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1 Article available at or A REVIEW OF THE ARHYTHMACANTHIDAE (ACANTHOCEPHALA) WITH A DESCRIPTION OF HETEROSENTIS HIRSUTUS N. SP. FROM CNIDOGLANIS MACROCEPHALA (PLOTOSIDAE) IN AUSTRALIA PICHELIN S.* & CRIBB T. H.* Résumé : UNE RÉVISION DE LA FAMILLE ARHYTHMACANTHIDAE Summary: (ACANTHOCEPHALA) ET UNE DESCRIPTION D'UNE ESPÈCE NOUVELLE DE Heterosentis hirsutus n. sp. is described from Cnidoglanis CNIDOGLANIS MACROCEPHALA (PLOTOSIDAE) EN AUSTRALIE macrocephala (Siluriformes: Plotosidae) from the Swan Estuary, Western Australia. It is distinguished by having 14 longitudinal Heterosentis hirsutus n. sp. est décrite de Cnidoglanis rows of 6-7 hooks per row on the proboscis, a trunk armed macrocephala (Siluriformes: Plotosidae) du Swan Estuary, Australie anteriorly and posteriorly (=genital spines) with minute spines and occidentale. L'espèce est distinguée par la présence de 14 files lemnisci that may extend to the posterior margin of the proboscis longitudinales de 6-7 crochets chacune sur le proboscis, un tronc receptacle. The new species also has prominent fragmented nuclei portant des épines cuticulaires de petite taille sur la partie in its ttunk wall. New information is given for Heterosentis plotosi antérieure et autour de l'orifice génital, et de lemnisques qui ne Yamaguti, 1935 from Plotosus lineatus (Siluriformes: Plotosidae) sont pas plus longs que le réceptacle. Le tégument de l'espèce and H. paraplagusiarum (Nickol, 1972) Amin, 1985 from nouvelle contient des fragments de noyaux géants. Des données Paraplagusia guttata (Pleuronectiformes: Cynoglossidae), both from nouvelles sur Heterosentis plotosi Yamaguti, 1935 récoltée chez Queensland. A key to the species of Heterosentis Van Cleave, Plotosus lineatus (Siluriformes: Plotosidae) et sur 1931 is provided. The Arhythmacanthidae subfamilies are H. paraplagusiarum (Nickol, 1972) Amin, 1985 récoltée chez reviewed: there is little utility in the recognition of these taxa Paraplagusia guttata (Pleuronectiformes:Cynoglossidae) sont because of the small number of genera involved and the validity présentées. Une clé de détermination est établie pour les espèces of the characters on which they are based is in doubt, particularly d'heterosentis Van Cleave, Les sous-familles whether ttunk spines are present or absent. Only darhythmacanthidae sont réexaminées: il nous semble que ces Acanthocephaloides Meyer, 1932, Breizacanthus Golvan, 1969, sous-familles sont de peu d'importance à cause du petit nombre Euzetacanthus Golvan & Houin, 1964, Heterosentis, de genres et que les caractères taxonomiques sont douteux, surtout Hypoechinorhynchus Yamaguti, 1939 and Paracanthocephaloides la présence ou l'absence d'épines sur le tronc. Seule Golvan, 1969 of the Arhythmacanthidae are considered valid. A Acanthocephaloides Meyer, 1932, Breizacanthus Golvan, 1969, key to these genera is provided. The monotypic genus Euzetacanthus Golvan & Houin, 1964, Heterosentis, Neoacanthocephaloides Cable & Quick, 1954 is considered a Hypoechinorhynchus Yamaguti, 1939 et Paracanthocephaloides new synonym of Acanthocephaloides thus creating Golvan, 1969 sont valides. Une clé de détermination pour ces Acanthocephaloides spinicaudatus (Cable & Quick, 1954) n. genres est donnée. Le genre Neoacanthocephaioides est comb. Arhythmacanthus Yamaguti, 1935 is maintained as a consideré comme un synonyme de Acanthocephaloides; donc la synonym of Heterosentis because the distinction between two and seule espèce du genre Neoacanthocephaioides Cable & Quick, three hook types is made equivocal when the transition between 1954 devient Acanthocephaloides spinicaudatus (Cable & Quick, the apical and subapical hooks is gradual. 1954) n. comb. Le genre Arhythmacanthus Yamaguti, 1935 reste un synonyme d'heterosentis car la différence entre les types de KEY WORDS : Arhythmacanthidae, Acanthocephala, Heterosentis, taxonomy, crochets apicaux et sous-apicaux n'est pas évidente. En effet, fish, Plotosidae, new species, Australia. lorsque la transition entre ces crochets se fait de manière MOTS CLÉS : Arhythmacanthidae, Acanthocephala, Heterosentis, taxonomie, graduelle, il devient difficile de distinguer précisément entre deux poisson, Plotosidae, nouvelle espèce, Australie. ou trois types de crochets. INTRODUCTION There are about fifty species of acanthocephalans known from Australian hosts (Edmonds, 1989). A recent investigation into the parasitic * Department of Microbiology and Parasitology, The University of Queensland, Brisbane, 4072 Australia. Correspondence: Dr Sylvie Pichelin. Tel. : (61) (7) Fax : (61) (7) pichelin@mailbox.uq.edu.au fauna of some Western Australian and Queensland fish yielded specimens of acanthocephalans. These appeared to belong to the Arhythmacanthidae Van Cleave, 1931 because they possessed six cement glands and an abrupt transition on the proboscis from the small basal hooks (= spines) without roots to larger subapical or apical hooks with roots. The only arhythmacanthids recorded from Australian hosts are Heterosentis paraplagusiarum (Nickol, 1972) Amin, 1985 from Paraplagusia guttata (Cynoglossidae) in Moreton Bay, Queensland (Nickol, 1972), Hypoechinorhynchus 293

2 PICHELIN S. & CRIBB T.H. alaeopis Yamaguti, 1939 from Callionymus calauropomus (Callionymidae) and Notolabrus tetricus (as Pseudolabrus tetricus) (Labridae) in southern Australian waters (Johnston & Edmonds, 1947; Edmonds, 1989) and Hypoechinorbynchus robustus Pichelin, 1999 from Notolabrus parilus (Labridae) from Western Australia (Pichelin, 1999). Collection of three species of arhythmacanthids in Australian waters created the opportunity to review the taxonomy within the family. MATERIALS AND METHODS Acanthocephalans were removed from the intestines of fish, washed in 0.85 % saline, fixed in Berland's fluid (95 % glacial acetic acid and 5 % formalin) and stored in 70 % ethanol. Specimens were stained with Mayer's haematoxylin, dehydrated through a graded series of alcohols, cleared with methyl salicylate and mounted in Canada balsam. Drawings were made with the aid of a camera lucida and added to by hand. Measurements, presented as the range with the mean in parenthesis, are given in micrometres. Abbreviations used: AHC - Australian Helminthological Collection, South Australian Museum, Adelaide, Australia; QM - Queensland Museum, Queensland, Australia. RESULTS HETEROSENTIS HIRSUTUS N. SP. (Fig. 1; Table I) Type host: Cnidoglanis macrocephala (Plotosidae) Type locality: Swan Estuary, Western Australia Site in host: intestine Specimens deposited: QM G (holotype), QM G (paratypes), AHC (paratypes). Description Arhythmacanthidae. Arhythmacanthinae. Sexual dimorphism not pronounced but females larger than males. Proboscis cylindrical, armed with 14 longitudinal rows: H. hirsutus n. males sp. H. hirsutus n. females sp. H. piotasi males H. plotosi females Proboscis apical hook (51) n = (55) n = (39) n = (43) n = 6 Proboscis subapical hook (73) n = (82) n = (74) n = (81) n = 6 Proboscis basal hook (23) n = (28) n = (22) n = (24) n = 5 Proboscis basal hook (22) n = (24) n = (18) n = (20) n = 5 Proboscis basal hook (19) n = (21) n = (16) n = (18) n = 5 Proboscis basal hook (17) n = (18) n = (13) n = (14) n = 2 Proboscis basal hook (15) n = (15) n = (most basal) Trunk length (2508) n = (2896) n = (2673) i i (4859) n = 9 Trunk width (533) n = (540) n = (555) n = (824) n = 9 Proboscis length (245) n = (236) n = (167) n = (183) n = 7 Proboscis width (120) n = (129) n = (100) n (137) n = 7 Proboscis receptacle length (387) n = (402) n = (411) n = (503) n = S Proboscis receptacle width (126) n = (126) n = (130) n = (163) n = 8 Proboscis length: trunk length 1:10 1:12 1:16 1:27 Trunk spines extending (307) n = (307) n = (490) n = 4 - posteriorly from anterior end of trunk Trunk spines extending ante (212) n = n = 1 not present not present riorly from posterior end of trunk Lemnisci length (312) n = (404) n = (447) n = n = 1 Lemnisci width (96) n = (94) n = (58) n = n = 1 Anterior testis length (352) n = (374) n = 11 - Anterior testis width (223) n = (217) n = 11 - Posterior testis length (312) n = (362) n = 11 - Posterior testis width (219) n (216) n = 11 - Safftigen's pouch length 320 n = Safftigen's pouch width (137) n (137) n 10 - Cement glands width (91) n = (100) n 26 - Bursa (everted) length 230 n = (181) n = 2 - Bursa (everted) width 243 n = (165) n = 3 - Egg length (61.3) n = (51.0) n = 10 Egg width (14.7) n = (11.4) n = 10 Table I. - Measurements of specimens of Heterosentis hirsutus n. sp. and of new specimens of H. plotosi from Australian hosts. 294 Mise au point

3 A REVIEW OF THE ARHYTHCANTHIDAE Fig Heterosentis hirsutus n. sp. a) male specimen (holotype). b) female specimen (paratype). c) armature of proboscis showing abrupt transition from small rootless hooks (= spines) to larger hooks with roots, d) egg with filaments. Scale bars: a & b= 500; c = 50; d = 25. Mise au point 295

4 PICHELIN S. & CRIBB Т.Н. each row consists o f 1 medium apical h o o k ( 5 3 ) n = 14 with root ( 2 9 ) n - 12, 1 larger subapical h o o k ( 7 7 ) n = 22 with root ( 4 0 ) n = 15 and 4-5 small, basal, curved, rootless h o o k s ( 2 1 ) n = 105. Neck present, unarmed. Trunk fusiform, armed with minute posteriorly-pointing spines, extending from anterior end o f trunk to just beyond posterior margin of lemnisci in a wedge or v-shape; trunk also armed with minute spines near genital pore at dorso-posterior end. Fragmented nuclei present in mid-trunk wall. Pro boscis receptacle double-walled with cephalic ganglion at base. Lemnisci roughly equal in length, extend to about posterior margin of proboscis receptacle. Testes roughly oval, tandem, in mid to posterior part o f trunk. Cement glands 6, pyriform; some glands contiguous with margin o f posterior testis. Safftigen's pouch tubular to pyriform. Seminal vesicle partially obscured by cement glands and their ducts. Copulatory bursa with digital rays. Male genital pore terminal. Eggs elongated, ovoid with polar extension o f fertilization membrane; fila ments present. Female genital pore terminal. Comparison Heterosentis hirsutus n. sp. is distinguished from the other 11 species o f the genus by having a combina tion o f the following characters: 14 longitudinal rows o f h o o k s on the proboscis consisting o f 2 large apical h o o k s and 4-5 small basal h o o k s, a trunk armed with minute spines at its anterior and posterior ends, and lemnisci that extend to about the posterior margin o f the proboscis receptacle. H. hirsutus differs from H. overstreeti Schmidt & Paperna, 1978 by having spines restricted to the ante rior and posterior regions o f the trunk. H. overstreeti has s p i n e s c o v e r i n g the entire trunk ( S c h m i d t & Paperna, 1978). H. parasiluri Yin & Wu, 1984 also has spines on its posterior end (Yu & Wu, ) but has fewer small basal h o o k s (n = 2) and more large apical h o o k s (n = 3 ) per longitudinal row on the proboscis (Yin & Wu, ) than H. hirsutus. This new species resembles a few species o f Heterosentis Van Cleave, 1931 that lack spines on the posterior part o f the trunk. H. paraplagusiarum and H. fusiformis Yamaguti, 1935 have longer hooks than H. hirsutus: the longest hooks o f H. paraplagusiarum (Nickol, 1972) are long (Nickol, 1972) and those o f H. fusiformis are long (Yamaguti, ) whereas the longest h o o k s o f H. hirsutus are only long. It is not clear whether H. pseudobagri (Wang & Zhang, 1987) has pos terior trunk spines but it differs from H. hirsutus by having fewer longitudinal rows (n = 12), fewer small basal hooks (n = 2 ) and more large apical hooks (n = 3 ) per longitudinal row on the proboscis (see Wang & Zhang, 1987). H. heteracanthus (Linstow, 1896) as redescribed by Zdzitowiecki ( ) has 10 rows o f 3-5 pro 296 boscis hooks whereas H. hirsutus has 14 rows o f 6-7; H. heteracanthus also has lemnisci longer than its pro boscis receptacle and the trunk spines extend further down the trunk. H. hirsutus differs from H. thapari (Gupta & Fatma, ) by having more than the longitudinal rows and fewer than the 7-8 hooks per row described by Gupta & Fatma ( ) ; the h o o k s o f H. hirsutus are also considerably longer. H. septacanthus (Sita in Golvan, 1969) has smaller apical proboscis hooks and lemnisci twice as long as the proboscis receptacle (see Golvan, 1969). T h e eggs o f H. zdzitowieckii (Kumar, ) are smaller, long, (Kumar, 1992) than those o f H. hirsutus. H. caballerof Gupta & Fatma, 1985 has only 10 rows o f h o o k s (Gupta & Fatma, ) as o p p o s e d to the 14 in H. hirsutus. H. plotosi Yamaguti, 1935 has a higher proboscis length to trunk length ratio than H. hirsutus: Yamaguti's (1935; 1939) specimens have a ratio o f 1:12 for his sole male specimen and 1:19 for females; see also Table I. Also the four giant muscle cells described for H. plotosi by Yamaguti ( ) were not seen in H. hirsutus. Conver sely, the scattered nuclei seen in H. hirsutus are absent in Yamaguti's ( ) H. plotosi. HETEROSENTIS PLOTOSI YAMAGUTI, ( F i g. 2; T a b l e I ) T y p e host: Plotosus lineatus (as syn. P. anguillaris) (Plotosidae) T y p e locality: Pacific coast o f W a k a y a m a Prefecture, Japan Site in host: intestine New specimens examined: QM G (vou chers) - all from Plotosus lineatus, Moreton Bay, Qld, Australia. Description Sexual dimorphism present; females larger than males. Proboscis short, globular, armed with longitu dinal rows: e a c h row consists o f 1 apical h o o k ( 4 0 ) n = 19 with root ( 2 2 ) n = 2, 1 larger subapical h o o k ( 7 6 ) n = 18 with root ( 3 4 ) n = 5 and 3-4 small basal curved rootless h o o k s ( 1 9 ) n = 54. Trunk fusiform, armed anteriorly with minute posteriorly-pointing spines, extending 'ventrally and posteriorly in v-shape; fragmented nuclei not seen in trunk wall. Proboscis receptacle double-walled, with cephalic ganglion at base. Large muscle cells 2, near base o f proboscis receptacle. Lemnisci equal, e x t e n d b e y o n d posterior margin o f p r o b o s c i s r e c e p t a c l e. Cement glands 6, pyriform. Testes oval, in mid to pos terior part o f trunk. Safftigen's pouch partially obscured by c e m e n t glands and ducts. Seminal vesicle oval. Genital pore terminal in males and females. Eggs elon gated, ovoid with polar extensions o f fertilization mem brane. Mise au point

5 Remarks The eggs of the specimens of H. plotosi from Moreton Bay (50-55 (51) x (11)) are slightly smaller than those recorded for the Japanese specimens (51-60 x 13-15) by Yamaguti (1939). However, the remainder of the measurements given by Yamaguti (1935; 1939) are sufficiently similar to those of the present study (Table I) that we believe our specimens to be conspecific with H. plotosi. Heterosentis paraplagusiarum (NICKOL, 1972) AMIN, 1985 Type host: Paraplagusia guttata (Cynoglossidae) Type locality: Moreton Bay, Qld, Australia Site in host: intestine Museum specimens examined: USNM (allotype), USNM (paratype) New specimens examined: QM G (vouchers) - all from Paraplagusia guttata, Moreton Bay, Qld. Description Sexual dimorphism not pronounced; females only slightly larger than males. Proboscis globular to claviform, armed with longitudinal rows: each row consists of 1 slender apical hook (43) n = 7, 1 large thick hook (77) n = 20 with root and 3-4 small basal curved rootless hooks (14) n = 19. Trunk fusiform, armed anteriorly with large posteriorly-pointing spines, extending ventrally and posteriorly in v-shape; spines become smaller posteriorly; fragmented nuclei in trunk wall absent. Proboscis receptacle double-walled, with cephalic ganglion at base. Lemnisci equal, extend beyond posterior margin of proboscis receptacle. Cement glands 6, pyriform. Testes round to oval, in mid to posterior part of trunk. Safftigen's pouch and seminal vesicle partially obscured by cement glands and ducts. Eggs elongated, ovoid with polar extensions of fertilization membrane. Fig Male specimen of Heterosentis plotosi Yamaguti, Scale bar: 500. Fig Male specimen of Heterosentis paraplagusiarum (Nickol, 1972) Amin, Scale bar: 250. Mise au point 297

6 males Nickol (1972) females males Presen t study females Proboscis apical hook (35) (35) (50) n = (41) n = 5 Proboscis subapical hook I (68) (68) - - Proboscis subapical hook II (116) (127) (71) n = (80) n - 13 Proboscis basal hooks (14) (23) (15) n = (14) n - 15 Trunk length (1358) n = (1818) n = 4 Trunk width (288) n = s (245) n = 4 Proboscis length (196) (212) (179) n = (171) n = 3 Proboscis width (145) (178) (104) n (115) n = 3 Proboscis receptacle length (228) n = s (265) n = 4 Proboscis receptacle width (80) n (92) n = 4 Trunk spines extending posteriorly n = 1 n a from anterior end of trunk Trunk length: spines distance 1:0.15 1:0.15 1:0.14 n/a Lemnisci length (528) - n/a (211) n = 4 Lemnisci width (60) - n/a 29 n = 2 Anterior testis length (370) (160) n = 7 - Anterior testis width (232) (122) n Posterior testis length (370) (152) n Posterior testis width (232) (119) n = 7 - Safftigen's pouch length Safftigen's pouch width (86) n = 8 - Cement glands width (125) Bursa (everted) length (111) n = 2 - Bursa (everted) width (127) n Table II. - Measurements of specimens of Heterosentis paraplagusiarum collected during the present study compared with those published by Nickol (1972). Remarks The measurements of the new specimens (Table II) are generally smaller than those given by Nickol (1972), particularly in the length of the largest hooks on the proboscis. However, since our specimens appear to be similar in most other respects (e.g. proboscis armature, ratio of trunk length to extent of trunk spines) we consider them tentatively to be Heterosentis paraplagusiarum. Our specimens are also from the type host and locality. KEY TO SPECIES OF THE HETEROSENTIS This key is based on information contained in the descriptions for Heterosentis caballerof by Gupta & Fatma (1985), for H. fusiformis by Yamaguti (1935), for H. heteracantbus by Zdzitowiecki (1984), for H. overstreeti by Schmidt & Paperna (1978), for H. paraplagusiarum by Nickol (1972), for H. parasiluri by Yin & Wu (1984) and Yu & Wu (1989), for H. plotosi by Yamaguti (1935, 1939), for H. pseudobagri by Wang & Zhang (1987), for H. septacanthus by Golvan (1969), for H. thapari by Gupta & Fatma (1979), for H. zdzitowieckii by Kumar (1992) and for H. hirsutus n. sp. from the present study. * The original spelling "cabellorof by Gupta & Fatma (1985) was a mistake since they dedicated Dr Caballero. their new species in honour of 1(0). Up to 12 longitudinal rows of hooks on proboscis or more longitudinal rows 8 2(1). Apicalmost hook up to 30 am long..//, thapari - Apicalmost hook longer than 30 \IM 3 3(2). Trunk spines extend well past receptacle but not to trunk end H. heteracantbus - Trunk spines cover entire body H. overstreeti - Trunk spines other than above 4 4(3). 3 or more small basal hooks on proboscis H. caballeroi - Fewer than 3 small basal hooks H. pseudobagri 8(1). Lernnisci not twice as long as proboscis receptacle..9 - Lemnisci twice as long as proboscis receptacle (8). No spines on posterior end of trunk 10 - Spines present on posterior end of trunk 12 10(9). Lemnisci equal in length 11 - Lemnisci unequal H. zdzitowieckii 11 (9).Longest proboscis hook less than 100 u.m long H. plotosi - Longest proboscis hook 100 u.m or longer H. paraplagusiarum 12(9). 3 large apical (incl. subapical) hooks or fewer on proboscis H. hirsutus - More than 3 apical hooks on proboscis..h.parasiluri 13(8). Anterior testis less than 500 u,m long H. septacanthus -Anterior testis 500 (im or longer H. fusiformis 298 Mise au point

7 DISCUSSION T h e diagnosis o f the Arhythmacanthidae Y a m a guti, as a m e n d e d by Golvan ( ) distinguishes this family from other a c a n t h o c e phalan families. T h e two most characteristic features of the family is the abrupt transition from small basal h o o k s (spines) without roots to larger apical (or subapical if present) h o o k s with roots o n the proboscis and the possession o f six c e m e n t glands. SUBFAMILIES Golvan ( ) used the presence and a b s e n c e o f trunk spines and their distribution to recognise three subfa milies in the Arhythmacanthidae. He suggested that the Arhythmacanthinae Yamaguti, are distinguished by having spines only o n the anterior part o f the trunk and a tendency for the proboscis to b e spherical; the Neoacanthocephaloidinae Golvan, I are dis tinguished by having spines on the anterior part o f the trunk and genital spines (= posterior trunk spines); and the Paracanthocephaloidinae Golvan, 1969 are distin guished by having n o trunk spines and a short and cylindrical proboscis. Recent discoveries o f spines on the posterior e n d o f the trunk o f species o f Arhyth macanthinae (Yu & Wu, ; present study) and the placement by Schmidt & Paperna ( ) o f their n e w species which has spines over the entire b o d y into Arhythmacanthus Yamaguti, has made these dis tinctions o f equivocal value. Arhythmacanthinae Yamaguti, This subfamily is currently represented by Heterosentis and Hypoechinorhynchus ( s e e Pichelin, ). T h e subfamily also previously contained Arhythmacanthus but this genus was synonymised with Heterosentis and all species o f Arhythmacanthus were transferred to Heterosentis ( s e e Amin, ). Kumar ( ) disagreed with this move, stating that species o f Arhythmacan thus had three types o f h o o k s and species o f Hetero sentis only two. T h e distinction b e t w e e n two and three types o f h o o k s is not clear. For e x a m p l e, H. plotosi was described by Yamaguti ( ) as having two kinds o f h o o k s and was put into Heterosentis. Schmidt & Paperna ( ), however, transferred H. plotosi to Arhythmacanthus, presumably b e c a u s e they consi dered the slender apical h o o k s distinct from the subapical h o o k s and small basal h o o k s. T h e transition from small basal spines to large apical (or subapical if present) h o o k s is abrupt in all arhythmacanthids (except A. cyrusi) but the transition from apical to subapical hooks, if it exists, is less evident and clearly gra dual in s o m e species. For this reason it can b e diffi cult to decide w h e t h e r there are two or three types o f h o o k s. It is p r o p o s e d h e r e that Arhythmacanthus should remain a junior synonym o f Heterosentis since the distinction b e t w e e n two and three h o o k types cannot b e m a d e reliably and consistently. This syno nymy requires the n e w combinations H. zdzitowieckii (Kumar, ) n. c o m b, and H. pseudobagri (Wang & Zhang, ) n. c o m b. T h e s e n e w combinations, Hete rosentis hirsutus n. sp., H. parasiluri Yin & Wu, 1984 and H. caballeroi Gupta & Fatma, 1985 have b e e n des cribed since Amin's ( ) classification. Thus, there appear to b e 12 species o f Heterosentis (including H. hirsutus) and four species o f Hypoechinorhynchus (H. alaeopis Yamaguti, 1939, H. magellanicus Szidat, 1950, H. thermaceri de Buron, 1988 and H. robustus Pichelin, ). A k e y to the species o f Heterosentis is provided above. Diagnosis: Arhythmacanthidae. Trunk spines always present; spines may b e restricted to the anterior end of the trunk, may b e present o n anterior and poste rior ends or may cover entire trunk. Proboscis short, globular or claviform with a tendency to have either about the same number o f large apical h o o k s as small basal h o o k s or fewer large h o o k s than small h o o k s. Included genera: Heterosentis Van Cleave, 1931 and Hypoechinorhynchus Yamaguti, Neoacanthocephaloidinae Golvan, I This subfamily is distinguished by the presence o f pos terior trunk (= genital) spines (Golvan, 1969) and is represented by two genera, Acanthocepbaloides and Neoacanthocephaloides ( s e e Amin, 1985). Species o f Acanthocepbaloides were considered to b e devoid o f trunk spines until Golvan ( I ) discovered spines along the entire length o f the trunk o f the type species, A. propinquus (Dujardin, ) Meyer, He a m e n d e d the generic diagnosis and considered the genus to contain provisionally A. propinquus, A. distinctus Golvan, 1969, A. incrassatus (Molin, ) Meyer, 1932, A. kostylewi Meyer, 1932 and A. soleae (Porta, ) Petrotschenko, Golvan ( ) assi gned Acanthocepbaloides rhinoplagusiae Yamaguti, 1935 and A. neobythitis Yamaguti, 1939 to Yamagutisentis Golvan, 1969 in the Echinorhynchidae b e c a u s e he considered the h o o k s on the proboscis to b e simply diminishing in size from anterior to posterior rather than being o f two distinct types. Paggi & Orecchia ( ) transferred Acanthocepba loides soleae to Paracanthocephaloides Golvan, 1969 b e c a u s e it lacked trunk spines. D e Buron & Maillard ( ) created Solearhynchus in the Echinorhynchidae to a c c o m m o d a t e this species principally b e c a u s e it lacked trunk spines and had only o n e type o f h o o k on the proboscis. Araki & Machida ( ) described two new species, Acanthocepbaloides ichiharai Araki & Machida, 1987 and Acanthocepbaloides claviformis Araki & Machida, Mise au point 299

8 1987. T h e y synonymised Yamagutisentis with Acanthocephaloides b e c a u s e they considered the p r e s e n c e or a b s e n c e o f trunk spines to b e unreliable at the generic level. Thus Y. rbinoplagusiae and Y. neobythitis were returned to Acanthocephaloides. As a result o f this action, the genus Acanthocephaloides n o w contains species with trunk spines that either are confined to the anterior region o f the trunk or cover the trunk enti rely. Bray, S p e n c e r J o n e s & Lewis ( ) described Acan thocephaloides cyrusi Bray, S p e n c e r J o n e s & Lewis, T h e y suggested that A. incrassatus and A. kostylewi s h o u l d b e p l a c e d in Paracanthocephaloides b e c a u s e descriptions o f these species failed to report spines on the trunk. A. cyrusi possesses h o o k s that gra dually increase in size towards the anterior e n d o f the proboscis (Bray, S p e n c e r J o n e s & Lewis, 1988). This feature is more characteristic o f the rhadinorhynchid genus Micracanthorhynchina than o f any arhythmacanthid genus. However, s p e c i m e n s o f A. cyrusi have six c e m e n t glands (Bray, Spencer J o n e s & Lewis, ) w h e r e a s Micracanthorhynchina is characterised as having o n l y four ( G o l v a n, ). It m a y b e that A. cyrusi requires a n e w genus. Cable & Quick ( ) created a monotypic genus, Neoacanthocephaloides, within the Echinorhynchidae o n the basis o f differences in proboscis armature, rela tive lengths o f lemnisci and proboscis receptacle, size and shape o f trunk, the distribution o f trunk spines and having anterior trunk spines directed posteriorly and posterior trunk spines directed anteriorly. T h e s e diffe rences n o longer warrant the recognition o f Neoa canthocephaloides particularly since Golvan ( I ) placed it in the Arhythmacanthidae. T h e proboscis armature o f N. spinicaudatus is similar to that o f Acan thocephaloides ichiharai Araki & Machida, 1987: N. spi nicaudatus has 10 rows o f 13 h o o k s (Cable & Quick, ) and A. ichiharai has rows o f h o o k s (Araki & Machida, ). T h e lengths o f the lemnisci of species o f Acanthocephaloides range from nearly as long as the proboscis receptacle as in A. rhinoplaguisae Yamaguti, 1935 ( s e e Yamaguti, ) to nearly twice as long as the receptacle as in A. claviformis Araki & Machida, 1987 ( s e e Araki & Machida, ). Thus, the relative length o f the lemnisci to proboscis receptacle length is not useful for distinguishing b e t w e e n the two genera. T h e posteriorly directed spines o f N. spini caudatus are also n o longer unique. This condition has b e e n shown for Acanthocephaloides propinquus by Golvan (1969, Fig ) and has b e e n noted by us using SEM (personal observations) also for A. propin quus. T h e description by Cable & Quick ( ) o f N. spinicaudatus is b a s e d o n a single male specimen. T h e y noted that the trunk tapered towards e a c h e n d from a prominent enlargement which they considered 300 a thickening o f the b o d y wall. Such enlargements or deformities are quite c o m m o n a m o n g a c a n t h o c e p h a lans and sometimes are the result o f the m e t h o d used to fix the worms. T h e size o f the trunk and its tape ring ends (= fusiform) are also not unusual in arhythmacanthids ( s e e descriptions a b o v e ). W e therefore p r o p o s e Neoacanthocephaloides as a junior synonym o f Acanthocephaloides and the n e w combination A. spi nicaudatus (Cable & Quick, ) n. c o m b. T h e Neoacanthocephaloidinae is thus restricted to a single genus, Acanthocephaloides. T h e proboscis o f neoacanthocephaloidines tends to b e elongate rather than spherical and also tends to have a greater n u m b e r o f large apical h o o k s than small basal h o o k s. As o p p o s e d to the arhythmacanthines w h i c h have either fewer or about the s a m e n u m b e r o f large apical (including subapical) h o o k s as small basal h o o k s o n the proboscis. B o t h subfamilies appear to have species with trunk spines confined to the ante rior e n d o f the trunk (e.g. Heterosentis heteracanthus, Acanthocephaloides rbinoplagusiae), have spines o n the anterior and posterior e n d s (e.g. H. hirsutus, A. spinicaudatus), have their trunks c o v e r e d with spines (H. overstreeti, A. propinquus). T h u s the main distinctions b e t w e e n arhythmacanthines and n e o a c a n t h o c e p h a l o i d i n e s are the s h a p e and armature o f the proboscis, not the distribution o f spines o n the trunk. This subfamily therefore contains A. propinquus, A. distinctus, A. geneticus de Buron, Renaud & Euzet, 1986, A. claviformis, A. ichiharai, A. rbinoplagusiae, A. neo bythitis, A. cyrusi and A. spinicaudatus n. c o m b. Diagnosis: Arhythmacanthidae. Trunk spines always present; spines may b e restricted to the anterior e n d o f the trunk or may- b e present on anterior and pos terior ends or may cover the entire trunk. Proboscis long, cylindrical with a t e n d e n c y to have a greater n u m b e r o f large apical proboscis h o o k s than small basal h o o k s. Included genera: Acanthocephaloides Meyer, 1932 ( n e w syn. Neoacanthocephaloides Cable & Quick, ). Paracanthocephaloidinae Golvan, T h e Paracanthocephaloidinae presently contains Para canthocephaloides, Euzetacanthus and Breizacanthus (see Amin, ) and is distinguished from the other subfamilies b y the c o m p l e t e a b s e n c e o f trunk spines (Golvan, 1969). It is possible that trunk spines will b e found o n n e w s p e c i m e n s o f these species b e c a u s e these spines are often small and difficult to see or, pos sibly, lost. This difficulty has b e e n discussed by Golvan ( ) w h o found spines on the type species o f Acan thocephaloides which was thought previously to b e without spines. It is also exemplified by the recent dis covery o f small spines o n the posterior region o f the Mise au point

9 trunk of H. parasiluri by Yu & Wu (1989) and H. hirsutus (present study). Euzetacanthus and Breizacanthus are also very similar to each other with few morphological characters to separate them (see Golvan (1969) for generic diagnoses). Conceivably some of the paracanthocephaloidine genera and perhaps the entire subfamily will fall into synonymy. Until then, we consider that the three genera should be retained despite the similarities in the proboscis hooks between species with trunk spines and those without. The following five species have been described or transferred to this subfamily and are considered to belong to this subfamily in addition to the six species listed in Amin (1985): Breizacanthus gofcwra Gaevskaja & Shukgaltor, 1984, Euzetacanthus golvani Gupta & Fatma, 1985, Euzetacanthus chorinemusi Gupta & Naqvi, 1984, Paracanthocephaloides kostylewi (Meyer, 1932) Bray, Spencer Jones & Lewis, 1988, Paracanthocephaloides incrassatus (Molin, 1858) Bray, Spencer Jones & Lewis, Diagnosis: Arhythmacanthidae. Trunk spines always absent. Included genera: Breizacanthus Golvan, 1969, Euzetacanthus Golvan & Houin, 1964 and Paracanthocephaloides Golvan, SUMMARY At present it seems reasonable to recognise just six genera within the Arhythmacanthidae: Heterosentis, Hypoechinorhynchus, Acanthocephaloides, Breizacanthus, Euzetacanthus and Paracanthocephaloides. Given this small number of genera, we argue that there is little utility in the recognition of subfamilies. Further, absolute validity of the characters on which they are based is in doubt (spines may not be genuinely lacking from the trunk of some paracanthocephaloidines) and may in any case be a poor reflection of evolution within the family. We suggest a de-emphasising of subfamilies within the family and the distinction of genera as per the following key. KEY TO GENERA OF THE ARHYTHMACANTHIDAE 1(0). Proboscis globular or claviform 2 - Proboscis cylindrical 4 2(1). Trunk with spines 3 - Trunk without spines Paracanthocephaloides 3(2). Trunk with antero-dorsal curvature Hypoechinorhynchus - No trunk curvature Heterosentis 4(1). Trunk with spines Acanthocephaloides - Trunk without spines 5 5(4). Only anterior end of trunk dilated, lemnisci longer than receptacle Breizacanthus - Anterior and posterior ends of trunk dilated, lemnisci not longer than receptacle Euzetacanthus A C K N O W L E D G E M E N T S We wish to thank Eileen Harris from the Natural History Museum, London and J. Ralph Lichtenfels and Patricia Pilitt from the United States National Parasite Collection for making type material available to us. This research was supported by the Australian Biological Resources Study (99/ABRS009G) to SP. We wish also to thank Pierre Sasal for providing us with specimens of Acanthocephaloides propinquus and for Matt Wayland for providing us with SEM photos of these specimens. REFERENCES ARAKI J & MACHIDA M. Some acanthocephalans from marine fishes of northern Japan, with descriptions of two new species, Acanthocephaloides ichiharai and A. claviformis. Bulletin of the National Science Museum, Tokyo Series A, 1987, 73,1-11. AMIN O. Classification, in: Biology of the Acanthocephala. Crompton, D.W.T. & Nickol, B.B. (eds), Cambridge University Press, Cambridge, 1985, BRAY R.A. SPENCER JONES M. E. & LEWIS J. W. Acanthocephaloides cyrusi n. sp. (Acanthocephala: Arhythmacanthidae) from southeast African teleost fishes. Systematic Parasitology, 1988, 12, BURON I. de & MAILLARD C. Acanthocéphales de Pleuronectiformes méditerranéens (Golfe du Lion). I. Création du genre Solearhynchus (Palaeacanthocephala). Annales de Parasitologic Humaine et Comparée, 1985, 60, CABLE R.M. & QUICK L.A. Some Acanthocephala from Puerto Rico with the description of a new genus and three new species. Transactions of the American Microscopical Society, 1954, 73, EDMONDS S.J. A list of Australian Acanthocephala and their hosts. Records of the South Australian Museum, 1989, 23, GOLVAN Y.J. Le Phylum des Acanthocephala. Troisième note. La Classe des Palaeacanthocephala (Meyer, 1931) (suite). Annales de Parasitologic Humaine et Comparée, I960, 35, GOLVAN Y.J. Systématique des Acanthocéphales (Acanthocephala Rudolphi 1801) Première Partie. L'Ordre des Palaeacanthocephala Meyer Premier fascicule. La Superfamille des Echinorhynchoidea (Cobbold 1876) Golvan et Houin Mémoires du Muséum National d'histoire Naturelle, Série A, 1969, 57, GUPTA V. & FATMA S. On three new species of acanthocephalan parasites of marine fishes of Mandapam, Tamil Nadu. Indian Journal of Helminthology, 1979, 31, GUPTA V. & FATMA S. On some acanthocephalan parasites of fishes. Indian Journal of Helminthology, 0985) [19831, 35, JOHNSTON T.H. & EDMONDS S.J. Australian Acanthocephala. No. 5. Transactions of the Royal Society of South Australia, 1947, 71, Mise au point 301

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