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 & 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.

A new species of Heteronybelinia (Cestoda: Trypanorhyncha) from Sympterygia bonapartii (Rajidae), Nemadactylus bergi (Cheilodactylidae) and Raneya brasiliensis (Ophidiidae) in the south-western Atlantic, with comments on host specificity of the genus

Adults and plerocercoids of a new species of Heteronybelinia (Trypanorhyncha, Tentaculariidae) were recovered from the skate Sympterygia bonapartii (Rajiformes: Rajidae) and two species of teleosts, Raneya brasiliensis (Ophidiiformes: Ophidiidae) and Nemadactylus bergi (Perciformes: Cheilodactylidae), respectively. Heteronybelinia mattisi n. sp. differs from its congeners in its possession of a tentacular armature consisting of hooks with slight differences in size and shape on opposite surfaces of the tentacle (uncinate with rounded bases on the bothrial surface and uncinate with elongate bases on the antibothrial surface), without a characteristic basal armature, hooks increasing in size toward the tip of the tentacles, and pars bothrialis slightly overlapping with bulbs. The description of Heteronybelinia is emended regarding the distribution of testes to include species without postovarian testes (H. palliata and H. mattisi), and without testes anterior to cirrus sac on the poral side (H. robusta and H. mattisi). Host data are summarized for all 15 valid species of Heteronybelinia. Host specificity of adults and plerocercoids of Heteronybelinia is variable among species, the adults being more host specific than the plerocercoids. With the exception of H. mattisi, the definitive hosts of all species of Heteronybelinia for which adults are known include carcharhiniform sharks. Heteronybelinia mattisi seems to have oioxenous specificity for its definitive batoid host, S. bonapartii, and to be more specific for the intermediate hosts than most of its congeners.

Prochristianella Dollfus, 1946 (Trypanorhyncha: Eutetrarhynchidae) from elasmobranchs off Borneo and Australia, including new records and the description of four new species

Prochristianella cairae n. sp. is described from the spiral intestines of two species of bamboo sharks, Chiloscylliumpunctatum Müller & Henle and Chiloscyllium indicum (Gmelin) (Hemiscyllidae) off the coast of Malaysian Borneo. Thespecies is distinguished from congeners by enlarged microtriches covering the whole scolex peduncle, a uniquearrangement of hooks on the basal swelling, a dissimilar number of hooks in each principle row in the metabasal armatureand hook files 1 and 1’ not being distinctly separated. Prochristianella jensenae n. sp. is described from the spiralintestines of three species of whiptail stingrays, Pastinachus solocirostris Last & Manjaji-Matsumoto, Pastinachus atrus(Macleay) and Pastinachus gracilicaudus Last & Manjaji-Matsumoto (Dasyatidae) from coastal waters off Indonesianand Malaysian Borneo and Western Australia, from Himantura uarnak (Gmelin) (Dasyatidae) off Nickol Bay, WesternAustralia and from Rhinoptera neglecta Ogilby (Myliobatidae) off Weipa, Queensland, Australia. This species lacksgland-cells within the tentacular bulbs, one of the most distinctive features of this family. Prochristianella kostadinovaen. sp. is described from the spiral intestines of Himantura uarnak 2 (Dasyatidae) (sensu Naylor et al. 2012) from the Gulfof Carpenteria. It differs from congeners in its metrical data, a metabasal tentacular armature with 10 hooks per principlerow, hooks 1(1’) being uncinate with an elongate base and widely spaced and hooks 4(4’) smaller than neighbouring hooks3(3’) and 5(5’). Prochristianella scholzi n. sp. is described from specimens of the Taeniura lymma species complex(Dasyatidae) (sensu Naylor et al. 2012) from three localities in Malaysian and Indonesian Borneo. This species has arraysof billhooks on the basal swelling, but differs from similar congeners in having very few, tiny gland-cells within thetentacular bulbs and a metabasal tentacular armature with 9–10 hooks per half spiral row and hooks 4(4’) being muchsmaller than the neighbouring hooks 3(3’) and 5(5’). Examinations of new material from northern Australia andIndonesian and Malaysian Borneo provided additional information on Prochristianella aciculata Beveridge & Justine,2010, Prochristianella butlerae Beveridge, 1990 and Prochristianella clarkeae Beveridge, 1990. In total, 17, 7 and 29(respectively) new host records and 14, 9 and 28 (respectively) new locality records are added. These records extend thegeographical range of all three species in the Australasian region and also represents the first record of P. aciculata fromAustralian waters and the first record of P. butlerae from the Indo-Malayan region. Prochristianella clarkeae is the least host specific taxon within Prochristianella, infecting 43 different host species.