The surface topography of Callorhynchocotyle callorhynchi (Manter, 1955) (Monogenea: Hexabothriidae), a parasite of the holocephalan fish Callorhinchus capensis

Abstract

A scanning electron microscopical study, incorporating some transmission electron microscopical observations, was undertaken on the surface topography of the gill parasite Callorhynchocotyle callorhynchi (Manter, 1955) (Monogenea: Hexabothriidae) from the Cape elephant fish Callorhinchus capensis (Holocephali) off the western coast of South Africa. The study revealed the presence of several new characteristics for this species. These include the presence of regularly distributed, knob-shaped projections on the surface of the haptor, haptoral appendix and sucker peduncles measuring 0.2 μm and in concentrations of approximately 100 per 10 μm(2) and the existence of a ridge which bisects each sucker lumen, forming two different loculi. We also report, for the first time for any monogenean, the presence of 'true spines'; these occur on the luminal surface of the haptoral suckers and have all of the characteristics of the tegumental spines of digeneans, i.e. they are situated within the distal syncytial tegumental cytoplasm, rest on the basal plasma membrane, have a uniform structure and are covered apically by the tegumental surface plasma membrane. These spines are simple, straight and single-pointed. Under the scanning electron microscopy (SEM), within an area of 20 μm in diameter, 23 such spines were counted, but their concentration and arrangement varies in different regions of the sucker. At their base, they measure about 1.5 μm in width and reach approximately 2 μm in height above the general level of the tegument, but transmission electron microscopy (TEM) measurements of an entire spine indicate that they may reach 3 μm in total length. The presence of spines, possessing similar morphological characteristics in both basal polyopisthocotylean monogeneans and digeneans, represents another characteristic which may prove useful in understanding the evolutionary relationships within the Neodermata.

Spermiogenesis and spermatozoon ultrastructure in basal polyopisthocotylean monogeneans, Hexabothriidae and Chimaericolidae, and their significance for the phylogeny of the Monogenea

“…In this paper we present, for the first time, observations on two species of the family Hexabothriidae (Diclybothriidea) and one of the family Chimaericolidae (Chimaericolidea), thus filling the gaps in our knowledge of sperm ultrastructure in the Monogenea. These observations complement previous studies on the tegument [ 88 ], attachment organs [ 84 , 85 ], reproductive organs [ 83 , 87 ], and digestive system [ 86 ] of the same species.…”

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

“…Implementing parasites as conservation targets and learning more about the unique host-parasite interactions and life histories, we would gain insights into the biology of the host and ultimately help to preserve the biodiversity by protecting the threatened host species and a wide array of parasite species, which may face extinction together with their host species. This study along with previous reviews (Smit and Hadfield 2015, Reed 2015, Van As 2015 and faunal checklists (e.g. Van As and Basson 1984, Oldewage and Avenant-Oldewage 1993 illustrates that South Africa boasts a prodigious fauna in both marine and freshwater systems.…”

“…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.…”

“…,Vaughan and Christison (2012),Poddubnaya et al (2015) Order: Monocotylidea (Monopisthocotylea) F a m i l y : Monocotylidae Dendromonocotyle citrosaVaughan, Chisholm et Christison, 2008 ex Dasyatis chrysonota (Smith) (Myliobatiformes: Dasyatidae);Vaughan et al (2008) ex Maculabatis gerrardi (Gray) (Myliobatiformes: Dasyatidae);Vaughan et al (2008) [in captivity] Dendromonocotyle ukuthena Vaughan, Chisholm et Christison, 2008 ex Himantura cf. uarnak (Myliobatiformes: Dasyatidae); Vaughan et al (2008) [in captivity] ex Maculabatis gerrardi (Gray) (Myliobatiformes: Dasyatidae); Vaughan et al (2008) [in captivity] Dermophthirius carcharhini MacCallum, 1926 ex Carcharhinus obscurus (Lesueur) (Carcharhiniformes: Carcharhinidae); Bullard et al (2004) Heterocotyle tokoloshei Vaughan et Chisholm, 2010 ex Bathytoshia brevicaudata (Hutton) (Myliobatiformes: Dasyatidae); Vaughan and Chisholm (2010a) Neoheterocotyle robii Vaughan et Chisholm, 2010 ex Acroteriobatus annulatus (Müller et Henle) (Rhinopristiformes: Rhinobatida); Vaughan and Chisholm (2010b)F a m i l y : Microbothriidae Pseudoleptobothrium christisoni Vaughan et Chisholm, 2011 ex Acroteriobatus annulatus (Müller et Henle) (Rhinopristiformes: Rhinobatidae); Vaughan and Chisholm (2011) C l a s s : Trematoda (Neodermata) O r d e r : Aspidogastrida (Aspidogastrea) F a m i l y : Multicalycidae Multicalyx cristata Faust et Tang, 1936 ex Carcharias taurus Rafinesque (Lamniformes: Odontaspinidae); Bray (1984) ex Sphyrna lewini (Griffith et Smith) (Carcharhiniformes: Sphyrnidae); Parukhin and Tkachuk (1980), Bray (1984) O r d e r : Plagiorchiida (Digenea) F a m i l y : Gorgoderidae…”

Parasite community structure as a predictor of host population structure: An example using Callorhinchus capensis

“…Of these, only nine publications were relevant to Callorhinchus spp. and their parasitic species (Amato and Pereira, 1995; Beverley-Burton et al, 1993; Llewellyn and Simmons, 1984; Luque and Iannacone, 1991; Morris et al, 2016; Larisa G Poddubnaya et al, 2015a, b; Larisa G. Poddubnaya et al, 2015a, b; Poddubnaya et al, 2017; Simmons et al, 1972). These search terms were also searched for in Google Scholar.…”