IntermAnta/ Journal/or Printed in Great Britain

Parasitology

Vol. 20, No. 6, pp. 155-767,

1990 0

002~75lV/!Xl S3.00 + 0.00 Pergamon Press p/c Societyfor Parasirology

1590 Awtralion

THREE NEW SPECIES OF MONOCOTYLE (MONOGENEA: MONOCOTYLIDAE) FROM THE STINGRAY, HIMANTURA UARNAK (RAJIFORMES: DASYATIDAE) FROM THE GREAT BARRIER REEF: PHYLOGENETIC RECONSTRUCTION, SYSTEMATICS AND EMENDED DIAGNOSES L. N. MEASURES,*?

M. BEVERLEY-BURTON*$

and A. WILLIAM@

*Department of Zoology, College of Biological Science, University of Guelph, Guelph, Ontario, Canada NlG 2Wl @chool of Environmental and Life Science., Murdoch University, 101 Coghlan Road, Subiaco, Western Australia 6008, Australia (Received 29 June 1989; accepted 10 April 1990)

AbstrRCt-MEASURESL.N., BEVERLEY-BURTON M. and WILLIAMS A. 1990. Three new species of Monocotyle (Monogenea: Monocotylidae) from the stingray, Himanturu uarnak (Rajiformes: Dasyatidae) from the Great Barrier Reef: phylogenetic reconstruction, systematics and emended diagnoses. International Journal for Parasitology 20: 155-161. Three new species of Monocotyle were found on the gills of the coachwhip stingray, Himantura uarnak (Rajiformes: Dasyatidae) collected at Heron Island, Great Barrier Reef, Australia (23’27’S, 151”SSE). Monocotyle helicophallus new species, Monocotyle multiparous new species and Monocotyle spiremae new species all have a single testis and are distinguished from other described Monocotyle species by size of body and hamulus and number of coils of the sclerotized male copulatory organ (21-22, three to four and 29-42, respectively). Monocotyle helicophallus new species is characterized by several muscular genital papillae, one of which is traversed by the ejaculatory duct; M. spiremae new species is distinguished by a sclerotized accessory structure associated with the distal end of the male copulatory organ, a vaginal sclerite and a conspicuous spherical, ejaculatory bulb; M. multiparous new species is distinguished by a large number of retained, thin-shelled eggs, many of which contain a fully developed oncomiracidium. A phylogenetic analysis of the 14 described species of Monocotyle utilizing 13 characters (11 binary and two multistate) produced the most parsimonious cladogram involving 18 steps with a consistency index of 0.78, two homoplasies and four unresolved polychotomies. Emended diagnoses of the Monocotylinae and Monocotyle are provided. INDEX KEY WORDS: Monocotyle helicophallus Monocotyle spiremae new species; Monocotylidae; Himantura uarnak; Rajiformes; phylogeny.

INTRODUCTION BASEDon material collected from elasmobranch fishes collected off the east coast of Australia, Young (1967) reviewed and revised the monocotylid subfamilies Monocotylinae Gamble, 1896 and Dendromonocotylinae Hargis, 1955. Young (1967) included seven species in Monocotyle Taschenberg, 1878 including three new species which he described. Four other species have also been proposed: M. spirophallus (Tripathi, 1959) Timofeeva, 1985; M. trygoni (Venkatanarsaiah & Kulkarni, 1980) Timofeeva, 1985; M. ancylostomae Timofeeva, 1984; and M. undosocirrus Timofeeva, 1984. While participating in the preICOPA VI workshop held on Heron Island in August

TPresent address: Maurice Lamontagne Institute, Fisheries and Oceans, Mont Joli, Quebec, Canada G5H 324 $To whom all correspondence should be addressed.

new species; Monocotyle multiparous new species; Monocotylinae; new species; emended diagnoses;

1986, we found three previously undescribed Monocotyle species on the gills of the coachwhip stingray, Himantura uarnuk (Dasyatidae). The present paper contains descriptions of these new species and a phylogenetic reconstruction of the genus Monocotyle. Emended diagnoses of Monocotyle and Monocotylinae are provided. MATERIALS AND METHODS Collection and preparation of material were as described by Beverley-Burton & Williams (1989). Measurements are presented as the mean with range in parentheses and are in micrometres unless otherwise indicated. Terminology of monocotylid haptoral morphology (Fig. 1) basically follows Young (1967). The following museum specimens were borU.S.N.M. Helminthological rowed and examined: Collection Nos. 49348,49349 Monocotyle diademalis Hargis, 1955; Nos. 61740, 61741 Monocotyle granulatae Young, 1967; Nos. 61142, 61143 Monocotyle kuhlii Young, 1967; Nos. 36960, 49350 Monocotyle pricei Pearse, 1949; Nos. 755

756

L. N. MEASURES,M. BEVERLEY-BURTON and A. WILLIAMS

61744, 61745 Monocotyle tritestis Young, 1967. Additional material of the three new ~o~oco~~~e species described herein was loaned by Dr I. D. ~ttin~on, Department of Parasitology, University of Queensland, Brisbane, Queensland 4067, Australia. All potential characters and character states were identified. Where discrete characters and character states could not be defined satisfactorily, either by study of the literature (including original specific descriptions which are cited in the references) and/or type material, these characters were not used in the phylogenetic analysis. Problematic characters such as the presence or absence of a central loculus and dorsal accessory somatic sclerites were

excluded from the analyses. Character states not adequately described for some species were coded as missing data (9). The following type species or well described species were chosen as monocotylid outgroups: Ano~~~otylo~~s papillarus (Doran, 1953) Young, 1967 (Monocotyhnae), Culicotyle kroyeri Diesing, 1850 (Calicotylinae), Merizocoryle icopae Beverley-Burton & Williams, 1989 (Merixocotyhnae), Dendromonocotyle kuhlii Young, 1967 and Ciemacotyie au.strafis Young, 1967 (Dendromonocotylinae). Characters were initially polarized based on examination of outgroups. However, as the outgroup relationships were uncertain, unconstrained one-step simultaneous analysis of the ingroup

FIG. 1. Schematic representation of idealized monocotylid haptor (after Young, 1967). cl, central loculus; sl, loculus of series surrounding central loculus; ir, inner rim; or, outer rim; rs, radial septum; mp, marginal papillae; mm, marginal membrane; h, hamulus; lh, larval hook. FIG. 2. Schematic representation of the five types of ventral sclerites on the haptor of the three new species of Monocotyle described herein (ventral view). A, similar to ‘funnel-shaped sclerites of Young (1967); B, similar to ‘v-shaped’ sclerites of Young (1967); C, similar to terminal or ‘semicircular’ sclerites of Young (1967); D, similar to ‘wing-nut’ shaped scletites of Young (1967); and E, trilocular sclerites. Note that type C sclerites have some variation. FIG. 3. Schematic representation of a portion of the haptor showing the arrangement of the types of ventral sclerites (Fig. 2) as seen in M. heli~ophQllusnew species. FIG. 4. Schematic repr~tation

of a portion of tire haptor showing the urrungetnenf of the types of ventral sclerites as seen in &f. spiremue new species and M. rnu~t~par~snew species.

~o~ocu~y~e new species-description and outgroups was utilized (Maddison, Donoghue & Maddison, 1984; Clark & Curran, 1986). As some characters were considered to have more than one possible transformation the most parsimonious interpretation was selected. Analyses were performed using PAUP version 2.4. t (Phylo~net~c Analysis Using Parsimony, available from Dr D. L. Swofford, Illinois Natural History Survey, 607 East Peabody Drive, Champaign, IL 61820, U.S.A.) on an IBM personal computer, using the global swap and mulpars options. Nomenclature of elasmobranchs follows Nelson (1984). RESULTS Capsaloidea Price, 1936 Monocotylidae Tascbenberg, 1879 As defined by Beverley-Burton &Williams, 1989 Monocotylinae Gamble, 1896 Emended diagnosis. Based on Young (1967) and Timofeeva (1984). Oral sucker absent; head organs and associated cephalic glands or three clusters of adhesive gland cells present. Intestinal caeca simple,

rarely confluent posteriorly; single, anteriorly directed diverticulum sometimes present on each side of pharynx. Haptor with one circle of seven, eight or 10 loculi surrounding defined central loculus or less discrete central depression. Marginal haptoral papillae and marginal membrane present or absent; sclerites usually present on haptoral septa and marginal papillae. Dorsal accessory sclerites on haptor or body present or not. Hamuli present, associated with septal pair 1 (see Fig. 1). Testis one, two or three; ejaculatory bulb usually present; male copulatory organ a sclerotized tube. Vagina single. Parasitic on gills of rajiform elasmabranchs-Rhinobatidae, Dasyatidae, Pristidae and My~iobatididae. Type genus. Monocotyle Taschenberg, 1878. Included genera. Anoplocotyloides Young, 1967; Dasybatotrema Price, 1938; Decacotyle Young, 1967; Diploheterocotyle Yamaguti, 1965; Heterocotyle Scott, 1904; Horrlcautda Tripathi, 1959; Neoheterocotyle Hargis, 1955; ~a~illi~otyle Young, 1967; Spinuris Doran, 1953; Troglo~e~bal~ Young, 1967; Potamotrygonocotyle Mayes, Brooks & Thorson, 198 1, IWmocotyle Tasehenberg, 1878 Synonyms. Tritestis Price, 1938 and Heterocotyloides Yamaguti, 1965 (see Young, 1967); Tympanocirrus Tripathi, 1959 (see Timofeeva, 1985). Emerzded diagnosis. Mon~otylidae: Mon~otylinae. Head organs present. Eyespots present or absent. Haptor round, with eight loculi, divided by muscular septa, surrounding central loculus or depression; marginal papillae and marginal membrane present. Sclerites present on haptoral septa and marginal papillae. Dorsal accessory sclerites on haptor or body present or absent. Ham&i with long deep and reduced superficial roots. Vaginal pore ventral, submedian; vagina sclerotized or not. Testis one or three; ejaculatory bulb present; male copulatory organ tubular, sclerotized and usually a spiral coil; distal extremity of male copulatory organ with or without

157

and phylogeny

accessory structures. Common genital pore median. Parasites on gills of rajiform elasmobranchsDasyatidae, Myliobatididae and Rhinobatidae. Type species. Monocotyle myliobatis Taschenberg, 1878. Additional species. M. ijimae Goto, 1894; M. pricei 1949; M. diademalis Hargis, 1955; M. spirophallus (Tripathi, 1959) Timofeeva, 1985; M. granulatae Young, 1967; M. kuklii Young, 1967; M. tritestis Young, 1967; M. trygoni (Venkatanarsaiah & Kulkarni, 1980) Timofeeva, 1985; M. ancylostomae Timofeeva, 1984; M. undosoeirrus Timofeeva, 1984; 1K. bef~~o~ball~ new species; M. mulf~parous new species; 44. spiremae new species.

Pearse,

new species Figs. 2,3,5-10 Description (N = 11). Total length 3.18 (2.17-4.95) mm long, 1.04 (0.71-1.59) mm maximum width, haptor 1.07 (0.71-1.41) mm long by 1.03 (0.6~1.~) mm wide with central locufus surrounded by eight loculi. Central loculus with distinct, muscular septal rim, contiguous with radial septa. Somatic accessory sclerites absent. Hamuli, 73 (43-107) long (A of Fig. 8); distal tip of hamulus to tip of superficial root 18 (10-32) (B of Fig. 8). Larval hooks, 12 (9-14) long, each located in small oval lobe indented on edge of marginal membrane. Marginal papillae 108-l 13 in total, i.e. 12-17 per locuh~s; each papilla with six to eight sclerites. Haptoral sclerites of five types (Fig. 2): A - similar to ‘funnel-shaped’ sclerites of Young Monocotyle helicapldb

(1967); B -

similar to ‘v shaped’

sclerites

of Young

E

9 r

5 FIG.5. Monocotyle heiicophallusnew species.Holotype ventral view. Note haptor twisted slightly to right on this specimen.

758

L. N. MEASURES, M. BEVERLEY-BURTON and A. WILLIAMS

FIGS.610.

Monocotyle helicophallus new species. Views are ventral except where indicated.

FIG. 6. Larval hook, lateral view. FIG. 7. Egg. FIG. 8. Bight hamulus, lateral view. A, length; B, distal tip of hamulus to tip of superficial root; dr, deep root; sr, superficial root. FIG. 9. Detail of reproductive system. eb, ejaculatory bulb; cgp, common genital pore; ed, ejaculatory duct; g, germarium; &p, genital papillae; mco, male copulatory organ (muscular sheath of male copulatory organ indicated by shading on distal section only); ag, accessory gland; sr, seminal receptacle; sv, seminal vesicle; t, testis; o, oijtype; v, vagina; vd, vas deferens. FIG. 10 Genital papillae and distal extremity of the male copulatory organ. c, canal; dt, distal tip of male copulatory organ.

Monocotyle new speciedescription

(1967); C - similar to terminal or ‘semicircular’ sclerites of Young (1967); D - similar to ‘wing-nut’ shaped sclerites of Young (1967) and E - trilocular sclerites. Schematic arrangement of sclerites as in Fig. 3: radial septa with 17-25 type D sclerites (15-30 wide); rim of central loculus with total of 354 sclerites: 27-36 type D (15-28 wide) on rim of central loculus and a single type E sclerite (16-3 1 wide) where each radial septum meets central rim. Outer rim bears circle of 223-242 type A sclerites (5-17 wide) central to marginal papillae, with one (or rarely two) sclerite between each of the marginal papillae. Remaining sclerites on marginal papillae type B (5-22 wide) proximally and a single type C sclerite of variable morphology (see Fig. 2) (Q-24 wide) distally. Mouth ventral, pharynx 381 (177499) long, 232 (105-292) wide. Head organs eight or nine on each side. Intestine with single short, anteriorly directed diverticulum on each side, lateral to pharynx; caeca simple, not confluent posteriorly. Eyes dorsal, with scattered pigment granules near anterior margin of pharynx. Testis single, generally pyriform, median, posterior and partially ventral to germarium; vas deferens arising from left antero-lateral margin of testis, passing ventral to spiralling male copulatory organ, before turning toward midline to enlarge slightly before passing posteriad to enter, via a small sphincter, fine muscular spherical seminal vesicle. Two elongate, thin-walls accessory glands, one dorsal and one ventral to seminal vesicle. Duct from each accessory gland and seminal vesicle entering posterior end of bipartite ejaculatory bulb which has thick muscular walls and wide lumen. Proximal region of ejaculatory bulb separated by sphincter from more elongate distal region. Ejaculatory duct narrow, transparent, extending anteriorly from ejaculatory bulb to enter, via slight inflation at proximal end, the sclerotized male copulatory organ. Male copulatory organ 1.16 (0.78-2.01) mm long (length measured from proximal extremity, along coils to distal extremity) with 36 (2942) coils. Male copulatory organ usually coiled sinistrally (seven of 11 specimens) with coils encompassed by narrow muscular sheath extending beyond proximal extremity of male copulatory organ. Genital complex with up to six muscular papillae, one of which is traversed by canal accommodating sharply pointed, distal extremity of male copulatory organ. Genital complex posterior and partly ventral to ejaculatory bulb. Germarium transversely elongate, originating medially, anterior and partly dorsal to testis; looping left then right, to pass dorsoventrally around right intestinal caecum and extending medially to form a short, narrow oviduct. Vitelline follicles prominent, extending from level of anterior margin of pharynx, posteriorly to level of anterior margin of haptor; anterior and posterior vitelline ducts of each side merge to form transverse vitelline ducts meeting medially. Vaginal pore ventral, lateral to left caecum.

and phylogeny

159

Vagina tubular, distally sinuous with thick convoluted lumenal lining and glandular walls distally; proximally fin-wills, non-glandular before narrowing to duct leading to seminal receptacle. Oviduct receives duct from seminal receptacle and median vitelline confluence before expanding to form thick-walled glandular o6type. OGtype flask-shaped, anterior to seminal receptacle; Mehlis’ gland ducts enter proximal portion of oiitype; egg, if present, held in distal portion of oiitype. Eggs tetrahedral, polar appendage with minute, bifid extremity. Measurements (one egg) 109 in maximum width, polar appendage 161 long. Common genital pore a narrow slit, median, near distal end of oiitype and complex of genital papillae. Specific diagnosis. Mo~acoiyle helicopha~~us new species is most similar to M. s~iropha~l~ and M. trygoni but is distinguished from these and other described species (including M. spiremae new species and U. multiparous new species) by a combination of the following characters: size of hamuli, a single testis, a long tightly coiled male copulatory organ of 29-42 coils and absence of a sclerotized structure associated with the distal extremity of the male copulatory organ. The muscular papillae of the genital complex are unique to M. helicophallus new species. Type host. Himantura uarnak (Dasyatidae). Type locality. Heron Island, Queensland, Australia (23”27’S, 151”55’E). Location on host. Gills. Etymology. Relative to the highly coiled male copulatory organ. From Greek he& meaning spiral and chalky meaning male copulatory organ. Museum specimens. Holotype No. GL 10387 and two paratypes Nos. GL 10388, GL 10389 deposited in the Invertebrate Collection, Queensland Museum, P.O. Box 300, South Brisbane, Queensland 4101, Australia; two paratypes HWML No. 31127 in the Research and Systematic Collections, Division of Parasitology, Harold W. Manter Laboratory, 529 W Nebraska Hall, Lincoln, NE 68588-0514, U.S.A. Monocotyk mnitiparous new species

Figs. 2,4, 1l-16 ~escr~~ion (N = 14). Total length 0.92 (0.78-1.17)

mm long, 0.27 (0.12-0.44) mm maximum width, haptor 0.30 (0.21-0.40) mm long by 0.29 (0.2g0.39) mm wide with eight loculi surrounding the central loculus as described above for M. heficophalius new species. Somatic accessory sclerites absent. Hamuli 58 (53-63) long, distal tip of hamulus to tip of superficial root 13 (10-18). Larval hooks 14 (8-16) long, located as described above. Marginal papillae 96-104 in total, i.e. nine to 16 per loculus; each papilla with six to seven (range four to eight) sclerites. Haptoral sclerites of haptor of five types (Fig. 2 and as described above). Schematic arrangement of sclerites as in Fig. 4: radial septa with 12-18 type D sclerites (f&l 1 wide); rim of central loculus with total of 28-33 sclerites: 20-25 type D (7-10 wide) on rim of central toculus and a single type E selerite (7-10 wide) where each radial septum

760

L. N. MEASURES,M. BEVERLEY-BURTON and A. WILLIAMS

FIGS. 11-16 Monocotyle

multiparous

new species. Views are ventral except where indicated.

FIG. 11. Holotype (gravid specimen). FIG. 12. Egg containing oncomiracidium. FIG. 13. Right.hamulus, lateral view. FIG. 14 Larval hook, lateral view. FIG. 15. Distal portion ofmale reproductive system showing eb, ejaculatory bulb; ed, ejaculatory duct; mco, male copulatory organ; smco, sheath of male copulatory organ. FIG. 16. Distal extremity of male copulatory organ.

Monocotyle new speciesdescription meets central rim. Outer rim bears circle of 201-221 A

and B sclerites; type B at base of marginal papillae with one (rarely two) type A sclerite (24 wide) between each of the marginal papillae. Marginal papillae each with two more type B sclerites (3-7 wide) proximally and a single type C sclerite of variable morphology (see Fig. 2) (4-7 wide) distally. Mouth ventral, pharynx 140 (1 l&181) long, 120 (8&179) wide. Head organs indistinct, apparently eight on each side. Intestine as described above for M. helicophallus new species. Eyes two pairs, present near anterior margin of pharynx. Gonads seen only in juvenile, non-gravid worms: testis single, median and posterior to germarium which loops left then right to pass dorsoventrally around right intestinal caecum; vas deferens, seminal vesicle and accessory glands not observed. In gravid worms these structures are presumed senescent as thin-shelled, embryonated eggs fill central region of body. Ejaculatory bulb bipartite with muscular walls, receiving distal extremity of vas deferens into proximal oblong region; distal region subspherical. Ejaculatory duct originating from ejaculatory bulb, passing left and anteriorly, uniting with proximal inflated base of male copulatory organ. Male copulatory organ with three to four coils, measuring 180 (113-263) in a straight line from distal to proximal extremities or 3 14 (270-350) along curvature of coils. Male copulatory organ left of pharynx, usually coiled sinistrally (12 of 13 specimens). Male copulatory organ enclosed by thin sheath inflated distally. Distal tip of male copulatory organ oblique with shorter spade-like flange and longer tapering spirally grooved extremity. Vitelline follicles poorly defined along lateral body margins, extending from level of pharynx to anterior region of haptor. Vitelline ducts, vaginal pore, vagina, seminal receptacle, ootype and common genital pore not observed. Eggs 65 (5&80) in maximum width, thin-shelled spheroidal, with short, bluntly ending polar appendage, 39 (3 l-50) long, numerous (up to 50, usually 20) eggs, present in body from pharyngeal region to posterior terminations of intestinal caeca. Active oncomiracidia with two discrete pairs of eyes, and developed haptor present in a number of eggs. Common genital pore (seen in living specimens) median, posterior to bifurcation of intestine. Specific diagnosis. Monocotyle multiparous new species is most similar to M. ancyclostomae but is distinguished from it and other described species (including M. helicophallus new species and M. spiremae new species) by a combination of the following characters: relatively small total length and hamuli, a single testis and a short male copulatory organ of three to four coils lacking a sclerotized structure associated with the distal extremity. The presence within the midbody of many eggs containing embryos with developed eyespots and haptor is unique to M. multiparous new species. Type host. Himantura uarnak (Dasyatidae). Type locality. Heron Island, Queensland, Australia

and phylogeny

761

(23”27’S, 151’55’E). Location on host. Gills. Etymology. Relative to

the many eggs each containing an oncomiracidium in midbody region. From Latin multi meaning many and parous meaning giving birth to. Museum specimens. Holotype No. GL 10390 and two paratypes Nos. GL 10391, GL 10392 deposited in the Queensland Museum, address as given above; two paratypes HWML No. 3 1128 deposited in the Harold W. Manter Laboratory, address as given above. Monocotyle spiremae new species Figs. 2,4, 17-23 Description (N = 9). Total length 4.79 (3.39-6.20) mm long, 1.82 (1.13-2.48) mm maximum width, haptor 1.60 (1.12-2.06) mm long by 1.60 (0.96-2.27) mm wide with eight loculi surrounding the central loculus as described above for M. helicophallus new species. Somatic accessory sclerites absent. Hamuli 254 (188-330) long, distal tip of hamulus to tip of superficial root 27 (2347). Larval hooks 15 (9-23) long, located as described above. Marginal papillae 69-71 in total, i.e. seven to 10 per loculus; each papilla bearing four sclerites. Haptoral sclerites of five types (Fig. 2 and as described above). Schematic arrangement of sclerites as in Fig. 4: radial septa with 13-23 type D sclerites (7-25 wide); rim of central loculus with total of 20-25 sclerites: 12-17 type D (11-16 wide) on

FIG. 17. Monocotylespiremaenew species. Holotype ventral view.

L. N. MEASURES, M. BEVERLEY-BURTON and A. WILLIAMS

762

FKX 18-23. h&mcary~espirernae new species. Views are ventral except where indicated. FIG. 18. Detail of reproductive system. Abbreviations as per Fig. 9, ass, accessory sclerotized structure; FIG. 19. Vaginal FIG. FIG. 21

FIG. 22. Distal

extremity

vs, vaginal

sclerite.

sclerite.

20. Larval hook, lateral view. Right hamulus,

ventrolateral

view.

of male copulatory organ with ejaculatory duct in muscular structure, Abbreviations as indicated above.

sheath

and accessory

sclerotized

FIG. 23. Egg.

rim of central loculus and a single type E sclerite fl i17 wide) where each radial septum meets central rim. Outer rim bears a circle of 142-157 A and 3 &e&es; type B (17-17 wide) at base of marginal papillae with one (or rarely two) type A sclerite (5-Z wide) between each of the marginal papillae. Remainder of sclerites on marginal papillae each with two more type B sclerites (640 wide) proximally and a single type C variable in morphology (see Fig. 2) (7-27 wide) distally. Mouth ventral, pharynx 566 (356-748) long, 479 (284-779) wide. Head organs nine or 10 on each side. fntestinal caeca, simple, not confluent posteriorly. Eyes dorsal, present only in immature specimens as scattered pigment granules near anterolateral margin of pharynx.

Testis single, generally oval, median and posterior to germarium; vas deferens arising from anterolateral margin of testis, passing anteriorly, dorsal to vagina, then medially towards right intestinal caecum before turning posteriorly to enter seminal vesicle; seminal vesicle elongated, thin walled; vesicular duct receives small duct from each of two oval, thin-walled accessory glands (one dorsal and one ventral to seminal vesicle) before entering ejaculatory bulb. Ejaculatory bulb circular, 148 (127-I 66) by 146 (112168), with complex musculature and thin surrounding membrane. Ejaculatory duct originating ventrally from. ejaculatory bulb, passing 1eAto coil around male copulatory organ, and entering into proximal intlated base of male ~opulato~ organ situated anterior and to left of pharynx. Mafe copulatory organ, elongate, 1.3

Monocotyle

new species-description

(1.1-1.6) mm long with 21 (21-22) coils lying left of pharynx. Male copulatory organ usually coiled sinistrally (seven of nine specimens). Male copulatory organ enclosed by wide muscular sheath extending beyond proximal extremity of male copulatory organ. Distal extremity of male copulatory organ with sharply pointed blade-like sclerotized accessory structure 141 (99-191) long with irregular surface, partially enclosing distal tip of male copulatory organ. Germarium transversely elongate with bilobed proximal extremity, anterior to testis; extending right to pass dorsoventrally around right intestinal caecum and then medially to form short, narrow oviduct. Vitelline follicles prominent, extending from level just anterior to pharynx, posteriorly to anterior margin of haptor; anterior and posterior vitelline ducts of each side unite to form transverse vitelline duct meeting medially. Vaginal pore with thick muscular rim, left of median at level of ejaculatory bulb; vagina bipartite with distal glandular region, where lumenal walls are irregularly folded, and proximal muscular region 157 (125-216) by 162 (100-200) containing sclerotized valve-like structure; vagina narrowing proximally giving rise to short duct entering seminal receptacle. Seminal receptacle thin walled, variable in shape with short duct exiting to oviduct near point of entry of duct from confluence of transverse vitelline ducts. Oiitype flask-shaped, with thick glandular walls, usually containing a single egg; Mehlis’ gland ducts entering proximal region. Egg (N = 5) tetrahedral, 89 (68-l 12) in maximum width, with polar appendage, 238 (227-249) long. Common genital pore narrow slit surrounded by muscle, median in position. Immature specimen (N = 1) 1.42 mm total length, 0.33 mm maximum width, morphology as per adult specimens above except as indicated below. Haptor 0.36 mm long by 0.37 mm wide. Hamuli, 123 (120126) long, 27 (2627) from distal tip of hamulus to tip of superficial root. Larval hooks 10 (8-l 1) long. Type D sclerites on radial septa 3-33 wide, on rim of central loculus 7 wide; type E sclerite on rim of central loculus 7 wide. Type B sclerites at base of marginal papillae 56 wide; type A sclerites between marginal papillae 3-3 wide, remaining type B sclerites on marginal papillae 4-6 wide; type C sclerites 38-48 wide. Female reproductive system indistinct except for vaginal sclerite and enlarged seminal receptacle. Male reproductive system apparently functional: male copulatory organ 0.347 mm long with 15 sinistral coils; sclerotized accessory structure 64 long; ejaculatory bulb 66 by 65. Specific diagnosis. Monocotyle spiremae new species is most similar to M. spirophallus and M. trygoni but is distinguished from these and other described species (including M. helicophallus new species and M. multiparous new species) by a combination of the following characters: relatively large total length and hamuli, a single testis, a long male copulatory organ of 21-22 coils and presence of a vaginal sclerite. Type host. Himantura uarnak (Dasyatidae).

and phylogeny

763

Type locality. Heron Island, Queensland, Australia (23”27’S, 151”55’E). Location on host. Gills. Etymology. Relative to the male copulatory organ. From Greek spiremae meaning a coil or twisted thread. Museum specimens. Holotype No. GL 10393 and two paratypes Nos. GL 10394, GL 10395 deposited in the Queensland Museum, address as given above; two paratypes HWML No. 31129 deposited in the Harold W. Manter Laboratory, address as given above. Phylogenetic

analysis

The following 13 morphologic characters (11 binary and two multistate) involving 28 character states (11 binary = 22; two tertiary = six) were utilized in the phylogenetic analysis of Monocotyle. Each character, the number of character states and the polarity of each state are indicated. The number in parentheses refers to the code assigned, all of which are summarized in the data matrix for the ingroup and outgroups in Table 1.

TABLE

I-DATA MATRIX OF CHARACTERSCODED IN THE PHYLOGENETIC ANALYSISOF Monocotyle

Anoplocotyloides papillatus Denalromonocotyle k&ii Clemacotyle australis Calicotyle kroyeri Merizocotyle icopae Monocotyle ancylostomae M. spiremae M. diademalis M. multiparous M. granulatae M. ijimae M. kuhlii M. myliobatis M. pricei M. helicophallus M. spirophallus M. tritestti M. trygoni M. undosocirrus

OOOOOO9OOOOOo 0101112000010 0101119000011 10100011OOOOO 2010002100010 0191001010100 0101002010100 0101001000100 0101001991000 0101001OOOW0 0901009000900 0101009010100 0101002090999 0101001000109 0101001000100 0199002010100 0101009010000 0101001000109 0191001010100

The first five taxa are the outgroups. Remaining taxa are species of Monocotyle (ingroup). Thirteen characters as numbered and described in text for each taxon are coded in columns left to right: 1. number of loculi immediately surrounding the central loculus or ‘depression’ of the haptor; 2. presence/absence of marginal papillae on the haptor; 3. presence/absence of marginal membrane on the haptor; 4. presence/absence (other than hamuli and larval hooks) of ventral sclerites on the haptor; 5. presence/absence of hamuli; 6. form of intestine; 7. egg appendage; 8. number of vaginae; 9. sclerotization of vaginal duct; 10. development of eggs; 11. accessory sclerotized structure at distal extremity of male copulatory organ; 12. form of male copulatory organ; 13. sclerotization of male copulatory organ. Eleven characters are binary and two are multistate. Refer to text for plesiomorphic and apomorphic states. Missing data are indicated by 9.

764

L. N. MEASURES, M. BEVERLEY-BURTON and A. WILLIAMS

1. Haptor with a number of locuh immediately surrounding the central loculus or ‘depression’. This character has three states. Plesiomorphic (ancestralF eight loculi (0). Apomorphic (derivedj-seven loculi (1). Apomorphic-five ioculi (2). 2. Haptor with marginal papillae. This character has two states (binary). Plesiomorphic-marginal papillae absent (0). Apomorphic-marginal papillae present (1). 3. Haptor with marginal membrane. Binary. Plesiomorphic-marginal membrane present (0). Apomorphic-marginal membrane absent (I). 4. Haptor bearing ventral sclerites other than hamuh and larval hooks. Binary. Plesiomorphichaptoral ventral sclerites absent (0). Apomorphichaptoral ventral sclerites present (1). 5. Hamuli. Binary. Plesiomorphic-hamuli present (0). Apomorphic-hamuli absent (1). 6. Form of intestine. Binary. Plesiomorphic-simple intestine (0). A~mo~hic~end~tic intestine (1). 7. Egg appendage. This character has three states. Plesiomorphic-egg appendage absent (0). Apomorphic-egg appendage short (1). Apomorphicegg appendage long (2). 8. Number of vaginae. Binary. Plesiomorphicsingle vagina (0). Apomorphicdouble vaginae (I). 9. Sclerotization of vaginal duct. Binary. Plesiomorphic-non-sclerotized vaginal duct (0). Apomorphic-sclerotized vaginal duct (1).

10. Development of eggs. Binary. Plesiomorphicegg(s) shed at early stage of embryonation (0). Apomorphic*gg(s) retained to advanced stage of embryonation (egg containing oncomiracidium) (1). Il. Accessory sclerotized structure (= piece) associated with the distal extremity of the male copulatory organ. Binary. Plesiomorphic-accessory sclerotized structure absent (0). Apomorphicaccessory sclerotized structure present (1). 12. Form of male copulatory organ. Binary. Plesiomorphic-coiling or looping (0). Apomorphicnot coiling or looping (I), 13. Scleroti~tion of male copulatory organ. Binary. Plesiomorphic-sclerotized (0). Apomorphic-nonsclerotized (I). The most parsimonious cladogram (Fig. 24) involved 18 steps with a consistency index of 0.78. Two character states [captor with marginal papillae (2:l) and haptor bearing ventral sclerites other than hamuli and larval hooks (4:1)] were shared by the ingroup, Mo~ocotyIe, and two of the outgroups, Dendromonocotyle kuhlii and Clemacotyle australis (Dendromonocotylinae). No character states unique to Monocotyle were identified. Characters 1, 3 and 8 were apomorphic in the outgroups Calicotyle kroyeri and Merizocotyle icupae and plesiomorphic in the ingroup Monoeotyle and the outgroup Anop~ocotyl~idespapillat~. These characters thus do not appear on the cladogram (Fig. 24).

FIG. 24. CIadogram of hypothesized phylogenetic relationships of species of Monocoryie (Monocotylinae). Rendromonocotyle kuhliiand Ciemacotyfeaustralis (Dendromonocotylinae) originally used as outgroups should, as suggested by thephylogenetic analysis, be grouped with Monocotyle as they share two character states. Characters are transformed at steps indicated. Each step is described by character number: character state number (see text for explanation). A circle indicates a synapomorphy at the indicated step. A triangle indicates a homoplasous transformation at the indicated step. HA, Hypothetical ancestor.

Monocotyle new species-description and phylogeny

DISCUSSION The female reproductive system of most monogeneans has a relatively short distal chamber (oiitype) which contains fewer than 20 eggs (en~ps~ated embryos) (Tinsley, 1983) and more often than not, a single egg. ~onocotyle muftipurous new species retains many eggs (four to SO), some of which contain a fully developed oncomiracidium. Retention of eggs has not been reported previously in the monocotylids and it has not yet been established if the eggs are accommodated in utero (Keam, 1986, considered a uterus was lacking in mon~otylids). In addition, further studies are in progress to determine if M. multiparous new species is ovoviviparous or viviparous. According to Kearn (1986) the retention of developing ‘progeny’ within the parasite body appears to have arisen independently several times (in the gyrodactylideans, acanthocotylids, chimaericolids, hexabothriids, mazocraeideans and many polystomatids). Egg retention may be a strategy which permits transmission only when environmental conditions or host behaviour, which could be seasonal, are favourable (see Keam, 1986 for discussion of adaptive value). In the present study no attempt was made to identify and quantify the precise microhabitat of each of the three new species of ~onoc~ryle described herein. However, each species was found on different regions of the gill lamellae. Studies by various workers have demonstrated some site and gill specificity by some species of monogeneans (see review by Bray, 1987). Three species of Monocotyle co-existing on the gills of the same species of elasmobranch host (Himunturu uurnuk) would afford an excellent opportunity for ecological studies. Species of Monocotyle appear to be restricted to rajiform elasmobranchs with the majority of reports from the Oriental and Australasian zoogeographic regions. Most of the described species of Monocotyle appear to be highly host specific. However, in addition to the three new species of ~onocotyle described herein from the same host species (Himuntura unrnuk), M. kuhlii and M. tritestis also occur concurrently on one species of host, namely Dasyatis kuhli. All known species of Monocotyle parasitize members of the families Dasyatidae and Myliobatididae (Rajiformes: Myliobatidoidei) with the exception of &f. ancylostomae which is found on Rhina ~cylostoma, a member of the Rhinobatidae (Rajiformes: Rajoidei). All but three Monocotyle species (M. myliobatis from Myliobatis aquila, M. undosocirrus from Gymnura bimaculata and M. trygoni from an unidentified species of the defunct genus Trygon) have been reported from members of the genera Dasyutis or ~~~nturu. It is unfo~unate that we do not know the identity of the species of host of M. trygoni which is morphologically most similar to M. helicophallus new species and M. spiremae new species. According to Compagno (1977) the Myliobatiformes (the Myliobatidoidei of Nelson, 1984) include

765

some of the most derived rays, but the interrelationships of the various rays are poorly understood (also see Compagno, 1973; Heemstra & Smith, 1980; Maisey, 1984a,b; Rosa, R.S., unpub1ishedPh.D thesis, College of William and Mary in Virginia, 1985; !&ret, 1986). Rosa (1985, thesis cited above) presented a cladogram of potamotrygonids and some outgroup genera belonging to the Myliobatiformes in an attempt to elucidate phylogenetic relationships of the Potamotrygonidae. While Dasyatis, Himantura, Taeniura and Gymnura were considered closely related to each other, Gymnura’s position was considered less certain. If species of Monocotyle are primarily parasites of rays, Rhina ancylostoma (a guitarlish) may represent a host capture (sensu Chabaud, 1965). However, with over 140 extant species of rays worldwide (Compagno, 1977), it is likely that many more species of Monocotyle are to be discovered and studied before we can begin to understand relationships of the monocotylids with their hosts. In the present study an attempt was made to determine interrelationships between species of Monocotyle. The analysis indicated two homoplasies and four unresolved polychotomies some of which are, no doubt, a function of our poor knowledge of species of Monocotyle as well as our poor understanding of the phylogeny of the mono~otylids. For example, three characters (marginal membrane, number of vaginae, form of the male copulatory organ) had been originally considered as plesiomorphic but analyses indicated they were apomorphic. Analysis supported the opinions of Bykovsky (1957), Young (1967) and Timofeeva (1985) that the characteristic of eight loculi immediately surrounding the central loculus or ‘depression’ of the haptor is plesiomorphic. Some characters such as those of the dorsal accessory somatic sclerites, testicular number, seminal vesicle, accessory glands, ejaculatory bulb, ejaculatory duct and oijtype could not be included in the analysis because, for some species, these are either not described or are not described adequately. Although museum specimens were examined, we frequently could not confirm the presence of or identify some described structures. The dorsal accessory somatic sclerites of Young (1967) are an example. Other characters were uniform within the ingroup and outgroups and thus were not utilized. These characters were the pharynx, eyespots @resent as two pairs of discrete eyespots or as scattered pigment granules, not described in M. myliobatis, M. trygoni or M. spirophallus), larval hooks (14 in number, but not well described in most species), seminal receptacle, germarium (elongated, looping right gut caecum; some are lobed proximally), egg shape (tetrahedral except spheroidal in M. rnu~tip~ro~ new species), vaginal opening (sinistral), and common genital pore (medial, not described in M. undosocirrus or M. ancylostomae). The head organs, which are difficult to observe and are generally poorly described with regard to number and morphology, are not useful characters.

766

L. N. MEASURES,M. BEVERLEY-BURTON and A. WILLIAMS

As indicated by Kearn (1986) and Beverley-Burton & Williams (1989) the central loculus or “depression’ of the haptor is also problematic and its apparent absence in Dendromonocotyle kuhlii, Merizocotyle icopae, Monocotyfe ijimae and M. myiiobatis requires further study. In the present analysis there was no character belonging to Monocotyle which separated the genus from the outgroups. Although it was not our intention to examine the Dendromonocotylinae, analysis suggests that the two studied species of this subfamily may not warrant separate generic status from Monocotyfe on mo~holo~~l grounds. Each of the four subfamilies of Monocotylidae are differentiated primarily by their particular habitat on the host: Monocotylinae on the gills, Dendromonocotylinae on the skin, Calicotylinae in the internal cavities (rectum, cloaca, coelom, oviduct) and Merizocotylinae in the nasal cavities (Young, 1967). Young (1967) and later Timofwva (1985) also noted the similarities between Nonocotyle and members of Dendromonocotylinae and Young (1967) suggested the latter had probably arisen from ancestors similar to Monocotyle. Dendromonocotyle, Clemacotyle and Monocotyle share many characters but the first two genera have some specialized features (e.g. dendritic intestine, absence of hamuli, non-coiling male copulatory organ) which may relate to their habitat on the host. We prefer to leave the Dendromonocotylinae as it presently stands until museum specimens are examined and all four subfamilies of Monocotylidae can he reviewed concurrently. Resolution of the cladogram in the present analysis is poor. This is due primarily to our lack of knowledge of certain species such as M. ijimae and M. myliobatis and absence of a character(s) to resolve the group consisting of M. trygoni, M. pricei, M. helicophalfus new species, M. ijimae and M. diademalis. We assumed homology between the genital papillae of M. helicophailus new species and the accessory sclerotized structure associated with the distal extremity of the male copulatory organ. As discussed helow this homology may not be valid. Potentially the most useful characters to use in a phylogenetic analysis of the Monocotylidae are those of the male genital complex. Klassen & BeverleyBurton (1987, 1988) and Beverley-Burton & Klassen (1990) found copulatory structures useful in phylogenetic reconstructions of Nearctic ancyrocephalids (Monogenea). The monocotylid male copulatory organ is generally sclerotized, variable in shape and size and may or may not possess accessory structures. All outgroups, M. multiparous new species, M. gramdatae, M. tritestis and possibly M. ijimae and M. myfiobat~ lack an accessory structure while the remaining species except M. heli~ophall~ have an elongated accessory sclerotized structure of variable form. Monocotyfe helicophallus new species had an unusual, complex structure consisting of a number of genital papillae. It is not known whether this latter

structure is homologous to the accessory sclerotized structures seen in other species of Monocotyfe, e.g. M. kuhfii, with ‘complicated terminal accessory piece’ or whether it represents a unique autapomorphy. However, all these structures likely have the same function, serving to guide the male copulatory organ. As suggested by Euzet & Combes (1980) the copulatory apparatus often serves to differentiate congeners occupying the gills of the same host and, as pointed out by Bray (1986), may provide the mechanism by which species retain reproductive isolation and thus avoid introgression. Acknowledgemenfs-We thank Dr R. J. G. Lester, Department of Parasitology, University of Queendand, who organized the pre-ICOPA VI workshop held on Heron Island in August 1986. We acknowledge the assistance of and thank Mr T.A. Wheeler, Department of Environmental Biology, University of Guelph, who translated the cited Russian literature, assisted in the phylogenetic analysis and provided helpful criticism of the manuscript. We also thank Mr G.J. Klassen, Department of Ichthyology and Herpetology, Royal Ontario Museum, Toronto who assisted in preliminary work with the Australian material, provided advice on the phylogenetic analysis and critically reviewed the manuscript. We appreciate the assistance of Mrs Uta Strelive who translated the cited German literature. We extend our thanks to Dr JR. Lichtenfels of the United States National Museum, Helrnin~oio~~l Collection, U.S.D.A., Beltsville, Maryland, U.S.A. who kindly loaned museum specimens. We also thank Dr I.D. Whittington of the Department of Parasitology, University of Queensland, Australia who loaned additional material of the three new species of Monocotyle described herein. BEVERLEY-BURTON M. & WILLIAMSA. 1989. Merizocotyle icopae sp. nov. and Thaumatocotyle austraiensis sp. nov.

(Monogenea: Monocotylidae) from the nasal cavities of rajiform elasmobranchs of the Great Barrier Reef. Australian Journal of Zoology 37: 25-35. BEVERLEY-BURTON M. & KLASSENG.

J. 1990. New approaches to the systematics of the ancyrocephalid monogenea from Near&c freshwater fishes. Jrwnal of Parasitology 76: l-2 1.

BRAY R. A. 1986. Patterns in the evolution of marine helminths. In: Proceedings of the Sixth International Congress of Parasitology (Edited by HOWELLM. J.), pp. 337-344. Australian Academy of Science, Canberra. BYKOVSKYB. E. 1957. Monogenetic Trematodes, Their Systematics and Phylogeny (in Russian). Akademii Nauk

SSSR. English translation by American Institute of Biological Sciences, Washington, D.C. (Edited by HARGISW. J.), 1961. Virginia Institute of Marine Sciences Translation Series Number I. CHABAU~A. G. 1965. Specificit& parasitaire. I. Chez les nematodes parasites de vertebrts. In: Trait& de Zoologie, Vol. 4 (Edited by GRASSYP. P.), pp. 548-557. Masson et Cie, Paris. CLARKC. & CURRAND. J. 1986. Outgroup analysis, homoplasy, and global parsimony: a response to Maddison, Donoghue, and Maddison. Systematic .Zoology 35: 422426. COMPACNO L. J. V. 1973. Interrelationships of living elasmobranchs. In: Interrelationships of Fishes (Edited by

Monocotyle

new species-description

P. H., Mtt~f R. S. & PAnERSON c.), pp. IS-6 1. Lianean Society of London, Academic Press, London, CMPAGNO L. J. V. 1977. Phyletic relationships of living sharks and rays. AmericaR Zoologist 17: 303-322. DIESINGK. M. 1850. Sysrema ~Im~nthum 1. Vindobonae. DORAN D. J. 1953. New monogenetic trematodes from the shavelnose guitarfish, Rhinobatos productus (Ayres). @IEENWOOD

The

Journal of Parasitology

39: 145-15 1.

COMBES C. 1980. Les problemes de l’espece chez les animaux parasites. In: Les Problemes de Pespece dans le Re Animal, Vol. 3 (Edited by B~CQUETC., GENERMONT J. & LAMO~~E M.), pp. 239-285, Memoire No. 40 de la Socibte Zoologique de France. GAMBLEF. W. 1896. Platyhelminthes and Mesazoa, Chapter 2, Trematoda. In: Cambridge NuturaIHistory Vol. 2, pp. l96. GOTOS. 1894. Studies on the ectoparasitic trematodes of Japan. Jou~~Ioft~ C&ege ofScience, 1mpetiar tiniversiiy

&JzET L. &

of Tokyo 8: l-273.

W. J. 1955. Monogenetic trematodes of Gulf of Mexico fishes. Part IV. The superfamily Capsaloidea Price, 1936. Revisra iberica de parasitologia (Libro - Homenaje Lopez - Neyra): l-16. BBEMSIXA P. C. & SMITHM. M. 1980 Hexatrygonidae, a new family of stingrays (Myliobatiformes: Batoidea) from South Africa, with comments on the classification of batoid fishes. IchthyologicaI Bulletin of the J.L.B. Smith Institute of Ichthyology Rhodes University, Grnhamstown 43: l17. KEARN G. C. 1986. The eggs of monogeneans. Rdvances in Parasitology 25: 175-273. KLASSENG. J. & B~v~~~~y-~u~~~ M. 1987. Phylogenetic relationships of ~~g~c~urj~ spp. (Monagenes: Ancyrocepbalidae) and their Ictalurid fSiluriformes) hosts.

HARGIS

Proceedtngs of the ~~~~tho~ogjc~ Society of Washington 54: 84-90. KLASSEN G. J. & BEVERLEY-BURTON M. 1988. North

American freshwater ancyrocephalids (Monogenea) with articulating haptoral bars: phylogeny reconstruction. Systematic

Parasitology

11: 49-U.

MADWON

W. P., D~N~GHUEM. J. & M~nmso~ D. R. 1984. Outgroup analysis and parsimony. Systematic Zoology 33: O-103.

MASSEYJ. C. 1984a. Higher elasmobranch phylogeny and biostratigraphy. Zoological Journul of the I&mean Society 82: 33-54. MAWS J. C. lQ84b. Chond~ch~yan phylogeny: a look at the evidence. Journal of Vertebrate P~~to~og~ 4: 359-371. MAYES M. A.. BROOKSD. R. L THORSON1. B. 1981. Pot~otr~~go~ocoty~e ts&skisi, new genus and species

(Monogenea: Monocotyhdae)

and Par~~eteronch~oryIe

and phylogeny

161

-~o~~~,

new genus and species (Monogenea: Hexabothriidae) from Potu~o~~g~ c&&r& Garmen ~~on~chthy~: Po~mot~gonidae) in No&western Bras& Proceedings of the BialogicuI Society of Washingfort 94: 12051210. NELSONJ.

S. 1984. Fiihes ofthe World. John Wiley and Sons, New York. PEARCEA. S. 1949. Qbservations on flatworms and nemerteans collected at Beaufort, N.C. Proceedings ofthe United States National Museum 100:25-38. PRICE E. W. 1936. North American Monogenetic Trematodes, George Washington University Bulletin, Summaries Doctoral Theses (19341936), pp. 10-13. PRICEE. W. 1938. North American monogenetic trematodes. II. The Families Monocotylidae, Microbothriidae, Acanthocotvlidae and Udonellidae (Car&aide& Journal of the W~~~gto~ Aca&my of S&e&es %: li39-126,183-l& Scorr T. 1304. Gn some parasites of fishes new to the Scottish marine fauna. Report of the PLshery Board of ScoiI~ 2% 242-261.

SERETB. 1986. Classification et phylogenese des chondrichthyens. Oceanis 12: 161-180. TA~CHENBERG E.G. 1878. Helminthologisches. Zeitschrtftfir die Gesammten Naturwissenshaften (Berlin) 51, 3.F., 3: 562-511. TASCHENBERG E. 0. 1879. Ziir Systematik der monogenetischen Trematoden. Zeitschrift fir die Gesammten Naturwissenshaften (Berlin) 52,3.F.: 41232-265. TMOFEEVAT. A. 1984. Mew members of monocotvlids of the genera Monocotyle and Merizocotyle from rays of the South Chinese and Yellow Seas (Monogenea, Monocotylldae).] P~~~io~o~a 1% 296305 (in Russian). TXX~OFEEVA T. A. 1985. ~o~holo~c~ and ecological aspects ofmon~tylids evolution (Monogenea, Mo~~o~~~~e~.] P~r~ito~og~cheskji Sbornik 33: 4+76 (in Russian), TINSLEVR. C. 1983. Ovoviviparity in platyhe~inth lifecycles. Parasitology 86: 161-196. TRIPATHI Y. R. 1959. Monogenetic trematodes from fishes of India. Indian Journal ofHelminthology 9: 1-149. VENKATANAR~A~AH J. & KULKARNIT. 1980. Studies on the monogenetic trematades ofAndhra Pradesh: contribution to our knowledge of Tvmounocirrus Trinathi, 1959 with a description of ?‘. trygon; n. sp. and a redkscription of Gnchiodiscus pterodiscoides Kulkami, 1969. Rivista di Parassitoiogia

41: 85-91.

YAMAGUT~ ST 1965. New monogenetic trematodes from Hawaiian fishes. 1. Pacific Science 19: 55-95. Yoti~o P. C. 1957. A taxonomic revision of the subfamilies Mon~otyli~e Gamble, 1896 and ~n~omon~oty~nae Hargis, 1955 (Monogenoidea: Monocotylidaej. Journnf of Zoology (London) 153: 381-422.