Review of the genus Shirleyrhynchus Beveridge & Campbell, 1988 (Trypanorhyncha: Shirleyrhynchidae), with the resurrection of S. butlerae Beveridge & Campbell, 1988 and the description of S. panamensis n. sp

Phylogeny of the cestode family Escherbothriidae (Cestoda: Rhinebothriidea) reveals unexpected patterns of association with skate hosts

The rhinebothriidean tapeworm family Escherbothriidae has recently been expanded to include the genus Ivanovcestus , species of which parasitise arhynchobatid skates. Similarities in morphology and host associations between Ivanovcestus and Semiorbiseptum - a genus yet to be assigned to one of the families in the order Rhinebothriidea - led us to explore the possibility that Semiorbiseptum might also belong in the Escherbothriidae. Morphological similarities with Scalithrium ivanovae , Scalithrium kirchneri and Rhinebothrium scobinae , all of which also parasitise arhynchobatid skates, raised questions regarding the generic placements of these species. In addition, new collections from the skate Sympterygia brevicaudata revealed two new species that morphologically resemble species of Ivanovcestus . A combination of morphological and molecular data were used to assess the generic placement of the newly discovered species and refine our understanding of the membership of the family Escherbothriidae. Sequence data for the D1-D3 region of the 28S rDNA gene were generated de novo for 14 specimens of 7 rhinebothriidean species and combined with comparable published data to represent all 6 families in the Rhinebothriidea in the analysis. The phylogenetic tree resulting from maximum likelihood analysis strongly supports the inclusion of the genus Semiorbiseptum in the family Escherbothriidae. Our work also suggests that the skate-hosted species previously assigned to Scalithrium and Rhinebothrium are also members of Semiorbiseptum and that Ivanovcestus is a junior synonym of Semiorbiseptum . Six species are transferred to Semiorbiseptum , bringing the total number of species in the genus to ten. The diagnosis of Semiorbiseptum is amended to accommodate the additional species. A second species in the previously monotypic type genus of the family, Escherbothrium , is described. The diagnosis of the Escherbothriidae is amended to include the new and transferred species. This study underscores the importance of integrating morphological and molecular data in bringing resolution to cestode systematics. We believe our findings provide a robust foundation for future research into the evolutionary history and host associations of cestodes within the order Rhinebothriidea and beyond. These also highlight the importance of expanding our understanding of skate-hosted cestodes. ZooBank: urn:lsid:zoobank.org:pub:8052AFCA-5FBD-4430-95F4-0E5E368DEA3D.

A synergistic, global approach to revising the trypanorhynch tapeworm family Rhinoptericolidae (Trypanobatoida)

Since 2010, the trypanorhynch tapeworm family Rhinoptericolidae Carvajal & Campbell, 1975 has housed just two distinctive, monotypic genera (Rhinoptericola Carvajal & Campbell, 1975 and Nataliella Palm, 2010). However, global collections of tapeworms from sharks and rays over the last more than three decades brought to light the need for major revision of the family by suggesting a much greater species-level diversity for the nominal genus Rhinoptericola. Through synonymy and the description of new species, the number of species in the genus is increased from one to eight. A phylogenetic analysis of the D1-D3 gene region of 28S rRNA (28S), including seven of the now nine species of rhinoptericolids, and a broad sampling of the other Trypanobatoida is the first to recover a monophyletic Rhinoptericolidae. In addition to systematic revision, this study allowed for the first evaluation of the degree of intraspecific vs interspecific variation in 28S for adult trypanorhynchs across the various hosts and geographic localities from which they have been reported, suggesting a relatively consistent boundary for Rhinoptericola. It is further suggested that detailed scanning electron microscopy (SEM) images of both the basal and metabasal armatures greatly aid in the interpretation of hook arrangement and shape. A schematic to streamline determination of the tentacular surface presented in scanning electron micrographs and line drawings of trypanorhynchs is presented for species with both two and four bothria. In combination, these methodological refinements can now be used as a model to resolve issues of classification and non-monophyly within both major lineages of the Trypanorhyncha. As a result of the taxonomic work, Rhinoptericola megacantha Carvajal & Campbell, 1975 (previously only known from the American cownose ray from the Chesapeake Bay and the Ticon cownose ray from the Gulf of Mexico, Venezuela, and Brazil) is now known from an additional species of cownose ray and a species of stingray, and is revealed to have a transatlantic distribution. Data from SEM suggest a simpler interpretation of hook arrangement in the metabasal armature for Rhinoptercola and-in combination with 28S sequence data-support Shirleyrhynchus Beveridge & Campbell, 1988 (a former rhinoptericolid) as its junior synonym. The three species formerly assigned to Shirleyrhynchus are thus transferred to Rhinoptericola. Data from light microscopy on whole-mounted specimens and histological sections, SEM, and 28S showed the eutetrarhynchid Prochristianella jensenae Schaeffner & Beveridge, 2012b to be morphologically consistent with species of Rhinoptericola and it is thus transferred to the genus. The type series of P. jensenae was determined to be mixed, representing two distinct species which are here redescribed and described as new, respectively. Two additional novel species of Rhinoptericola are described from cownose rays from off Mozambique and the Gulf of California.

Phylogenetic placement and microthrix pattern of Paranybelinia otobothrioides Dollfus, 1966 (Trypanorhyncha) from krill Nyctiphanes simplex Hansen, 1911

Plerocerci of the monotypic Paranybelinia otobothrioides were found parasitizing the subtropical neritic krill Nyctiphanes simplex in the Gulf of California, Mexico. The plerocerci were recovered from two microhabitats of the intermediate host, typically embedded inside the digestive gland (hepatopancreas) or rarely in the hemocoel. The morphology of the simple, single-layered blastocyst surrounding the entire scolex is unique within the Trypanorhyncha by having four large funnel-like pori or openings possibly with feeding and/or excretory function. One of the openings is located anteriorly and three at the posterior end. Scolex surface ultrastructure shows hamulate and lineate spinitriches covering the bothrial surface, capilliform filitriches at the anterior scolex end and on the scolex peduncle, and short papilliform filitriches on the long appendix. This pattern resembles that of species of the Tentaculariidae; but differs in that the hamulate spinitriches, which appear lineate at the bothrial margins, densely cover the entire distal bothrial surface. Tegumental grooves are present on the posterior bothrial margin, lacking spinitriches. Paranybelinia otobothrioides and Pseudonybelinia odontacantha share the following unique combination of characters: two bothria with free lateral and posterior bothrial margins, homeoacanthous homeomorphous armature, tegumental grooves, the distribution of the hamulate spinitriches, and the absence of prebulbar organs. Both genera infect euphausiids as intermediate hosts. Sequence data of the partial ssrDNA gene place Pa. otobothrioides sister to the family Tentaculariidae, and the Kimura two-parameters (K2P) distance between Pa. otobothrioides and species of the family Tentaculariidae ranged from 0.027 to 0.039 (44-62 nucleotide differences). These data suggest both species be recognized in a family, the Paranybeliniidae, distinct from, albeit as sister taxon to, the Tentaculariidae. High prevalence of infection (<14%) and ontogenetic changes of Pa. otobothrioides support N. simplex as a required intermediate host and suggest a zooplanktophagous elasmobranch as final host in the Gulf of California.

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First description of the microthrix pattern of Paranybelinia otobothrioides Dollfus (1966) larva.

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The krill Nyctiphanes simplex is the first known host of larvae of P. otobothrioides.

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Blastocyst morphology surrounding the scolex is unique within the Trypanorhyncha.

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SsrDNA sequence places P. otobothrioides as sister taxon to the Tentaculariidae.

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We emmend the superfamily diagnosis in the most recent classification.

Hispidorhynchus styracurae n. sp. (Trypanorhyncha: Eutetrarhynchidae) From the Chupare Stingray, Styracura schmardae (Werner), from the Caribbean Sea, Including New Records of Oncomegas wageneri (Linton, 1890)

Species of the eutetrarhynchid genus Hispidorhynchus Schaeffner and Beveridge, 2012 possess an uncinate macrohook on the bothrial surface of the basal swelling of each tentacle. This unique feature of the oncotaxy is only shared with the closely related genus Oncomegas Dollfus, 1929 . A new species of Hispidorhynchus is described from specimens infecting Styracura schmardae (Werner, 1904) (Potamotrygonidae) from the western Caribbean Sea off the coast of Belize and Panama. Hispidorhynchus styracurae n. sp. differs from its 3 congeners in the possession of smaller and narrower bulbs, fewer principle hooks in the metabasal armature, size of the macrohook, and different scolex proportions. Scanning electron microscopy reveals new information on the microthrix morphology of the genus. A diagnostic key for the differentiation of species of Hispidorhynchus is provided. In addition, new host and locality records are reported for Oncomegas wageneri ( Linton, 1890 ) Dollfus, 1929 , collected from Hypanus guttatus (Bloch and Schneider, 1801) (Dasyatidae) off the coast of Maceió, Alagoas (Brazil). This considerably expands the geographical distribution of this species in the western Atlantic Ocean.

Integrative taxonomy unravels the species diversity of Parachristianella (Cestoda : Trypanorhyncha) from both sides of the Panamanian isthmus

The uplift of the Panamanian isthmus in the Pliocene caused the termination of gene flow among members of many ancestral populations of marine lineages leading the diversification of geminate species confined to opposite sides of Central America. This palaeogeographical event has been evoked to explain the diversification of few lineages of batoids with trans-isthmian distribution. As such, there is the expectation that this vicariance event also affected lineages of parasites associated with them. Our study suggests that this event can explain the diversification of Parachristianella Dollfus, 1946 (Trypanorhyncha:Eutetrarhynchidae) in the Caribbean Sea and tropical eastern Pacific Ocean. We provide molecular, morphological and biogeographical evidence to recognise five lineages within this genus inhabiting the coastal waters of Panama, including P. parva Campbell &amp; Beveridge, 2007 and four new species: P. mendozai, sp. nov., P. kuchtai, sp. nov., P. campbelli, sp. nov. and P. soldanovae, sp. nov. These species can be diagnosed by unambiguous sets of molecular characters. The morphological cohesiveness of sister species, which most likely diverged from around 3million years ago through the uplift of the Panamanian isthmus, suggests that the traditional emphasis on the tentacular armature to circumscribe species within trypanorhynchs might underestimate the diversity of recently diverged lineages.

Genetic identity of eutetrarhynchids from the Persian Gulf, with intraindividual and intraspecific variability of Prochristianella butlerae Beveridge, 1990

The examination of the two batoid species, Pastinachus sephen (Forsskål) and Himantura gerrardi (Gray), resulted in a morphologic identification of the five eutetrarhynchid species, namely Parachristianella indonesiensis Palm, 2004 reported for the first time from Himantura gerrardi, Pa. monomegacantha Kruse, 1959, Prochristianella clarkeae Beveridge, 1990, Pr. butlerae Beveridge, 1990 and Dollfusiella spinulifera (Beveridge et Jones, 2000). By sequencing the partial 28S rDNA and calculating the genetic distances between the morphologically identified specimens from the Persian Gulf and their allopatric morphological conspecifics as well as using a phylogeny, the specimens of the Persian Gulf were considered as the allopatric conspecifics of Parachristianella indonesiensis, Pa. monomegacantha and Prochristianella clarkeae. Since the specimens of Dollfusiella from the Persian Gulf and D. spinulifera from Australia had a high genetic distance and placed in two separate clades, the Iranian specimens of Dollfusiella were treated as the cryptic species of D. spinulifera. Following the treatment of Prochristianella macracantha Palm, 2004 as the synonym of Pr. butlerae Beveridge, 1990, it was also expressed that although Pr. butlerae appeared to be a variable species in terms of its metric data, there was an identical oncotaxy in all the conspecifics. A detail examination of the specimens from the Persian Gulf as well as Australian voucher specimens revealed a great intraindividual and intraspecific variability in this species. Since, the sequence information is only available for the Iranian specimens and there is no possibility to evaluate the genetic distance and their monophyly, we consider these two allopatric populations as one species.