Parasites of cartilaginous fishes (Chondrichthyes) in South Africa - a neglected field of marine science

Abstract

Southern Africa is considered one of the world's 'hotspots' for the diversity of cartilaginous fishes (Chondrichthyes), with currently 204 reported species. Although numerous literature records and treatises on chondrichthyan fishes are available, a paucity of information exists on the biodiversity of their parasites. Chondrichthyan fishes are parasitised by several groups of protozoan and metazoan organisms that live either permanently or temporarily on and within their hosts. Reports of parasites infecting elasmobranchs and holocephalans in South Africa are sparse and information on most parasitic groups is fragmentary or entirely lacking. Parasitic copepods constitute the best-studied group with currently 70 described species (excluding undescribed species or nomina nuda) from chondrichthyans. Given the large number of chondrichthyan species present in southern Africa, it is expected that only a mere fraction of the parasite diversity has been discovered to date and numerous species await discovery and description. This review summarises information on all groups of parasites of chondrichthyan hosts and demonstrates the current knowledge of chondrichthyan parasites in South Africa. Checklists are provided displaying the host-parasite and parasite-host data known to date.

Four new species of Acanthobothrium van Beneden, 1849 (Cestoda: Onchoproteocephalidea) from the spotted skate, Raja straeleni Poll, off the Western Cape, South Africa

“…In addition, a molecular phylogenetic analysis on newly collected specimens will reveal their phylogenetic position and will highlight new perspectives on the evolutionary relationships between these cestodes and their elasmobranch hosts. With merely 9% (18 of 204) of elasmobranchs (Ebert andvan Hees 2015, Schaeffner andSmit 2019) off southern Africa examined for cestode infections, it is also expected that the species diversity of cestodes infecting elasmobranchs in South African waters is much higher than currently reported (Schaeffner and Smit 2019) and future large-scale surveys on elasmobranch parasites will, without any doubt, lead to numerous new species discoveries.…”

“…Sampling efforts focussed on parasitological observations of elasmobranchs off South Africa have been extremely sparse Hadfield 2015, Schaeffner andSmit 2019). This particularly applies to the spotted skate, Raja straeleni, a relatively common species along the western and southern coastlines of southern Africa that has only once been examined for cestode infections (see Caira et al 2014).…”

“…The diversity, biogeography and biology of elasmobranchs off southern Africa have been well documented, with 204 elasmobranch species reported from this region (Ebert and van Hees 2015). However, only 18 of these species have been examined for cestode infections (Schaeffner and Smit 2019).…”

The Sawshark Redemption: Current knowledge and future directions for sawsharks (Pristiophoridae)

“…Note: Following the redescription by Izawa (2010), A. oblongus is considered to only occur in North American waters. Although still listed in the recent checklist by Schaeffner and Smit (2019), it is possible that copepods identified as A. oblongus in South African waters are actually A. pinguis .…”

“…Izawa (2010); Oldewage and Smale (1993); Schaeffner and Smit (2019)…”