TWO NEW SPECIES OF STILLABOTHRIUM (CESTODA: RHINEBOTHRIIDEA) FROM STINGRAYS FROM NORTHERN AUSTRALIA AND ONE NEW COMBINATION.

A study of cestode specimens that were collected during survey work on elasmobranchs collected from Taiwan and Northern Territory, Australia, revealed the presence of 1 new combination into the genus Stillabothrium (Rhinebothriidea: Escherbothriidae) and 2 new species of the genus. Phyllobothrium biacetabulatum, collected from Rhinobatos schlegelii, is transferred to Stillabothrium and its description is emended, as is the diagnosis for the genus Stillabothrium and the family Escherbothriidae. Stillabothrium biacetabulatum n. comb. differs from existing species of the genus in that the face of its bothridia is laced with a network of longitudinal and horizontal muscle fibers that do not contribute to the formation of septa. Stillabothrium lunae n. sp. is described from Himantura leoparda and differs from existing species of the genus in that its bothridium possesses an anterior field of 7-8 loculi that are wider than long. Stillabothrium mariae n. sp. is described from Maculabatis astra. This species differs from all species of Stillabothrium except Stillabothrium campbelli in possessing 10-12 horizontally oriented bothridial loculi. Stillabothrium mariae n. sp. differs from S. campbelli in having longer bothridia and from all other species of Stillabothrium in that it lacks, rather than possesses, conspicuous septa and loculi that are longer than wide in the posterior region of its bothridia. Bayesian and parsimony-bootstrap analysis of 28S rDNA revealed S. biacetabulatum n. comb., S. lunae n. sp., and S. mariae n. sp. to be part of Clade 1 of Stillabothrium, with S. biacetabulatum n. comb. being the sister species to S. mariae n. sp. Stillabothrium lunae n. sp. was found to be the sister species to Stillabothrium borneoense.

Intrigue surrounding the life-cycles of species of Clistobothrium (Cestoda: Phyllobothriidea) parasitising large pelagic sharks.

This study aimed to locate the adults, and thus also the definitive hosts, of three species of marine mammal-parasitising larval cestodes that have molecular affinities with Clistobothrium. New collections led to the discovery of adults of two new species of Clistobothrium, one from the longfin mako shark and one from the salmon shark. New material of Clistobothrium tumidum was collected from the great white shark and new material of a previously reported undescribed species of Clistobothrium was collected from the porbeagle shark. Larvae of Clistobothrium were opportunistically collected from sockeye salmon and four species of small squaliform sharks. Sequence data for the D1-D3 region of the 28S rDNA gene were generated for all but one of these taxa. The tree resulting from maximum likelihood analysis of those data, in combination with comparable data from GenBank, indicates that squaliform sharks can serve as intermediate hosts for the species from the porbeagle shark. The larvae from salmon exhibit a unique molecular signature and, based on diet data, may be conspecific with adults from the salmon shark. Informed by sequence data for new material of Monorygma and existing data for Phyllobothrium, the larvae provisionally identified as Monorygma grimaldii and Phyllobothrium delphini were formally transferred to Clistobothrium. Especially puzzling was that the molecular signatures of none of the eight species of Clistobothrium match those of the three marine mammal-parasitising larval forms. We are at a loss as to where else to look for the three corresponding adult forms. The great white shark remains the most likely candidate given it consumes marine mammals with some regularity, but seems unlikely to host five species of Clistobothrium. Alternatively, we are left wondering if the large marine mammal predator Carcharocles megalodon may not be extinct after all.

Two new species of Stillabothrium (Cestoda: Rhinebothriidea) from stingrays of the genus Fontitrygon from Senegal.

Morphological and molecular analyses of cestode specimens collected during survey work of batoid elasmobranchs and their parasites in Senegal revealed two new species of the rhinebothriidean cestode genus Stillabothrium Healy et Reyda 2016. Stillabothrium allisonae Dedrick et Reyda sp. n. and Stillabothrium charlotteae Iwanyckyj, Dedrick et Reyda sp. n. are both described from Fontitrygon margaritella (Compagno et Roberts) and Fontitrygon margarita (Günther). Both new cestode species overlap in geographic distribution, host use and proglottid morphology, but are distinguished from each other, and from the other seven described species of Stillabothrium, on the basis of their pattern of bothridial loculi. Phylogenetic analyses based on sequence data for 1,084 bp from the D1-D3 region of 28S rDNA that included multiple specimens of both new species and eight other species of Stillabothrium corroborated the morphologically-determined species boundaries. The phylogenetic analyses indicate that S. allisonae sp. n. and S. charlotteae sp. n. are sister species, a noteworthy pattern given that the two species of the stingray genus Fontitrygon they both parasitise, F. margaritella and F. margarita, are also sister species. Although species of Stillabothrium vary widely in their patterns of facial loculi, the variation does not appear to correlate with phylogeny. Most species of Stillabothrium parasitise myliobatiform elasmobranch genera of the Dasyatidae Jordan. This study brings the number of described species of Stillabothrium to nine, three of which occur in the eastern Atlantic, two of which occur off the northern coast of Australia, and four of which are from coastal Borneo.

A new genus of rhinebothriidean cestodes from batoid elasmobranchs, with the description of five new species and two new combinations.

Survey work of batoid elasmobranchs in the eastern Atlantic and Indo-Pacific revealed multiple species of a new genus of cestode. Stillabothrium Healy et Reyda gen. n. (Rhinebothriidea: Escherbothriidae) is unique in its possession of an even number of non-medial longitudinal septa in the posterior portion of the bothridia, resulting in a series of loculi that are longer than wide (i.e. vertically oriented) and are arranged in columns. Five new species of Stillabothrium are described, S. ashleyae Willsey et Reyda sp. n., S. davidcynthiaorum Daigler et Reyda sp. n., S. campbelli Delgado, Dedrick et Reyda sp. n., S. hyphantoseptum Herzog, Bergman et Reyda sp. n., S. jeanfortiae Forti, Aprill et Reyda sp. n., and two species are formally transferred to the genus, S. amuletum (Butler, 1987) comb. n., and S. cadenati (Euzet, 1954) comb. n., the latter of which is redescribed. The species differ in the configuration of the other bothridial septa and in proglottid anatomy. Species of Stillabothrium were found parasitising a total of 17 species of batoid elasmobranchs of the genera Dasyatis Rafinesque, Glaucostegus Bonaparte, Himantura Müller et Henle, Pastinachus Rüppell, Rhinobatos Linck and Zanobatus Garman, including several host species that are likely new to science. A phylogenetic hypothesis based on Bayesian analysis of 1 084 aligned positions of the D1-D3 region of 28S rDNA for 27 specimens representing 10 species of Stillabothrium and two outgroup species supported the monophyly of Stillabothrium. These results also supported morphologically determined species boundaries in all cases in which more than one specimen of a putative species was included in the analysis. Host specificity appears to vary across species of Stillabothrium, with the number of host species parasitised by each species of Stillabothrium ranging from one to four. The geographic distribution of species of Stillabothrium spans the eastern Hemisphere, including the eastern Atlantic (coastal Senegal) and several locations in the Indo-Pacific (coastal Vietnam, Borneo and Australia). In addition, Phyllobothrium biacetabulatum Yamaguti, 1960 is formally transferred into family Escherbothriidae, although its generic placement remains uncertain (species incertae sedis).

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 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.