ASCARIDOID NEMATODES OF TELEOSTEAN FISHES
FROM THE EASTERN NORTH ATLANTIC AND SEAS OF THE NORTH OF EUROPE
PETTER A.J.* & CABARET J.**
Technical collaboration : TCHEPRAKOFF R.*
S u m m a r y :
Ascarid parasites of Teleostean fishes from the North Eastern Atlantic and seas of the North of Europe deposited in the collec- tions of the "Museum National d'Histoire Naturelle de Paris" are studied. The ratios oesophagus length/width of cervical alae and ventricular appendage length/width of cervical alae allow
Hysterothylacium aduncum to be divided into two subspecies : H.
aduncum aduncum was found in Alosa fallax, A. alosa, Belone belone, Psetto maxima, Lophius piscatorius, Trachurus trachurus, Merluccius merluccius and Trisopterus luscus whereas H. aduncum gadi was found in Pollachius pollachius, P. virens, Cadus morhua, Merlangus merlangus, Scomber scombrus and Salmo salar.
Hysterothylacium cornutum, H. rigidum and Maricostula incurva are recorded respectively from Thunnus germo alalonga, Lophius piscatorius and Xiphias gladius. The following species are descri- bed : Hysterothylacium reliquens from Pagellus acarne and Microchirus azevia, Hysterothylacium sp. from Callionymus lyra and Goezia sp. from Trisopterus luscus. A key is presented for the species of Raphidascaridinae parasites of Teleostean fishes from North Eastern Atlantic and seas of the North of Europe.
KEY W O R D S : nematoda. A s c a r i d o i d e a . teleostean f i s h . N o r t h Eastern Atlantic, seas of the North of Europe, systematics.
Résumé : ASCARIDES PARASITES DE POISSONS TÉLÉOSTÉENS DE L'ATLAN- TIQUE NORD-ORIENTAL ET DES MERS DU NORD DE L'EUROPE
Les espèces d'Ascarides parasites de Poissons Téléostéens de l'Atlantique Nord-oriental et des mers du Nord de l'Europe présentes dans les collections du Museum National d'Histoire Naturelle de Paris sont étudiées. Les mesures relatives, longueur de l'oeso- phage/largeur des ailes cervicales et longueur de l'appendice oesophagien/largeur des ailes cervicales, permettent de distinguer deux sous-espèces chez Hysterothylacium aduncum : H. aduncum aduncum est présente chez Alosa fallax, A. alosa, Belone belone, Psetta maxima, Lophius piscatorius, Trachurus trachurus, Merluccius merluccius et Trisopterus luscus ; H. aduncum gadi est présente chez Pollachius pollachius, P. virens, Gadus morhua, Merlangius merlan- gus, Scomber scombrus ef Salmo salar. Hysterothylacium cornutum, H. rigidum et Maricostula incurva sont signalés respectivement chez Thunnus (Germo) alalunga, Lophius piscatorius ef Xiphias gladius ; Hysterothylacium reliquens est redécrit chez Pagellus acarne et Microchirus azevia ; Hysterothylacium sp. et Goezia sp. sont décrits respectivement chez Callionymus lyra et Trisopterus luscus. Une clef dichotomique des espèces de Raphidascaridinae parasites de Poissons Téléostéens de l'Atlantique Nord-oriental et des mers du Nord de l'Europe est donnée.
MOTS CLES : nematodes. Ascaridoidea. poissons téléostéens. Atlantique nord- oriental, mers du nord de l'Europe, systématique.
INTRODUCTION
The ascarid fauna o f T e l e o s t e a n fishes o f North E a s t e r n A t l a n t i c a n d S e a s o f t h e N o r t h o f E u r o p e h a s b e e n s t u d i e d b y m a n y a u t h o r s a n d is relatively well k n o w n . E x c l u d i n g the s p e c i e s insufficiently d e s c r i b e d , s e v e n s p e c i e s are k n o w n : Hysterothylacium aduncum, H. gadi, H. auctum, H.
rigidum, H. cornutum, Maricostula incurva a n d Goezia sigalasi. H o w e v e r , t h e v a l i d i t i e s o f Hysterothylacium gadi a n d H. auctum are u n d e r dis- c u s s i o n , t h e s e s p e c i e s b e i n g c o n s i d e r e d as j u n i o r s y n o n y m s o f H. aduncum b y m a n y authors.
* Laboratoire de Biologie Parasitaire, Protistologie, Helminthologie (CNRS UA 114), Museum National d'Histoire Naturelle, 6 1 , rue Buffon, 75231 Paris Cedex 05, France.
** INRA, Centre de Recherches de Tours, Station de Pathologie aviaire et de Parasitologie, 37380 Nouzilly, France.
Correspondence : A.J. Petter, Tel : 33(1) 40 79 35 08 ; Fax : 33 ( 1 ) 40 79 34 99.
This p a p e r gives the results o f the study o f Ascarids from t h e s e s e a s d e p o s i t e d in t h e c o l l e c t i o n s o f t h e M u s e u m N a t i o n a l d ' H i s t o i r e N a t u r e l l e d e P a r i s (MNHN). A m o r p h o l o g i c a l a n d b i o m e t r i c a l study w a s p e r f o r m e d f o r s p e c i m e n s from v a r i o u s h o s t s a n d localities referred to Hysterothylacium aduncum a n d H. gadi, in o r d e r to d i s c o v e r if the t w o s p e c i e s c o u l d b e d i s t i n g u i s h e d . S i x o t h e r s p e c i e s w e r e p r e s e n t , including H. reliquens, w h i c h is r e c o r d e d for the first time in the North Eastern Atlantic.
MATERIALS AND METHODS
S
p e c i m e n s h a d b e e n initially fixed in formalde- h y d e o r in 7 0 % a l c o h o l , a n d w e r e p r e s e r v e d in 7 0 % a l c o h o l . T h e m o r p h o l o g i c a l s t u d y a n d m e a s u r e m e n t s w e r e m a d e after clearing in l a c t o p h e - nol. Variations in m e a s u r e m e n t s are c a u s e d b y fixa- t i o n a n d c l e a r i n g m e t h o d s ( s e e F a g e r h o l m , 1 9 7 9 ; F a g e r h o l m a n d Lövdahl, 1 9 8 4 ) : for t h e b i o m e t r i c a lParasite, 1995, 2, 217-230
Mémoire
217Article available athttp://www.parasite-journal.orgorhttp://dx.doi.org/10.1051/parasite/199502s2217
PETTER A.J. & CABARET J.
analysis, w e used the m e a s u r e d lengths without cor
rection. All m e a s u r e m e n t s are in µm e x c e p t the b o d y length and distance anterior extremity-vulva, w h i c h are given in mm.
RESULTS
HYSTEROTHYIACIUM ADUNCUM (Rud., 1 8 0 2 ) S o m e confusion exists concerning the systematics o f the s p e c i e s Hysterothylacium aduncum ( R u d o l p h i , 1802) and H. gadi (O.F. Müller, 1 7 7 6 ) [= H. clavatum ( R u d o l p h i , 1 8 0 9 ) ] . Rudolphi originally d e s c r i b e d in 1802 the species Ascaris adunca from Alosa alosa (L., 1756) (= Clupea alosa); Ascaris gadi was created by Müller in 1776, and synonymised b y Rudolphi ( 1 8 0 9 ) w i t h his n e w s p e c i e s Ascaris clavata p a r a s i t e o f Trisopterus luscus (L., 1 7 5 8 ) (= Gadus barbatus); the description o f Müller being older, the name gadi must prevail. T h e descriptions o f Müller and Rudolphi are very brief, but Rudolphi ( 1 8 0 9 ) placed A. clavata in a group o f s p e c i e s with an alate head ("capite alato") and A. adunca in a group with a bare head ("capite nudo"). Later, m a n y authors s e e m to have assigned their s p e c i m e n s to o n e species or the other, by relying only on their hosts. Punt ( 1 9 4 1 ) synonymised H. gadi with H. aduncum, and this was followed b y Berland
( 1 9 6 1 ) , Petter ( 1 9 6 9 ) and F a g e r h o l m ( 1 9 8 2 ) . O n the other hand, Dollfus ( 1 9 5 3 ) , in accordance with a per
s o n a l c o m m u n i c a t i o n from Baylis, q u e s t i o n e d this synonymy and proposed an attempt o f differentiation based on the shape o f labial flanges and the width o f cervical alae, and Hartwich ( 1 9 7 5 ) considered the two species valid and gave descriptions and a key o f diffe
rentiation b a s e d on the study o f specimens from the
"Berliner Zoologischen Museum".
According to Hartwich ( 1 9 7 5 ) , H. gadi differs from H.
aduncum : — b y having cervical alae b e c o m i n g wide at the b a s e o f the lips, their m a x i m u m width reaching 140 urn, w h e r e a s in H. aduncum, cervical alae widen progressively, and their maximal width r e a c h e s only 50 µm; - by flanges o f the dorsal lip less rounded;
- b y spicules measuring 5 - 8 % o f b o d y length, w h e reas in H. aduncum they measure m o r e than 1 0 % o f b o d y length; - b y having o n e or t w o adanal pairs and six postanal pairs o f papillae, w h e r e a s in H. adun
cum only four to six pairs o f single postanal papillae are present. Also according to Hartwich, H. gadi is chiefly a parasite o f Gadiformes, but probably also o f other carnivorous and o f a few migratory fish, w h e reas H. aduncum is a parasite o f Clupeiformes, but has also b e e n r e c o r d e d in other plankton and small prey eating fish.
MATERIAL STUDIED
Each lot includes s p e c i m e n s c o l l e c t e d in o n e or s e v e ral fish o f the s a m e s p e c i e s , at the s a m e date and from the s a m e locality.
Material used for the biometrical studies
8 6 w o r m s ( 4 7 males and 39 females) w e r e analysed, corresponding to the s p e c i m e n s o n w h o m all m e a s u rements c o u l d b e made. Numbers in square b r a c k e t s are the serial n u m b e r s o f s p e c i m e n s used in multiva
riate analyses.
Pollachius virens (L., 1758) (Gadidae, Gadiformes) : Lot n° 1 : 8 8 and 7 9 n° MNHN 484 BB; western Scotland, Faroe islands; collected by V. Angot, April and September 1958 [ 1-8; 1-71. Lot n° 2 : 2 and 3 n° 1BF; Dublin (Ireland); collection R. Ph. Dollfus; 25-10-1937 [ 19-20;
18-201. Pollachius pollachius (L., 1758) : Lot n° 3 : 5 and 3 n° 2 BF; Concarneau (France); collection R. Ph.
Dollfus; 3-7-1940 [3 21-25; 21-23]. Lot n° 4 : 1 n° 701 BB; Roscoff (France); collection R. Ph. Dollfus; 18-9-1913 [ 24]. Gadus morhua L., 1758 (Gadidae) : Lot n° 8 : 3 and 2 n° 3 BF; Dogger Bank (North Sea); collection R.
Ph. Dollfus; October 1928 [ 26-28; 9 25-26]. Merlangius merlangus (L., 1758) (Gadidae) : Lot n° 11 : 2 n° 489 BB;
North Sea; c o l l e c t e d by de Panafieu; 1985 [ 3 8 - 3 9 ] . Merluccius merluccius (L., 1758) (Merluciidae, Gadiformes) : Lot n° 12 : 2 and 1 n° 687 BB; Rabat (Morocco); collec
tion R. Ph. Dollfus; Januaryl954 [ 40-41; 33]. Lot n° 13 ; 2 and 2 9 n° 691 BB; Rabat; collection R. Ph. Dollfus;
29-3-1949[ 42-43; 34-35]. Mullus surmuletus L., 1758 (Mullidae, Perciformes) : Lot n° 16 : 1 n° 707 B B ; Concarneau; collection R. Ph. Dollfus; 23-6-1944 [ 36]. Lot n° 17 ; 1 and 3 n° 708 BB; Concarneau; collection R.
Ph. Dollfus; 18-6-1942 [ 44; 37-39]. Lot n° 18 : 1 n°
709 B B ; Concarneau; collection R. Ph. Dollfus; 18-6-1943 [ 45]. Mullus barbatus L., 1758 : Lot n° 20 ; 1 n° 719BB;
Rabat ; collection R. Ph. Dollfus; 30-9-1926 [ 46]. Lot n°
21 : 1 n° 138 G; St Malo (France); collected by A.
Coumbaras; 12-7-1962 [ 47]. Scomber scombrus L., 1758 (Scombridae, Perciformes) : Lot n° 22 : 4 and 3 9 n° 7 BF;
Concarneau; collection R. Ph. Dollfus; 26-6-1940 [ 34-37;
3 0 - 3 2 ] . Trachurus trachurus (L., 1 7 5 8 ) (Carangidae, Perciformes) : Lot n° 24 : 2 and 1 n° 8 BF; Concarneau;
collection R. Ph. Dollfus ; 9-7-1941 [ 32-33; 291. Lophius piscatorius L., 1758 (Lophiidae, Lophiiformes) ; Lot n° 27 ; 3
3 and 1 9 n° 468 Q; île d'Yeu (France); collected by A. J . Petter; 22-7-1968 [ 29-31; 27]. Lot n° 28 : 1 n° 570 HD;
Concarneau; collection R. Ph. Dollfus; 22-6-1933 [ 28].
Alosa fallax (Lacepe.de, 1803) (Clupeidae, Clupeiformes) : Lot n° 35 : 10 and 10 n° 511 BB; Morocco; collection R.
Ph. Dollfus; 20-5-1951 [ 9-18; 8-17].
O t h e r material
Pollachius pollachius (L. 1758) : Lot n° 5 : 1 n° 137 BA;
Roscoff; collected by A.J. Petter ; 17-7-1970. Trisopterus lus
cus (L., 1758) (Gadidae) : Lot n° 6 : 1 n° 472 Q; Le Croisic
218 Mémoire Parasite, 1995, 2, 217-230
ASCARIDOID N E M A T O D E S OF FISH F R O M EASTERN N O R T H ATLANTIC.
(France); collected by A.J. Petter; 22-7-1968. Lot n° 7 : 2 n° 663 BB; Casablanca (Morocco); collection R. Ph. Dollfus;
24-4-1950. Gadus morhua L., 1758 : Lot n° 8 : 1 n° 3 BF;
Dogger Bank (North Sea); collection R. Ph. Dollfus; October 1928. Merlangius merlangus (L., 1758) (Gadidae) : Lot n° 9 : 3 n° 526 BB; Concarneau; collection R. Ph. Dollfus; 18-6- 1941. Lot n° 10 : 1 n° 4 BF; Boulogne (France); collection R. Ph. Dollfus; 17-11-1955. Merluccius merluccius (L., 1758) (Merlucciidae, Gadiformes) : Lot n° 14 : 1 and 1 n°5 BF; Concarneau; collection R. Ph. Dollfus; 2-7-1931. Lot n°
15 : 1 n° 469 Q; Le Croisic; collected by A. J . Petter; 22-7- 1968. Mullus surmuletus L., 1758 (Mullidae, Perciformes) : Lot n° 19 : 1 n° 6 BF; Bay of Biscay; collection R. Ph.
Dollfus; June 1948. Mullus barbatus L., 1758 : Lot n° 20 : 1 n° 719 BB; Rabat; collection R. Ph. Dollfus; 30-9-1926. Lot n° 21 : 3 n° 138 G; St Malo (France); collected by A.
Coumbaras; 1 2 - 7 - 1 9 6 2 . Scomber scombrus L., 1 7 5 8 (Scombridae, Perciformes) : Lot n° 23 : 1 and 1 n° 723 BB; Stornoway (Hebrides isles); collection R. Ph. Dollfus;
18-7-1929. Psetta maxima (L. 1 7 5 8 ) (Scophthalmidae, Pleuronectiformes) : Lot n° 25 : 2 n° 497 Q; Le Croisic;
collected by A. J . Petter; 5-8-1968. Lot n° 26 : 1 n° 9 BF;
Concarneau; collection R. Ph. Dollfus; 18-6-1943. Zeusfaber L., 1758 (Zeidae, Zeiformes) : Lot n° 29 : 4 n° 10 BF;
Concarneau; collection R. Ph. Dollfus; 2-9-1943. Lot n° 30 : 1 and 1 n° 11 BF; collection R. Ph. Dollfus; locality and date not mentioned. Lot n° 31 : 1 and 2 n° 716 BB;
Concarneau; collection R. Ph. Dollfus; 14-5-1943. Lot n° 32 : 2 n° 12 BF; Morocco; collection R. Ph. Dollfus; 19-6-1966.
Lot n° 33 : 1 n° 13 BF; locality not mentioned; collection R. Ph. Dollfus; 1933. Belone belone (L., 1758) (Belonidae, Beloniformes) : Lot n° 34 : 1 n° 710 BB, Concarneau; col
lection R. Ph. Dollfus; 28-4-1946. Alosa alosa (L., 1758) ; Lot n° 36 ; 1 6 n° 652 BB; Casablanca; collection R.Ph. Dollfus;
30-4-1953. Lot n° 37 ; 1 n° 528 BB; Morocco; collection R.
Ph. Dollfus; 9-9-1926. Salmo salar L., 1758 (Salmonidae, Clupeiformes) : Lot n° 38 : 2 n° 726 BB; Concarneau; col
lection R. Ph. Dollfus; 18-6-1943.
MORPHOLOGICAL STUDIES
D e t a i l e d d e s c r i p t i o n s o f t h e s p e c i e s w e r e given b y Punt ( 1 9 4 1 ) , B e r l a n d ( 1 9 6 1 ) a n d Hartwich ( 1 9 7 5 ) , s o it a p p e a r e d u n n e c e s s a r y to give a c o m p l e t e descrip
tion o f t h e m a t e r i a l s t u d i e d , a n d w e o n l y d i s c u s s b e l o w t h e different characters w h i c h have b e e n sug
gested to differentiate t h e t w o s p e c i e s . Cervical alae
At first sight, t w o groups s e e m to be present, differing b y t h e w i d t h o f c e r v i c a l a l a e : in t h e first g r o u p (Fig. 1A, F, J ) the cervical alae are very w i d e in the o e s o p h a g e a l region, w h e r e a s in t h e s e c o n d group, alae are hardly wider in t h e anterior region than in t h e m i d d l e a n d p o s t e r i o r o n e s ( F i g . 2 A , C, J ) . However, this character is not sufficient to differen
tiate the s p e c i e s , as all intermediaries exist b e t w e e n wide a n d narrow alae a n d w h a t e v e r width might b e
c h o s e n to differentiate the t w o groups, in s o m e lots the range o f width overlaps those o f t h e t w o groups.
I n d e p e n d e n t l y o f their width, in most s p e c i m e n s the cervical alae are wide from their beginning a n d the figure o f the anterior extremity o f Hysterothylacium gadi given b y Hartwich actually c o r r e s p o n d s to the s p e c i m e n s with narrow cervical alae (Fig. 2 C ) .
S h a p e o f lips
W e did not find a n y difference in the s h a p e o f the labial flanges b e t w e e n t h e t w o putative groups; indi
vidual variations in this s h a p e w e r e observed, inde
p e n d e n t o f the width o f cervical alae (Fig. I D , E - Fig. 2C, D ) .
Caudal papillae (Fig. 1L, M, N, O - Fig. 2L, M, N, O, Fig. 3A, B , C)
No difference in the n u m b e r a n d disposition o f cau
dal papillae could b e found. W e o b s e r v e d in the t w o groups : - t w o subventral rows o f precloacal papillae;
the 10 to 12 posterior o n e s are small and close toge
ther; their n u m b e r varies from 22 to 32 pairs in the s p e c i m e n s e x a m i n e d (Fig. 1L, Fig. 2L); the most pos
terior o r t h e t w o p o s t e r i o r pairs m a y b e a d c l o a c a l (Fig. 1 N ) - o n e p r e c l o a c a l m e d i o v e n t r a l papilla; - seven o r eight postcloacal pairs including : - five s u b - ventral pairs with third pair from t h e c l o a c a doubled;
the most anterior o r t h e t w o anterior pairs m a y b e adcloacal (Fig. 1O, Fig. 2 0 ) ; o n e papilla m a y be lac
king o n o n e side Fig. 2 0 , Fig. 3C); - o n e lateral pair c o r r e s p o n d i n g t o p h a s m i d s ; - o n e s u b d o r s a l pair, often invisible in ventral view; - a s e c o n d lateral pair can b e s e e n in s o m e juvenile s p e c i m e n s (Fig. 3A, B ) . Spicules (Fig. 1P - Fig. 2 P )
T h e s h a p e o f spicules is t h e s a m e in all s p e c i m e n s ; their length in relation to b o d y length varies b e t w e e n the lots, but there is n o evident correlation b e t w e e n this length a n d t h e width o f cervical alae; t h e length r a n g e s o b s e r v e d in e a c h g r o u p a r e different from those given b y Hartwich for H. gadi a n d H. adun- cum.
Therefore, the morphological analysis d o e s not allow a separation into t w o species; h o w e v e r , the biometri- cal analysis given b e l o w s h o w s that t w o morphologi
cal entities exist.
BIOMETRICAL STUDIES Data analysis
T h e following multivariate analyses w e r e used ; prin
cipal c o m p o n e n t analysis (PCA) a n d clustering ana
l y s e s b a s e d o n u n w e i g h t e d a r i t h m e t i c a v e r a g e (UPGMA) in order to identify putative groups, discri
m i n a n t a n a l y s i s t o i d e n t i f y t h e m o s t i n t e r e s t i n g v a r i a b l e s , a n d finally s e g m e n t a t i o n b a s e d o n Chi-
Parasite, 1995, 2, 217-230
Mémoire
219Fig. 1. - Hysterotbylacium aduncum gadi (O.F. Müller, 1776, species), specimens parasitizing Pollacbius virens (lot n° 1).
A, anterior part, median view ; B , anterior part, lateral view ; C,D, dorsal lips ; E, latero-ventral lip ; F, female, anterior end, lateral view ; G, female, posterior end, ventral view ; H, female, posterior end, lateral view ; I, egg ; J , cross-section at level of oesophagus ; K, cross-section at level of ventricular appendage ; L, male, posterior part, lateral view ; M, male, posterior end, lateral view ; N.O, males, posterior ends, ventral views ; P, spicule, distal end. Scale lines (pm) : A,B,L, 1000 ; C,D,E,I,M,N,0,P, 100 ; H, 500 ; F,GJ,K, 200.
Parasite, 1995, 2, 217-230 P E T T E R A J . & C A B A R E T J .
О О П
ASCARIDOID NEMATODES OF FISH FROM EASTERN NORTH ATLANTIC.
Fig. 2. - Hysterothylacium aduncum aduncum (Rud., 1802), specimens parasitizing Alosa fallax (lot n° 35). A, anterior part, median view ; B, anterior part, lateral view ; C, anterior end, lateral view ; D,E, dorsal lips ; F, latero-ventral lip ; G, female, posterior end, lateral view ; H, female, posterior end, ventral view ; I, egg ; J , cross-section at level of oesopha
gus; K, cross-section at level of ventricular appendage ; L, male, posterior part, lateral view ; M, male, posterior end, late
ral view; N , 0 , males, posterior ends, ventral views ; P, spicule, distal end. Scale lines (um) : A,L, 1000 ; B, 250 ; C,GJ,K, 200; D,E,F,H,I,M,N,0,P, 100.
Parasite, 1995, 2, 217-230
PETTER A.J. & CABARET J .
Table II. - Hysterotbylacium aduncum -. measurements of females analysed for the biometrical study .
Table I. - Hysterotbylacium aduncum : measurements of males analysed for the biometrical study.
a ventricular appendage length (um); c : intestinal caecum length (pm); 1 : body length (mm); L : width of cervical alae (pm); o : oeso
phagus length (um); s : spicules length (um).
; ? ) Parasite, 1995, 2, 217-230
square in order to find e a s y criterion for identifica
tion. T h e a n a l y s e s w e r e p e r f o r m e d with a Stat-Ictf ( 1 9 8 8 ) statistical c o m p u t e r p a c k a g e and interpreted according to Dagnelie ( 1 9 7 5 ) .
T h e data matrix was constituted with five m e a s u r e s for e a c h female w o r m and b y six m e a s u r e s for e a c h m a l e w o r m . T h e m e a s u r e s w e r e : cervical alae (L), b o d y length (1), o e s o p h a g u s length ( o ) , ventricular a p p e n d a g e ( a ) , intestinal c a e c u m ( c ) , and additionally spicule length for males ( s ) [ tables I ( m a l e s ) and II (females)].
Results
T h e d i f f e r e n t m e a s u r e s w e r e s i g n i f i c a n t l y l i n k e d ( P < 0 , 0 1 ) . A m o n g m a l e s , width o f cervical alae and b o d y l e n g t h , l e n g t h o f s p i c u l e s a n d b o d y l e n g t h , o e s o p h a g u s and intestinal c a e c u m lengths, ventricular a p p e n d a g e and intestinal c a e c u m lengths. T h e w o r m s h a r b o u r e d b y Pollachius virens w e r e very different from others, o n s e c o n d axis, w h e r e a s first axis did n o t a l l o w d i f f e r e n t i a t i o n b e t w e e n g r o u p s . T w o groups (in males and females) w e r e distinguished b y m e a n s o f cluster analysis b a s e d o n relative values o f parameters (actual value/width o f cervical alae). T h e m e a s u r e s o f t h e t w o putative g r o u p s (gadi versus aduncum) are s h o w n in table III. T h e use o f discri
minant analysis did a l l o w identification o f t h e t w o groups : 1 0 0 % o f the w o r m s w e r e successfully classi
fied into gadi and aduncum. Pseudo-F w a s 122 w h e r e a s h i g h e s t F v a l u e w a s 1 1 8 f o r v e n t r i c u l a r a p p e n d a g e in m a l e w o r m s . P s e u d o - F w a s 2 3 5 and highest F value 190 for o e s o p h a g u s in female worms.
T h e advantage o f multivariate analysis was r e d u c e d for males ( p s e u d o - F and F values w e r e similar) but was clear for female identification. Segmentation ana
l y s i s b a s e d o n t w o m o s t i m p o r t a n t p a r a m e t e r s (lengths o f o e s o p h a g u s and ventricular a p p e n d a g e ) did s h o w that t w o groups w e r e significantly distinct ( P < 0 , 0 1 ) , e i t h e r in m a l e o r f e m a l e w o r m s ( r e s u l t s s h o w n in Figs. 4 and 5 ) . B o t h m e a s u r e s w e r e useful in identification (Chi-square o f respectively 7 0 . 7 and 7 0 . 4 for 8 6 s p e c i m e n s ) . G r o u p 1 igadi) was characte
rized with a/L < 15 and o/L < 54 and group 2 (adun
cum) w a s characterized with a/L >15 and o/L > 5 4 . T h o s e identification criteria w e r e tested o n 39 additio
nal s p e c i m e n s (Fig. 6 ) . Eight s p e c i m e n s (four parasites o f Zeus faber, t w o o f Mullus surmuletus, o n e o f
Trisopterus luscus and o n e o f Merluccius merluccius) could not b e classified, as the two parameters placed them in different groups. All s p e c i m e n s from the same lot and all the lots from the s a m e host species b e l o n g e d to the s a m e group, e x c e p t in four host s p e c i e s the s p e c i m e n s o f which w e r e distributed as follows : Gadus morhua : six s p e c i m e n s studied : four in group 1, two in group 2 (lot n ° 8 ) . Zeus faber: 12 s p e c i m e n s
studied : six in group 1 (in lots n° 29 and 3 D , two in group 2 (in lots n° 29 and 3 0 ) , four could not b e clas
sified (in lots 3 0 , 3 2 and 3 3 ) . Mullus surmuletus -.
seven s p e c i m e n s studied : o n e in group 1 (in lot n°
17), four in group 2 (in lots n° 1 6 , 17 and 1 8 ) , two could not b e classified (in lots n° 17 and 1 9 ) . Mullus barbatus : six s p e c i m e n s studied : two in group 1 (in lot n° 2 1 ) , four in group 2 (in lots n° 2 0 and 2 1 ) . CONCLUSIONS
T h e preceding data allowed a differentiation into two groups, w h i c h in the majority o f c a s e s w e r e isolated, p r o b a b l y b e c a u s e o f e c o l o g i c a l rather than g e o g r a phical reasons. In four hosts only, these two groups c o h a b i t e d and in two o f these four hosts (Zeus faber, Mullus surmuletus), intermediary forms w e r e found, w h i c h , a c c o r d i n g to o u r i n t e r p r e t a t i o n , are c r o s s breeds. In the present state o f k n o w l e d g e , w e there
f o r e p r o p o s e t o c o n s i d e r t h e s e g r o u p s a s t w o s u b s p e c i e s o f Hysterothylacium aduncum.
T h e s u b s p e c i e s gadi was found chiefly in Gadiformes (Pollachius virens, P. pollachius, Gadus morhua, Merlangius merlangus), but a l s o in o n e Perciform (Scomber scombrus) a n d o n e C l u p e i f o r m (Salmo salar) ; t h e s u b s p e c i e s aduncum in C l u p e i f o r m e s (Alosa fallax, A. alosa), Beloniformes (Belone belone), P l e u r o n e c t i f o r m e s (Psetta maxima), L o p h i i f o r m e s (Lophiuspiscatorius), Perciformes (Tracburus trachu- rus), but also in Gadiformes (Merluccius merluccius, Trisopterus luscus).
In most lots, the fishing places w e r e not known. Only t h e h a r b o u r s o f a r r i v a l o f b o a t s w e r e r e c o r d e d . Nevertheless, w e may c o n c l u d e that fishes parasitised b y the subspecies gadi have a geographical range not e x t e n d i n g southwards b e y o n d the E u r o p e a n coasts, while the geographical range o f the subspecies adun
cum e x t e n d s m o r e southwards. T h e s e results are in agreement with the observations o f Hartwich ( 1 9 7 5 ) .
Table III. - Hysterothylacium aduncum : Relative values of para
meters of the two subspecies distinguished by means of cluster analysis (means, standard deviations in brackets),
a : ventricular appendage length (pm); c : intestinal caecum length (pm); 1 : body length (pm); L ; width of cervical alae (pm); o ; oesophagus length (pm); s : spicules length (pm).
Parasite, 1995, 2, 217-230
P E T T E R A . J . & C A B A R E T J .
Fig. 3. - Male posterior ends. A, Hysterothylacium aduncum gadi, juvenile male parasitizing Scomber scombrus (lot n° 22), lateral view; B , Hysterothylacium aduncum aduncum, juvenile male parasitizing Trachurus trachurus (lot n° 24), lateral view; C, Hysterothylacium aduncum aduncum, male parasitizing Lophius piscatorius (lot n° 27), ventral view.
Fig. 4. - Hysterothylacium aduncum. Distribution of males in relation to parameters o/L (oesophagus length/width of cervical alae) and a/L (ventricular appendage length/width of cervical alae) in 11 fish species. Groups 1 (gadi) and 2 (aduncum) are significantly distinct according to segmentation analysis.
Fig. 5. - Hysterothylacium aduncum. Distribution of females in relation to parameters o/L and a/L in 9 fish species. Groups 1 (gadi) and 2 (aduncum) are significantly distinct according to segmentation analysis.
">~>A Parasite, 1995, 2, 217-230
VSCARIDOID NEMATODES OF FISH FROM EASTERN NORTH ATLANTIC
o/L
Fig. 6. - Hysterothylacium adun
ami. D i s t r i b u t i o n o f male and female s p e c i m e n s in relation to parameters o/L et a/L in 17 fish species. 1 : sub-species gadi; 2 : sub-species aduncum.
HYSTEROTHYLACIUM RELIQUENS (Norris and Overstreet, 1 9 7 5 ) Fig. 7
Material : 3 6 and 12 9 n° MNHN 6 7 5 B B , 4 8 6 B C , 5 3 7 B C ; h o s t : Pagellus acarne ( R i s s o , 1 8 2 6 ) (Sparidae); M o r o c c o ; 2 1 - 6 - 1 9 5 7 and 1 8 - 4 - 1 9 6 8 . 1 3 n°
M N H N 6 6 9 B B ; host : Microcheirus azevia (Capello, 1 8 6 7 ) ( S o l e i d a e ) ; M o r o c c o . Collection R.Ph. Dollfus.
DESCRIPTION
B o d y t h i n n e r a n t e r i o r l y . Lateral a l a e v e r y thin ( 5 - 10um), with supports V-shaped in cross-section, origi
nating from t h e b a s e o f t h e lips a n d e x t e n d i n g all along the body. Dorsal lip slightly wider than long, latero-ventral lips longer than wide. Lips lacking pos
terior l o b e s . Labial flanges constricted at middle o f lips. Interlabia very short, not m o r e than 1/4 o f lip length. O e s o p h a g u s 8.5-14.7 % o f b o d y length, ventri
cular a p p e n d a g e very thin, ratio o e s o p h a g u s / v e n t r i cular a p p e n d a g e 1.8-3-9, intestinal c a e c u m short, ratio o e s o p h a g u s / c a e c u m 3-6-7.9. Excretory p o r e at level o f n e r v e ring. Tail with s p i n e d c o n i c a l m u c r o n a t e extremity.
Male : Spicules 4 . 9 - 7 % o f b o d y length. About 27 pairs o f preanal papillae, the ten most posterior pairs very c l o s e together; o n e big large medio-ventral preanal papilla; 5-7 postcloacal pairs (including p h a s m i d s ) : o n e or t w o lateral and four o r five ventro-laterals;
s e c o n d or third pair from the cloaca doubled.
F e m a l e : vulva without salient lips, slightly posterior to anterior third o f body.
Measurements (range, m e a n s in p a r e n t h e s e s ) :
F e m a l e s , n = 7 : l e n g t h 1 8 - 7 5 ( 3 6 . 6 ) ; o e s o p h a g u s 2 3 5 0 - 8 0 0 0 ( 4 1 2 4 . 3 ) ; c a e c u m 5 0 0 - 1 1 0 0 ( 6 7 1 ) ; ventricu
lar a p p e n d a g e 1 1 0 0 - 2 0 5 0 ( 1 4 9 5 ) ; tail 3 0 0 - 6 5 0 ( 4 5 7 . 5 ) . Males, n = 4 : length 14-43 ( 2 4 . 1 ) ; o e s o p h a g u s 2 0 6 0 - 3 6 5 0 ( 2 6 8 7 . 5 ) ; c a e c u m 2 6 0 - 6 8 0 ( 4 2 5 ) ; v e n t r i c u l a r a p p e n d a g e 1 0 8 0 - 2 0 0 0 ( 1 4 0 7 . 5 ) ; tail 1 9 0 - 2 0 0 ( 1 9 6 . 6 ) ; spicules 7 2 0 - 2 1 6 0 ( 1 3 7 1 . 2 ) .
DISCUSSION
Measurements and m o r p h o l o g y o f these s p e c i m e n s , especially the s h a p e o f lips, agree with those o f H.
reliquens, given b y Norris and Overstreet, 1975 and Deardorff and Overstreet, 1980. H. reliquens has b e e n
Parasite, 1995, 2, 217-230 i l . 2 2 5
Fig. 7. - Hysterothylacium reliquens (Norris and Overstreet, 1975). A, dorsal lip; B, latero-ventral lip; C, anterior end, late
ral view; D, cross-section of lateral ala at level of the anterior part of oesophagus; E, male, anterior part, lateral view; F,G, female, posterior ends; H, egg; I, male, posterior end, ventral view; J , male, posterior part, lateral view ; K, male, posterior end, lateral view. Scale lines (um) : A,C,G, 200; D, 50; B,H J : 100; E, 500; F, 250; J , 400; K, 150.
Parasite, 1995, 2, 217-230
ASCARIDOID NEMATODES O F FISH FROM EASTERN N O R T H ATLANTIC,
reported from a Sparidae (Archosargus probatocepha- lus) (type-host) and other hosts in the Gulf o f Mexico, Western Nonh Atlantic and Pacific, but is recorded for the first time from Eastern North Atlantic.
HYSTEROTHYLACIUM CORNUTUM (Stossich, 1 9 0 4 )
Material : several S and 9 n° MNHN 5 6 8 H D and 4 5 5 B B , C o n c a r n e a u , 1 9 3 1 - 1 9 3 7 , 1 9 4 7 ; c o l l e c t i o n R.Ph.
Dollfus. 1 3 and 1 9 n° MNHN 517 Q, Le Croisic, 10- 8 - 1 9 6 8 ; c o l l e c t e d b y A . J . P e t t e r . H o s t ; Thunnus (Germo) alalunga ( S c o m b r i d a e ) .
A part o f the material from Concarneau was described by Dollfus, as Thynnascaris legendrei (n. gen. n. sp.), a species synonymised with T. cornutum by Berland ( 1 9 6 1 ) . S p e c i m e n s from Le Croisic w e r e studied b y Petter ( 1 9 6 9 ) . T h e species is otherwise well k n o w n by the d e s c r i p t i o n s o f Hartwich ( 1 9 7 5 ) , D e a r d o r f f and Overstreet ( 1 9 8 2 ) and B r u c e and Cannon ( 1 9 8 9 ) .
HYSTEROTHYLACIUM RIGIDUM (Rudoiphi, 1809) Fig. 9 H Material ; 6 3 and 5 9 , n° MNHN 7 0 4 B B and 5 4 0 BC, C o n c a r n e a u , 1-2-1943 and 2 0 - 2 - 1 9 4 6 ; c o l l e c t i o n R.Ph. Dollfus. 2 9 , 2 S and 4 anterior extremities, n°
MNHN 4 8 8 Q, 6 3 7 Q, 6 5 3 Q and 696 Q, Le Croisic, 22-7-1968, 11-7-1969 and 26-7-1969; c o l l e c t e d b y A.J.
Petter. Host : Lophiuspiscatorius L., 1 7 5 8 (Lophiidae).
A part o f this material was studied by Petter ( 1 9 6 9 ) a n d t h e s p e c i e s w a s w e l l d e s c r i b e d b y H a r t w i c h ( 1 9 7 5 ) . Contrary to the observations o f Petter ( 1 9 6 9 ) , t h e t w o c o m p o n e n t s o f t h e v e n t r i c u l a r a p p e n d a g e a p p e a r unequal in cross-section in the anterior part o f the a p p e n d a g e , as in H. aduncum; t h e r e f o r e , this c h a r a c t e r c a n n o t b e u s e d to differentiate the c r o s s - sections o f the two s p e c i e s .
HYSTEROTHYLACIUM SP. Fig. 8
Material : 2 9 , 1 mature and 1 juvenile 3, n° MNHN 5 3 8 B C ; host ; Callionymus lyra L., 1 7 5 8 (Calliony- midae); La R o c h e l l e ( F r a n c e ) ; May 1 9 4 1 ; c o l l e c t e d b y J . Cadenat.
DESCRIPTION
B o d y t h i n n e r a n t e r i o r l y . In t h e f e m a l e s a n d t h e mature male, very thin ( 3 - 5 p m ) lateral alae originate at 3 4 0 - 8 0 0 p m p o s t e r i o r f r o m lips a n d d i s a p p e a r before the posterior e n d o f o e s o p h a g u s . In the juve
nile m a l e , t h e y o r i g i n a t e just p o s t e r i o r to lips, are wider at their beginning and e x t e n d all along body.
In cross-section, alal sclerotized supports nearly flat.
Dorsal lip slightly w i d e r than long, latero-ventral lips longer than wide. Lips lacking posterior l o b e s . Labial flanges triangular. Interlabia about half length o f lips.
L a b i a l p u l p w i d e n i n g a n t e r i o r l y ; l o b i r o u n d e d . O e s o p h a g u s 9.4-13.1 % o f b o d y length. Ratio o e s o phagus/ventricular a p p e n d a g e 2.6-3.2. Ratio o e s o p h a gus/intestinal c a e c u m 2.7-3- Intestinal c a e c u m slightly longer than ventriculus plus a p p e n d a g e in the biggest female, and slightly shorter in the o t h e r s p e c i m e n s . E x c r e t o r y p o r e slightly posterior to nerve ring. Tail with spined c o n i c a l m u c r o n a t e extremity.
Male : spicules slightly unequal, 5-7% o f b o d y length.
Preanal papillae 26-29 pairs, o n e large medioventral preanal papilla, postanal papillae eight pairs : five subventral with the fourth from c l o a c a doubled, o n e lateral a n d o n e small lateroventral ( p r o b a b l y phas- mids).
F e m a l e : vulva sligthly posterior to the anterior third o f body. Thin shelled eggs 6 5 / 6 0 pm.
Measurements
Females : length 6 3 , 42; oesophagus 6 0 5 0 , 3950; ven
triculus : length 3 5 0 , 2 5 0 ; width 3 2 5 , 3 2 5 ; intestinal c a e c u m 2250, 1350; ventricular appendage 1850, 1400;
distance vulva-anterior extremity 22, 16; tail 4 0 0 , 2 2 5 . Males : length 3 5 , 16; o e s o p h a g u s 3 6 0 0 , 2 1 0 0 ; ventri
culus : length 180,100; width 2 0 0 , 1 0 0 ; intestinal c a e c u m 1 2 0 0 , 7 2 5 ; ventricular a p p e n d a g e 1 3 0 0 , 8 0 0 ; tail 150,115; left spicule 2 3 5 0 , 7 5 0 ; right spicule 2 4 2 0 , not visible.
DISCUSSION
T h e s e s p e c i m e n s are c l o s e to H. aduncum by their m e a s u r e m e n t s and m o r p h o l o g y , but the mature spe
c i m e n s differ by having very thin lateral alae origina
t i n g far b e h i n d l i p s a n d n o t e x t e n d i n g b e y o n d p o s t e r i o r e n d o f o e s o p h a g u s . B y a l a e o r i g i n a t i n g b e h i n d the lips, the s p e c i m e n s are similar to H. auc- tum according to the description o f Hartwich ( 1 9 7 5 ) , a s p e c i e s s y n o n y m i s e d with H. aduncum b y Punt ( 1 9 4 1 ) . H. auctum was r e c o r d e d from Callionymus lyra b y Baylis ( 1 9 3 9 ) ; h o w e v e r , in this latter s p e c i e s lateral alae e x t e n d all along the b o d y and originate nearer the b a s e o f the lips ( 5 0 p m ) , and the n u m b e r o f p o s t a n a l p a p i l l a e is l a r g e r ( e i g h t p a i r s ) . E x a m i n a t i o n o f m o r e s p e c i m e n s from Callionymus lyra w o u l d b e necessary to k n o w if t h e s e differential characters are constant and so w e prefer to designate the s p e c i m e n s as Hysterothylacium sp.
MARICOSTULA INCURVA (Rudolphi, 1819) Fig. 9 G Material : 1 ™ n° MNHN 5 3 9 BC; host : Xiphias gla- dius L., 1 7 5 8 ( X i p h i i d a e ) ; H o s s e g o r ( F r a n c e ) ; 5 - 1 0 - 1960 ; collection R.Ph. Dollfus.
T h i s f e m a l e c o r r e s p o n d s t o t h e d e s c r i p t i o n o f Hysterothylacium incuruum given by Hartwich ( 1 9 7 5 ) . Bruce and Cannon ( 1 9 8 9 ) placed this species in their n e w g e n u s Maricostula. Lateral alae are p o i n t e d in
Parasite, 1995, 2, 217-230 T T 7
ETTER A.J. & CABARET J .
Fig. 8. - Hysterotbylacium sp. A, female, dorsal lip; B , female, latero- ventral lip; C, female, anterior end, ventral view; D, juvenile male, ante
rior end, dorsal view; E, anterior part, lateral view: F, juvenile male, cross- section of lateral ala; G, female, poste
rior end; H, egg; I, male, posterior end. ventral view: J , male, posterior end, lateral view; K, male, posterior part, lateral view. Scale lines ( p ) ; A , B J , 100; C, 150; D,I, 75; E, 1000; F, 10; G, 200; H, 20; K, 500.
Fig. 9. - A - F, Goezia sp. A, anterior part, lateral view; B, posterior end, lateral view; C, cross-section at level of ventricular appendage:
D, spines at different levels : 1, anterior part of oesophagus; 2, pos
terior part of oesophagus; 3, vulva ; 4, anus; E, deirid; F, egg; G, Maricostula incurva (Rud.. 1819), cross-section of lateral ala; H, Hysterotbylacium rigidum (Rud., 1809), cross-section of lateral ala.
Scale lines (urn) : A, 500 ; B, 200 ; C, 250 ; D,E,F,H, 100 ; G, 50.
2 2 8 Parasite, 1995, 2, 217-230
ASCARIDOID NEMATODES OF FISH FROM EASTERN NORTH ATLANTIC.
cross-section as in the specimens from Mediterranean Sea studied by Petter and Maillard ( 1 9 8 7 ) . Deardorff and Overstreet ( 1 9 8 1 ) identified as H. incurvum speci
m e n s from Florida with lateral alae bifurcated at the tips. T h e i r material was c o l l e c t e d from t w o hosts : Xiphias gladius and Tetrapterus albidus. B r u c e and Cannon ( 1 9 8 9 ) reexamined material o f Deardorff and Overstreet from T. albidus and observed that it is not conspecific with M. incurva, differing by characters o f the male caudal extremity and b y narrower cervical alae. Alae bifurcated at the tip should b e another cha
racter differentiating these parasites from M. incurva.
GOEZIA SP. Fig. 9A-F
M a t e r i a l : 1 a, 1 0 9 n ° M N H N 5 0 8 В С ; h o s t : Trisopterus luscus (L., 1 7 5 8 ) ( G a d i d a e ) ; î l e d ' Y e u ( F r a n c e ) ; c o l l e c t e d b y J . Callot.
DESCRIPTION
S m a l l n e m a t o d e s w i t h t r a n s v e r s e r o w s o f s p i n e s . O e s o p h a g u s short, small ventriculus wider than long ( 8 0 / 1 5 0 pm); ventricular a p p e n d a g e thin, double, 1.3- 2 times length o f o e s o p h a g u s ; intestinal c a e c u m thick, variable in length (ratio intestinal c a e c u m / o e s o p h a g u s 1 / 6 - 1 / 2 ) . E x c r e t o r y p o r e slightly a n t e r i o r to n e r v e ring. Deirids slightly posterior to nerve ring, surroun
d e d by an area without spines. Tail short with a fin
gerlike terminal portion without spines, terminating in 5-6 small spikes. Transverse rows o f spines b e g i n just p o s t e r i o r to lips ( 7 0 p m ) from a n t e r i o r e x t r e m i t y ; s p a c e s b e t w e e n rows 10 pm in anterior part, 5 0 p m in middle part and 1 6 - 2 0 pm in posterior part; length o f spines 3-6 pm in anterior part, 8-12 pm in middle part and 1 5 - 2 0 pm in anal region; about 1б0 spines per row in the middle part o f body.
Male : spines lacking dorsally from caudal extremity up to 3 5 0 pm. Spicules subequal. G u b e r n a c u l u m lac
king. T h e single male s p e c i m e n b e i n g damaged, the n u m b e r a n d d i s p o s i t i o n o f p a p i l l a e c o u l d n o t b e determined.
F e m a l e : rows o f spines interrupted laterally in the a n a l r e g i o n . V u l v a g e n e r a l l y s l i g h t l y p o s t e r i o r to middle o f body. R o u n d e d , thin shelled e g g s ( 4 0 p m in diameter).
DISCUSSION
As the m o s t important characters differentiating the s p e c i e s in the g e n u s Goezia [number and disposition o f anal papillae, s e e Deardorff and Overstreet ( 1 9 8 0 ) ] w e r e not studied, specific identification was not per
formed.
T w o s p e c i e s o f Goezia w e r e d e s c r i b e d in e a s t e r n North Atlantic and seas o f North o f E u r o p e : Stefanski ( 1 9 3 8 ) d e s c r i b e d G. sigalasi from Trachinus draco in
the Atlantic; this s p e c i e s differs from the s p e c i m e n s d e s c r i b e d a b o v e b y having u n e q u a l s p i c u l e s ; Punt ( 1 9 4 1 ) identified as G. ascaroides a female parasite o f
Trachinus vipera in the North Sea; this identification, b a s e d only o n females, is doubtful, as G. ascaroides w a s o r i g i n a l l y d e s c r i b e d from a f r e s h w a t e r fish, Silurus glanis.
CONCLUSION
K
e y t o t h e A s c a r i d s p e c i e s p a r a s i t i z i n g T e l e o s t e a n fishes from Eastern North Atlantic and Seas o f the North o f E u r o p e :1(6) Cuticule with transverse rows of spines 2(3) Male unknown
Goezia sp. (= G. ascaroides sensu Punt, 1941) 3(2) Male known
4(5) Spicules markedly unequal
Goezia sigalasi Stefanski, 1938 5(4) Spicules subequal Goezia sp. Petter (present paper) 6(1) Cuticule without transverse rows of spines
7(8) Male tail ending in a long tapering spike, without spines. Four pairs of single postanal and one pair of dou
bled adanal papillae. Intestinal caecum more than 2/3 of oesophagus length. Lips with posterior lobes not extending as far as the posterior margins of interlabia. Parasites of Xiphias gladius Maricostula incurva (Rud., 1819) 8 ( 7 ) Male tail ending in a short spike with or without spines. More than four pairs of postanal papillae. Intestinal caecum less than 2/3 of oesophagus length
9(10) Lips with posterior lobes extending as far as the pos
terior margins of interlabia. Ventricular appendage longer than oesophagus. Parasites of Lophius piscatorius
Hysterothylacium rigidum (Rud. 1809) 10(9) Lips lacking posterior lobes. Ventricular appendage shorter than oesophagus
11(12) 10 pairs or more than 10 pairs of postanal papillae.
Caudal extremity lacking spines. Parasites of fishes belon
ging to the genus Thunnus
Hysterothylacium comutum (Stossich,1904) 12(11) Less than 10 pairs of postanal papillae. Caudal extre
mity with spines. Host specificity not restricted to one genus or one species
13(14) Lips constricted at mid-length. Interlabia measuring less than 1/4 of lip length
....Hysterothylacium reliquens (Norris and Overstreet, 1975) 14(13) Lips constricted at anterior third of lips. Interlabia measuring about half the lip length
15(18) Lateral alae originating far behind the base of lips 16(17) Lateral alae originating at about 50 pm from base of lips and extending all along body
Hysterothylacium auctum(Rud., 1802) (this species was synonymized with H. aduncum by Punt, 1941)
Parasite, 1995, 2, 217 230 н д п и р . ^ . j ^ i О О О
PETTER A.J. & CABARET J.
17(16) Lateral alae originating at more than 300 pm from base of lips and not extending beyond posterior end of oesophagus in mature worms
Hysterothylacium sp. Petter (present paper) 18(15) Lateral alae originating from base of lips
Hysterothylacium aduncum (Rud.,1802) 19(20) Cervical alae very wide. Ratio oesophagus/maximal width o f cervical alae < 5 4 . Ratio ventricular appen
dage/maximal width of cervical alae<15
H. aduncum gadi (O.F.Muller, 1776, species) 20(19) Cervical alae hardly wider than lateral alae. Ratio oesophagus/maximal width of cervical alae >54. Ratio ven
tricular appendage/maximal width of cervical alae>15 H. aduncum aduncum (Rud., 1802, species) T h e s e s p e c i e s h a v e v a r i o u s g e o g r a p h i c a l distribu
tions. T h r e e s p e c i e s o r s u b - s p e c i e s w e r e r e c o r d e d only in Eastern North Atlantic and seas o f the North o f E u r o p e : Hysterothylacium auctum, H. aduncum gadi and Goezia sigalasi. Hysterothylacium reliquens is c o m m o n to E a s t e r n a n d W e s t e r n A t l a n t i c a n d Pacific. H. rigidum o c c u r s like its host, Lophiuspisca-
torius, in M e d i t e r r a n e a n S e a a n d E a s t e r n N o r t h Atlantic. T h e three other s p e c i e s have a widespread g e o g r a p h i c a l distribution, t w o o f them, Maricostula
incurva and Hysterothylacium cornutum parasitizing only o n e g e n u s or o n e host s p e c i e s , while the third o n e , H. aduncum aduncum was found in fishes o f different orders.
ACKNOWLEDGEMENTS
W
e are very grateful to Pr R.S. Bray for revising the english text.
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Accepté le 27 janvier 1995
P a r a s i t e , 1995, 2, 2 1 7 - 2 3 0
