Bothridial Hooks Research Articles

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.

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.

Two New Species of Acanthobothrium in Narcine entemedor (Rajiformes: Narcinidae) from the Northwest Coast of Guanacaste Peninsula, Costa Rica

This paper describes 2 new species of Acanthobothrium collected in Narcine entemedor from Cuajiniquil, Guanacaste Province, Costa Rica (10 degrees 57'N, 85 degrees 42'W). Acanthobothrium franus n. sp. averages 27 mm long, composed of 110 proglottides, has bothridial hooks 344-469 microns long, and 24-56 testes per proglottis. This new species resembles Acanthobothrium colombianum, Acanthobothrium coquimbensis. Acanthobothrium dujardini, Acanthobothrium lineatum, Acanthobothrium lintoni, and Acanthobothrium paulum. The new species differs from these 6 species by having a relatively shorter cirrus sac length not reaching the middle region of the proglottis. Additionally, A. franus differs from these species by having longer bothridia (627-1,408 microns vs. 299-391 microns for A. colombianum, 312-480 microns for A. coquimbensis, 240-560 microns for A. dujardini, 275-624 microns for A. lineatum, 389-720 microns for A. lintoni, and 300-880 microns for A. paulum), and larger bothridial hooks (344-469 microns vs. 175-193 microns, 120-192 microns, 180-210 microns, 118-216 microns, 108-230 microns, and 104-229 microns, respectively). Acanthobothrium inbiorium n. sp. averages 59 mm long, composed of 198 proglottides, has bothridial hooks 95-120 microns long, and possesses 44-73 testes per proglottis. Among species of Acanthobothrium, the new species resembles Acanthobothrium electricolum, Acanthobothrium dasybati, Acanthobothrium dighaensis, Acanthobothrium icelandicum, Acanthobothrium indicum, Acanthobothrium microcephalum, and Acanthobothrium wedli. The new species closely, resembles A. dasybati, but differs from that species in average strobila length and number of proglottides (58 microns long and 198 proglottides in A. inbiorium vs. 20 and 80 in A. dasybati, respectively). The new species can be distinguished from A. electricolum by having a wider scolex (450-900 microns vs. 189-252 microns), from A. dighaensis by having a narrower scolex (450-900 vs. 1,050-1,429), and from A. indicum by average strobilar length and number of proglottides (58 mm and 198 for A. inbiorium vs. 25 mm and 145 for A. indicum). Finally, A. inbiorium differs from A. icelandicum by having a shorter cirrus sac (122-285 for A. inbiorium vs. 380-410 for A. icelandicum), and A. microcephalum and A. wedli by having longer bothridia (an average of 603 microns vs. 447 microns for A. microcephalum and 350 microns for A. wedli), and fewer testes per proglottis (44-73 vs. 105-115 and 80-100, respectively). Morphological similarities suggest that some components of the eastern Pacific fauna of Acanthobothrium might share historical associations with the Caribbean and the western Pacific/Indian Ocean fauna.

Six Species of Acanthobothrium (Eucestoda: Tetraphyllidea) in Stingrays (Chondrichthyes: Rajiformes: Myliobatoidei) from Ecuador

Six species of Acanthobothrium, 4 described as new, are reported in stingrays from southern Ecuador. Acanthobothrium atahualpai n. sp. in Gymnura afuerae most closely resembles Acanthobothrium fogeli and Acanthobothrium parviuncinatum by having bothridial hooks with recurved prongs and short handles. It differs from A. fogeli by having bothridial hooks 163-195 microns vs. 78-114 microns long and averaging 25 vs. 32 testes per pruglottis: it differs from A. parviuncinatum by having bothridial hooks 163-195 microns vs. 87 microns long and averaging 25 vs. 13 testes per proglottis. Acanthobothrium minusculus n. sp. in Urolophus tumbesensis most resembles Acanthobothrium campbelli and Acanthobothrium vargasi by being no more than 3 mm long and having 6-30 testes per proglottis. It can be distinguished from them by having bothridial hooks averaging 86 microns vs. 108-111 microns and 130-133 microns long, and 6-10 vs. 15-23 and 22-29 testes per proglottis, respectively. Acanthobothrium monksi n. sp. in Aetobatus narinari resembles Acanthobothrium tasajerasi from Himantura schmardae by having a prominent genital atrium and a large globose cirrus sac; it differs by averaging 21 vs. 35 testes per proglottis and having bothridial hooks averaging 150 microns vs. 165 microns long. Acanthobothrium obuncus n. sp. in Dasyatis longus resembles a group of species characterized by wider than long to square immature and mature proglottides, bothridia at least partially fused to the scolex at their posterior ends, and asymmetrical ovarian arms with aporal arms extending anteriorly to the vaginal level. It resembles Acanthobothrium americanum by averaging 73 vs. 72 testes per proglottis, but differs by having bothridial hooks averaging 120-131 microns vs. 151 microns long; it resembles Acanthobothrium chilensis by having bothridial hooks averaging 120-131 microns vs. 130 microns long, but differs by averaging 73 vs. 90 testes per proglottis. Acanthobothrium campbelli in Urotrygon chilensis and Acanthobothrium costarricense in Dasyatis longus, previously known in those hosts from the Pacific coast of Costa Rica, are reported from Ecuador for the first time.

A New Species of Acanthobothrium Van Beneden, 1849 (Eucestoda: Tetraphyllidea: Onchobothriidae) in Dasyatis longus Garman (Chondrichthyes: Myliobatiformes: Dasyatididae) from Chamela Bay, Jalisco, Mexico

A new species of Acanthobothrium in Dasyatis longus from Chamela Bay, Jalisco, Mexico, is a member of a presumed clade of species diagnosed by being anapolytic or nearly so, having more than 100 testes per proglottis, with immature and mature proglottides wider than long to square, aspinose scolex, muscular bothridia fused to the scolex at their posterior ends, H- to V -shaped ovaries, relatively short symmetrical to asymmetrical ovarian arms that extend anteriorly to, or nearly to, the cirrus sac, and vitellaria arranged in fields rather than a single row of follicles. The new species most closely resembles Acanthobothrium terezae from the freshwater stingray Potamotrygon motoro in the following characters: bothridial hooks longer than 200 microns with inner hooks having bent asymmetrical prongs, an average of 130-140 testes per proglottis, and shallow genital atria located posterior to midline of proglottis. The new species differs from A. terezae by having outer hooks approximately the same size and shape as the inner hooks, inner hooks averaging 230 microns rather than 313 microns in total length, and cirrus sacs averaging 255 microns rather than 450 microns in length. The new species is unique among all described species of Acanthobothrium by having a cleft in the posterior margin of each apical bothridial pad. The apparent close relationship of the new species to one inhabiting a Neotropical freshwater stingray provides support for the hypothesized Pacific marine ancestry of Neotropical freshwater stingrays and raises the possibility that the Neotropical freshwater stingrays may not be monophyletic.

Two New Species of Tetraphyllidean Cestodes in Himantura pacifica (Chondrichthyes: Myliobatiformes: Dasyatididae) from the Northwest Coast of Costa Rica

Two new species of tetraphyllidean cestodes inhabiting Himantura pacifica from the northwest coast of Costa Rica are apparently most closely related to species inhabiting Himantura schmardae from the Atlantic coast of Colombia. Acanthobothroides pacificus n. sp. differs from Acanthobothroides thorsoni, the only other species in the genus, primarily by having smaller lateral (98-123 microns rather than 168-198 microns long) and medial (handles 92-116 microns rather than 162-168 microns long) hooks, and more testes (up to 125 rather than up to 97) per proglottis. The generic diagnosis of Acanthobothroides is modified to include the presence of a small inner prong on the large medial bothridial hooks. Rhinebothrium geminum n. sp. and Rhinebothrium magniphallum are the only 2 species in the genus possessing unusually long cirrus sacs, extending from the genital atrium all the way to the ovarian isthmus; R. geminum averages 12 (12-14) loculi per bothridium and 11 (9-12) testes, whereas R. magniphallum averages 17 (16-18) loculi and 14 (10-16) testes per proglottis.

Acanthobothrium nicoyaense n. sp. (Eucestoda: Tetraphyllidea: Onchobothriidae) in Aetobatus narinari (Euphrasen) (Chondrichthyes: Myliobatiformes: Myliobatidae) from the Gulf of Nicoya, Costa Rica

A new species of Acanthobothrium in Aetobatus narinari from the Gulf of Nicoya, Costa Rica, most closely resembles Acanthobothrium colombianum in the same host and A. urotrygoni in Urotrygon venezuelae from Cartagena, Colombia, by having relatively few proglottides per strobila, spinose cephalic peduncles, bothridial margins free at their posterior ends, and irregularly shaped rather than spherical or elongate cirrus sacs. Acanthobothrium colombianum differs from the new species by being as much as 35 mm rather than no more than 4.7 mm long and by having 31-48 rather than 13-19 proglottides, an average of 46 rather than 15 testes per proglottis, and bothridial hooks averaging 185 microns rather than 137 microns in total length. Acanthobothrium urotrygoni differs from the new species by being as much as 15 mm rather than no more than 4.7 mm long and by having V-shaped rather than H-shaped ovaries, bothridial hooks averaging 95 microns rather than 137 microns in total length, by having an average of 28 rather than 15 testes per proglottis, and by having poral ovarian arms extending anteriorly to the posterior margin of the cirrus sac and aporal arms extending to the lateral margin of the cirrus sac.

A Review of the Genus Pedibothrium Linton, 1909 (Tetraphyllidea: Onchobothriidae) with Description of Two New Species and Comments on the Related Genera Pachybothrium Baer and Euzet, 1962 and Balanobothrium Hornell, 1912

A review of the genus Pedibothrium Linton, 1909, is based on type and voucher specimens. The type species, Pedibothrium globicephalum Linton, 1909, is redescribed; descriptions of Pedibothrium brevispine Linton, 1909, and Pedibothrium longispine Linton, 1909, are emended; 2 new species are described; the generic diagnosis is emended; and a key is provided. The bothridia of all species were found to possess a pair of symmetrical bipronged hooks, each with 2 separate channels and 2 pores, a single loculus and an apical muscular pad. Pedibothrium lintoni n. sp. from the spiral valve of Ginglymostoma cirratum (Bonnaterre) collected at Dry Tortugas, Florida, is most like P. globicephalum but differs in having fewer testes (mean number 145 rather than 252), larger testes (mean diameter 65 rather than 16 ,um), abaxial prongs of hooks no longer than bases, and narrow inconspicuous longitudinal excretory ducts. Pedibothrium maccallumi n. sp. from the spiral valve of G. cirratum, locality unknown, is unique in possessing flat, ovoid, non-contiguous loculi with hooks approximately one-sixth the length of the loculus. A diagnosis for Pachybothrium Baer and Euzet, 1962, is provided, and the description of the type and only species, Pachybothrium hutsoni (Southwell, 1911) Baer and Euzet, 1962, is emended. Species of Balanobothrium Hornell, 1912, possess bipronged hooks with 2 separate channels and 2 separate pores like the hooks of Pedibothrium spp., but the morphology of the Balanobothrium scolex has not been thoroughly elucidated. The bothridial hooks of most onchobothriids possess a single internal channel (branched or unbranched) with a single pore. Judging from the published figures (Linton, 1909; Baer and Euzet, 1962), the bothridial hooks of Pedibothrium globicephalum Linton, 1909 and Pedibothrium longispine Linton, 1909 have two separate channels and two pores. To investigate these unusual onchobothriid hooks, as many as possible of the type and voucher specimens of Pedibothrium spp.

Two New Species of Acanthobothrium Van Beneden 1849 (Cestoidea: Tetraphyllidea) from Freshwater Stingrays in South America

Two new species of Acanthobothrium are reported from freshwater stingrays in northern South America. Acanthobothrium quinonesi sp. n. is described from Potamotrygon magdalenae Dumeril collected from the Magdalena River in northern Colombia and A. amazonensis sp. n. from P. circularis Garman collected in the Itacuai River of northwestern Brazil. Acanthobothrium quinonesi differs from A. amazonensis by having a smaller and anteriorly-curved cirrus sac, 43-60 rather than 50-72 testes, and bothridial hooks 100--142 ,urn long rather than 145-184 ,urn long. Characters used in the taxonomy of Acanthobothrium species are listed to show that the new species resemble each other and A. terezae, also from a South American freshwater stingray, more than they do any other members of the genus. Species of Acanthobothrium van Beneden 1849 parasitize a variety of marine and estuarine elasmobranchs (Goldstein, 1967; Williams, 1969) . Collections from the freshwater stingrays Potamotrygon magdalenae Dumeril in the Magdalena River of Colombia and from P. circularis Garman in th e Itacuai River of Brazil, contained specimens of two new species of Acanthobothrium which resemble each other more than they do any other known species. Worms were removed from host spiral valves, examined alive and fixed with warm AFA, or fixed in situ with 10% formalin; all were stored in 70 % ethanol. Study included examination of whole mounts stained with Mayer's hematoxylin and mounted in Canada balsam as well as study of serial cross sections cut at 8 p.m and stained with hematoxylin-eosin. Measurements are in urn unless otherwise stated with number of measurements (N) and mean values (x) indicated for certain characteristics. Figures were drawn with the aid of a drawing tube. Acanthobothr;um qu;nones; sp. n.

Acanthobothrium electricolum sp. n. and A. lintoni Goldstein, Henson, and Schlicht 1969 (Cestoda: Tetraphyllidea) from Narcine brasiliensis (Olfers) (Chondrichthyes: Torpedinidae) in Colombia

Acanthobothrium lintoni and a new species of Acanthobothrium are reported from the lesser electric ray Narcine brasiliensis in Colombia. The new species resembles all other members of the genus parasitizing torpedinids by having a relatively small scolex, long and spinose cephalic peduncle, fewer than 75 testes per proglottid, an indistinct genital atrium, and V-shaped ovaries with ovarian lobes of equal length which do not reach the posterior margin of the cirrus sac. The new species differs from all known species by having bothridial hooks only 46 to 64 ,um in total length. A key to the species of Acanthobothrium parasitizing torpedinids is presented. Species of tetraphyllidean cestodes belong- ing to the genus Acanthobothrium Beneden 1849 and parasitizing elasmobranchs of the family Torpedinidae possess relatively small scolices, extremely long cephalic peduncles covered with spines, fewer than 75 testes per proglottid, indistinct genital atria, and V- shaped ovaries with equal-length lobes which do not reach anteriorly to the posterior margin of the cirrus sac. Examination of 14 specimens of the lesser electric ray Narcine brasiliensis (Olfers) captured in the vicinity of Cartagena, Colombia, revealed infections of two species of Acanthobothrium: A. lintoni Goldstein, Hen- son, and Schlicht 1969, and a new species described herein. Rays were collected with beach seines and kept in holding tanks until examined. Helminths were removed from the

The bothridial hooks of Acanthobothrium quadripartitum Williams, 1968 (Cestoda: Tetraphyllidea): Their growth and use in taxonomy

McVicar A. H. 1977. The bothridial hooks of Acanthobothrium quadripartitum Williams, 1968 (Cestoda: Tetraphyllidea): their growth and use in taxonomy. International Journal for Parasitology 7: 439–442. Bothridial hooks are absent from juvenile Acanthobothrium quadripartitum in Raja naevus but develop to full size before there is much growth of the bothridia and strobila. There is a linear relationship between the lengths of the different components of the hooks during their development and it is suggested that the ratios of these lengths to the total hook length may be useful parameters in dstinguishing between species of Acanthobothrium. Principal component analysis of published hook dimensions gave good separation of most species of Acanthobothrium.

Two Tetraphyllidean Cestodes from the Freshwater Stingray Potamotrygon magdalenae Dumeril 1852 (Chondrichthyes: Potamotrygonidae) from Colombia

Two new tetraphyllidean cestodes are described from the freshwater stingray Potamotrygon magdalenae from Colombia. The new genus Potamotrygonocestus is proposed for P. magdalenensis, which differs from Pedibothrium by having a bilobed rather than X-shaped ovary, and simple rather than bifid hooks. It further differs from Pachybothrium hutsoni by having bothridial hooks inserted immediately posterior to an accessory sucker rather than inserted in the middle of a thick muscular pad. Potamotrygonocestus magdalenensis is unique among known tetraphyllideans by possessing vitellaria which are compact, cylindrical bands in the lateral portions of the middle of the proglottid. The second new species, Rhinebothrium moralarai, resembles R. scorzai by having its genital pore and terminal genitalia at the ovarian level, greatly reduced poral ovarian lobes, and by parasitizing a freshwater stingray. It differs from R. scorzai in number of bothridial loculi, testes per proglottid, and proglottids per strobila; by having quadrate rather than canoe-shaped bothridia; and by parasitizing Potamotrygon magdalenae rather than P. hystrix.