Seven Gymnura altavela (Linnaeus, 1758) (Elasmobranchii, Myliobatiformes) caught off the Tunisian coast were examined for endoparasites during a three-year period (1995-1998). A phyllobothriid cestode new to science was found in the spiral intestine of all host specimens. The presence of a tetrabothridiate scolex, bothridia lacking an apical sucker, laciniate strobila, and possession of postvaginal testes are sufficient to place this species in the genus Anthobothrium Van Beneden, 1850. In this genus, we consider that only two species, both previously reported from carcharhiniform sharks, are valid: Anthobothrium cornucopia Van Beneden, 1850 and A. laciniatum Linton, 1890. Anthobothrium altavelae sp. n. can be distinguished from its congeners by its length, strobila morphology, and the number of testes. The taxonomic position of the species attributed to Anthobothrium parasitic in gymnurids is discussed.
Five new species of Acanthobothrium van Beneden, 1850 from the spiral intestine of a specimen of an unusual species of Himantura from the Arafura Sea off northern Australia are described. Acanthobothrium oceanharvestae sp. n. is one of 26 category 1 species (sensu Ghoshroy and Caira 2001) lacking post-ovarian testes; it differs from these in total length, number of proglottids, number of testes, cirrus sac size and details of the terminal genitalia. Acanthobothrium popi sp. n. is unique among category 2 species in its possession of post-ovarian testes. Acanthobothrium rodmani sp. n. is a category 6 species distinct from all congeners in the dense blade-like spinitriches on the distal surfaces of its anterior-most bothridial loculi and conspicuously tapered posterior bothridial margins, which are reflexed anteriorly. Acanthobothrium romanowi sp. n. differs from most other category 1 species in that its genital pore is distinctly posterior. It differs from the remaining category 1 species in size, testis number, cephalic peduncle microthrix form, proglottid shape, and bothridial loculus dimensions. Acanthobothrium zimmeri sp. n. is among the six category 1 species with post-ovarian testes. It differs from these species in total length, ovary shape, number of proglottids and testes and vas deferens extent. This brings the number of Acanthobothrium species with post-ovarian testes to 10, all of which are Indo-Pacific in distribution, and 7 of which parasitize Himantura species. A key to the five new species parasitizing Himantura sp. is provided. Sequence data for the D1-D3 region of 28S rDNA for the five new species and two congeners parasitizing other Himantura species shows no intraspecific variation. Analysis of these and comparable data for two species available in GenBank (Acanthobothrium parviuncinatum and Acanthobothrium sp. 1) showed an interspecific variation of 0.7-11.3% among species pairs. Bayesian, Likelihood and Parsimony phylogenetic analyses of these data for these nine species indicate that the five new species parasitizing Himantura sp. are generally not each others' closest relatives.
Helminthological examination of the snaggletooth shark, Hemipristis elongata (Klunzinger) (Carcharhiniformes: Hemigaleidae), from Moreton Bay, Queensland, Australia, yielded a phyllobothriid genus and species previously unknown to science. Hemipristicola gunterae gen. n., sp. n. is described here, and is placed in the subfamily Phyllobothriinae Braun, 1900. Of the other phyllobothriid genera, the new genus most closely resembles Paraorygmatobothrium in that both genera possess bothridia with a single loculus and apical sucker, post-vaginal testes and lateral vitellarium. Hemipristicola, however, differs from Paraorygmatobothrium in the morphology of the proximal bothridial surface microthrix, possessing serrate gladiate spinitriches with marginal serrations restricted to the distal half of the blade, and in the possession of a more extensive uterus, extending anteriorly from the anterior margin of the ovary to well past the level of the cirrus-sac. The new genus also differs from Paraorygmatobothrium by possessing testes that are more than one layer deep. Hemipristicola gunterae further differs from Paraorygmatobothrium species found in hemigaleid sharks in possessing vitelline follicles arranged in two lateral bands that are restricted to the lateral margins of the proglottid and not possessing a cephalic peduncle. Bayesian inference analysis of partial 28S rDNA data shows that H. gunterae forms a sister taxon to species of Paraorygmatobothrium. These two genera were resolved with high posterior probability support in the analysis. Hemipristicola gunterae is only the second phyllobothriid species to be described from Hemipristis elongata from Australian waters, and the fourth from the Australian hemigaleids.
The tetraphyliidean metacestode diversity of 310 teleost fishes, including 87 species from 31 families, was examined from Heron Island, The Great Barrier Reef, Australia. Eleven metacestode ‘types’ were identified with the use of light microscopy. Host-specificity varied greatly among metacestode types. Incorporation of in vitro cultivation allowed generic identification for some types. Types 1 and 2 belong to Uncibilocularis Southwell, 1925, and have triloculate bothridia and one pair of forked hooks with unequal prongs; Type 3 has quadriloculate bothridia. Hook development was insufficient to determine in which genus, Acanthobolhrium van Beneden, 1849 or Calliobothrium van Beneden, 1850, this type may belong. Type 4 has unilocular bothridia with simple edges and belongs to Anthobothrium van Beneden, 1850. Type 5 has multiloculated bothridia which are invaginated within pouches. This type belongs lo the Rhinebothriinae although its generic identity cannot be determined. The bothridia of Type 5 everted within 24 hours of in vitro cultivation and revealed the presence of two forms, one having 48 loculi per bothridium, the other 72 per bothridium. In vitro studies provide additional support for existing theories of onchobothriid scolex development.
As part of a metazoan parasite survey of elasmobranchs from Malaysian Borneo, specimens of Rhoptrobothrium Shipley et Hornell, 1906 were collected from the eagle rays Aetomylaeus maculatus (Gray) and Aetomylaeus niehofii (Bloch et Schneider). The type species is redescribed from its type host, and a neotype specimen is designated. In addition, three new species of Rhoptrobothrium are described: R. chongi sp. n., R. gambangi sp. n. and R. limae sp. n. Rhoptrobothrium myliobatidis conspicuously differs from the three new species in its lack of a secondary areola; R. limae is distinguished from R. chongi and R. gambangi based on its greater total length; R. chongi possesses conspicuously stalked remi, while R. gambangi possesses short remi, often folded anteriorly. Rhoptrobothrium is somewhat unusual among tetraphyllideans in its possession of a ''metascolex,'' a character it shares with other taxa in the Thysanocephalinae (i.e., Myzocephalus Shipley et Hornell, 1906, Myzophyllobothrium Shipley et Hornell, 1906 and Thysanocephalum Linton, 1889). The morphology of the ''metascolex'' of Rhoptrobothrium is investigated and new terminology is suggested to standardise the names given to structures constituting a metascolex. As a result, Rhoptrobothrium is considered to possess cephalic peduncle extensions, termed remi. In Rhoptrobothrium, each remus bears, at its distal end, a primary areola, and, in the case of the three new species, also a secondary areola proximal to the primary areola. Myzocephalus and Myzophyllobothrium are tentatively considered to possess remi; the configuration of the ''metascolex'' of Thysanocephalum, however, is not considered homologous to the condition in the other three genera currently placed in the Thysanocephalinae.
The type species (Spiniloculus mavensis Southwell, 1925) of the previously monotypic tetraphyllidean genus Spiniloculus Southwell, 1925 is redescribed from the type material from Moreton Bay, Australia. As a consequence the identity of this species is definitively resolved. Three new species in the genus, all collected from Chiloscyllium punctatum Müller et Henle (brownbanded bambooshark), in Borneo, are described. Spiniloculus calhouni sp. n. conspicuously differs from all three of its congeners in its possession of post-poral testes. Spiniloculus fylerae sp. n. and Spiniloculus paigeae sp. n. differ from their two other congeners in that they are relatively small worms (4-6.5 and 2.2-5 mm in total length, respectively) with fewer than 30 proglottids. They can be distinguished from one another in that, while the vitelline follicles are interrupted at the level of its ovary in S. fylerae, this is not the case in S. paigeae. Furthermore, whereas the cirrus sac of the former species is pyriform, it is elongate-oval in the latter species. This brings the total number of species in the genus to four, and lends support to the suggestion that the original identity of the type host of S. mavensis as Mustelus sp. was in error. This work also extends the range of the genus to include the island of Borneo. A key to the species of Spiniloculus is provided. Morphological data generated here, using both light and scanning electron microscopy, support the suggested close affinities between Spiniloculus and Yorkeria Southwell, 1927, both of which parasitize bamboosharks.
Spermiogenesis in Phyllobothrium lactuca Beneden, 1850 begins with the formation of a differentiation zone bordered by cortical microtubules and containing a nucleus and two ccntrioles separated by an intercentriolar body and disposed one in the prolongation of the other. Later, formation of flagellar buds, striated roots and a median cytoplasmic extension takes place. Each centriole gives rise to a flagellimi that rotates and fuses with the median cytoplasmic extension. At this stage, arched membranes appear at the front of the differentiation zone. The nucleus elongates, becomes filiform and migrates between the striated roots into the spermatid. After the migration of the nucleus, the old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. Absence of striated roots, right at the beginning of spermiogenesis has never been described before in the Tctraphyllidea. Likewise, centrioles made up of doublets of microtubules and spermatids with two axonemes have never been reported before during spermiogenesis of a Phyllobothriidae. In this work we show, for the first time, the existence in cestodes of thick-walled microtubulcs surrounded by a layer of electron-dense material. In addition, we describe, for the first time, the existence of an accumulation of electron-dense granules around striated roots and an hour-glass-shaped constriction at the anterior extremity of a median cytoplasmic extension in a platyhelminth.