaped vitelline duct runs. A scanning electron microscopical study of specimens from Pomatomus saltatrix off Rio de Janeiro, Brazil by Cohen et al. (1995) is in general agreement with the present description except for the lack of an oral papilla, which obvious in all of our specimens, and the genital aperture which is protuberant and provided with a muscular sphincter, structures that are lacking in our specimens. The oral papilla of P. arcuatus is similar to that described by [START_REF] Manter | Some digenetic trematodes, including eight new species, from marine fishes of La Jolla[END_REF] for Bucephalopsis (=Prosorhynchoides) labiatus [START_REF] Manter | Some digenetic trematodes, including eight new species, from marine fishes of La Jolla[END_REF] from Paralichthys californicus (Ayres) and by [START_REF] Santos | Morphological features of Prosorhynchus crucibulum and P. aculeatus (Digenea: Bucephalidae), intestinal parasites of Conger conger (Pisces: Congridae), elucidated by scanning electron microscopy[END_REF] for Prosorhynchus crucibulum (Rudolphi, 1819) from Conger conger (L.).

Distribution

Prosorhynchoides arcuatus is listed by Greze et al. (1975, p. 501) Laurer's canal not detected. Mehlis' gland poorly developed, posterior to ovary, dorsal to anterior testis (Figure 11B). Anterior uterine loops at level of posterior extremity of rhynchus

Discussion

The present description of P. tergestinum is in close agreement with those of [START_REF] Stossich | Brani di elmintologia tergestina[END_REF][START_REF] Stossich | Osservazioni elmintologiche[END_REF] and [START_REF] Nicoll | On Gasterostomum tergestinum Stossich[END_REF]. As reported by [START_REF] Stossich | Brani di elmintologia tergestina[END_REF], but unlike [START_REF] Nicoll | On Gasterostomum tergestinum Stossich[END_REF], the only specimen found reported in this study shows a wide digestive caecum extending anteriorly as well as posteriorly to the pharynx, an entire and oval seminal vesicle, and two vitelline clusters larger than the pharynx. This is a very rare species which has not been reported since the original record of Stossich in 1883.

Figures 1

 1 Figures 1-4. Bucephalus gorgon (Linton, 1905) from the pyloric caeca of Seriola dumerili, off Scandola Nature Reserve, Corsica. Specimens with their rhynchus not retracted. 1. General morphology. A. Dorsal view of a specimen with rhynchus with retracted tentacles; B. Ventral view of a specimen with rhynchus with expanded tentacles (its dorsal vitelline follicles are hidden by uterine loops). 2. Rhynchus. A. Ventral view; B. Dorsal view. C. Details of the primary tentacles of the Figure 2B. 3. Cirrus-sac, distal uterus and genital atrium enclosing the genital lobe (ventral view). 4. Proximal female genitalia (dorsal view). Abbreviations: P, primary tentacle; S, secondary tentacle; D, dorsal; LD, latero-dorsal; LV, latero-ventral.

  characters are markedly different: the larger bodysize, pharynx, gonads, Mehlis' gland and cirrussac; and the oblique testes. Type-host and locality: Seriola lalandi, off Beaufort, North Carolina, USA. Records: 1. Linton (1905); 2. Linton (1940); 3. Manter (1940) 1 ; 4. Bravo-Hollis & Sogandares-Bernal (1953) 1 ; 5. Oshmarin (1965); 6. Parukhin (1966) 1 ; 7. Corkum (1967); 8. Nahhas & Powell, 1971; 9. Fischthal (1982), Fischthal et al. (1982); 10. Luque & Oliva (1993) 1 , 11. Montero et al. (2002); 12. Present study. Descriptions:1 ,2 ,3 ,5 ,7 ,1 0 ,1 2 . Definitive hosts: Carangidae: Carangoides otrynter (4-as Citula dorsalis), Caranx hippos (3), Pseudo-caranx dentex (9-as Caranx); Seriola lalandi (1, 2, 3-as dorsalis, 10-as mazatlana), S. dumerili (3, 7, 9, 11, 12), S.'nigromaculata' (5), S. zonata (7, 8), Seriola sp. (3), Seriolina nigrofasciata (6-as Seriola nigrophasciata). Distribution: Off Beaufort, North Carolina (1); off Woods Hole, Massachusetts (2); Gulf of Mexico (7, 8); Eastern Mediterranean (off Israel) (9); Western Mediterranean: Balearic Sea (11), off Corsica (12); Pacific off Colombia (3), Pacific off Mexico (3, 4), off Chile (10), Gulf of Vietnam (

Figure 5 .

 5 Figure 5. Bucephalus gorgon (Linton, 1905) from the pyloric caeca of Seriola dumerili, off Scandola Nature Reserve, Corsica. A-B: specimens with rhynchus retracted in the forebody. (Dorsal views).

Figures 6 -

 6 . Prosorhynchoides arcuatus[START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF] from the pyloric caeca of Sarda sarda, off Scandola Nature Reserve, Corsica. 6. General morphology. A. Ventral view; B. Dorsal view. 7. Digestive system (ventral view). 8. Oral papilla and oral glandcells (ventral view). 9. Cirrus-sac, distal uterus and genital atrium. A. Genital lobe protruding into genital atrium -usual condition (ventral view); B. Genital atrium everted; genital lobe projected outside through the genital pore (dorsal view).

Figure 10 .

 10 Figure 10. Prosorhynchoides arcuatus (Linton, 1900) from the pyloric caeca of Sarda sarda, off Scandola Nature Reserve, Corsica. Proximal female genitalia (ventral view). Abbreviations: CVD, common vitelline duct; LC, Laurer's canal; LVD, left vitelline duct; MG, Mehlis' gland; OVI, oviduct; RVD, right vitelline duct; USR, uterine seminal receptacle.

Figures 11 -

 11 . Prosorhynchoides tergestinum[START_REF] Stossich | Brani di elmintologia tergestina[END_REF] from the mid-intestine of Gobius geniporus, off Scandola Nature Reserve, Corsica. 11. General morphology of the same specimen (only some eggs are figured in the anterior uterine loops). A. Ventral view; B. Dorsal view. 12. Mouth, oral papilla and oral gland-cells (ventral view). Abbreviations: M, mouth; P, oral papilla; PH, pharynx.

Table 1 .

 1 Measurements of ovigerous Bucephalus gorgon specimens with a normal rhynchus compared with specimens with a retracted rhynchus, all from the stomach and the pyloric caeca of Seriola dumerili from Scandola, Corsica.

	Specimens with:	Normal rhynchus	Retracted rhynchus
	n1 0	6
	Body length	1,562-2,750 (1,974)	2,085-2,844 (2,497)
	Body width at level of ovary	178-241 (208)	237-343 (290)
	Rhynchus	186)230 • 160)208 (210 • 173)	192)230 • 134)205 (214 • 174)
	Tentacles:
	-primary	109-125 (116)	-
	-secondary (mid-dorsal)	84-106 (95)	-
	-secondary (latero-dorsal)	71-96 (80)	-
	-secondary (latero-ventral)	46-70 (63)	-
	-papillae	27-50 (36)	-
	Pharynx	44)64 • 54)64 (52 • 61)	70)77 • 70)93 (72 • 80)
	Digestive caecum	95)160 • 50)112 (127 • 81)	128)176 • 74)96 (151 • 84)
	Oesophagus	27-64 (45)	54-112 (81)
	Anterior testis	133)262 • 90)144 (171 • 111)	182)246 • 141)170 (220 • 159)
	Posterior testis	109)214 • 90)122 (143 • 103)	160)224 • 122)192 (190 • 153)
	Ovary	85)147 • 70)108 (119 • 92)	141)214 • 99)160 (164 • 125)
	Cirrus-sac	272)428 • 86)99 (364 • 93)	576)736 • 122)147 (654 • 131)
	Thickness of cirrus-sac wall	4-7 (6)	4-8 (6)
	Seminal vesicle	74)118 • 32)48 (99 • 38)	122)166 • 36)96 (145 • 62)
	Pars prostatica	224)336 • 32)51 (275 • 40)	224)464 • 48)80 (344 • 62)
	Genital atrium	96)192 • 90)125 (145 • 103)	144)208 • 74)144 (179 • 118)
	Length of right vitelline cluster	267-445 (341)	165-537 (442)
	Length of left vitelline cluster	412-889 (580)	527-933 (765)
	Number of right vitelline follicles	12-14 (13)	12-13 (13)
	Number of left vitelline follicles	16-20 (19)	16-21 (18)
	Diameter of vitelline follicles	35-50 (41)	50-74 (61)
	Eggs (uncollapsed) (n=50)	21)24 • 13)15 (22 • 14)	21)22 • 13)14 (22 • 13)
	Distance from anterior end of body to:
	-anterior limit of uterus	254-635 (399)	(#) 305-445 (392)
	-anterior limit of right vitelline field	540-1,016 (726)	(#) 559-838 (674)
	-anterior limit of left vitelline field	577-972 (733)	(#) 603-921 (710)
	-anterior extremity of caecum	794-1,330 (1,042)	(#) 700-1,270 (1,044)
	-pharynx	838-1,700 (1,144)	(#) 603-1,460 (1,163)
	-anterior testis	978-1,746 (1,280)	(#) 1,016-1,632 (1,335)
	-ovary	889-1,480 (1,137)	(#) 825-1,378 (1,172)
	Pharynx to posterior end of body	614-1,054 (806)	1,143-1,416 (1,278)
	Body width %*	7.3-15.0 (10.8)	(#) 9.0-13.5 (11.7)
	Space anterior to pharynx %*	53.6-63.6 (57.7)	(#) 28.9-55.3 (46.0)
	Previtelline region %*	31.5-45.0 (37.0)	(#) 23.8-31.7 (26.9)
	Cirrus-sac length %*	12.8-22.4 (15.5)	(#) 21.8-32.2 (26.4)
	Cirrus-sac length %**	33.4-53.9 (45.6)	47.3-57.4 (51.2)
	Post-testicular region %*	17.7-21.8 (19.6)	(#) 26.5-36.8 (29.4)
	(#) Distance from apparent anterior end of body.

*As % of body length. **As % of length of body posterior to pharynx.

Table 2 .

 2 Comparative measurements of Bucephalus gorgon according to the literature. Bucephalus polymorphus von Baer, 1827 corresponds to B. gorgon. B. polymorphus is a parasite of freshwater fishes, with freshwater lamellibranchs acting as its first intermediate hosts. Oshmarin (1965) described B. gorgon from 'Seriola nigromaculata' (not listed by Froese & Pauly, 2004) from the Gulf of Vietnam. The illustration suggests that this Pacific Ocean form is, indeed, very similar to the Atlantic concept of B. gorgon. Two other species of Bucephalus have been described from Seriola spp: (1) B. introversus Manter, 1940 from Seriola lalandi Valenciennes (as S. dorsalis (Gill)) and S. dumerili, off the Pacific coast of Colombia and Mexico

		Linton (1905) Linton (1940)	Corkum (1967) Fischthal et al. (1982) Present study
	n	1	5	?	60	10
	Body:
	-length	1.650	2,380-3,130 (2,900)		615-3,230	1,562-2,750 (1,974)
	-width	360	290-420 (360)			178-241 (208)
	Rhynchus:
	-length		210-280 (240)			186-230 (210)
	-width	360	180-220 (200)			160-208 (173)
	Tentacles:		''tentacle'': 150
	-primary			104		109-125
	-secondary			73		46-70
	-papillae			42		27-50
	Anterior extremity to:
	-vitellarium		560-910 (740)			540-1,016 (726)
	-uterus		10-560 (310)			254-635 (399)
	-pharynx		1,570-1,680			838-1,700
	Diameter of pharynx		60			50-112
	Number of follicles		13+17			13+19
	Eggs	22 • 14	18-21 • 10-12			21-24 • 13-15

  Prosorhynchoides Dollfus, 1929 Syns Bucephalopsis Diesing, 1855; Neobucephalopsis Dayal, 1948; Bucephaloides Hopkins, 1954

	Prosorhynchoides arcuatus (Linton, 1900) Love &
	Moser, 1983
	Syns Gasterostomum arcuatus Linton, 1900;
	Bucephalopsis arcuatus (Linton, 1900) Eckmann,
	1932; Bucephaloides arcuatus (Linton, 1900)
	Velasquez, 1959; Bucephalopsis callicotyle Kohn,
	1962; Bucephaloides callicotyle (Kohn, 1962)
	Corkum, 1968
	Host: Sarda sarda (Bloch), Scombridae, Percifor-
	mes.
	Locality: off Scandola Nature Reserve, Corsica,
	France (41°25¢N; 8°38¢E).
	Site: Pyloric caeca.
	Number of fish examined:1 .Intensity: several
	hundreds.
	Material studied: 36 adult specimens.
	Voucher specimens: BMNH 2005.2.16.1-6.
	Description (Figures 6-10; Table 4)
	General morphology (Figure 6A,B). Body more or
	less cylindrical, elongate; some specimens arched

Table 3 .

 3 Comparative measurements of ovigerous specimens with non-retracted rhynchus of Bucephalus introversus and B. gorgon.

		B. introversus	B. gorgon
	Source	Manter (1940)	Present study
	Host(s)	Seriola spp., Caranx hippos	Seriola dumerili
	Sites	Stomach	Stomach and pyloric caeca
	Locality	Off Colombia and Mexico	Off Scandola (Corsica)
	n4	1 0
	Body length	1,202-1,707	1,562-2,750
	Body width	225-285	178-241
	Rhynchus	length: 170-345	length: 186-230
	Anterior end to mouth	817-1,035	838-1,700
	Pharynx width	37-61	54-64
	Eggs	22)26 • 12)15 (24 • 14)	21)24 • 13)15 (22 • 14)

Table 4 .

 4 Comparative measurements of Prosorhynchoides arcuatus and P. tergestinum.

	P. arcuatus	P. tergestinum

*As % of body length. **As % of length of body posterior to pharynx.

  as present in the Black and Azov Seas in Sarda sarda (as Bucephalopsis arcuatus) and Scomber scombrus (as Bucephalus arcuatus), andDimitrov (1989) reported P. arcuatus from Pomatomus saltatrix and Sarda sarda from the Bulgarian Black Sea coast. In the Mediterranean, Male reproductive system. Testes 2, contiguous, oblique, entire, spherical; anterior dextral, in ventral parenchyma, slightly overlaps ovary; posterior submedian. Cirrus-sac curved, sinistral; proximal extremity contiguous with left side of anterior testis. Seminal vesicle oval, entire (i.e. not twisted); length slightly more than twice width. Pars prostatica sub-rectilinear, curved at anterior extremity. Distal ejaculatory duct curved. Genital lobe weakly bi-lobed. Genital atrium thick-walled; surrounding gland-cells apparently missing. Genital tube absent. Genital pore sub-terminal.Female reproductive system. Ovary pre-equatorial, dextral, anterior and dorsal to anterior testis, oval.

		Material studied: 1 adult specimen.
		Voucher specimens: BMNH 2005.2.28.6.
		Description (Figures 11, 12; Table 4)
		General morphology (Figure 11A,B). Body pyri-
		form, not elongate, widest at level of pharynx,
		narrowing in post-testicular field. Extremities
		rounded.
		Tegument. Entire body-surface densely spined;
		spines scale-like.
		Rhynchus. Rhynchus sucker-like, subterminal,
		large, circular, muscular, with wide cavity but
		small ventral aperture.
		Cephalic gland-cells. Numerous discrete gland-cells
		among parenchymal cells of pre-vitelline field;
		ducts pass dorsally to rhynchus and open on its
		anterior lip.
		Digestive system. Mouth on ventral surface, near
		anterior extremity of middle third of body.
	Sarda sarda appears to have been investigated for digeneans only by Barbagallo & Drago (1903), who listed ''Distoma clavatum Rudolphi'' (a spe-cies inquirendum) found in their stomach of Sarda sarda from the Ionic Sea, eastern Mediterranean. In contrast, numerous studies have been con-	Prepharynx short. Pharynx transversely oval, large, with thick basal lamina; at level of ovary but separated from it. Oesophagus absent. Caecum sac-like, oval, dorsal to pharynx, posteri-orly oriented. Gastrodermis with tall columnar cells. Oesophageal glands not detected.
	ducted on the digenean fauna of Scomber scombrus	Oral gland-cells. Numerous discrete gland-cells
	and S. japonicus Houttuyn at various places in the	radiate in ventral parenchyma anterior to pharynx;
	Mediterranean, but none have reported a buceph-	ducts open at tip of oral papilla (Figure 12). Oral
	alid species. As a result, we report Prosorhyncho-	papilla conical, distinct, emerges from anterior
	ides arcuatus for the first time in the	wall of prepharynx and projects into prepharyn-
	Mediterranean.	geal cavity.
	Prosorhynchoides tergestinum (Stossich, 1883) n.
	comb.
	Syns Gasterostomum tergestinum Stossich, 1883;
	Bucephalopsis tergestina (Stossich, 1883) Nagaty,
	1937; Bucephalus tergestinus (Stossich, 1883)
	Yamaguti, 1958
	Host: Gobius geniporus Valenciennes, Gobiidae.
	Locality: Off Scandola Nature Reserve, Corsica,
	France (41°25¢N; 8°38¢E).
	Sites: Mid-intestine.
	Number of fish examined: 17.
	Prevalence: 5.9%. Intensity:1 .Abundance: 0.06.
	Negative hosts:1 6Gobius paganellus L. and 11 G.
	cobitis Pallas from the same locality.

  . Eggs numerous, all collapsed. Metraterm not detected. Vitelline follicles in 2 clusters, in dorsal parenchyma of mid-body, lateral to caecum at ovarian level; follicles closely packed, not clearly outlined, of variable shape and size; number difficult to count. Left vitelline duct only slightly longer than right. Excretory system. Excretory vesicle I-shaped, wide, with its anterior extremity reaching anterior margin of posterior testis, in ventral parenchyma. Excretory pore terminal. Type-host and locality: Gobius niger L. [first host listed], Adriatic Sea off Trieste. Records: 1. Stossich (1883); 2. Stossich (1901; repeat of 1); 3. Present study. Descriptions: 1, 2, 3 (and Nicoll, 1910, from specimens in Stossich's collection). Definitive hosts: Gobiidae: Gobius niger (1; and G. jozo -according to Froese & Pauly, 2004, a synonym of G. niger); G. geniporus (3).

Distribution: Mediterranean: Adriatic Sea (1,2); Western Mediterranean (Corsica) (3).

As Bucephalus introversus.

As Bucephalopsis callicotyle;

as Bucephaloides arcuatus;

as Bucephaloides callicotyle;

as Bucephalopsis arcuatus;

as Bucephalus arcuatus.

Acknowledgements

Fieldwork on Corsica of PB was carried out under the auspices of the Comite´Scientifique de la Re´serve Naturelle de Scandola.


Pierre Bartoli

Rodney A Bray

Two species of the fish digenean genus Rhipidocotyle Diesing, 1858 (Bucephalidae) reported for the first time from European seas

diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Two species of the fish digenean genus Rhipidocotyle Diesing, 1858 (Bucephalidae) reported for the first time from European seas

Introduction

The Bucephalidae Poche, 1907 from fish from the Mediterranean Sea have not received much attention since the studies of pioneers such as [START_REF] Rudolphi | Entozoorum synopsis, cui accidunt mantissa duplex et indices locupletissimi[END_REF], [START_REF] Wagener | Enthelminthica. No. III[END_REF], [START_REF] Molin | Nuovi myzelmintha raccolti ed esaminati[END_REF], [START_REF] Stossich | Brani di elmintologia tergestina[END_REF][START_REF] Stossich | Brani di elmintologia tergestina. Serie IV[END_REF] and [START_REF] Nicoll | On Gasterostomum tergestinum Stossich[END_REF]. The few recent contributions include those of [START_REF] Paggi | Su un nuovo trematode parassita dell'intestino di Morone labrax: Bucephalus labracis n. sp[END_REF], [START_REF] Maillard | Labratrema lamirandi (Carre`re, 1937) (Trematoda, Bucephalidae) parasite de Dicentrarchus labrax (L., 1758). Cre´ation du genre Labratrema, Cycle e´volutif[END_REF], [START_REF] Munoz | Contribucion al estudio de algunos bucefalides (Trematoda: Bucephalidae) parasitos de peces marinos de aguas ibericas[END_REF], [START_REF] Spakulova | Description of Bucephalus anguillae n. sp. (Trematoda: Bucephalidae), a parasite of the eel Anguilla anguilla (Anguillidae) from a brackish water lagoon of the Adriatic Sea[END_REF] and [START_REF] Gargouri-Ben Abdallah | Cycle e´volutif de Bucephalus anguillae Spakulova, Macko, Berrilli & Dezfuli, 2002 (Digenea, Bucephalidae) parasite de Anguilla anguilla (L.)[END_REF]. As far as Rhipidocotyle Diesing, 1858 is concerned, only three species have been reported from the Mediterranean, namely R. galeata [START_REF] Rudolphi | Entozoorum synopsis, cui accidunt mantissa duplex et indices locupletissimi[END_REF], R. pentagonum [START_REF] Ozaki | Some gasterostomatous trematodes of Japan[END_REF] and R. genovi Dimitrov, Kostadinova & Gibson, 1996(see Gibson, 2001).

During the course of our studies in the Scandola Nature Reserve, off Corsica (western Mediterranean), two previously described species of Rhipidocotyle, hitherto unreported from European seas, have been recovered from pelagic piscivorous hosts: R. capitata [START_REF] Linton | Trematodes from fishes mainly from the Woods Hole region, Massachusetts[END_REF] from the scombrid Auxis rochei and R. longicirrus [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF] n. comb. from the carangid Seriola dumerili. As they are not often reported and are poorly known, these two species are redescribed and illustrated here.

Materials and methods

Fish were caught by fishermen colleagues near the external limit of the Scandola Nature Reserve, Corsica, and immediately autopsied. Digeneans were collected live, fixed under a slight cover-glass pressure in Bouin's fluid, stained in Borax carmine and mounted in Canada balsam. Only ovigerous specimens were taken into account in the description and measured. Measurements are given in micrometres as the range with the mean in parentheses. Worms were studied using differential interference contrast microscopy and illustrations were made using a drawing tube. The fish nomenclature used was based on [START_REF] Froese | FishBase. World Wide Web electronic publication[END_REF]. Voucher specimens have been deposited in the Natural History Museum, London (BMNH).

*Author for correspondence: (E-mail: rab@nhm.ac.uk) Family Bucephalidae Poche, 1907Genus Rhipidocotyle Diesing, 1858 Rhipidocotyle capitata [START_REF] Linton | Trematodes from fishes mainly from the Woods Hole region, Massachusetts[END_REF] [START_REF] Manter | The digenetic trematodes of marine fishes of Tortugas, Florida[END_REF] Syn. Gasterostomum capitatum [START_REF] Linton | Trematodes from fishes mainly from the Woods Hole region, Massachusetts[END_REF] Host: Auxis rochei (Risso), Scombridae, Perciformes. Locality: Off Scandola Nature Reserve, Corsica, France (41°25¢N, 8°38¢E). Site: Rectum. Infection: Number of fish examined 1. Intensity 2. Material studied: 2 adult specimens. Voucher specimens BMNH 2004.6.25.1-2.

Description (Figures 12345; Table 1) General morphology (Figures 1,3). Body flattened, fusiform; anterior half narrowing gradually; posterior half more or less plump; anterior end truncate; posterior extremity tapered. Maximum width at level of ovary, c.1/3-1/2 length. Tegument. Entire surface of body spinose, except for hood surface at anterior extremity of body. Spines strongly developed, acuminate. Rhynchus. Rhynchus sucker-like, with oval, ventro-terminal aperture; dorsal surface with heavily developed, muscular, horse-shoe-shaped hood; ventral aspect with 2 extremities bearing distinct lobes (Figures 23). Digestive system. Mouth on ventral surface, more or less equatorial. Feeble conical papilla protrudes through mouth. Oral gland-cells not distinct. Prepharynx short. Pharynx subspherical. Oesophagus shorter than pharynx, thick-walled, surrounded by distinct oesophageal gland-cells (Figure 1). Caecum saccular, directed posteriorly, with thick gastrodermis; posterior extremity reaches level of anterior testis; external surface transversally folded. Male reproductive system (Figures 1,3,4). Testes 2, spherical to sub-triangular, entire, in anterior part of posterior half of body, dextral, tandem, contiguous or nearly so; anterior testis contiguous with or adjacent to ovary. Cirrus-sac conspicuous, thin-walled, cylindrical, rectilinear to slightly curved, sinistral; proximal extremity at level of, but not contiguous with, posterior testis; distal portion forming genital lobe projecting into genital atrium. Seminal vesicle ovoid, twice as long as wide. Pars prostatica cylindrical, rectilinear to slightly sinuous, lined by thick layer of anuclear structures, surrounded by prostatic cells. Ejaculatory duct passing through genital lobe, opening into genital atrium, Genital lobe voluminous, multilobed; proximal end with dorsal and ventral muscular fibres (at junction between genital atrium and cirrussac) radiating into parenchyma of mid-line of body. Genital atrium very large, only slightly smaller than cirrus-sac, thinwalled, with surrounding gland-cells. Genital pore ventral, subterminal. Female reproductive system (Figures 1,3,5) Ovary ovoid or slightly elongated, entire, at mid-body length, dextral, close to body margin, at level of caecum. Oo¨capt straight, emerging from median posterior face of ovary. Oviduct tubular, directed posteriorly, prolonged as Laurer's canal. Laurer's canal almost rectilinear, uncoiled, thin-walled, devoid of external glandular cells, post-ovarian, opening dorsally at level of posterior testis. Oo¨type thick-walled. Mehlis' gland well developed. Uterine seminal receptacle present. Uterine loops fill most of body posterior to vitellarium; distal part differentiated as metraterm, which opens into anterior genital atrium through powerful sphincter. Eggs thin-shelled, operculate, very numerous. Vitelline follicles 32 in total, 14-15 on right side, 17-18 on left, irregular in outline, in 2 lateral groups, not confluent along mid-line of body, in second quarter of body, with posterior limit at level of pharynx; left and right vitelline fields of same length. Vitelline ducts in dorsal parenchyma of body; left longer than right. Vitelline reservoir not developed; common vitelline duct joins oviduct just proximal to oo¨type. Excretory system. Excretory vesicle tubular, runs parallel dextral to cirrus-sac; anterior extremity reaches level of posterior testis (Figure 3). Excretory pore terminal Type-host: Auxis rochei (Risso). Type-locality: Off Woods Hole, Massachusetts, USA. Records: 1. Linton (1940); 2. [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF]; 3. Present study. Descriptions:1 ,2 ,3 . Definitive hosts: Scombridae: Auxis rochei (1, 3), A. thazard (2). Distribution: Off Woods Hole (1); off Hawaii (2); Western Mediterranean (3).

Comments

The description and figures of Rhipidocotyle capitata given in the present study are in close agreement with those of [START_REF] Linton | Trematodes from fishes mainly from the Woods Hole region, Massachusetts[END_REF] for specimens from Auxis rochei off Woods Hole (Massachusetts) and of [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF] for specimens from A. thazard off Hawaii. The only difference observed concerns the larger size of the Mediterranean specimens (2,230-2,440 long vs 1,050-1,960 [START_REF] Linton | Trematodes from fishes mainly from the Woods Hole region, Massachusetts[END_REF] and 1,300-1,500 [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF]). R. capitata is the only species of this genus reported from A. rochei. By contrast, three Rhipidocotyle species have been reported from A, thazard: (1) R. capitata off Hawaii [START_REF] Yamaguti | Digenetic trematodes of Hawaiian fishes[END_REF]; (2) R. pentagonum [START_REF] Ozaki | Preliminary notes on Gasterostomata with three new genera[END_REF] from the Bay of Bengal [START_REF] Madhavi | Digenetic trematodes from marine fishes of Waltair coast, Bay of Bengal. Family Bucephalidae[END_REF] and the coast of Brazil off Rio de Janeiro [START_REF] Fernandes | Some Digenea parasites of tunny from the coast of Rio de Janeiro State, Brazil[END_REF]; and (3) R. nagatyi Manter, 1940 from off the north-eastern coast of Africa [START_REF] Szuks | Bucephaliden (Trematoda: Digenea) aus Fischen der Ku¨stengewa¨sser Nordwestafrikas[END_REF].

R. pentagonum has been reported not only from A. thazard, but also from various other fishes including Scomberomorus niphonius (Cuvier & Valenciennes) by [START_REF] Ozaki | Preliminary notes on Gasterostomata with three new genera[END_REF][START_REF] Ozaki | Some gasterostomatous trematodes of Japan[END_REF] off Japan, Thynnus sp. by [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF] off the Israeli Mediterranean coast, Thunnus thynnus (L.) by [START_REF] Yamaguti | Studies on the helminth fauna of Japan. Part 21. Trematodes of fishes[END_REF] from off Japan, Euthynnus affinis (Cantor) by [START_REF] Madhavi | Digenetic trematodes from marine fishes of Waltair coast, Bay of Bengal. Family Bucephalidae[END_REF] from the Bay of Bengal, E. lineatus Kishinouye by [START_REF] Castillo-Sanches | Helmintofauna de Euthynnus lineatus (Perciformes: Scombridae) en Jalisco, Mexico[END_REF] off the Pacific coast of Mexico and Katsuwonus pelamis (L.) by [START_REF] Fernandes | Some Digenea parasites of tunny from the coast of Rio de Janeiro State, Brazil[END_REF] off the Atlantic coast of Brazil. R. pentagonum has been described and figured by [START_REF] Ozaki | Preliminary notes on Gasterostomata with three new genera[END_REF][START_REF] Ozaki | Some gasterostomatous trematodes of Japan[END_REF], [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF] and [START_REF] Fernandes | Some Digenea parasites of tunny from the coast of Rio de Janeiro State, Brazil[END_REF]. Judging from these descriptions, R. pentagonum is similar to R. capitata as described in the present study, but seems to differ in the narrower body (width about 16% of length [START_REF] Ozaki | Some gasterostomatous trematodes of Japan[END_REF]; other descriptions of R. pentagonum give greater figures), the shape of the hood of its rhynchus which is definitely pentagonal and provided with more or less pointed lateral lobes, its relatively smaller cirrus-sac (14-16% of body-length) and genital atrium, and its larger eggs (20-22 • 13-15 lm).

R. nagatyi, reported and sketched by [START_REF] Szuks | Bucephaliden (Trematoda: Digenea) aus Fischen der Ku¨stengewa¨sser Nordwestafrikas[END_REF] from Auxis thazard off Mauritania, was originally described by [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF] from Euthynnus alletteratus (Raffinesque) off Florida. It differs of R. capitata by its distinctly pentagonal hood, deeply notched mid-ventrally and more or less pointed laterally, by its rather slender cirrus-sac containing a small ovoid seminal vesicle and its longer excretory vesicle extending to the pharynx. Based on the only sketch provided by [START_REF] Szuks | Bucephaliden (Trematoda: Digenea) aus Fischen der Ku¨stengewa¨sser Nordwestafrikas[END_REF], and lacking any written description, it is difficult to establish whether the Mauritanian specimens correspond to R. nagatyi or to R. capitata. [START_REF] Sey | Parasitic helminths occurring in Adriatic fishes. Part II (Flukes and tapeworms)[END_REF] listed Bucephalopsis gracilescens [START_REF] Rudolphi | Entozoorum synopsis, cui accidunt mantissa duplex et indices locupletissimi[END_REF] from Auxis thazard in the Adriatic Sea. We feel that this could not correspond to a confusion between B. gracilescens and R. capitata, due to the absence in the former species of the hood-like structure characteristic of members of Rhipidocotyle, which is so obvious in R. capitata. [START_REF] Sparks | Some digenetic trematodes of marine fishes of the Bahama Islands[END_REF] reported R. capitatum [sic] from the holocentrid Holocentrus adscensionis (Osbeck) from off The Bahamas. He believed that it might be synonymous with R. nagatyi, but stated that Manter (in personal correspondence) thought they should be recognised as separate until further study was made. [START_REF] Sparks | Some digenetic trematodes of fishes of Grand Isle, Louisiana[END_REF] then reported 'R. capitatum' from Euthynnus alleteratus (Rafinesque) off Louisiana, but made no further comment. [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephaloides Hopkins, 1954 and Rhipidocotyle Diesing[END_REF] studied type-specimens of both R. capitata and R. nagatyi and concluded that both were 'good species', R. capitata has uterine coils which reach further anteriorly, a longer cirrus [sic, ? cirrus-sac] and much smaller eggs. The anterior hood also 'appears quite different'. [START_REF] Williams | Parasites of offshore big game fishes of Puerto Rico and the western Atlantic[END_REF] considered R. nagatyi and, probably, R. angusticollis [sic] Chandler, 1941 synonyms of R. capitata. They considered that R. capitata is 'almost tribe specific to little tunas' [i.e. Auxis spp.]. R. nagatyi, in our view, differs from R.capitata in the characters mentioned above. R. angusticolle was originally reported from Sarda sarda (Bloch) off Texas in the Gulf of Mexico. [START_REF] Chandler | Two new trematodes from the bonito, Sarda sarda, in the Gulf of Mexico[END_REF] somewhat perfunctory description suggests that it differs from R. capitata in that it has dorsal 'hornlike projections' on the rhynchus, in addition to larger eggs. Fabio (1976) described a worm, under the name R. angusticolle from Scomber colias Gmelin from off Brazil, with four protuberances on the hood. The status of the group of Rhipidocotyle species from scombrids, i.e. R. pentagonum, R. capitata, R. nagatyi and R. angusticolle, is worthy of further exploration.

The worm described as R. angusticolle from the serranid Epinephelus fasciata (Forsska˚l) in the Red Sea by [START_REF] Shalaby | On the rhynchus and body surface of three digenetic trematodes; family: Bucephalidae Poche, 1907 from the Red Sea fishes based on scanning electron microscopy[END_REF] lacks the horn-like projections on the rhynchus and may not be correctly identified.

Rhipidocotyle longicirrus [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF] n. comb. Syns Bucephalopsis longicirrus Nagaty, 1937; Bucephaloides longicirrus [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF][START_REF] Hopkins | The American species of trematodes confused with Bucephalus (Bucephalopsis) haimeanus[END_REF]; Bucephalopsis arcuatus [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF] of [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF][START_REF] Manter | The digenetic trematodes of marine fishes of Tortugas, Florida[END_REF]; Bucephaloides arcuatus [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF] 10A); more posteriorly and around aperture of rhynchus, spines are erect and triangular resembling sharks' teeth (Figures 9B,10B) Rhynchus. Rhynchus sucker-like with truncate anterior extremity and rounded posterior end; lateral extremities of anterior lip slightly pointed (Figure 9A-B); aperture not well delimited anteriorly in some specimens but well delimited posteriorly in all cases; dorsal face of rhynchus not thickened, devoid of collar or tentacles; hood (if present) not obvious; dorsal wall provided with some longitudinal muscle fibres (Figure 9A). Gland-cells not detected associated with rhynchus.

Digestive system 11). Mouth ventral, in anterior part of posterior half of body. Oral lip absent. Prepharynx short. Oral gland-cells large, widespread in ventral parenchyma lateral to mouth; their ducts lead into small prepharyngeal papilla. Pharynx globular, posterior to vitellarium. Oesophagus longer than pharynx. Oesophageal gland-cells not detected. Intestinal caecum saclike, directed antero-dorsally from pharynx (100%), reaching level of vitelline follicles, then recurving posteriorly near its middle. Male reproductive system. Testes 2, postequatorial, contiguous (90%) or slightly (25 lm) separated (10%), entire, spherical to ovoid, tandem (60%) or slightly oblique (40%). Anterior testis dextral (50%) (Figure 6), sometimes median (30%), more rarely sinistral (20%) (Figure 8), often contiguous with ovary (80%), rarely separated (27-150 lm) (20%). Posterior testis often dextral (80%), more rarely median (20%). Vasa efferentia fuse at base of cirrus-sac. Cirrus-sac conspicuous, rectilinear, thick-walled (6-15 (10) lm), sinistral (100%), its anterior extremity extends as far as posterior testis (60%) (Figure 6) or to level of anterior testis (30%) (Figure 7) and in 1 case ovarian level (10%). Seminal vesicle ovoid, twice (or slightly more) as long as wide; longitudinal axis parallel to that of cirrus-sac, with distal extremity opening into well-developed, broad, rectilinear pars prostatica (Figure 12). Distal ejaculatory duct opens into genital atrium through fleshy, mittenshaped genital lobe which acts as intromittent organ (Figure 12A-B). Genital atrium thickwalled, surrounded by numerous small gland-cells. Genital pore ventro-subterminal. Female reproductive system. Ovary equatorial or just post-equatorial, dextral (100%), anterior to anterior testis, entire, rounded or sub-triangular. Oo¨capt posteriorly directed, leads to wide and thick-walled chamber, probably acting as a fertilisation chamber (Figure 13). Laurer's canal rectilinear, opening dorsally posteriorly to hind testis. Oo¨type thin-walled; Mehlis' gland poorly developed, difficult to detect. Uterine seminal receptacle well developed (Figure 8). Uterus winds between anterior vitelline follicles and level of genital pore; distal portion not differentiated as metraterm; opening into genital atrium not detected. Eggs numerous, relatively thick-shelled, operculate, embryonated; in 30% of specimens, abnormal eggs coexist with normal ones. Vitelline follicles number 29-33 (31) in 2 lateral clusters; right field with 14-16 (15) follicles; left with 13-18 (16); fields of similar length, with posterior limit just anterior to or at level of ovary, almost confluent anteriorly. Vitelline ducts in dorsal body field, directed posteriorly; left vitelline duct describes U-shaped loop, reaches anterior testis (100%) (Figure 8); right vitelline duct distinctly shorter than left, reaches directly to vitelline reservoir. Vitelline reservoir inconspicuous. Excretory system. Excretory vesicle I-shaped, thinwalled, extends to level of ovary (Figure 6). Excretory pore terminal.

Type-host:'Sphyraena agam'. According to [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF] this species is locally (i.e. Red Sea) called ''Agam''. According to Froese & Pauly (2004), in

Discussion

Specimens from Corsica belong to Rhipidocotyle

The specimens from the rectum of Seriola dumerili off Corsica have a rhynchus which is not a regular oval or circular sucker, such as that found in species of Prosorhynchoides Dollfus, 1929, but is a feeble anteriorly truncate sucker with slightly pointed lateral extremities and is devoid of a clearly defined dorsal hood. Clearly the rhynchus of this species does not possess the prominent dorsal hood characteristic of most species of Rhipidocotyle (see [START_REF] Overstreet | Superfamily Bucephaloidea Poche[END_REF], but, due to the peculiar shape of the rhynchus, the slightly curved pars prostatica in most specimens and the pre-testicular ovary, we consider that Rhipidocoyle is the appropriate genus for our specimens.

Historical review of Rhipidocotyle longicirrus

Bucephaloides longicirrus Nagaty, 1937 was described as a parasite of Sphyraena 'agam'; from the Red Sea by [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF]. Its subsequent history has been confused with that of the species now known as Prosorhynchoides arcuatus [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF]. [START_REF] Linton | Fish parasites collected at Woods Hole in 1898[END_REF] described Gasterostomum arcuatum from Sarda sarda off Woods Hole, Massachusetts. Later, this author reported the species again successively: in 1901, from the carcharinid shark Carcharhinus obscurus (Lesuieur) (probably an accidental host); in 1905, from Scomberomorus regalis (Bloch) and Caranx hippos (L.); and in 1940, from Scomber scombrus L., Trichiurus lepturus L. and Gadus morhua L. The species was placed in Bucephalopsis Diesing, 1855 by [START_REF] Eckmann | Beitra¨ge zur Kenntnis der Trematodenfamilie Bucephalidae[END_REF]. [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF] added Sphyraena barracuda (Walbaum) as a further host for B. arcuatus. From S. barracuda, [START_REF] Linton | Helminthfauna of the Dry Tortugas, II. Trematodes[END_REF] described and illustrated a 'Gasterostomum sp.' (Linton, 1910, figures 223-225). [START_REF] Manter | Studies on digenetic trematodes of fishes of Fiji, IV, Families Haploporidae, Angiodictyidae, Monorchiidae, and Bucephalidae[END_REF] pointed out that the species he found earlier (1940) from the barracuda (probably the same species as that of Linton, 1910, figure 223) has an excretory vesicle ending at the level of the pharynx, more separated vitelline fields and a longer cirrus-sac than B. arcuatus, and he identified it as Bucephaloides longicirrus Nagaty, 1937, basing his opinion on the truncate rhynchus, the location of the organs, the extent of the vitellarium and uterus and egg-size. B. longicirrus was transferred to Bucephaloides Hopkins, 1954[START_REF] Hopkins | The American species of trematodes confused with Bucephalus (Bucephalopsis) haimeanus[END_REF].

Specimens from off Corsica compared to

Rhipidocotyle longicirrus

It is our opinion that our specimens correspond most closely to B. longicirrus, as described by [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF] (see also figure 223 of [START_REF] Linton | Helminthfauna of the Dry Tortugas, II. Trematodes[END_REF], although it is known only from Sphyraena spp. Rather smaller dimensions are quoted by Nagaty (1937-body-length 662-1,286) and Manter (1940body-length 667-1,444). The criteria justifying such an identification are: the truncate rhynchus, the arrangement of the organs, the extent and location of the vitelline fields, the uterine loops and the excretory vesicle. According to [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF], and as the etymology of the specific name indicates, the cirrus-sac of B. longicirrus from Sphyraena sp. from the Red Sea is very long, reaching the ovarian level or further anteriorly. Nevertheless, the specimens from S. barracuda off Florida found by [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF], and later identified by him [START_REF] Manter | Studies on digenetic trematodes of fishes of Fiji, IV, Families Haploporidae, Angiodictyidae, Monorchiidae, and Bucephalidae[END_REF] as B. longicirrus, show a great variation in body shape (elongate to oval), in the arrangement of the testes (contiguous to separated), in cirrus-sac 1 As Bucephalopsis arcuatus 2 As Bucephaloides arcuatus length (anterior extremity reaching the vitellarium or only to the posterior testis) and in the location of the pharynx and the caecum (between or entirely posterior to the vitellarium) (see Manter, 1940, figures 15-16). [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephaloides Hopkins, 1954 and Rhipidocotyle Diesing[END_REF] studied, but unfortunately did not illustrate, B. longicirrus from S. barracuda from the Gulf of Mexico. His specimens, compared with Nagaty's description, 'were noted to have larger overall dimensions but with a relatively shorter cirrus [sic -? cirrus-sac].... the cirrus is not one-half or even more than the length of the whole trematode...'. His specimens from the Gulf of Mexico, compared with the material of [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF] from Florida, were noted to never have a 'cirrus that reached beyond the posterior testis'. Our specimens from Corsica are in close agreement with the observations of [START_REF] Corkum | Bucephalidae (Trematoda) in fishes of the northern Gulf of Mexico: Bucephaloides Hopkins, 1954 and Rhipidocotyle Diesing[END_REF] and our illustrations (Figures 678) exhibit the same variations as those pointed out by [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF]. We cannot ascertain whether B. longicirrus of [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF] from Florida corresponds strictly to B. longicirrus [START_REF] Nagaty | Trematodes of fishes from the Red Sea. Part 1. Studies on the family Bucephalidae Poche[END_REF] from the Red Sea, but our Mediterranean specimens show a greater similarity to those of Florida than to those of the Red Sea. Despite these uncertainties, we prefer to retain the specific name of longicirrus for the specimens collected in the rectum of Seriola dumerili off Corsica. Another source of doubt as to the identity of these worms is the host. Previous records of B. longicirrus are all from Sphyraena spp. and bucephalids have a tendency to show a higher degree of host-specificity than is implied by our findings.

Other Rhipidocotyle species from Seriola Three species of Rhipidocotyle have been reported from Seriola spp.: R. nagatyi [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF]R. tonimahnkei Reimer, 1985 from Seriolina (as Seriola) nigrofasciata (Ruppell) off the Mozambique coast by [START_REF] Reimer | Bucephalidae (Digenea) aus Fischen der Ku¨ste von Moc¸ambique[END_REF], and Rhipidocotyle sp. from Seriola dumerili off the Spanish Mediterranean coast by [START_REF] Montero | Parasite fauna in cultured greater amberjacks (Seriola dumerili) from Spanish Mediterranean[END_REF].

R. nagatyi, as described by [START_REF] Manter | Gasterostomes (Trematodes) of Tortugas, Florida[END_REF], differs from the specimens described in the present study, with its distinctly pentagonal hood which is deeply notched at the mid-ventral line. The specimens described as R. nagatyi by [START_REF] Reimer | Bucephalidae (Digenea) aus Fischen der Ku¨ste von Moc¸ambique[END_REF] are dissimilar from the specimens from Corsica, having the vitellarium contiguous with the rhynchus. R. tonimahnkei is distinguished from the specimens reported in the present study by the uterine loops, which extend well anterior to the vitellarium, the small number of vitelline follicles and much longer eggs. [START_REF] Montero | Parasite fauna in cultured greater amberjacks (Seriola dumerili) from Spanish Mediterranean[END_REF] gave no information on the morphology of their worms.

Other bucephalid species from Seriola dumerili from the Mediterranean An unidentified species of Bucephalopsis has been listed from Seriola dumerili from the Balearic Sea (western Mediterranean) by [START_REF] Grau | Some protozoan and metazoan parasites of the amberjack from the Balearic Sea (western Mediterranean)[END_REF].

Bucephalopsis is now regarded as a synonym of Prosorhynchoides (see [START_REF] Overstreet | Superfamily Bucephaloidea Poche[END_REF]. Because no morphological data and no figures were provided by [START_REF] Grau | Some protozoan and metazoan parasites of the amberjack from the Balearic Sea (western Mediterranean)[END_REF], and because the site in which they found their specimens in the fish host is too imprecise (''digestive tract''), it is not possible to ascertain whether the specimens from the Balearic Sea correspond to R. longicirrus from off Corsica.

Figures 1- 5 .

 5 Figures 1-5. Rhipidocotyle capitata (Linton, 1940) Manter, 1947. Slightly flattened adult specimens from the rectum of Auxis rochei, off Scandola Nature Reserve, Corsica, August 2002 (same data for all figures). 1, Dorsal view; 2, Anterior extremity of the specimen in Figure 1 (ventral view) (Figures 1-2 to the same scale) (the specimen illustrated in the Figures 2 and 5 was initially mounted ventrally; later it was unmounted, inverted and remounted, and redrawn as Figure 1); 3, Ventral view (in Figures 1 and 3, only a small proportion of eggs in anterior uterine loops are shown); 4, Cirrus-sac of the specimen in Figure 3 (ventral view); 5, Proximal female genitalia of the specimen in Figure 1 (ventral view). Abbreviation: LC, aperture of Laurer's canal.

Figures 6 -

 6 Figures 6-8. Rhipidocotyle longicirrus (Nagaty, 1937) n. comb. Slightly flattened adult specimens from the rectum of Seriola dumerili, off Scandola Nature Reserve, Corsica, September 2002 (same data for all figures). 6-7, Ventral views; 8, Dorsal view. (In Figures 6 and 8, only a small proportion of eggs are shown).

Figures 9 -

 9 Figures 9-13. Rhipidocotyle longicirrus (Nagaty, 1937) n. comb. Slightly flattened adult specimens from the rectum of Seriola dumerili, off Scandola Nature Reserve, Corsica, September 2002 (same data for all figures). 9, Rhynchus; A. dorsal view; B. ventral view; 10, Tegumental spines: A. Spines near the antero-ventral extremity of the body lying flat on the body-surface; B. Erect spines around the aperture of the rhynchus; 11, Digestive system (ventral view); 12, Distal male reproductive system (ventral views): A. Cirrus-sac; B. Genital lobe and genital atrium; 13, Proximal female reproductive system (dorsal view).

Table 1 .

 1 Comparative measurements of specimens of the two Rhipidocotyle species from off Corsica.

	Species	R.capitata	R. longicirrus
	Host family	Scombridae	Carangidae
	Host species	Auxis rochei	Seriola dumerili
	Site	rectum	rectum
	Sample	n=2	n=10
	Body length	2,230-2,440	1,288-1,962 (1,646)
	Body width	790-760	184-343 (240)
	From anterior extremity of body to:
	Anterior uterine loops	995-1,074	580-1,060 (781)
	Anterior limit of vitellarium	743-578	527-895 (668)
	Pharynx	980-1,106	718-1,314 (1,011)
	Ovary	1,027-1,248	686-1,143 (888)
	Anterior testis	1,140-1,343	730-1,226 (982)
	Number of right vitelline follicles	14-15	14-16 (15)
	Number of left vitelline follicles	18-17	13-18 (16)
	Length of right vitelline row	316-458	173-256 (219)
	Length of left vitelline row	371-427	170-300 (225)
	Diameter of vitelline follicles	58-63	32-42 (37)
	From pharynx to posterior extremity of body	1,162-1,209	422-775 (635)
	Post-testicular space	750-656	254-572 (421)
	Rhynchus	198-259 • 275-280	84-112 • 95-111 (99 • 101)
	Pharynx	106-106 • 124-131	46-60 • 51-70 (54 • 62)
	Oesophagus	160-140	55-103 (81)
	Digestive caecum	166-240 • 112-159	88-144 • 63-140 (125 • 86)
	Anterior testis	163-218 • 230-240	106-186 • 96-166 (136 • 133)
	Posterior testis	182-240 • 192-227	122-192 • 95-160 (145 • 128)
	Ovary	182-227 • 128-115	112-163 • 80-160 (129 • 107)
	Cirrus-sac	448-528 • 169-205	410-582 • 70-125 (456 • 94)
	Thickness of cirrus-sac wall	10 and 10	6-15 (10)
	Seminal vesicle	218-240 • 106-115	92-163 • 35-80 (123 • 53)
	Pars prostatica	340-378 • 100-96	176-298 • 54-110 (262 • 75)
	Genital atrium	320-290 • 217-262	86-198 • 74-126 (164 • 100)
	Eggs (uncollapsed) (n=50)	17-19 • 11-13 (18 • 12)	19-24 • 12-14 (21 • 13)
	Body width *	35.4-31.4	17.4-23.7 (20.0)
	Region anterior to pharynx %*	43.9-45.3	55.7-68.6 (61.3)
	Pre-vitelline field*	33.3-30.4	35.6-47.3 (40.7)
	Cirrus-sac length*	20.1-21.6	21.3-37.3 (28.3)
	Cirrus-sac length**	38.6-43.7	53.1-106.2 (73.7)
	Post-testicular region*	33.6-26.9	19.4-29.7 (25.4)
	Rhynchus/pharynx length ratio	1:0.53-0.41	1:0.50-0.63
	*a s% of body length.

** as % of body length posterior to pharynx.

Acknowledgements

Fieldwork on Corsica of PB was carried out under the auspices of the Comite´Scientifique de la Re´serve Naturelle de Scandola. David Gibson kindly read the manuscript.


Carmen Jiménez

Tristan Caroff

A Bartasyte

S Margueron

Adulfas Abrutis

Odette Chaix-Pluchery

François Weiss

O Chaix- Pluchery

Raman study of the CeO2 texture as

Introduction

The CeO 2 /La 2 Zr 2 O 7 /Ni piled-up structure is a very promising architecture for YBa 2 Cu 3 O 7 (YBCO) coated conductors. Coated conductors developed by all-chemical routes are based on the excellent quality of lanthanum zirconate, La 2 Zr 2 O 7 (LZO), as buffer layer. Metal organic decomposition (MOD) allows the growth of LZO on Nibased substrates in reducing atmosphere, which avoids the undesirable oxidation of the substrate. Pyrochlore LZO (Space Group Fd-3m) lattice parameters match these of YBCO (|(ε YBCO -ε LZO )/ε LZO | = 1.05%), and it provides a good barrier against O 2 diffusion 1,2 . This material filling all the characteristics for buffer layers (structural and chemical compatibility between substrate and active layer) has been already probed as a simple low cost architecture YBCO MOCVD /LZO MOD /NiW RABiTS 3 . Nevertheless, we tried to improve the YBCO performance by adding a CeO 2 layer grown by MOCVD. The architecture YBCO (800 nm MOCVD) / CeO 2 (120 nm MOCVD) / LZO (80 nm MOD)

/NiW exhibited a higher Jc value (1.2 MA/cm 2 ) than the one-layer buffered structure YBCO/LZO/Ni (Jc= 0.8 MA/cm 2 ).

The improvement of the YBCO properties by the addition of a CeO 2 layer has been also found by other authors 4 concerning the CeO 2 and YBCO deposited by physical methods on LZO buffered tapes and also by Paranthaman et al 5 with the more complex architecture YBCO (0.8 µm MOD-TFA)/ CeO 2 (60 nm MOD) / LZO (200 nm MOD) / Y 2 O 3 (10 nm PVD) / Ni , but with very good transport properties (Jc = 2.5 MA/cm 2 and Ic/w= 200 A/cm).

The main factor determining texture as well as physical properties of YBCO layer is the epitaxial and crystalline quality of the CeO 2 layer. However, the quality of CeO 2 films in the CeO 2 /LZO/Ni architecture cannot be evaluated by conventional X-ray Diffraction method due to very similar lattice parameters of CeO 2 and LZO films. CeO 2 presents a fluorite structure with a lattice parameter of 5.41134 Å, while LZO crystallizes either in pyrochlore structure with a lattice parameter of 10.808 Å or in a disorder fluorite structure with a half value of the lattice parameter (5.407 Å).

In this paper we propose a simple and non-destructive Raman study of the texture quality of CeO 2 films based on the variation with polarization of the intensity of the CeO 2 F 2g mode in polarized spectra. The ability of Raman spectroscopy to analyse the in-plane texture of YBCO thin films has been reported since a long time [6][7][8][9] . We show that the texture quality of the CeO 2 layer can be determined by the intensity variation of the first order F 2g mode with polarization

Experimental

Ni-5%at.W RABiTS tapes presenting a cubic texture were provided by Evico GmbH (Dresden) and described previously 10 . The full width at half maximum (FWHM) values of the φ-scan (111) reflection (in plane texture) is 6° ± 0.5°, and the FWHM values of the rocking curve (ω, out-of -plane) of the (002) reflection in the longitudinal (RD) and transverse (TD) direction with respect to the rolling direction are 5.5° ± 0.3° and 9°± 0.3° respectively. RABiTs tapes also present a small roughness (mean square roughness, rms < 5 nm). The grain size of the substrate is around 50 µm and its thickness is 150 µm. (00l) oriented LaAlO 3 (LAO) pseudocubic single crystals provided by Crystec were also used as substrates.

Lanthanum zirconate (LZO) was grown on nickel or LAO substrates by MOD according to a procedure previously described 11 . Lanthanum (III) Raman spectra were collected using a Jobin Yvon/Horiba LabRam spectrometer equipped with a liquid nitrogen cooled charge coupled device detector. Experiments were conducted in the micro-Raman mode in a backscattering geometry with a notch filter technology. Spectra were measured at room temperature in air-conditioned room and calibrated using the 520.7 cm -1 silicon Raman peak.

Visible Raman scattering experiments were performed using the TE 00 514.5 nm line of an Ar + ion laser and a x50 long working distance (LWD) Olympus objective (numerical aperture = 0.5). The laser power was kept at ~ 5 mW at the sample surface on a spot size close to 2 µm. The output light was dispersed on a 1800tr/mm spectrometer with notch filter cutting at ~100 cm -1 . In the following, backscattering VV and VH polarized Raman spectra will refer to the polarization of the analyzer parallel (V) and crossed (H) with respect to the incident polarization (V). The direction of the incident and scattered laser beams was normal to the substrate plane.

UV Raman scattering experiments were done at 266 nm wavelength produced from the fourth harmonic of a Nd:YAG laser. Acquisitions were obtained through a x40

UV OFR objective and with an UV extended spectrometer with 2400 tr/mm grating.

The notch filter cuts at ~350 cm -1 and no analyzer was used.

Results

LZO layers (~ 80 nm thick) were obtained by MOD on LAO single crystal and on

Ni substrates. As already reported 3 , XRD analyses confirm the biaxial texture of the sample. For LZO layers deposited on LAO, the in-plane texture quantified from ϕ-scans performed on the (222) reflection was FWHM= 1° and the out-of-plane texture quantified from rocking curves measured on the (002) reflection was FWHM= 0.7°. On

Ni-based substrates, LZO out-of-plane orientation was given by FWHM RD =5.3° ± 0.2° in the rolling direction, FWHM TD =8° ± 0.3° in the transverse direction and the in-plane texture was such that FWHM=7° ± 0.3. These results confirm that LZO grains have a caxis orientation and that the LZO film nucleates with a biaxial texture over the substrate with its unit cell axis rotated by 45° with respect to the substrate in both cases (Figure 1).

CeO 2 grows epitaxially on LZO, with a cube-on-cube configuration. By XRD, the crystalline quality of the CeO 2 layer can be only quantified by the comparison of the intensity (counts/sec) of the (400) X-ray reflection for the same sample before and after CeO 2 deposition. If the CeO 2 layer is not completely textured or polycrystalline, an additional (222) reflection will be detected at theoretical position of 2θ=28.6° when using λ Cu . In the case of partial crystallisation or amorphous state of the CeO 2 layer, no increase of the intensity of the (400) reflection will be measured after deposition.

In any case, the systematic measurements of the intensity before and after CeO 2 deposition are not compatible with sequential experiments and increase the delay in production of samples. As a consequence, an alternative method is needed to evaluate the texture quality of the CeO 2 layer. We will expose now the main principles involved in the Raman characterization of these buffer layers.

Raman selection rules for LZO and CeO 2 and texture evaluation

Raman spectra of LZO crystallized in the pyrochlore structure (space group Fd-3m

or O h 7 ) have been reported by Vandenborre 12 as well as their mode assignment.

CeO 2 presents a fluorite structure lattice (space group Fm-3m or O h 5 ). Its first-order Raman spectrum is very simple and consists of a triply degenerated F 2g mode at 465 cm - 1 , assigned to the symmetrical Ce-O stretching mode. The second order Raman spectrum is more complex and has been reported by Weber 13 .

The observation of Raman modes strongly depends on polarization selection rules.

Considering the polarization directions of the incident and scattered beams, e i and e s , respectively, the intensity of the Raman peak F 2g is given by [9]:

2 2g , , 2 ) , F ( s i Z Y X g F e R e I ⋅ ⋅ ∝ = γ γ (1.1)
where R(F 2g ,γ) is the Raman polarizability tensor defined in the cubic crystallographic coordinate system (X=[100], Y=[010], Z=[001]) as:

⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ = d d x F g ) ( 2 ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ = d d y F g ) ( 2 ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ = d d z F g ) ( 2 (1.2)
From the above relations, the intensity of the F 2g mode in both LZO and CeO 2 crystals will be zero in the VV polarization configuration with VV = XX (or YY or ZZ) whereas it will give a Raman signal in the VH polarization configuration with VH= XY (or YZ or XZ). However, this technique has the disadvantage to depend on the efficiency of the spectrometer in VH and VV configurations.

Another way of varying the Raman intensity consists in rotating the crystal in the (X,Y) plane for a given polarization configuration. Considering the crystal oriented in the (X,Y,Z) system with the incident beam along Z and (X,Y) the plane of incidence, θ is defined as the angle between the incident polarization V and the X crystallographic axis of CeO 2 . The intensity variation of the F 2g (z) Raman mode present resulting from Eq. 1.1 and Eq.1.2 is given by:

2 2 ) 2 sin( ) ( θ θ d I VV g F ∝ (1.3) 2 2 ) 2 cos( ) ( θ θ d I VH g F ∝ (1.4)
Taking into account these equations, in a fully biaxially oriented film, a rotation of the sample around an axis normal to the substrate plane will modulate the intensity from 0 to I max whereas a sample exhibiting a fibre texture or a polycrystalline sample will

show no modulation at all.

Raman spectra of LZO and CeO 2

The Raman spectra of 160 nm thick MOD LZO films on Ni and on LAO did not show any detectable peak whatever the incident laser light, whereas a strong peak associated to CeO 2 peak is detectable even for very thin films (30 nm thick). We deduce that LZO presents a weak Raman scattering efficiency that is hardly detectable in our thin films. As a consequence, Raman spectroscopy cannot be used to evaluate LZO texture quality and the Raman spectrum of the CeO 2 /LZO structure did not differ from the CeO 2 film spectrum.

We also studied the CeO 2 /LZO/Ni heterostructure by UV Raman scattering. The excitation at 266 nm (above the optical gap of CeO 2 at 3.2 eV) results in a strong absorption of light at the CeO 2 surface. The visible and UV Raman spectra confirms that the Raman intensity result mainly from the CeO 2 layer. Nevertheless, these spectra show some differences: the CeO 2 film Raman spectrum obtained with Ar + laser light involved a single Raman line at 465 cm -1 related to the CeO 2 F 2g mode (Figure 2). When using UV excitation, higher frequency bands near 600 and 1180 cm -1 were also collected in addition to the F 2g mode. They were assigned to second-order features of CeO 2 exalted by the UV laser light (Figure 2). In the following, we will focus on the F 2g mode measured with Ar + laser excitation.

The CeO 2 /LZO structure (Figure 3) grows biaxially textured on a nickel cubic substrate and on (001) LAO, but rotated by 45°. We will define a new reference system The equivalence between both experimental configurations can be observed for a CeO 2 -MOCVD (30nm)/LZO-MOD (80 nm)/ Ni structure as shown in Figure 4. First, spectra were collected at αs = 45°, i.e. in the CeO 2 crystal reference system, to obtain the standard variation of the F 2g mode with polarization (Figure 4a). The intensity of VH spectrum was corrected form the spectrometer efficiency by increasing the acquisition time (x3) in comparison with VV spectrum. The highest CeO 2 F 2g mode intensity was obtained in VH spectra for α s = 45° (equivalent to VV α s = 0°) and decreases in VV spectra for α s = 45°. Then (Figure 4b), spectra were measured in VV polarisation configuration for two rotation angles: at α s = 0° and at α s = 45°. The highest CeO 2 F 2g mode intensity was obtained in VV spectra for α s = 0°. Both series of measurements give evidence that spectra obtained in VV polarisation at 0° and at 45° contain the same texture information than spectra issued from a change in polarisation configuration, but it is a faster and more direct method.

Some additional Raman modes are also observed in this spectrum. As suggested by the reference spectrum of nickel oxide obtained by thermal oxidation of a nickel substrate in air at 800°C for 5min, they have been identified as NiO modes due to the nickel oxidation through the LZO layer during the MOCVD process.

Angular dependence of CeO 2 F 2g Raman intensity

The dependence of the intensity of the CeO 2 F 2g mode in a CeO 2 /LZO/LAO sample has been studied by varying α s in VV polarization configuration. For this experiment, we have used a CeO 2 layer deposited on LZO-buffered LAO instead of Ni substrate to avoid the NiO signal in the spectrum. Both spectra shown in Figure 5 for α s =0° and α s =45° correspond to the highest intensity variation. The peak observed at 462 cm -1 is related to the CeO 2 F 2g mode whereas the 500 cm -1 one corresponds to the E g mode of LAO [14]. Both modes are Raman active in VH configuration, but they appear out of phase due to the 45° rotation between the LAO and CeO 2 lattices.

The modulation of the CeO 2 F 2g mode intensity with the rotation angle, α s, has been determined by measuring four points at each angle to estimate the dispersion. Peaks were fitted and the integrated intensities thus obtained are reported in Figure 6.The intensity variation with α s follows a cosinus law (or a sinus with θ) as predicted by Eq.

(1.3)

Raman Intensity Ratio and YBCO performances

To determine the correlation of the CeO 2 layer texture with the intensity ratio of the F 2g Raman mode at 0° and 45°, we have defined a Raman Intensity Ratio (RIR) given by the integrated intensity ratio of CeO 2 F 2g Raman mode at 0° and 45° in VV polarization (RIR= I VV (0°) / I VV (45°)). We have studied the correlation of YBCO performance (J c values) for several YBCO/CeO 2 /LZO samples on Ni and on LAO with RIR. The quality of the YBCO layer was not identical in all the samples, so the J c values are strongly dependent on the experiment. Results are summarized in Table I as well as FWHM values obtained from XRD characterizations. A correlation diagram between the RIR and J c values is presented in Figure 7 for each sample. It is to be noticed that the number included in the sample label denotes the YBCO deposition experiment; so V19Ni and V19LAO are related to the same YBCO deposition but on two different substrates: the poor J c value obtained with the LAO sample, correlated to an absence of texture in YBCO film, can be only explained by a poorly textured CeO 2 layer. This is characterized by a RIR value smaller than 1. On the other hand, the highest J c values were obtained for samples with RIR values higher than 2.5.

Discussion

Raman studies performed on CeO 2 layers have indicated that information about the film texture can be easily obtained from the F 2g Raman mode. This mode does not overlap with other Raman modes coming from the different materials used in the coated conductor architecture and its intensity is very high, even for very thin films (30 nm thick CeO 2 , Figure 4). It has also been shown that the biaxial texture of this layer gives an intensity modulation of the F 2g Raman mode when rotating the sample around an axis normal to the substrate plane; this modulation is not thickness dependent.

Raman spectra obtained in VV polarization configuration at 0° and at 45° rotation angles allow to detect a modulation in the CeO 2 F 2g mode intensity due to the film texture. The calculation of the intensity ratio from both spectra allowed to define a quality factor RIR. RIR values higher than 1 attests the biaxial texture of the CeO 2 layer.

Otherwise, the buffer layer is poorly or not textured and will not transmit the texture template to the YBCO layer. The CeO 2 crystalline quality depends on the crystalline quality of the LZO surface. Indeed, despite a well-textured structure revealed by the (00l) reflections in their XRD pattern, some LZO layers did not offer a sufficiently high crystalline quality of their surface to obtain a well crystalline contrast in EBSD or by RHEED analyses. Unfortunately, last techniques cannot be routinely used in coated conductor fabrication to qualify the substrates. When using LZO layers as template in next steps, i.e. CeO 2 deposition and YBCO deposition, XRD diagrams are no more accurate enough to evaluate the crystalline quality of the CeO 2 layer while the RIR estimation can give this information before YBCO deposition. Thus, this quality factor can be very useful to qualify substrates for YBCO deposition during the fabrication process.

The collection of the Raman data was performed with using a large working distance x50 objective, which allows the analysis into a small spot (~2 µm) at a relatively long distance from the sample (~2 cm). On the other hand, this analysis is non destructive, rapid and extremely local. It can be performed without sample preparation, at atmospheric pressure, directly or through a quartz window on any substrate shape. All these features indicate that Raman characterization of CeO 2 layer can be used to control the sample quality in an on-line process or to perform selective tests on sample uniformity.

Conclusions

Raman spectroscopy has been used to characterize CeO 2 /LZO structures with different CeO 2 thicknesses. We have shown that the F 2g Raman mode of CeO 2 can be quantified from spectra collected either in two polarization configurations (VV and VH)

or at two rotation angles around an axis perpendicular to the substrate plane (0° and 45°) in VV polarization configuration to obtain information about the sample texture. This kind of information cannot be obtained from XRD measurements due to the overlap of the LZO and CeO 2 lattices. We have defined a quality factor (RIR) consisting in the calculation of the intensity ratio of the CeO 2 F 2g mode at 0° and 45° in VV polarization.

The RIR value quantifies the intensity modulation between both configurations. We have correlated this factor to superconducting performances (Jc). RIR should be higher than 1 to ensure a crystalline quality of the CeO 2 layer sufficiently high to template the YBCO layer. This determination is fast, non destructive and compatible with an on-line characterization during the fabrication of coated conductors.

V 1 3 L A O V 1 3 N i V 1 5 L A O V 1 5 N i V 1 7 L A O V 1 7 N i V 1 9 L A O V 1 9 N i V 2 1 N i V 2

(

  X,Y,Z) made of the geometrical axis of the sample with Z=z normal to the surface and (X,Y) in coincidence with the [100] and [010] directions of the LAO or Ni substrate. On the other hand, the reference system (X', Y') for the definition of the Raman tensor taking into account the CeO 2 crystal axis used in Eq. (1.2) is rotated by 45° on the (X, Y) reference system. We will define the rotation angle α s around the normal Z in the (X,Y,Z) system to be 0° (Figure2a) in the [100] direction of the LAO substrate or the Ni tape. The rotation angle α s and the θ angle defined in Eq. (1.3) and Eq. (1.4) are related as follows: α s =θ+45°. This means the F 2g mode is Raman active in the parallel configuration (VV) at 0° rotation angle.

Figure 2 : 2 Figure 3 :Figure 4 :

 2234 Figure 2: Raman spectra of a CeO 2 layer on LZO/Ni obtained with a UV laser (continuous line) or an Ar + laser (dashed line). Labelled modes are related to CeO 2

Figure 5 :

 5 Figure 5: Raman spectra of a CeO 2 layer on LZO/LAO. The peak near 500 cm -1 is

Figure 6 :

 6 Figure 6: Intensity modulation of the F 2g Raman mode of CeO 2 (465 cm -1 ) in a CeO 2 /LZO/LAO

Figure 7 :

 7 Figure 7: Correlation diagram between RIR (=I(0°) / I(45°)) and J c values measured in

Table 1

 1 Ni and LZO pole figures obtained by XRD on a LZO/Ni sample

			YBCO texture: in plane and out of	J c	CeO 2 thickness
	Sample	RIR
			plane FWHM (°)		(MA.cm -2 )	(nm)
			(103) ϕ	(005)ω RD (005)ω TD
	V13LAO	33	1.5°	0.67°		2.5	30
	V13Ni	3.3	8.7°	5°	7.1°	0.1	30
	V15LAO	9.6	1.6°	0.55°		0.5	150
	V15Ni	1.33	-	-	-	0.07	150
	V17LAO	1.6	-	-	-	0	200
	V17Ni	2.6	8.2°	5.2°	6.7°	0.5	200
	V19LAO	0.88	Non-textured	1°		0	60
	V19Ni	3.8	7.9°	5.5°	7.5°	0.25	60
	V21Ni	5.85	7.7°	5.2°	7.4°	1.2	120
	V23Ni	2.6	7.9°	5.3°	7.8°	0.2	60

Acknowledgement

This work has been financially supported by the French Research National Agency (ANR) through the MADISUP Project and by Région Rhône-Alpes SESUC project. We acknowledge Dr Ph. Odier (Institut Louis Néel -CRETA) for fruitful discussions and Dr. M. Decroux (Geneve University) for the collaboration in the Jc measurements.