Threatened, host-specific affiliates of a red-listed host: Three new species of Acanthobothrium van Beneden, 1849 (Cestoda: Onchoproteocephalidea) from the endangered white skate, Rostroraja alba (Lacépède)

Two new species of Acanthobothrium Blanchard, 1848 (Cestoda, Onchoproteocephalidea) from Urobatisjamaicensis (Cuvier, 1816) (Elasmobranchii, Batoidea, Myliobatiformes) of the Mexican Caribbean

Eight specimens of Urobatisjamaicensis were collected from four localities of the Yucatan Peninsula, Mexico, of which four specimens were infected with cestodes of two new species of Acanthobothrium. Acanthobothriumgarciaprietoisp. nov. differs from congeners by a combination of characters including the size of the scolex and bothridia, length of the cephalic peduncle, length of the axial and abaxial prongs and total length of the abaxial prongs of the hooks, size of the cirrus sac and testes in mature proglottids, and the total number of proglottids. The most prominent characteristic distinguishing A.pulidofloresaesp. nov. from other species of the Atlantic Ocean/Caribbean Sea/Gulf of Mexico is the form of the scolex, which has the "clover leaf" configuration. In addition, it can be distinguished by the total length of the worm, total number of proglottids, small accessory suckers, the form of the bothridia, length of the axial and abaxial prongs and total abaxial prong length of hooks, and the number of testes. According to the current category scheme, A.garciaprietoisp. nov. and A.pulidofloresaesp. nov., belong to categories 1 and 5, respectively.

Tapeworms (Platyhelminthes, Cestoda) from marine chondrichthyans of the Southwestern Atlantic Ocean, and the sub-Antarctic and Antarctic islands: a checklist

A parasite-host list of cestodes parasitizing chondrichthyans in the Southwest Atlantic off Argentina and surrounding waters of Antarctica is compiled based on the available literature. The list is based on published descriptions and redescriptions of species, and newly collected worms during the current study. A total of 57 valid species belonging to 28 genera of the orders Cathetocephalidea, Diphyllidea, Gyrocotylidea, Lecanicephalidea, Onchoproteocephalidea, Phyllobothriidea, Rhinebothriidea, "Tetraphyllidea", and Trypanorhyncha is listed. Information on hosts, localities, specimens in collections and comments on tapeworms are also included. A host-parasite list including chimaeras (1 order, 1 genus), batoids (4 orders, 10 genera), and sharks (3 orders, 5 genera) is provided. Tapeworm diversity, distribution range, and host associations are discussed. The cestodes orders Phyllobothriidea and Rhinebothriidea exhibit the highest species richness, with 13 and 12 species, respectively. Onchoproteocephalideans and rhinebothriideans have the broadest geographic distribution in the study area. Regarding hosts, arhynchobatid skates are the group most frequently associated with cestodes. However, further collecting efforts are necessary to understand whether this data reflect the real diversity and host association of these parasites or is a result of a bias in sampling.

A new species of Phoreiobothrium Linton, 1889 (Cestoda: Onchoproteocephalidea) from the spinner shark, Carcharhinus brevipinna (Valenciennes) off the coast of KwaZulu-Natal, South Africa

The extreme sparsity of collection efforts in many parts of the word, including southern Africa, leaves a vast hidden diversity of marine cestode species, such as species of Phoreiobothrium. The examination of a common South African coastal-pelagic shark species, Carcharhinus brevipinna (Valenciennes), resulted in the discovery of a new species of Phoreiobothrium Linton, 1889. Phoreiobothrium martini sp. n. is undoubtedly different from all other congeners in several morphological characteristics, however, it is most easily distinguished from other species by its total length, the size of its hooks, and the number of post vaginal testes. The addition of P. martini sp. n. increases the total number of valid species of Phoreiobothrium to 20 worldwide. Furthermore, P. martini sp. n. marks the description of representatives of only the second onchoproteocephalidean genus from southern Africa, therefore expanding the generic biogeographical representation and introducing new host associations. Apart from the description of this new species of cestode, the discovery of additional species of Phoreiobothrium will be beneficial regarding future ecological investigations. With the high degree of host-specificity found amongst species of Phoreiobothrium, species such as P. martini sp. n. could be used as sentinel species for the accurate identification, separation and diagnosis of commonly misidentified shark species.