Marginal Loculi Research Articles

Molecular phylogeny, including a new species of Anindobothrium (Cestoda, Rhinebothriidea) from the Southern eagle ray Myliobatis goodei, finally solves the taxonomic enigma of Phyllobothrium myliobatidis

During a parasitological survey of tapeworms from Myliobatis goodei Garman, 1885 (Myliobatiformes: Myliobatidae) in coastal waters off Argentina in the Southwestern Atlantic, a new rhinebothriidean cestode species, Anindobothrium danielaesp. nov., is described using morphological and molecular techniques. This species differs from its congeners by a particular combination of features, including the configuration of the bothridia, the number of marginal loculi, and the number and distribution of testes. Additionally, Anindobothrium myliobatidiscomb. nov. is proposed based on several morphological traits, including the presence of stalked bothridia with marginal loculi and an apical sucker, euapolytic strobila, and postvaginal testes. The diagnosis of the genus Anindobothrium Marques, Brooks & Lasso, 2001 is amended to include the features exhibited by these two species; two species subsets are suggested based on the configuration of the bothridia. The presence of A. danielaesp. nov. and A. myliobatidiscomb. nov. in the studied area not only increases the number of cestodes in M. goodei here from eight to ten but also represents the first report of a rhinebothriidean cestode parasitizing stingrays of the family Myliobatidae in the Southwestern Atlantic.

New species of Rockacestus (Cestoda, Phyllobothriidea) from skates of the genus Bathyraja (Rajiformes, Arhynchobatidae) in the Southwestern Atlantic Ocean with comments on the distribution of the genus

Three new species of Rockacestus Caira, Bueno & Jensen, 2021 were recovered from arhynchobatid skates taken between 37°S–55°S in the Magellanic Province, Southwestern Atlantic Ocean. Rockacestus blasisp. nov. was found in Bathyraja macloviana (Norman, 1937), whereas Rockacestus magellanicussp. nov., and Rockacestus ottavianoisp. nov. were found in Bathyraja magellanica (Philippi, 1902). These species differ from their congeners in having a particular combination of anatomical features, including a moderate to highly folded bothridia, presence of a uteroduct, and a seminal receptacle. Cross-sections of mature proglottids were made for the first time in members of the genus. In addition, the microthrix pattern was described in detail, focusing on the distal bothridial surface, including the apical sucker and marginal loculi resulting in a common microthrix configuration with filitriches and small lanceolate, lingulate, and a particular kind of coniform spinitriches. The diagnosis of Rockacestus is revised to include several features exhibited by the new species. The distribution data of the species currently assigned to Rockacestus are compiled and updated. The finding of R. blasisp. nov., R. magellanicussp. nov., and R. ottavianoisp. nov. not only increases the number of members of Rockacestus in the Magellanic Province in the Southwestern Atlantic from one to four but also expands our knowledge of phyllobothriideans and their association with the softnose skates of the genus Bathyraja Ishiyama, 1958 in the Southern Hemisphere.

Two new species of Scyphophyllidium (Cestoda: Phyllobothriidea) from Chaenogaleus macrostoma (Bleeker) (Elasmobranchii: Carcharhiniformes) from the Persian Gulf, Iran.

Two new species of Scyphophyllidium Woodland, 1927 are described from the Hooktooth shark, Chaenogaleus macrostoma (Bleeker), from the Persian Gulf, Iran. Scyphophyllidium hormuziense n. sp. is assigned to morphological category 2 of its genus because it possesses bothridial marginal loculi and an apical sucker on each flat bothridium, and lacks bothridial facial loculi. Within category 2, it is distinguished from its congeners, except for S. janineae (Ruhnke, Healy and Shapero, 2006), by possessing, rather than lacking, a prominent cephalic peduncle. It differs from S. janineae in the distribution of the vitelline follicles. Scyphophyllidium iraniense n. sp. is assigned to morphological category 5 because its bothridia are essentially flat and lack proximal apertures, marginal loculi, facial loci and semi-circular muscle bands, and bears weakly serrate gladiate spinitriches on its distal bothridial surfaces. Within its morphological category, the presence of a long cephalic peduncle distinguishes S. iraniense n. sp. from its congeners lacking this structure or possessing a short cephalic peduncle. It further differs from S. arnoldi (Ruhnke and Thompson, 2006) and S. typicum (Subhapradha, 1955) in total length, from S. paulum (Linton, 1897) in lacking a conspicuous band of muscles along the locular periphery of the bothridia, and from S. kirstenae (Ruhnke, Healy and Shapero, 2006) in the distribution of the vitelline follicles. This study brings the number of the valid Scyphophyllidium species of the Persian Gulf to five.

Diversity and phylogenetic relationships of 'tetraphyllidean' Clade 3 (Cestoda) based on new material from orectolobiform sharks in Australia and Taiwan.

In an effort to expand knowledge of Clade 3-one of the ten clades that compose the non-monophyletic order 'Tetraphyllidea' all current members of which parasitise orectolobiform sharks-we targeted species of orectolobiform sharks that had not previously been examined for 'tetraphyllidean' cestodes. That work led to the discovery of three new species off Australia and Taiwan. Ambitalveolus gen. n. was erected to accommodate these species. Ambitalveolus costelloae gen. n. et sp. n., Ambitalveolus kempi sp. n., and Ambitalveolus penghuensis sp. n. differ from one another in scolex size, genital pore position, and number of marginal loculi, proglottids, and testes. Among 'tetraphyllideans', the new genus most closely resembles the two other genera in Clade 3. It differs from Carpobothrium Shipley et Hornell, 1906 in lacking anterior and posterior flap-like extensions of its bothridia; instead, its bothridia are essentially circular. It differs from Caulopatera Cutmore, Bennett et Cribb, 2010 in that its vitelline follicles are in two lateral bands, rather than circum-medullary, and in that its bothridia bear, rather than lack, conspicuous marginal loculi. A key to the three genera in Clade 3 is provided. A phylogenetic analysis including new sequence data for one of the three new species of Ambitalveolus gen. n., the only species of Caulopatera, and all four described species and one undescribed species of Carpobothrium supports previously hypothesised close affinities between Caulopatera and Carpobothrium, with the new genus as their sister group. This is the first report of 'tetraphyllidean' cestodes from the orectolobiform shark family Brachaeluridae Applegate. The association of the new species with orectolobiform sharks is consistent with those of the other members of Clade 3. However, whereas species of Carpobothrium and Caulopatera parasitise members of the hemiscylliid genus Chiloscyllium Müller et Henle, species of Amitalveolus gen. n. parasitise members of the Brachaeluridae and Orectolobidae Gill.

A new genus and three new species of Anthocephaliidae (Cestoda, Rhinebothriidea) from the round fantail stingray, Taeniurops grabata (Chondrichthyes, Dasyatidae) from the Mediterranean Sea and Atlantic Ocean.

The spiral intestines of a total of 16 round fantail stingrays Taeniurops grabata from the Mediterranean Sea off Tunisia were examined for cestodes. A new genus is erected in the Anthocephaliidae (Rhinebothridea) as Alveobothrium gen. n., with Alveobothrium grabatum sp. n. as its type species; the new genus differs from the other genera in the order in that its members possess bothridia with an apical sucker, marginal loculi and multiple staggered rows of facial loculi. Alveobothrium zarzisense sp. n. is also described. The species differ in the number of marginal loculi and in proglotid anatomy. Another anthocephaliid belonging to the genus Anthocephalum is also described from T. grabata. Anthocephalum jeancadenati sp. n. is most similar to A. alicae and A. michaeli, but differs in size of terminal proglottid and number of proglottids. All these new species are also found in formalin-preserved cestodes from T. grabata collected at Gorée Island (Senegal) between 1946 and 1954 by the French ichthyologist J. Cadenat and conserved in the personal collection of the late L. Euzet. The presence of the same rhinebothriideans species parasitizing T. grabata in both the Mediterranean (Tunisia) and the eastern Atlantic (Senegal) is discussed.

Resurrection of Mycteronastes (Monogenoidea: Monocotylidae), with Description of Mycteronastes caalusi n. sp. from Olfactory Sacs of the Smalltooth Sawfish, Pristis pectinata (Pristiformes: Pristidae), in the Gulf of Mexico off Florida.

Mycteronastes Kearn and Beverley-Burton, 1990 (Monogenoidea: Monocotylidae: Merizocotylinae) was resurrected from subjective synonymy with Merizocotyle Cerfontaine, 1894 , and its diagnosis was emended to include monocotylids with a haptor lacking a central loculus and having 5 peripheral (2 bilateral pairs and an unpaired anteromedial loculus), 1 interhamular, and 17 marginal loculi. The 3 species of Mycteronastes accepted herein are parasitic within the olfactory sacs of rays and sawfishes: Mycteronastes icopae ( Beverley-Burton and Williams, 1989 ) Kearn and Beverley-Burton, 1990 (type species) from the giant shovelnose ray, Glaucostegus typus (Anonymous (Bennett)) (Glaucostegidae), in the southwestern Pacific Ocean; Mycteronastes undulatae Kearn and Beverley-Burton, 1990 from the undulate ray, Raja undulata Lacepède (Rajidae), in the northeastern Atlantic Ocean; and Mycteronastes caalusi n. sp. from the smalltooth sawfish, Pristis pectinata Latham (Pristidae), in the Gulf of Mexico. Mycteronastes caalusi is most easily differentiated from its congeners by the combination of having 2 median cephalic papillae, an oval haptor that is wider than the body proper and lacks a deeply scalloped margin, a comparatively large anteromedial peripheral loculus, an unsclerotized male copulatory organ that is wholly anterior to the vaginal pores, a relatively small distal portion of the uterus (ootype chamber) that is mostly anterior to the vaginae, and a delicate uterus. The present study is the first report of a monocotylid from the olfactory sacs of P. pectinata and the first record of a species of Mycteronastes from the Gulf of Mexico. Notes on the taxonomy and systematics of some species assigned to Calicotyle Diesing, 1850 (Monocotylidae: Calicotylinae) are included.

The cestode order Rhinebothriidea no longer family-less: A molecular phylogenetic investigation with erection of two new families and description of eight new species of Anthocephalum.

The spiral intestines of a total of 30 specimens of 14 species of batoids from around the world were examined for rhinebothriideans. These consisted of Taeniura grabata, Dasyatis margaritella, and Dasyatis sp. from Senegal, Dasyatis americana from Florida, Dasyatis dipterura and Dasyatis longa from México, Himantura jenkinsii, Himantura leoparda, Himantura uarnak 2, Urogymnus asperrimus 1, and Neotrygon kuhlii 4 from Australia, in addition to Himantura uarnacoides and Neotrygon kuhlii 1 from Borneo. Each of these hosted one or more species of Anthocephalum. Eleven of the cestode species were new to science; four represented described species. In addition, Urotrygon aspidura from Costa Rica hosted a species of Escherbothrium. Sufficient material was available for formal description of the following eight species of Anthocephalum: A. decrisantisorum n. sp., A. healyae n. sp., A. jensenae n. sp., A. mattisi n. sp., A. meadowsi n. sp., A. odonnellae n. sp., A. papefayi n. sp., and A. philruschi n. sp. These species differ from their nine described congeners in overall size, number of proglottids and marginal loculi, number and arrangement of testes, apical sucker size, arrangement and distribution of vitelline follicles particularly with respect in the post-poral field, and muscularity of the genital pore. The diagnosis of Anthocephalum is emended slightly to accommodate these new species. Material of four previously described Anthocephalum species, seven of the novel Anthocephalum species described here, 3 undescribed Anthocephalum species, and the species of Escherbothrium was preserved in 95% ethanol and partial 28S rDNA (D1-D3) and complete 18S rDNA sequence data were generated de novo. These data were combined with data from GenBank for Anthocephalum cf. centrurum (recognized as A. mattisi n. sp. below) and 29 species representing 12 other putative rhinebothriidean genera. Phylogenetic analyses using Bayesian Inference and Maximum Likelihood methods were conducted using a total of five representatives of the Lecanicephalidea, Cathetocephalidea and "Tetraphyllidea" as outgroups. The analyses yielded trees that were largely congruent and that supported the existence of four major subgroups of rhinebothriideans. Family designations were established for each of these clades. Echeneibothriidae was elevated from subfamily to family level to accommodate the group consisting of Echeneibothrium and Pseudanthobothrium; this family is unique in retaining the apical organ (as a myzorhynchus) into adulthood. Rhinebothriidae was elevated from subfamily to family level to accommodate the group consisting of Rhabdotobothrium, Rhinebothrium, Rhinebothroides, Rhodobothrium, Scalithrium and Spongiobothrium. This family is distinctive in its lack of apical suckers and also of a definitive anterior/posterior orientation to the bothridia. Anthocephaliidae n. fam. was established to house Anthocephalum and taxa identified as New Genus 1, New Genus 2, and New Genus 4 by previous authors. The bothridia of its members exhibit a conspicuous anterior/posterior orientation signaled by the presence of an apical sucker. In addition, its members bear marginal loculi or one or more rows of facial loculi and vitelline follicles that are usually interrupted by the ovary. Escherbothriidae n. fam. was established to house Escherbothrium and the taxon identified as New Genus 3 by previous authors. It most closely resembles Anthocephaliidae but the facial loculi are arranged in columns anteriorly and rows posteriorly, rather than arranged in multiple rows or entirely lacking. A key to the families is also provided.

Two new species and a new phyllobothriid cestode genus from sharks of the genus Negaprion Whitley (Carcharhiniformes)

Alexandercestus n. g. (Cestoda: Tetraphyllidea) is erected for two cestode species found parasitising the two known species of lemon sharks (Carcharhiniformes: Negaprion spp.). This new genus differs from all other phyllobothriid genera except for Hemipristicola Cutmore, Theiss, Bennett & Cribb, 2011, Marsupiobothrium Yamaguti, 1952, Nandocestus Reyda, 2008, Orectolobicestus Ruhnke, Caira & Carpenter 2006, Orygmatobothrium Diesing, 1863, Paraorygmatobothrium Ruhnke, 1994 and Phyllobothrium van Beneden, 1849 in possessing uniloculate bothridia with an apical sucker and neck scutes. Alexandercestus differs from Orectolobicestus and Nandocestus in lacking marginal loculi on the bothridia, from Paraorygmatobothrium in possessing uninterrupted vitelline follicles at the level of the ovary and from Phyllobothrium in being euapolytic as opposed to anapolytic and in lacking posteriorly bifid bothridia. The new genus lacks the central accessory bothridial organ seen in specimens of Orygmatobothrium, and lacks the central bothridial accessory sucker of specimens of Marsupiobothrium. Alexandercestus spp. compare most favourably with specimens of Hemipristicola, especially with respect to aspects of proglottid morphology, but differ in possessing aristate gladiate spinitriches rather than serrate gladiate spinitriches on the proximal bothridial surface. In addition, the bothridia of Alexandercestus spp. are comparatively more fleshy and foliose than those in specimens of Hemipristicola. Two new species of Alexandercestus n. g. are described, Alexandercestus gibsoni n. sp. from Negaprion acutidens, collected from off northern Australia and the Marshall Islands, and Alexandercestus manteri n. sp. from N. brevirostris, collected off the islands of Bimini and the Florida Keys. The two new species differ in total length and vitelline follicle distribution. Bayesian inference and parsimony analysis of the D1-D3 region of the large nuclear ribosomal DNA of 17 published and seven novel sequences placed A. gibsoni as the sister taxon to a clade containing Hemipristicola gunterae Cutmore, Theiss, Bennett & Cribb, 2011 and species of Paraorygmatobothrium. This result supports the erection of Alexandercestus as a genus separate from Hemipristicola and Paraorygmatobothrium. At the present time, species of Alexandercestus are known only from hosts of the carcharhinid genus Negaprion Whitley; examination of extensive survey data suggests this may be the extent of the host distribution of this genus.

Cairaeanthus gen. n. (Cestoda, Rhinebothriidea), with the Description of Two New Species from Dasyatis pastinaca in the Black Sea and the Sea of Azov

Cairaeanthusgen. n. (Cestoda, Rhinebothriidea), with the Description of Two New Species fromDasyatis pastinacain the Black Sea and the Sea of AzovTwo new species were identified among cestodes collected fromDasyatis pastinaca(Linnaeus, 1758) in the Black Sea and the Sea of Azov. Their morphology corresponds in the most characters to the descriptions ofPhyllobothrium lactucavan Beneden, 1850 andP. gracilisWedl, 1855 by L. Borcea (Borcea, 1934) and T. P. Pogorel'tseva (Pogorel'tseva, 1960) from the same host and seas. However, some morphological characters of these cestodes (namely, the marginal loculi on the pedicellate bothridia, cephalic peduncle, absence of the apical sucker and post-poral testes, genital pore opening marginally, close to posterior end of proglottid) correspond to diagnosis of Rhinebothriidea. Since the species from the Black Sea and the Sea of Azov did not fit diagnoses of any known genera currently belonging to Rhinebothriidea, the new genus,CairaeanthusKornyushin et Polyakova, gen. n., with two species,C. ruhnkeiKornyushin et Polyakova, sp. n. andC. healyaeKornyushin et Polyakova, sp. n., is established.Cairaeanthusgen. n. differs fromAnthocephalumLinton, 1890 in absence of apical sucker, posteriorly bifid bothridia and vitelline fields interrupted by the ovary, not extending in the posterior end of the proglottid. The new genus can be distinguished fromRhinebothriumLinton, 1890,Echeneibothiumvan Beneden, 1850,RhabdotobothriumEuzet, 1953,RhinebothroidesMayes, Brooks et Thorson, 1981,ScalithriumBall, Neifar et Euzet, 2003 by the absence of facial loculi on the bothridia and by numerous vitelline follicles, stopping at the anterior margin of the ovary; fromRhodobothriumLinton, 1889 - by absence of post-poral testes, and fromSpongiobothriumLinton, 1889 - by numerous vitelline follicles, stopping at the level of ovary.C. ruhnkeisp. n. differs fromC. healyaesp. n. in the lengths of the strobila, the cephalic peduncle and the bothridia pedicel, in size of marginal loculi and the ovary, in the number of the proglottids and the testes in the proglottid, and in the structure of genital atrium. Two new species are differentiated also from the morphologically related speciesPhyllobothrium pastinacaeMokhtar-Mocamouri, Zamali, 1981. Examined type specimens ofP. pastinacaewere attributed to Rhinebothiidea based on a set of morphological characters. However, they appear to differ from all known Rhinebothriidea, including the species from the generaAnthocephalumLinton, 1890 andCairaeanthusgen. n. Taxonomic position ofP.pastinacaeneeds further identification.

A New Species of Empruthotrema (Monogenea: Monocotylidae) from Pteromylaeus bovinus (Myliobatidae) from the Western Mediterranean

Empruthotrema chisholmae n. sp. is described from specimens recovered from a bull ray Pteromylaeus bovinus (Geoffroy Saint-Hilaire, 1817) at the Oceanogràfic Aquarium in Valencia, Spain. The bull ray was caught in the Spanish Mediterranean (Puerto de Mazarrón, Murcia). The new species resembles 4 others of the same genus ( Empruthotrema dasyatidis Whittington and Kearn, 1992, Empruthotrema kearni Whittington, 1990, Empruthotrema stenophallus Chisholm and Whittington, 2005, and Empruthotrema tasmaniensis Chisholm and Whittington, 1999) in having a haptor with 13 marginal loculi, the posteriormost loculus single and medial. The new species can be distinguished from these other species of the genus by the morphology of the sclerotized male copulatory organ, which is the shortest described. The new species also differs from the other species by the following combination of features: haptor with 13 marginal loculi, the presence of eyespots, the absence of an accessory piece associated with the male copulatory organ, and a long egg appendage (more than 150 µm). Empruthotrema chisholmae is the first species of the genus reported from the Mediterranean.

Three new species of Anthocephalum Linton, 1890 (Cestoda: Tetraphyllidea) from dasyatid stingrays of the Gulf of California

Three new species of Anthocephalum Linton, 1890 are described from dasyatid stingrays collected in the Gulf of California. Anthocephalum michaeli n. sp. is described from Dasyatis longus (Garman). This species most closely resembles A. alicae Ruhnke, 1994, but differs from this species in proglottid number. A. lukei n. sp. is also described from D. longus. This new species is most similar to A. cairae Ruhnke, 1994, but differs from that species in marginal loculi number and number of proglottids. The third new species, A. currani n. sp., is described from D. brevis (Garman). This species is most similar to A. centrurum (Southwell, 1925) Ruhnke, 1994, but differs from that species in marginal loculi number, number of testes and ovarian length. Phyllobothrium kingae Schmidt, 1978 is also consistent in morphology with species of Anthocephalum and is transferred to this genus, forming the new combination Anthocephalum kingae n. comb. This species most closely resembles A. michaeli n. sp., but differs in testicular shape. This brings the total number of species of Anthocephalum to nine. The transfer of the species Phyllobothrium arctowskii Wojciechowska, 1991, P. georgiense Wojciechowska, 1991, P. rakusai Wojciechowska, 1991 and P. siedleckii Wojciechowska, 1991 to Anthocephalum is not warranted, as these four species lack a posteriorly recurved cirrus-sac and a sinuous vagina, and have vitelline follicles uninterrupted by the ovary. Of the nine known species, all are parasitic in batoid fishes, and six are found in species of Dasyatis Garman. The phylogenetic status of Anthocephalum species in relationship to Rhinebothroides Mayes, Brooks & Thorson, 1981, Pararhineothroides Zamparo, Brooks & Barriga, 1999 and other rhinebothriin taxa is discussed.

Orectolobicestus n. g. (Cestoda: Tetraphyllidea), with the description of five new species and the transfer of Phyllobothrium chiloscyllii to the new genus

ORECTOLOBICESTUS N. G. (CESTODA: Tetraphyllidea) is erected for six cestode species parasitising bamboo sharks (Orectolobiformes: Chiloscyllium). Members of this genus differ from all other phyllobothriid genera in possessing modified maisiform spinitriches on their distal bothridial surfaces. In addition, they are easily recognised in that they share the following unique combination of characters: their vitelline fields are interrupted by the ovary, their necks are scutellate, and their bothridia bear an apical sucker and marginal loculi. Five new species of Orectolobicestus are described, including O. tyleri n. sp. from Chiloscyllium punctatum off Borneo, O. lorettae n. sp. from C. cf. punctatum off Australia, O. mukahensis n. sp. and O. kelleyae n. sp. from C. indicum off Borneo, and O. randyi n.sp. from C. hasselti also from off Borneo. In addition, Phyllobothrium chiloscyllii Subhapradha, 1955 is transferred to the new genus. O. chiloscyllii (Subhapradha, 1955) n. comb. is readily distinguished from all five new species in its greater total length. In addition to a number of proglottid features, O. kelleyae n. sp. and O. randyi n. sp. clearly differ from the other three new species in their possession of trifid, rather than fully serrate, spinitriches on their proximal bothridial surfaces. The latter two species conspicuously differ from one another in total number of proglottids (11-21 vs 27-38). O. tyleri n. sp. generally has fewer proglottids than O. lorrettae n. sp. (7-17 vs 13-23) and, like O. mukahensis n. sp., possesses scutes that are spathate rather than elongate. O. tyleri n. sp. is readily distinguished from O. mukahensis n. sp. in its possession of fewer proglottids (7-17 vs. 19-29). The five new species of Orectolobicestus share derived bothridial microthrix features with Phyllobothrium squali Yamaguti, 1952, Thysanocephalum sp., Orygmatobothrium sp., Ruhnkecestus Caira & Durkin, 2006 and species of Paraorygmatobothrium Ruhnke, 1994. Among these taxa, Orectolobicestus most closely resembles Paraorygmatobothrium and Ruhnkecestus in its vitelline fields being interrupted by the ovary and the possession of a scutellate neck.

Pararhinebothroides hobergi n. gen. n. sp. (Eucestoda: Tetraphyllidea) in Urobatis Tumbesensis (Chondrichthyes: Myliobatiformes) from Coastal Ecuador

A new species of tetraphyllidean eucestode inhabiting Urobatis tumbesensis from inshore waters of southeastern Ecuador shares 3 synapomorphies with Rhinebothroides spp.: apical bothridial suckers poorly differentiated from the marginal loculi, internal seminal vesicles, and insertion of the vas deferens dorsally closer to the poral than the aporal end of the cirrus sac. The new species differs from Rhinebothroides spp. by lacking medial bothridial septa and loculi and having symmetrical ovarian arms, and possesses an apparent autapomorphic trait by having the vas deferens tapering to a narrow tube before entering the cirrus sac, extending posteriorly to the posterior end of the cirrus sac where it expands into an external seminal vesicle running ventral to the cirrus sac anteriorly to anterior to the vagina. In Rhinebothroides spp., the vas deferens is expanded into an external seminal vesicle near the insertion into the cirrus sac As the sister group of Rhinebothroides, we propose a new genus to accommodate the new species. Phylogenetic evaluation of phyllobothriids recently assigned to Anthocephalum shows that they represent a paraphyletic assemblage of species of varying degrees of relatedness to Rhinebothroides spp. and the new species. Uncovering the relationships of the new species and the various species assigned to Anthocephalum permitted reevaluation of character transformations used in previous phylogenetic analysis of Rhinebothroides. Transformation series for 3 characters, previously based on functional outgroup comparisons, changed and a new character, length of cirrus sac, was added. The new phylogenetic analysis differs from the previous hypothesis only in placing R. scorzai as the sister species of R. circularisi + R. venezuelae + R. moralarai rather than of R. freitasi + R. glandularis + R. mclennanae. The occurrence of the sister species of Rhinebothroides in a Pacific Ocean stingray adds additional support to the hypothesis of Pacific origins of South American freshwater stingrays.

A revision of the Merizocotylinae Johnston and Tiegs, 1922 (Monogenea: Monocotylidae) with descriptions of new species of Empruthotrema Johnston and Tiegs, 1922 and Merizocotyle Cerfontaine, 1894

Empruthotrema tasmaniensis sp. nov. is described from the nasal fossae of the southern eagle ray, Myliobatis australis Macleay (Myliobatidae), from the east coast of Tasmania. Empruthotrema tasmaniensis is distinguished from others in the genus by the presence of an accessory piece associated with the male copulatory organ; no other species of Empruthotrema Johnston and Tiegs, 1922 has an accessory piece. Merizocotyle urolophi sp. nov. is described from the nasal fossae of the sparsely spotted stingaree, Urolophus paucimaculatus Dixon (Urolophidae), and is distinguished from other members of the genus by 12 marginal loculi on the haptor; this is the only species of Merizocotyle Cerfontaine, 1894 that has this configuration. Squalotrema llewellyni Kearn and Green, 1983, described previously from Squalus acanthias Linnaeus (Squalidae) from the English Channel, is recorded from the same host species caught off the east coast of Tasmania. We found Triloculotrema japanica Kearn, 1993, which was described originally in the nasal fossae of the Japanese topeshark, Hemitriakis japanica (Müller and Henle) (Triakidae), off Minabe, Japan, in the nasal fossae of Mustelus antarcticus (Günther) (Triakidae) caught off the east coast of Tasmania. Merizocotyle australensis (Beverley-Burton and Williams, 1989) Chisholm, Wheeler and Beverley-Burton, 1995, found in the nasal fossae of Himantura uarnak collected from Darwin, represents a new host and locality record. Empruthotrema and Merizocotyle are revised fully and additional information is provided for Squalotrema Kearn and Green, 1983 and Triloculotrema Kearn, 1993. A key is given to the Merizocotylinae Johnston and Tiegs, 1922 and illustrations are provided of all important taxonomic characters. We postulate how the different types of haptors found in Empruthotrema and Merizocotyle may have been derived and discuss the taxonomy of Merizocotyle which is still in a poor state.

Three New Genera and Species of Tapeworms from the Longnose Sawshark, Pristiophorus cirratus, with Comments on Their Modes of Attachment to the Spiral Intestine

The spiral intestines of 18 specimens of the longnose sawshark Pristiophorus cirratus, collected from southeastern Australia, were examined for parasites. Three new genera and species of tetraphyllidean tapeworms belonging to the Phyllobothriinae within the Phyllobothriidae were discovered as a result of these necropsies. Flexibothrium ruhnkei n. g., n. sp. differs from all other phyllobothriine tapeworms in its possession of bothridia that each bear an apical sucker and a posterior margin that is flexed anteriorly and fused along the median line of the distal bothridial surface, forming 2 essentially open-faced grooves. Light and scanning electron microscopy of worms attached to the mucosal surface suggest that this species uses the open-faced bothridial grooves, the outermost surface of the anteriorly flexed portion of each bothridium, and the interbothridial surfaces to grasp up to a total of 16 mucosal villi and/or ridges. Cardiobothrium beveridgei n. g., n. sp. is unique among the phyllobothriids in its possession of bothridia each with an apical sucker, marginal loculi, and 4 facial loculi arranged in 2 tandem pairs. This taxon is provisionally placed within the Phyllobothriinae, and the subfamilial diagnosis is emended to include species with facial loculi. Examination of specimens fixed in situ and then removed from the mucosal surface suggests that this species uses the larger, posterior pair of facial loculi of each bothridium to grasp the tips of a pair of adjacent villi in order to attach to the mucosal surface. Bibursibothrium gouldeni n. g., n. sp. also appears to belong in the Phyllobothriinae. Within this subfamily it most closely resembles species of Marsupiobothrium in its possession of pouchlike bothridia. However, it conspicuously differs from species in this genus in that its bothridial pouches are subdivided internally into 2 distinct compartments. Cross sections of individuals of this taxon attached to the mucosal surface indicate that each bothridium is used to grasp 2 adjacent mucosal elements such that the scolex has the ability to attach to up to a total of 8 villi and/or ridges. The discovery of 3 new genera of tapeworms from this host species is not unexpected given the high degree of host specificity generally exhibited by the phyllobothriids, and that this is the first report of tapeworms from a shark of the order Pristiophoriformes.

Serendip deborahae n. gen. and n. sp. (Eucestoda: Tetraphyllidea: Serendipidae n. fam.) in Rhinoptera steindachneri Evermann and Jenkins, 1891 (Chondrichthyes: Myliobatiformes: Myliobatidae) from Southeastern Ecuador

Cestodes collected in spiral valves of Rhinoptera steindachneri from the southern coast of Ecuador represent an undescribed species of Tetraphyllidea. The new species has bothridia possessing septa but lacking apical suckers. It is diagnosably distinct from all other tetraphyllidean genera by possessing a scolex comprising 4 triangular bothridia that are fused together forming a platelike structure, each of which is subdivided by 2 simple and 1 bifurcating septa radiating from its base and ringed by marginal loculi; therefore, a new genus is proposed for it. By exhibiting some degree of bothridial fusion, testes arranged in 2 layers in the proglottis and postovarian testes, the new species appears to be a member of a clade containing Dioecotaenia, Duplicibothrium, and Glyphobothrium. The new species possesses vitelline fields that converge dorsally in each proglottis, except for the ovarian and terminal genitalia areas, a feature that has been reported previously only in Duplicibothrium and Glyphobothrium. Furthermore, Duplicibothrium and Glyphobothrium, like the new species, are markedly protandric. Therefore, we propose that Duplicibothrium, Glyphobothrium, and the new species comprise the sister group of the Dioecotaeniidae, and propose a new family name for the clade. Tritaphros is rejected as a possible sister group for the clade; suggested alternatives include some species of Caulobothrium, Rhodobothrium, or some members of the Phyllobothrium centrurum group.

Resurrection of Anthocephalum Linton, 1890 (Cestoda: Tetraphyllidea) and taxonomic information on five proposed members

Anthocephalum Linton, 1890 is resurrected as a valid genus within the Tetraphyllidea. Anthocephalum differs from other tetraphyllidean genera in having pedicellate bothridia combined with complete, regular loculi on the bothridial margins. Phyllobothrium gracile from Torpedo marmorata and Phyllobothrium centrurum (the type-species) from Dasyatis centroura are added to Anthocephalum and their descriptions are amended. Anthocephalum alicae n.sp. from Dasyatis americana is described. It can be distinguished from the above two species in being shorter, in having fewer segments per worm and fewer testes per segment. Anthocephalum cairae n. sp. from Dasyatis americana is described. It can be distinguished from the above three species in having a greater number of marginal loculi per bothridium. Anthocephalum duszynskii n. sp. from Urolophus halleri is also described. It differs from all of the above species, except for A. gracile in loculi number and from A. gracile in being shorter, having fewer segments per worm and fewer testes in a dorsal/ventral field. The generic diagnosis of Anthocephalum is emended to include information from A. gracile, A. centrurum and the three new species. The proximal bothridial surfaces of Anthocephalum centrurum and the three new species are covered with short, stumpy microtriches and thick, spiniform microtriches, their distal bothridial surfaces are covered with slender spiniform microtriches and their cirri were found to be armed with spiniform microtriches, rather than spines. All species placed in Anthocephalum are parasites of batoid fish. A brief discussion of potentially covert members of Anthocephalum is also included.

Phyllobothrium pastinacae n. sp. (Cestoda, Tetraphyllidea, Phyllobothriidae parasite de Dasyatis pastinaca (Linnaeus, 1758)

Distinguishing characteristics include: - scolece divided into four distincty curled bilobed bothridia with marginal loculi, -anatomy without post vaginal tests, - lateral genital atrium always in posterior 1/4 of segments, - about 100 testes.

Phyllobothrium piriei sp.nov. (Cestoda: Tetraphyllidea) from Raja naevus with a comment on its habitat and mode of attachment

Phyllobothrium piriei sp.nov. (Cestoda: Tetraphyllidea) from the intestine of Raja naevus in the North Sea resembles P. dagnallium, P. radioductum and P. britannicum more closely than any other known species of the genus but differs from these mainly in its host, in having distinctly bifid bothridia with faint marginal loculi and about 150 testes in each proglottid. Brief comments are made on the preference shown by the adult for the posterior region of the intestine and on a modification of its bothridium for attachment to up to 12 villi.This work was supported by generous financial aid from the Natural Environment Research Council. I wish also to record my gratitude to Professor V. C. Wynne-Edwards and Dr P. A. Orkin for reading and suggesting improvements to the manuscript and to the Director and staff Marine Laboratory, Aberdeen, in particular Dr B. B. Rae and Mr Stuart Pirie, after whom this species has been named, for providing live rays. Alasdair McVivar of this department, who has now begun an independent study of the intestine of Raja naevus as a habitat for helminth parasites, kindly provided information for Fig. 9.