Scyphophyllidium uruguayense n. sp. (Eucestoda: Tetraphyllidea) in Mustelus mento (Cope, 1877) (Chondrichthyes: Carcharhiniformes: Triakidae) from La Paloma, Uruguay.

A new species of Scyphophyllidium inhabits Mustelus mento near La Paloma, Uruguay. It resembles Scyphophyllidium giganteum from the Atlantic Ocean and specimens identified as S. giganteum from California by having anapolytic strobilae 155-258 mm long, 250-300 craspedote proglottids, scoleces 1.2-1.4 mm wide, necks 34-41 mm long, immature and mature proglottids wider than long, gravid proglottids wider than long to longer than wide, genital pores averaging 28% of proglottid length from the anterior end, relatively flat ovaries with digitiform lobes reaching the lateralmost extent of the testicular field, vitellaria in 2 fields converging toward the proglottid midline, straight and short cirrus sacs, and postvaginal vas deferens. The bothridia of the new species have accessory bothridial suckers that are smaller than those of California specimens; European specimens reportedly lack accessory bothridial suckers. The new species possesses a uterine duct that joins the uterus at the level of the genital atrium and ventral osmoregulatory ducts medial rather than lateral to the dorsal ducts, an arrangement described for Californian but not European specimens. It differs from both European and Californian specimens by having longer cirri, more testes per proglottid, prominent scales covering the neck, and vaginae and uterine ducts coiled immediately preovarially. Pithophorus, Marsupiobothrium, and Scyphophyllidium may form a clade.     

A new species of Acanthobothrium (Cestoda: Tetraphyllidea: Onchobothriidae) from the ocellate river stingray, Potamotrygon motoro (Chondrichthyes: Potamotrygonidae), in Argentina

Examination of the spiral intestines of 44 freshwater stingrays, Potamotrygon motoro, from tributary rivers of the Parana River in Argentina, allowed for the collection of specimens of an undescribed species of Acanthobothrium. Acanthobothrium ramiroi n. sp. can be distinguished from all other congeners by the combination of the following characters: asymmetrical hooks (medial and lateral hooks conspicuously different in size and form, with axial prong of medial hooks stouter than abaxial prong), hook size (total length of medial hooks up to 242 microm, total length of lateral hooks up to 239 microm), bothridia not fused to the scolex proper at posterior ends, worm size (51-84 mm long), and the presence of a conspicuous vaginal sphincter. The new species is different from all other species of Acanthobothrium in freshwater potamotrygonids, except Acanthobothrium terezae, in having conspicuous asymmetrical hooks. The main differences that allow for the distinction between A. ramiroi and A. terezae include hook size, the way the bothridia are attached to the scolex proper, and the shape of the older gravid segments. The discovery of a new species of Acanthobothrium from a potamotrygonid extends our understanding of the diversity of the genus in freshwater stingrays in South America.     

Orygmatobothrium spp. (Cestoda: Tetraphyllidea) from triakid sharks in Argentina: redescription of Orygmatobothrium schmitti and description of a new species

Two species of Orygmatobothrium were found inhabiting triakid sharks collected from the coast of Buenos Aires Province, Argentina. Orygmatobothrium schmittii from Mustelus schmitti is redescribed, including new information on the microtrich pattern. Orygmatobothrium juani n. sp. from Mustelus fasciatus can be distinguished from all other species in the genus using the following combination of characters: worm length, number of proglottids, number of testes, testes distribution, size of eggs, ornamented egg shell, shape of bothridial cleft at level of the marginal accessory sucker, and the extension of vitelline follicles. Species in Orygmatobothrium share a common microtrich pattern with the distal bothridial surface covered with maisiform microtriches interspersed with filiform microtriches, a proximal bothridial surface covered with trifid microtriches, with a medial projection conspicuously larger than the lateral basal projections interspersed with filiform microtriches, an inner and outer surface of the accessory sucker and glandulomuscular organ covered with short filiform microtriches, the scolex proper and cephalic peduncle surface covered with bladelike microtriches, and the germinative zone and entire strobila covered with scutes formed by densely packed filiform microtriches. This general configuration is basically similar to the microtrich pattern described in species of Orectolobicestus and Paraorygmatobothrium.     

A new species of Calliobothrium (Tetraphyllidea: Onchobothriidae) from the whiskery shark, Furgaleus macki, in Australia

Calliobothrium pritchardae n. sp. is described from the whiskery shark, Furgaleus macki (Whitley, 1943), collected from Young Rocks in South Australia. This species differs from the 7 other known species of Calliobothrium in its possession of 2 rather than 3 posthook loculi. It is a further distinguished from all other Calliobothrium species except Calliobothrium evani in its possession of asymmetrical hooks. The lack of an accessory piece between the bases of the axial hooks and medial axial hook bases that are longer than the lateral axial hook bases further distinguish the new species from C. evani in which an accessory piece is present and the relative lengths of the medial and lateral axial hook bases are reversed. Scanning electron microscopy reveals spiniform microtriches on the neck and proximal bothridial surfaces, filiform microtriches on the apical bothridial surfaces, and a combination of the 2 microthrix types on the distal bothridial surfaces. The extended bases of the axial hooks are densely covered with spiniform microtriches. In addition, the number of testes within worms decreases substantially in progressively posterior (older) segments. The generic diagnosis of Calliobothrium is emended to include this species with 2 rather than 3 posthook loculi.     

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.     

Comparison of microthrix ultrastructure and morphology on the plerocercoid and adult scolex of Calliobothrium cf. verticillatum (Tetraphyllidea: Onchobothriidae)

The distal bothridial surfaces of adult triloculate onchobothriids are covered with short structures that have been tentatively classified as very short filitriches, but this hypothesis has never been tested. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate microthrix morphology in the plerocercoid and adult forms of Calliobothrium cf. verticillatum, a triloculate onchobothriid tapeworm from Long Island Sound (Connecticut). Plerocercoids of C. cf. verticillatum were collected from the anterior midgut ceaca of Pagurus pollicaris Say, 1817 (flat-clawed hermit crab), and adults were collected from the spiral intestine of the dusky smooth hound Mustelis canis (Mitchell, 1815). Two plerocercoids and 2 adults were examined using SEM; 2 plerocercoids and 2 adults were examined using TEM. Microthrix distribution and morphology (including measurements of total length, base length, shaft length, and base width) were investigated on all surfaces of the plerocercoid and adult scolex. Slender filitriches and large bladelike spinitriches were observed extending from the tegument of plerocercoid and adult forms. The filitriches were found to have significantly narrower bases than the spinitriches (65-167 nm vs. 466-1,936 nm, respectively). The scolex proper of the plerocercoid and adult forms were found to have filitriches of medium-length and bladelike spinitriches. The distal bothridial surfaces differed dramatically in microthrix morphology between plerocercoid and adult forms; on the distal surfaces of the plerocercoids were long filitriches and bladelike spinitriches. However, the distal surfaces of the adults had short structures (previously hypothesized to be short filitriches) and a few bladelike spinitriches. Serial transverse sections revealed that the short structures on the distal bothridial surfaces of the adults were homologous with filitriches. They included all of the structural components of a filithrix as well as a base width that conformed to the filitriches found on other surfaces. The bothridial margins of the plerocercoid and adult forms had a microthrix pattern similar to that seen on the proximal bothridial surfaces except that the filitriches on the margins were significantly longer than those found anywhere else on the bothridia. The most dramatic difference between the plerocercoid and adult forms occurred on the distal bothridial surfaces, where the filitriches of the adult cestodes were significantly shorter and narrower, and the spinitriches were almost entirely lacking.     

A new species of Onchobothriidae (Tetraphyllidea) from Chiloscyllium plagiosum (Elasmobranchii: Orectolobidae) in China

A new species of cestode, Yorkeria xiamenensis n. sp., is described from the spiral valve of Chiloscyllium plagiosum from coastal waters of Xiamen, China. It is the first record of Yorkeria in China. The new species is distinguished from all other species of Yorkeria by its possession of the following characters: the length of specimens, 15.8 mm; 63-95 proglottids; 71-85 testes per proglottid; large medial and lateral hooks in scolex; and eggs with 2 long polar filaments. The new species most closely resembles Y. parva Southwell, 1927 in the follicular vitellaria and similar ratio of lateral-to-medial hooks (1:2.15 vs. 1:2-2.5). However, Y. xiamenensis n. sp. has a longer strobila, more proglottids, a smaller ratio of pedicel to cephalic peduncle, larger hooks, more testes, and a different host.     

Anindobothrium n. gen. (Eucestoda: Tetraphyllidea) inhabiting marine and freshwater potamotrygonid stingrays.

Anindobothrium n. gen. is proposed to accommodate Caulobothrium anacolum inhabiting Himantura schmardae from Colombia, and 2 new species, one inhabiting Potamotrygon orbigny in Brazil and the other inhabiting Paratrygon aereiba in Venezuela. Members of the new genus resemble members of Pararhinebothroides, Rhinebothroides, and Anthocephalum by having bothridia with poorly differentiated apical suckers and vasa deferentia expanded into external seminal vesicles. It further resembles Pararhinebothroides, Rhinebothroides, and Anthocephalum cairae by having vas deferens inserted near the poral rather than aporal end of the cirrus sac. The 3 species assigned to the new genus form an apparent monophyletic group, based on the possession of 3 putative synapomorphies: (1) genital pores in the anterior 1/4 of the proglottid, a trait that is unusual, but not unique, among phyllobothriids; (2) anteroventral ovarian lobes converging to the center of the proglottid, a character not previously reported for phyllobothriids; and (3) ovarian lobes comprising a loose network of digitiform processes.     

Two new species of Yorkeria (Tetraphyllidea: Onchobothriidae) from Chiloscyllium punctatum (Elasmobranchii: Hemiscylliidae) in Thailand

Two new species of the tapeworm genus Yorkeria are described from the spiral intestine of a specimen of the Brownbanded bambooshark, Chiloscyllium punctatum, collected from a fish market in Bangsarai, Thailand in 1996. The larger of the 2 new tapeworm species, Y. hilli, possesses fewer proglottids, fewer testes, and is smaller than most of its congeners. The smaller of the 2 new species, Y. kelleyae, conspicuously differs from all of its congeners in its possession of medial hooks that are only slightly larger than the lateral hooks (rather than conspicuously larger). Scanning electron microscopy shows both species to possess elongate filitriches on their distal prehook locular surfaces and elongate filitrichs and spinitrichs on their proximal bothridial, distal posthook locular surfaces, pedicels, and cephalic peduncles. In both species, the spinitrichs on the proximal bothridial surfaces, pedicels, and peduncles are very large and readily visible with light microscopy. Whereas the spinitrichs on these 4 surfaces are bluntly rounded in Y. hilli, they are pointed in Y. kelleyae. Examination of specimens identified as Y. parva, collected by several previous workers from a diversity of hosts and localities, calls into question the conspecificity of at least some of this material. The unusual scolex form suggests that the configuration of the cerebral ganglionic mass in species of Yorkeria may differ from that seen in most other tetraphyllidean taxa.     

A new species of Acanthobothrium van Beneden, 1849 (Cestoda: Tetraphyllidea) from Rioraja castelnaui (Chondrichthyes: Rajoidei) in coastal waters of Argentina

Acanthobothrium marplatensis n. sp. is described from the spiral intestine of the skate Rioraja castelnaui taken off Mar del Plata, Argentina. The new species is compared with those species that it most closely resembles morphologically, to species reported from other skate hosts and to species described from the same geographical region. A. marplatensis is most similar to A. paulum, A. benedeni, A. costarricense, A. fogeli, A. himanturi, A. lintoni, A. monksi, A. olseni, A. puntarenasense and A. mathiasi. All of these species share a similar combination of characters (12–40 proglottids, 20–50 testes and total length of 2–10mm). A. marplatensis can be differentiated from these species and those described from skates by a combination of the following characters: 4.79–8.44 (6.18) mm long, with 18–30 (24) proglottids, spinose cephalic peduncle 160–338 (227) long, bothridial hooks with total length 93-134 (115), 24–39 (32) testes per proglottid, cirrus-sac curved anteriorly, ovarian lobes never reaching the level of the cirrus-sac and vaginal sphincter absent. Geographically, the new species can be distinguished from A. zapterycum and three different species designated as Acanthobothrium sp. reported from the coast of Uruguay and Argentina by the size of the worms, number of proglottids, position of the genital pores and size of the bothridial hooks. A. marplatensis showed the greatest preference for chambers 2 and 3 of the eight chambers of the spiral intestine. The mean intensity of infection in individual hosts increased with host size and was greater in spring and summer than in cold seasons. The intensity of infection was unrelated to host sex.     

Rhinebothrium xiamenensis n. sp. (Eucestoda: Tetraphyllidea) in Dasyatis zugei from the coast of Xiamen, China

A new species of Rhinebothrium inhabiting Dasyatis zugei is reported from the southeast coast of China. This is the first report of Rhinebothrium from D. zugei. It represents a new host and a new location. The new species resembles Rhinebothrium corymbum by having a V-shaped ovary. It differs in the fewer loculi and testes numbers, longer bothrium pedicel and cephalic peduncle, larger cirrus pouch and vitelline follicles, and an aspinose peduncle. Rhinebothrium xiamenensis differs from Rhinebothrium ezuti, Rhinebothrium walga, and Rhinebothrium hawaiiensis by having discrete vitelline follicles, fewer loculi, and ovarian shape.     

Reproduction in Mustelus canis (Chondrichthyes: Triakidae) from an unexploited population off northern Brazil

Aspects of the reproductive biology of Mustelus canis (Mitchill, 1815) (n = 100) were assessed for an unexploited population off northern Brazil. Based on clear maturation between juveniles and adults, total length (TL) at 50% maturity for males and females was estimated at 99 and 108 cm; slightly larger than previous estimates for more southern and northwestern Atlantic stocks. Ovulation and gestation occurred soon after parturition, and reproduction appeared to be non‐seasonal (possibly reflecting homogenous environmental conditions), with females having a range of oocyte and embryo sizes across the sampled months. Uterine fecundity ranged between 5 and 9 (mean ± SD of 7.15 ± 1.28) and, along with ovarian fecundity (range of 7–13 oocytes; mean ± SD of 10.0 ± 1.84), was positively correlated with TL. Nearly all gravid females had spermatozoa stored in their oviducal glands, which may be used for subsequent fertilization independent of copulation. The reproductive characteristics, and especially the apparent low fecundity, of the sampled M. canis warrant a precautionary approach to the management of any developing commercial fishery.     

Two new species of Paraorygmatobothrium (Cestoda: Tetraphyllidea) from weasel sharks (Carcharhiniformes: Hemigaleidae) of Australia and Borneo

Two new species of Paraorygmatobothrium Ruhnke, 1994, P. janineae n. sp. and P. kirstenae n. sp., are described from the spiral intestine of 2 shark species of the Family Hemigaleidae: Hemigaleus microstoma and Hemipristis elongata. The 2 new cestode species differ from other members of Paraorygmatobothrium in vitelline follicle distribution and possession of a cephalic peduncle. The 2 new species differ from 1 another in total length, maximum width, scolex size, number of proglottids per strobila, and number of testes per proglottid. The generic diagnosis of Paraorygmatobothrium is emended to include the new species. The results of this study extend the distribution of Paraorygmatobothrium to include the carcharhinid shark family Hemigaleidae.     

Notomegarhynchus navonae n. gen. and n. sp. (Eucestoda: Tetraphyllidea), from skates (Rajidae: Arhynchobatinae) in the southern hemisphere

Notomegarhynchus n. gen. (Eucestoda: Tetraphyllidea) is proposed to accommodate Notomegarhynchus navonae n. gen., n. sp. from Atlantoraja castelnaui in Mar del Plata, Argentina. Notomegarhynchus shetlandicum n. comb. from Bathyraja eatonii and B. maccaini in South Shetlands region, Antarctica, is a second species in the genus. Notomegarhynchus belongs to the Echeneibothriinae within the Phyllobothriidae. It can be distinguished from all other tetraphyllidean genera by the structure of the scolex in form of a massive myzorhynchus consisting of a proscolex and an apical organ, both of which are nonretractable and noninvaginable; in addition, there are 4 pedunculated and nonloculate acetabula. Notomegarhynchus shetlandicum is differentiated from N. navonae particularly in details of acetabular and myzorhynchus morphology, arrangement of testes, and shape of eggs. The inclusion of Notomegarhynchus in the Echeneibothriinae requires emendation of the diagnosis of the subfamily to include taxa possessing postvaginal testes. In addition, new terminology is proposed for distinct regions of the scolex.     

Five new species of Acanthobothrium (Tetraphyllidea: Onchobothriidae) from the freshwater stingray Himantura chaophraya (Batoidea: Dasyatidae) in Malaysian Borneo

Five new species of Acanthobothrium (Tetraphyllidea: Onchobothriidae) are described from the spiral intestine of the Freshwater whipray, Himantura chaophraya, in the Kinabatangan River in Malaysian Borneo. Based on criteria set forth in a previous categorization scheme for species of Acanthobothrium, these consist of 3 Category 1 species, Acanthobothrium asnihae n. sp., Acanthobothrium saliki n. sp., and Acanthobothrium zainali n. sp.; a Category 8 species, Acanthobothrium etini n. sp.; and a Category 2 species, Acanthobothrium masnihae n. sp.. Acanthobothrium asnihae n. sp. differs from all Category 1 species in its possession of a horizontal band of weak musculature that divides the posterior loculus in half. Among Category 1 species, A. saliki n. sp. differs from all but Acanthobothrium southwelli in its possession of postovarian testes. It differs from A. southwelli in its possession of fewer testes and a greater number of proglottids. Acanthobothrium zainali n. sp. differs from the 25 other Category 1 species in a combination of overall size, muscular pad and hook shape, arrangement and number of testes, ovary configuration in cross section, position of ovarian isthmus, and genital pore position. Acanthobothrium etini n. sp. is distinguished from all 5 other Category 8 species in its lack of testes from the proglottid antiporal and postporal regions and in testis number. Acanthobothrium masnihae n. sp. differs from the 35 other Category 2 species in its possession of fewer testes, postporal testes, or a greater number of proglottids. A key to Acanthobothrium species parasitizing H. chayophraya is presented. This represents the first report of Acanthobothrium from freshwater stingrays belonging to a family other than the Potamotrygonidae.     

A new species of Acanthobothrium van Beneden, 1850 (Tetraphyllidea: Onchobothriidae) from Pastinachus atrus (Macleay) (Batoidea: Dasyatidae) in Australian waters, with a reassessment of the host associations of Acanthobothrium spp. parasitising Pastinachus spp

A new Category 1 species of Acanthobothrium van Beneden, 1850 is described from the cowtail stingray Pastinachus atrus (Macleay) collected from the Gulf of Carpentaria near Weipa, Queensland, Australia. This species is unique among Acanthobothrium Category 1 species in that it retains gravid proglottids on its strobila. It differs further from the 34 other Category 1 species in total length, proglottid number and testis number. The host identities of other Acanthobothrium species reported from Pastinachus are revised based on recent taxonomic work on rays of this genus. Given the revised host taxonomy, according to which P. atrus is the only member of its genus occurring off Australia, this should be considered to be the fifth species of Acanthobothrium reported from this Australian endemic species.     

Five new species of Pedibothrium (Tetraphyllidea: Onchobothriidae) from the tawny nurse shark, Nebrius ferrugineus, in the Pacific Ocean

The spiral intestines of 7 Tawny nurse sharks (Nebrius ferrugineus; Rhincodontidae) from Australia and French Polynesia were examined for tapeworms. These sharks hosted 5 new species of Pedibothrium. The 5 species were prepared for light and scanning electron microscopy. Whereas 3 of the species exhibit the bipronged hooks typical of members of Pedibothrium, 1 species was found to possess tiny unipronged hooks or to lack some, or all, hooks, and all individuals of the fifth species appeared to lack bothridial hooks entirely. Nonetheless, the otherwise remarkable similarities between these species and the species of Pedibothrium bearing bipronged hooks were considered to be sufficient to justify the placement of these 2 species in this genus. All 5 species possess proglottid features typical of Pedibothrium, including a uterus that extends anteriorly only to the level of the cirrus sac and a cirrus sac that is bent anteriorly and is crossed by the vagina. All 5 species also exhibit uniloculated bothridia. Of particular note was the fact that all 5 species exhibit bladelike spinitrichs with elongated distal tips, a form of microthrix currently known only from species of Pedibothrium. As a consequence, these species were treated as possessing modified hooks or as having lost hooks. The diagnoses of Pedibothrium and Onchobothriidae were emended to include these species. Each of the 5 new species bears a strong resemblance to 1 or more species of Pedibothrium hosted by a species of rhincodontid shark other than N. ferrugineus. Much of Southwell's type and voucher material of Pedibothrium was located and used to verify the identity of Pedibothrium kerkhami and many of the hosts from which Southwell's material of Pedibothrium was collected. This material suggests that P. kerkhami parasitizes Stegostoma fasciatum and not N. ferrugineus.