Heterocotyle tokoloshei sp. nov. (Monogenea, Monocotylidae) from the gills of Dasyatis brevicaudata (Dasyatidae) kept in captivity at Two Oceans Aquarium, Cape Town, South Africa: Description and notes on treatment

Abstract

Heterocotyle tokoloshei sp. nov. is described from the gills of a single Short-tail stingray, Dasyatis brevicaudata, kept in captivity at the Two Oceans Aquarium in Cape Town, South Africa. The stingray exhibited laboured gill ventilation and deteriorating health on exhibit and was removed to the quarantine area for parasitological study and treatment. A 12 h bath treatment of praziquantel at 20mg/l, pre-dissolved in ethanol, removed 3084 parasites from the gills of the ray. However, the presence of a large number of eggs 24 h post-treatment indicated that viable egg laying adults remained on the gills and that the treatment was not 100% effective. Praziquantel was subsequently administered orally by intubation to the same ray at 150 mg/kg under anaesthetic (2-phenoxyethanol at 0.15 ml/l for approximately 1 h), which resulted in the removal of approximately 392 000 parasites from the gills 12 h post-oral treatment. Twenty-four h post-oral treatment, 3383 worms, but no eggs were recovered. No worms or eggs were recovered 48 h to 10 days post-oral treatment. The ray died approximately 30 days after the completion of the treatment. Heterocotyle tokoloshei sp. nov. is the first Heterocotyle species described from South Africa and represents the first record of a pathogenic Heterocotyle species. The new species can be distinguished from the other 16 species in the genus by the distal region of the male copulatory organ which has distinct small spines and by the morphology of the male copulatory organ accessory piece. Eggs of H. tokoloshei sp. nov. are laid singly and hatch spontaneously between 5 and 8 days at 18°C.

A new species of Heterocotyle Scott, 1904 (Monogenea: Monocotylidae) from the gills of Dasyatis guttata (Dasyatidae) in southwestern Atlantic waters off Rio de Janeiro, Brazil

“…Six species, including H. armata Timofeeva, 1983, H. capricornensis Chisholm & Whitttington, 1996, H. confusa Timofeeva, 1983, H. forcifera Neifar, Euzet & Ben Hassine, 1999, H. granulatae and H. sulamericana have been described with only a single sinuous ridge surmounting the septa. The remaining 13 species have the 1/2/3 sinuous ridge arrangement, which consists of: a single sinuous ridge on the inner and outer ring and three posterior septa; a double sinuous ridge on the two lateral septa; and three sinuous ridges surmounting the three anterior septa (Chisholm & Whittington, 1996) , 1983, H. dasyatis (Yamaguti, 1965) Chisholm, 1995, H. minima (MacCallum, 1916) Price, 1938, H. mokhtarae Neifar, Euzet & Ben Hassine, 1999, H. pastinacae Scott, 1904, H. pseudominima, H. scotti Neifar, Euzet & Ben Hassine, 1998, H. similis Neifar, Euzet & Ben Hassine, 1998, H. striata Neifar, Euzet & Ben Hassine, 1999, H. taeniuropi Cao, Ding, Zhang & Liu, 2010and H. tokoloshei Vaughan & Chisholm, 2010. Vaughan & Chisholm (2010 used the proteolytic digestion technique described by Vaughan et al (2008) to examine the haptor of H. tokoloshei.…”

A new species of Neoheterocotyle Hargis, 1955 (Monogenea: Monocotylidae) from the gills of Rhinobatos annulatus Müller & Henle (Rhinobatidae) off the southern tip of Africa

“…Therefore, it likely that the sinuous ridge is not sclerotised, as described previously for other members of Neoheterocotyle (see Chisholm & Whittington, 1997). We recently determined that the sinuous ridge(s) on the haptor of a species of Heterocotyle Scott, 1904 is/are also likely not sclerotised (see Vaughan & Chisholm, 2010). The dorsal haptoral accessory sclerites are lightly sclerotised and prolonged exposure of these structures to proteolytic digestion can destroy their outer walls.…”

“…These parasites are generally encountered in low intensities on wildcaught fishes but some monocotylids can be problematic on captive hosts (Janse & Borgsteede, 2003;Vaughan et al, 2008;Vaughan & Chisholm, 2009. Left uncontrolled, large numbers of feeding monocotylids can damage host tissue leading to disease and, in some cases, even death of the host fish (see Vaughan & Chisholm, 2010).…”

“…Although South Africa has a rich diversity of elasmobranchs, investigations of their associated monogeneans and the potential impact of these parasites on fish kept in local public aquaria are few (Bullard & Dippenaar, 2003;Vaughan et al, 2008;Vaughan & Chisholm, 2010). Accurate monogenean identification and knowledge of their specific biology is essential to ensure the selection of the most appropriate management methods for their control and treatment (Hayward et al, 2007).…”

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

“…In South Africa, research on marine monogeneans started with Manter (1955), who described two species from the Cape elephantfish, Callorhinchus capensis Duméril (Chimaeriformes: Callorhinchidae). At present, nine species of monogeneans belonging to three families have been recorded from eight species of chondrichthyans (Beverley-Burton et al 1991, Vaughan and Chisholm 2010a, b, 2011, Vaughan and Christison 2012, Poddubnaya et al 2015, Vaughan et al 2008. Given the high diversity of elasmobranchs and holocephalans in South African waters, it is expected that a large proportion of the monogenean diversity still remains to be discovered.…”