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1 Article available at or M III. Pa n g a s iid a e (S ilurifo rm es ) in S outheast A s ia : Five n e w species o f Th a p a r o c le id u s Ja in, 19 (A n c y l o d is c o id id a e ) FROM PANGASIUS BOCOURTI, P. DJAMBAL AND P. HYPOPHTHALMUS o n o g e n e a n s from PARISELLE A.*,**, LIM L.H.S.*** & LAMBERT A.** * Summary: R ésu m é : The examination of gill parasites from Pangasius bocourti Sauvage, 10; P. djambal Bleeker, 1; P. hypophthalmus (Sauvage, 17) and P. gigas Chevey, (Siluriformes, Pangasiidae) revealed the presence of seven species of Monogenea among which five are considered new species. They all belong to Thaparocleidus Jain, 19 (Ancylodiscoididae) as defined by Lim (199) and Lim et al. (001).. P. bocourti: T. combesi n. sp.: T. komarudini n. sp. and T. vietnamensis n. sp.. P. djambal: T. caecus (Mizelle & Kritsky, 199), T. combesi n. sp., T. euzeti n. sp., T. komarudini n. sp. and T. sadilii n. sp.. P. hypophthalmus: T. caecus, T. siamensis (Lim, 1990) and T. vietnamensis n. sp.. P. gigas: no Monogenea were found on this host species. KEY W O R D S : Monogenea, Ancylodiscoididae, Thaparocleidus combesi n. sp., Thaparocleidus euzeti n. sp., Thaparocleidus komarudini n. sp., Thaparocleidus sadilii n. sp., Thaparocleidus vietnamensis n. sp., Thaparocleidus caecus, Thaparocleidus siamensis, freshwater fish, Siluriformes, Pangasiidae, Pangasius bocourti, Pangasius djambal, Pangasius hypophthalmus, Pangasius gigas, South East Asia. INTRODUCTION W ithin the framework o f an EC project on the bio-diversity and culture o f Southeast Asian catfishes, the gills from pangasiid fishes (Siluriformes, Pangasiidae) w ere examined for m onoge neans. This third paper (see Pariselle et al., 001a, b ) presents the descriptions o f the five new species o f T h a p a ro c leid u s Jain, 19 (M onogenea, Ancylodiscoi didae) found on P a n g a siu s b o c o u r ti Sauvage, 10, * IRD (ex ORSTOM), Catfish Asia Project, Instalasi Penelitian Perikanan Air Tawar, Jalan Ragunan-Pasar Minggu, P.O. Box 70/jkspm, Jakarta 10, Indonesia. ** GAMET, BP 09, 0 Montpellier cedex 1, France. *** Institute of Biological Sciences, University of Malaya, 00 Kuala Lumpur, Malaysia. **** Laboratoire Génome, Populations, Interactions, UMR 000, CC, Université Montpellier II, Sciences et Techniques du Lan guedoc, Place Eugène Bataillon, 09 Montpellier cedex, France. Correspondence: A. Lambert. lambert@crit.univ-montp.fr M o n o g è n e s d e P a n g a siid a e ( S il u r if o r m e s ) en A s ie d u S u d - E s t : II I. C in q e s p è c e s n o u v e l l e s d e Th a p a r o c l e id u s J a in, 1 9 ( A n c y l o d is c o id id a e ) c h e z P a n g a s iu s b o c o u r t i, P. d ja m b a l e t P. HYPOPHTHALMUS L'examen des parasites branchiaux de Pangasius bocourti Sauvage, 10 ; P. djambal Bleeker, 1 ; P. hypophthalmus (Sauvage, 1 7 ) et P. gigas Chevey, 19 0 (Siluriformes, Pangasiidae) a révélé la présence de sept espèces de Monogenea appartenant au genre Thaparocleidus Jain, 19 (Ancylodiscoididae) tel que défini par Lim ( 199) et Lim et al. ( ). Parmi ces espèces, cinq sont considérées comme nouvelles.. P. bocourti : T. combesi n. sp., T. komarudini n. sp. et T. vietnamensis n. sp.. P. djambal : T. caecus (M izelle & Kritsky, 199), T. combesi n. sp., T. euzeti n. sp., T. komarudini n. sp. et T. sadilii n. sp.. P. hypophthalmus : T. caecus, T. siamensis (Lim, 1990) et T. vietnamensis n. sp.. P. gigas : aucun Monogène branchial n'a été trouvé sur cet hôte. MOTS CLÉS : Monogenea, Ancylodiscoididae, Thaparocleidus combesi n. sp., Thaparocleidus euzeti n. sp., Thaparocleidus komarudini n. sp., Thaparocleidus sadilii n. sp., Thaparocleidus vietnamensis n. sp., Thaparocleidus caecus, Thaparocleidus siamensis, poissons d'eau douce, Siluriformes, Pangasiidae, Pangasius bocourti, Pangasius djambal, Pangasius hypophthalmus, Pangasius gigas, Asie du Sud Est. P. d ja m b a l Bleeker, 1, P. h y p o p h th a lm u s (Sauvage, 17) and P. g ig a s Chevey, 190. Only P. h y p o p h th a lm u s have been previously exam ined for parasites (see Lim, 1990). To date a total o f 1 species o f T h a p a r o c l e id u s have b ee n d escribed from P a n g a s iu s h u m e r a lis Roberts, 199; P. h y p o p h th a lm u s (Sauvage, 17); P. k in a b a ta n g a n e n s is Roberts & Vidthayanon, 1991; P. lith o sto m a Roberts, 199; P. n ieu w en h u isii (Popta, 190); P. p a n g a s iu s (H am ilton, 1) and P. rh eo p h ilu s Pouyaud et al., 000 from Bangladesh, India, Indonesia, Malaysia and Thailand (see Tripathi, 197; Lim, 1990; Pariselle et al., 001 a, b). MATERIALS A N D METHODS F ish w ere bought in fish markets or directly from fishermen: P. b o c o u r ti from Vietnam, P. d ja m b a l from Indonesia (Java, Sumatra and Kalimantan Islands), P. h y p o p h th a lm u s from Vietnam and Indo 07

2 PARISELLE A., LIM L.H.S. & LAMBERT A. nesia, and P. g ig a s from Thailand. Fish w ere caught in rivers using lines, nets or in aquaculture facilities (cages or ponds). The left branchial arches o f each fishes w ere separated into dorsal and ventral sections, and frozen in liquid nitrogen, until examination. The host carcasses w ere num bered, fixed and preserved in formalin to verify the specific identity o f host fishes. In the laboratory, the gills w ere thawed and the monogeneans w ere detached from the gill using a strong w ater current. The m onogeneans w ere then trans ferred individually on a slide with a mounted needle, into a drop o f ammonium picrate-glycerine (mixture described by Malmberg (197)). The preparation was then covered with a round cover slip and sealed with Glyceel (GURR - BDH Chemicals Ltd.). From these pre parations, drawings w ere m ade o f the sclerotised pieces o f the haptor and o f the copulatory com plex using a cam era lucida. M easurements, m ade with a digitiser, in micrometers as the m ean ± the standard deviation follow ed by the range in parentheses, are those proposed by Gussev (19) (Fig. 1). The method o f num bering o f the haptoral pieces is that adopted at ICOPA IV (Euzet & Prost, 191). Term inology is that o f Pariselle & Euzet (199) and N D ouba et al. (1999). Fig Measurements used in this study. C = cuneus: L = length; l = lar gest width; e = extension length. DB = dorsal transverse bar: x = total length; w = width in the middle. DG = dorsal gripus: a, b, c. d and e = standard measurements. MA = male apparatus: Pe = total length of the penis; Ap - length o f the accessory piece; He = length of the heel. U = total length of the uncinuli. VB = ventral transverse bar: x = length of one branch: w = largest width. VG = ventral gripus: a, b, c, d and e = standard measurements; L and l = length and width of gripus aperture. Box: measurements of spiral dia meter for the penis (MA) and the vagina (Vg) in T. euzeti n. sp. 0

3 Mo n o gen ea n s fro m P angasiidaf. RESULTS Seven m onogenean species1 were recorded from P. bocourti, P. d ja m b a l and P. hypophthalm u s, all belonging to n a p a r o c le id u s (Ancylodiscoidinae, Monogenea) as defined by Lim (199). Two have been 1An eighth species was found on P. djam bal from the Indragiri River at Rengat (Riau province, Sumatra Island, Indonesia), but only four worms could be examined, it is too few to describe this new species. previously described: T h ap arocleid u s c a ecu s (Mizelle & Kritsky, 199), recovered from P. d ja m b a l both in ponds (Sukamandi Research Station, West Java, Java Island, Indonesia) and in the wild (Solo River at Cepu, East Java, Java Island, Indonesia); and on P. h yp op h thalm u s at the Sukamandi Research Station (West Java, Java Island, Indonesia), n a p a r o c le id u s siam en sis (Lim, 1990) recovered on P. hypophthalm u s in aquaculture facilities from Vietnam (cage on the Mekong River at Can Tho) and Indonesia (Sukamandi Research Station, West Java, Java Island). T hap arocleid u s ko m a ru d in i Fig.. - Thaparocleidus sadilii n. sp. C = cuneus; DB = dorsal transverse bar; DG = dorsal gripus; MA = male apparatus; VB = ventral transverse bar; VG = ventral gripus; U = uncinuli. Bar = 0 μm. 0 9

4 PARISELLE A.. LIM L.H.S. & LAMBERT A. n. sp. and T. c o m b e s i n. sp. w ere recorded from P. b o c o u r ti and P. d ja m b a l. T h a p a ro c leid u s v ietn am en sis n. sp. was found in Vietnam on P. b o co u r ti and P. h y p op h th a lm u s. T h a p a ro c leid u s s a d ilii n. sp. and T. e u z e ti n. sp. w ere recorded from P. d ja m b a l only (see descriptions below ). No m onogenean parasites w ere recorded on P. g ig a s in The M ekong River at Nong Khai (Thailand) (only two specim ens examined). DESCRIPTIONS T h a p a r o c l e id u s s a d il ii n. sp. (Fig. ) Type-host: P. d ja m b a l Bleeker, 1. Site: gills. Type-locality: Solo River at Cepu (East Java, Java Island, Indonesia). Material studied: 1 individuals. Type-m aterial: holotype deposited at the Muséum National d Histoire Naturelle (Paris): n HG, slide Tg 1. Paratypes deposited at the Muséum National d Histoire Naturelle (Paris): n HG, slide Tg 1; at The Natural History Museum (London): Adults: 9 ± 9.7 (1-7) long, ± 0. (79-19) w ide at level o f penis. Pharynx: 1 ± 7.1 (0-) wide. Dorsal gripus with blade bent at distal third, poorly marked guard: a = ± (-), b = ± 1. (0), c = 1 ± 0. (-), d = ± 1.1 (9-1), e = ± 1.1 (-7). Small cuneus with long extension: L = 9 ± 1. (-1), l = ± 0. (-), e = 7 ± 1. (-). Slightly curved, short dorsal transverse bar: x = ± 1. (), w = ± 0. (-). Ventral gripus with well-marked aperture, poorly developed guard: a = ± 0. (1), b = 1 ± 0.9 (19-), c = 1 ± 0. (-1.), d = ± (-7), e = 1 ± (1-1), L = ± (-), l = ± 0. (1-). Thin V-shaped ventral transverse bar with rounded extremities: x = 0 ± 1. (-), w = ± (-). Very thin uncinuli II = 1 ± 0.9 (9-1) long, uncinuli I and III to VII = 1 ± 0. (9-1) long. Long penis folded after bell-shaped basal bulb, constricted after proximal third and well developed heel: Pe = 1 ±. (-), He = ± 1. (-1). Long, large, Sshaped accessory piece linked to basal bulb o f the penis: Ap = ± -9 (-7). No visible vagina. Comments Among the 1 described species belonging to Th a p a ro cleid u s on P a n g asiu s hosts only four have a non spi rally coiled penis longer than 0 μm. T. s a d ilii n. sp. is easily distinguishable (no overlapping betw een the range o f m easurem ents) from: Only 1 individuals should be measured because P. d jam bal has become rare in the rivers of Java Island. - T. c h a n d p u r i Pariselle et al., 001 by the shape and size o f all the haptorial sclerotised pans, by the shape (non spirally coiled, thickening at the extrem ity) and the size (1 vs. μm) o f the penis. - T. p a n g a s i (Tripathi, 197) by the size o f the penis (1 vs. 11 pm) and the size o f the cuneus (9 vs. 0 pm) (m easurem ents from Pariselle et al., 001). - T. m a b a k a m e n s is Pariselle et al., 001 by the size o f the penis (1 vs. 19 pm) and the size o f the dorsal and ventral gripus ( vs. 9 pm and vs. 1 pm). T. s a d ilii n. sp. is close to T. s in e s p in a e Pariselle et al., 001 but may b e distinguished in having a shorter penis (1 vs. 1 pm). T h ap a rocleid u s sa d ilii n. sp. is named for M. Didi Sadili from the Department o f Sea Exploration and Fisheries in Jakarta w ho provide the specim ens o f P. d ja m b a l from Java Island. T h a p a r o c l e id u s k o m a r u d in i n. sp. (Fig. ) Type-host: P. d ja m b a l Bleeker, 1. Site: gills. Type-locality: Batang Hari River at Jam b i (Jam bi pro vince, Sumatra Island, Indonesia). Also found on P. b o c o u r ti Sauvage, 10 in aquacul ture cages on the M ekong River at Chau D oc (Viet nam). Material studied: 0 individuals (1 from P. d ja m b a l and 1 from P. bocou rti). Type-m aterial: h olotype d eposited at the M uséum National d Histoire Naturelle (Paris): n 9 HG, slide Tg 179. Paratypes deposited at the Muséum National d Histoire Naturelle (Paris): n 9 HG, slide Tg 10; at The Natural History Museum (London): Very large worms, adults: 1 ±. (71-7) long, ± 7. (19-) wide at level o f penis Pharynx: ± 1. (-1) wide. Dorsal gripus with blade bent at distal third, poorly marked guard: a = 7 ±. (9), b = 7 ± 1. (-0), c = l ± 0. (-), d = 1 ± 1. (-1), e = + 1. (-). Short cuneus with short extension: L = 9 ± 1. (7-1), l = ± (-), e = ± 0.9 (1-). Slightly straight dorsal transverse bar: x = ± 1. (-0), w = ± (-7). Ventral gripus with very small aperture (som etim es not visible), large, rounded blade, poorly developed guard: a = ± l (-7), b - 1 ± 0. (19-), c = l ± 0. (0.-), d = ± 1 (-), e = 1 ± 1 (1-1), L = ± 0.9 (0-), l = 1 ± 0. (0-). Thin V-shaped ventral transverse bar: x = ± (9-), w = ± (-). Thin uncinuli II = 1 ± 1. (-17) long, uncinuli I and III to VII = 1 ± 0. (9-1) long. Long penis folded after bell-shaped basal bulb, distal quarter covered with very thin scab bard, w hich extremity is thickened, developed heel: Pe = 1 ± 7. (91-), He = 7 ± 1. (-). D ouble accessory piece linked to basal bulb o f the penis: one long and S-shaped: Ap = 7 ±.7 (-), the second

5 M o n o gen ea n s fro m Pangasiidae Fig.. - Thapcirocleidus kom arudini n. sp. C = cuneus; DB = dorsal transverse bar; DG = dorsal gripus; MA = male apparatus; VB = ventral transverse bar; VG = ventral gripus; U = uncinuli. Bar = 0 μm. one straight and round ended: 0 ±. (0-) long. No visible vagina. Comments T. k o m a ru d in i n. sp. is morphologically close to the previously cited T haparocleidu s species found on P an - g asiu s host (see above), but may be easily distinguished in having a double accessory piece. Thaparocleidus kom aru din i n. sp. is named for M. Oman Komamdin from the Central Research Institute for Freshwater Fisheries in Sukamandi (Indonesia) who help in collecting material. Th a p a r o c l e id u s c o m b e s i n. sp. (Fig. A and B) Type-host: P. d ja m b a l Bleeker, 1. Site: gills. Type-locality: Barito River at Buntok (Central Kalimantan province, Borneo Island, Indonesia). Other locality: also found on the same host in the Batang Hari River at Jam bi (Jambi province, Sumatra Island, In d o n esia); in the ponds o f Sukam andi Research Station (West Java, Java Island, Indonesia) and in the Solo River at Cepu (East Java, Java Island, Indonesia). Also found on P. b ocou rti Sauvage, 10 in aquaculture cages on the Mekong River at Chau Doc (Vietnam). Material studied: 0 individuals. Type-material: holotype deposited at the Muséum National d Histoire Naturelle (Paris): n HG, slide Tg 177. Paratypes deposited at the Muséum National d Histoire Naturelle (Paris): n HG, slide Tg 17; at The Natural History Museum (London): Very large worms, adults: 17 ± 1. (-1) long, 197 ± 7 (1-) wide at level o f penis. Pharynx: 77 ±. (-90) wide. Very large dorsal gripus

6 Fig. A. - Thaparocleidus combesi n. sp. haptorial sclerotised parts: C = cuneus; DB = dorsal transverse bar; DG = dorsal gripus; VB = ventral transverse bar; VG = ventral gripus; U = uncinuli. Bar = 0 pm. Fig. B. - Thaparocleidus combesi n. sp. genitalia: MA = male apparatus; Vg = vagina. Bar = 0 μm. 1

7 M on o genean s with blade bent at distal third, short guard: a = ± - (1-17), b = ± - (0-1), c = ± 1 (1.-), d = 1 ±.7 (-), e = ±. (7-70). Very large cuneus with short extension: L = ± (7-9), 1 = 19 ± 1.1 (1-), e = ± 1. (-9). Very large, slightly curved dorsal transverse bar: x = 7 ±. (-91), w = ± 1 (-1). Very large ventral gripus without aper ture: a = ±.7 (-7), b = ± -1 (-1), c = ± 1. (1-), d = ± (19-7), e = 0 ± 1. (-). V-shaped ventral transverse bar: x = ±.1 (9-9), w = ± 0. (-). Thin uncinuli II = 1 ± 1. (-1) long, strong uncinuli I and III to VII = 17 ± 1. (1) long. Very long, thin, spirally coiled (1-1 turns) penis with short heel, ovoid basal bulb; as this tube is very long, coiled in a double helix and with a very thin ending it is virtually im possible to take a reliable measurement, the length have b een estimated on one specim en: Pe =, heel (m easured on 0 speci mens): He = 7 ± 1.1 (-). No accessory piece. The vagina is very long, sinuous and becom e less and less sclerotised so no m easurem ent could be taken. Comments Only three T h a p a ro c leid u s species have been des cribed with a spirally coiled penis: T. b rev ico ch le u s Pariselle et a l., 0 0 1, T. ka p u a sen sis Pari.selle et a l., 001 and T. g u stia n o i Pariselle e t al., T. c o m b e s i n. sp. is easily distinguishable from all these species (and all the species o f T h a p a ro c leid u s described until now ) by fr o m P a n g ash da e the larger size o f all the sclerotised parts o f genitalia and haptor apparatus. T h a p a ro c leid u s c o m b e s i n. sp. is named in honour o f Pr. Claude Combes, parasitologist from the University o f Perpignan (France). Th a p a r o c l e i d u s eu zeti n. sp. (Fig. A and B) Type-host: P. d ja m b a l Bleeker, 1. Site: gills. Type-locality: Batang Hari River at Jam bi (Jam bi pro vince, Sumatra Island, Indonesia). Other locality: also found on the same host in the Indragiri River at Rengat (Riau province, Sumatra Island, Indo nesia). Material studied: 0 individuals. Type-m aterial: holotype deposited at the Muséum National d Histoire Naturelle (Paris): n 1 HG, slide Tg 1. Paratypes deposited at the Muséum National d'histoire Naturelle (Paris): n 1 HG, slide Tg 1; at The Natural History Museum (London): n Adults: 99 ±. (-7) long, ± 1- (7-1) wide at level o f penis. Pharynx: ±. (-9) wide. Dorsal gripus with blade bent at distal third, poorly marked guard: a = ±.1 (0-), b = ±.1 (), c = 1 ± 0. (-), d = 17 ± 1.7 (1-1), e = 0 ± 1. (-). Large cuneus with extension: L = ± 1. (-), 1 = 7 ± (-), e = ± 1 (-9). Strong, slightly curved dorsal transverse bar: x = ± 1.9 (9-7), w = Fig. A. - T haparocleidus euzeti n. sp. haptorial sclerotised parts: C = cuneus; DB = dorsal trans verse bar; DG = dorsal gripus; MA = male appa ratus; VB = ventral transverse bar; VG = ventral gripus; U = uncinuli. Bar = 0 μm. Parasite, 00, 9,

8 PARISELLE A., LIM L.H.S. & LAMBERT A. Fig. B. - Thaparocleidus euzeti n. sp. genitalia: MA = male apparatus; Vg = vagina. Bar = 0 μm. ± 0.9 (7-). Ventral gripus with large aperture, poorly developed guard: a = ± (1-), b = ± (-), c = 1. ± 0. (0.-), d = 1 ± 0.9 (-1), e = 19 ± (1-0), L = ± (-), 1 = ± 0. (1-). Vshaped ventral transverse bar: x = ± 1. (1-7), w = ± (-). Long, thin uncinuli II = 17 ± 1. (10) long, strong uncinuli I and III to VII = 17 ±. (0) long. Extremely long and thin spirally coiled penis with an ovoid basal bulb attached on a large cupule like structure (diameter = ±. (19-1)), no visible heel. The length o f such very thin tube is impossible to mea sure because the specimens are squashed betw een slide and cover slip. W e could only give the diameter o f the spiral (1 ± 7. (7-7) from the 0 specim ens) and a rough estimation o f the total length and number o f turns, 1 taken from one very well preserved individual: 70 pm and = turns. Very simple accessory piece apparently not linked to basal bulb o f penis: Ap = ±.7 (). Extremely long, thin, well sclerotised, spirally coiled (double pitch) vagina, largest diameter o f spiral = ±. (-1), diameter o f tube at distal extremity = ± 0. (1-), the total length is impossible to estimate as w e could not count the number o f turns (squashed indi viduals and double pitch spiral). Comments Now four T h a p a ro c leid u s species have been described with a spirally coiled penis: T. h r ev ico ch leu s Pariselle e t al., 001, T. k a p u a sen sis Pariselle et a l., 001, T. gu st ia n o i Pariselle et al., 001 and T. c o m b e s i n. sp. (see

9 M o n o gen ea n s fro m P angashdae above); T. eu zeti n. sp. is easily distinguishable from all these species by the great number of turns and the huge length of the penis, and by the shape of the vagina (spirally coiled). The name Th a p a ro cleid u s eu zeti n. sp. is proposed in honour o f Pr. Louis Euzet, parasitologist from the University o f Montpellier (France). T h a p a r o c le id u s VIETNAMENSIS N. SP. (Fig. ) Type-host: P. b oco u rti Sauvage, 10. Site: gills. Type-locality: Aquaculture cages on the Mekong River at Chau D oc (Vietnam). Also found at the same location on P. hypophthalm u s Roberts, 199, P. ku n yit Pouyaud et a l, 000 and P. co n ch o p h ilu s Roberts & Vidthayanon, Material studied: individuals ( from P. bocourti, P. hypophthalm u s, P. con ch o p h ilu s and three from P. kunyit). Type-material: holotype deposited at the Muséum National d Histoire Naturelle (Paris): n 0 HG, slide Tg 11. Paratypes deposited at the Muséum National Fig.. Thaparocleidus vietnamensis n. sp. C = cuneus; DB = dorsal transverse bar; DG = dorsal gripus; MA = male apparatus; VB = ventral transverse bar; VG = ventral gripus; U = uncinuli. Bar = 0 μm. 1

10 PARISELLE A., LIM L.H.S. & LAMBERT A. Species T. vietnamensis T. caecus Measurements Mean St. D. Min Max Mean St. D. Min Max Total length Width at level of penis Pharynx diameter Copulatory tube total length Heel Accessory piece total Length Uncinuli II total length Other uncinuli total length Dorsal transverse bar total length Dorsal transverse bar width at middle Cuneus length 9 Cuneus extension length Cuneus maximum width Dorsal gripus a Dorsal gripus b Dorsal gripus c Dorsal gripus d Dorsal gripus e One branch of ventral bar length Ventral bar maximum width Ventral gripus a Ventral gripus b Ventral gripus c Ventral gripus d Ventral gripus e Ventral gripus aperture length Ventral gripus aperture width Table I. - Measurements from T. vietnam ensis n. sp. and T. caecus. d Histoire Naturelle (Paris): n 0 HG, slide Tg 1; The Natural History Museum (London): n T. v ietn a m en sis is very close to T. ca e cu s, but could b e easily distinguished (n o overlap o f range) by: the length o f the copulatory tube (91 vs. 9 pm), o f the M easurements are given in Table I, with those from accessory piece ( vs. pm and the distance b et 1 T. c a e c u s individuals recovered on both P. d ja m b a l w een the spine like structure and the extremity o f the and P. h y p o p h th a lm u s from the ponds o f the Sukacopulatory tube (1 vs. 1 μm). mandi Research Station (W est Java, Java Island, Indo The nam e T h a p a ro c leid u s v ietn a m en sis n. sp. is pro nesia). The m orphology o f all sclerotised parts is very posed for the location (Vietnam vs. Peninsular Malaysia close to that o f T. c a e c u s (see Lim, 1990): dorsal gripus (Lim, 1990) or Indonesia and Malaysia (Pariselle et al., with blade bent at distal third, poorly marked guard; 001b) for closely related species). cuneus with marked extension; slightly curved dorsal transverse bar; ventral gripus w ith large aperture, poorly developed guard; V-shaped thin ventral trans C O N C LU SIO N S verse bar; thin uncinuli I to VII; S-shaped penis with thin, curved extremity, spine like structure at 1 ±. (-1); cylindrical basal bulb attached on a large heel; h a p a ro cleid u s ca ecu s, described in the United no visible vagina. States on an unidentified aquarium fish com ing T Comments T. v ietn a m en sis n. sp. is m orphologically (shape o f sclerotised parts) close to T. s a d ilii n. sp., T. m a h a k a m en sis Pariselle et al., 001 and T. s in e s p in a e Pariselle et al., 001; but could be distinguished mainly because all these species have a copulatory tube longer than 0 pm {vs. 91 pm for T. vietn am en sis). 1 from Thailand (Mizelle & Kritsky, 199), was recovered by Lim (1990) from cage culture in Malaysia on P. su tc h i (syn. P. h y p op h th a lm u s) also imported from Thailand. This parasitic species was found again in Indonesia (nobis) on P. h y p o p h th a lm u s introduced from Thailand for culture purpose, and on P. d ja m b a l in the wild and in aquaculture facilities. So w e may w onder what is the natural host for T. ca ecu s, as Mono-

11 M o n o g e n e a n s fro m P angash dae genea are considered species specific toward their hosts. W e may say that it is P. d ja m b a l (only occurrence in the wild), but: - T. c a e c u s was found on P. d ja m b a l in two locations only (Solo River and Sukamandi Research Station), the ones w here P. h y p o p h tb a lm u s was also introduced (for culture purpose). - These two host species are naturally allopatric ( P. h ypo p h tb a lm u s from the M ekong basin, P. d ja m b a l from Indonesia) and phylogenetically well separated (Pouyaud et al., 000). - No P. d ja m b a l was introduced to Thailand or Malaysia. So w e may suppose that there was in Indonesia a lateral transfer o f T. c a e c u s betw een P. hyp op h th a lm u s and P. d ja m b a l both in the wild and in the ponds o f the Sukamandi Research Station. Is the p resence o f T h a p a ro c leid u s c o m b e s i n. sp. and T. k o m a r u d in i n. sp. both on P. b o co u r ti and P. d ja m b a l, due to lateral transfers? In this case: - There w as no introduction neither o f P. d ja m b a l in Vietnam nor o f P. b o c o u r ti in Indonesia. - These two fish species are closely related (Pouyaud et al., 000). So w e may suppose that T. c o m b e s i and T. k o m a r u d in i occur naturally on both host species and were inherited from their ancestor. The presence o f T. v ietn am en sis n. sp. on four different host species (P. bocourti, P. hypophth alm us, P. ku n yit Pouyaud et al., 000 and P. c o n c h o p b ilu s Roberts & Vidthayanon, 1991) sampled in aquaculture facilities on the M ekong Delta, may be the result o f lateral transfer or o f natural occurrence, as all these host species ori ginate from this river. The present five new species bring the number o f T h a p a r o c le id u s species described on species o f pangasiids (P. bocou rti, P. d ja m b a l, P. gigas, P. h u m eralis, P. hypophthalm us, P. k in a b a ta n g a n e n sis, P. lithostom a, P. n ieu w en hu isii, P. p a n g a s iu s and P. rheophilu s) to 17. The diversity o f m onogenean species on the stu died host species is now variable from zero to six. ACKNOWLEDGEMENTS T his work was part o f a project on the characte risation utilisation and m aintenance o f biological diversity for the diversification and sustainability o f catfish culture in Southeast Asia supported by the European Commission (grant IC1-CT9-00). D raw ings by: Dr. N athalie Le B ru n, L abo rato ire G énom e, Populations, Interactions, UMR 000, CC, Université M ontpellier II, Sciences et Techniques du Languedoc, Place Eugène Bataillon, 09 Montpellier, Cedex, France. REFERENCES L. & P r o s t M. Report of the meeting on Monogenea: problems of systematics, biology and ecology. In: Slusarski W. (Eds). Review o f advances in parasitology. Warsaw: P.W.N. Polish Scientific Publishers, 191, pp G u ssev A.V. In: Bychovskaya-Pavlovskaya I.E. et al. (Eds) [Key to parasites o f freshw ater fish o f the USSR] Moscow-Leningrad: Academiya Nauk SSSR, 19, 919 pp. (In Russian: English translation IPST, Ser. No., Jerusalem, 19). Eu zet Silurodiscoides Gussev, 191 (Monogenea: Ancyrocephalidae) from Pangasius sutchi Fowler, 191 (Pangasiidae) cultured in Peninsular Malaysia. Raffles Bulletin o f Zoology, 1990,, -. Lim L.H.S. Thaparocleidus Jain, 19, the senior synonym of Silurodiscoides Gussev, 197 (Monogenea: Ancyrodiscoidinae). Systematic Parasitology, 199,, Lim L.H.S., T im o fe e v a T.A. & G ib s o n D.I. Dactylogyridean monogeneans of the siluriform fishes of the old world. Systematic Parasitology, 001, 0, M a lm b e rg G. [On the occurrence of Gyrodactylus on Swe dish fishes.] Skrifterutgivna av Sodra Sveriges Fiskeriforening, (19), 197, pp (In Swedish, with descrip tion of species and a summary in English). Lim L.H.S. J. & K r its k y D.C. Studies on monogenetic trematodes. XXXIX. Exotic species of monopisthocotyles with the pro posal of Archidiplectanum gen. n. and Longihaptor gen. n. Amer. Midi. Nat., 199, 1, 70-. N D o u b a V., L a m b ert A. & E u z e t L. Gill parasites of the genus Q uadriacanthus Paperna, 191 from Heterobranchus longifilis and H. isopterus with description of seven new spe cies from Côte d Ivoire, West Africa. Systematic Parasito logy, 1999,, -. P a r is e lle A. & E u z e t L. Gill parasites of the genus Cichlidogyrus Paperna, 190 (Monogenea, Ancyrocephalidae) from Tilapia guineensis (Bleeker, 1), with descriptions of six new species. Systematic Parasitology, 199, 0, P a r is e lle A., Lim L.H.S. & L a m b e rt A. Monogeneans from Pangasiidae (Siluriformes) in Southeast Asia: I. Five new spe cies of Thaparocleidus Jain, 19 (Ancylodiscoidinae) from Pangasius pangasius, P. kinabatanganensis, P. rheophilus and P. nieuwenhuisii. Parasite, 001a,, P a r is e lle A., Lim L.H.S. & L a m b e rt A. Monogeneans from Pangasiidae (Siluriformes) in Southeast Asia: II. Four new spe cies of Thaparocleidus Jain, 19 (Ancylodiscoidinae) from Pangasius humeralis. Parasite, 001b,, 17-. P o u y a u d L., T e u g e ls G.G., G u s tia n o R. & L e g e n d re M. Contri bution to the phylogeny of pangasiid catfishes based on allozymes and mitochondrial DNA. Jou rn al o f Fish Biology, 000,, T r ip a th i Y.R. Monogenetic trematodes from fishes in India. Indian Jou rn a l o f Helminthology, 197, 9, M iz e lle On P. djam bal, including T. caecu s (lateral tranfer?) and the rare non described one. Parasite, 0 0, 9, Reçu le 1 novembre 001 Accepté le 1 mai 00 17