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

Abstract

Abstract 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 investigation of a common South African coastal-pelagic species, the spinner shark Carcharhinus brevipinna (Valenciennes) resulted in the discovery of a new species of Phoreiobothrium Linton, 1889. Phoreiobothrium martini n. sp. is undoubtedly different from all other congeners in several morphological characteristics, however, it is most easily distinguished from other species by the size of its hooks. Furthermore, this species is peculiar in the sense of its microthrix pattern. It only possesses filitriches on its proximal bothridial surface. Additionally, P. martini n. sp. also displays a scarcity of gladiate spinitriches on its cephalic peduncle. This has not been recorded in any other congener within this genus and could resemble a new, generic characteristic. The addition of P. martini n. sp. increases the total number of valid species of Phoreiobothrium to 18 worldwide. Furthermore, P. martini n. sp. 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 P. martini n. sp. as well as additional species of Phoreiobothrium is beneficial regarding future ecological investigations. With the high degree of host-specificity found amongst species of Phoreiobothrium, species such as P. martini n. sp. could be used as sentinel species for the accurate identification, separation and diagnosis of commonly misidentified shark species, such as C. brevipinna and C. limbatus (Valenciennes).