Host relationships and geographic distribution of species of Acanthobothrium Blanchard, 1848 (Onchoproteocephalidea, Onchobothriidae) in elasmobranchs: a metadata analysis

Abstract

Species of Acanthobothrium have been documented as parasites of the spiral intestine of elasmobranchs. Results of a metadata analysis indicate that 114 species of elasmobranchs have been reported as hosts of 200 species of Acanthobothrium. The metadata analysis revealed that 3.7% of species of sharks and 14.9% of species of rays that have been reported as hosts to date; some species are parasitized by more than one species of Acanthobothrium. This work provides a Category designation, as proposed by Ghoshroy and Caira (2001), for each species of Acanthobothrium. These Category designations are a tool to facilitate comparisons among members of Acanthobothrium for descriptions of new species in the future.

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)

“…The present study describes three, host-specific species of onchoproteocephalidean cestodes of the genus Acanthobothrium. Merely 7% (16 of 207) of all species of this genus have been reported from this region (see Zaragoza-Tapia et al, 2020a ). The new species from South Africa further increase the diversity of this already very diverse genus, with a new total of 210 valid species worldwide ( Caira and Jensen, 2017 ; Franzese and Ivanov, 2018 , 2020 ; Maleki et al, 2018 , 2019 ; Rodríguez-Ibarra et al, 2018 ; Zaragoza-Tapia et al, 2019 , 2020b ; Van Der Spuy et al, 2020 ).…”

“…For this reason, the phylogenetic relationships of these congeners are presently unknown. Globally, there is still a great shortfall in molecular data regarding species belonging to this genus, supported by the fact that the GenBank database contain molecular sequences and records of merely 7.6% (16 of 210) of species of Acanthobothrium ( Zaragoza-Tapia et al, 2020a ). The information gained through phylogenetic analyses will not only address phylogenetic placement of parasite lineages, but further advance our knowledge on evolutionary host-parasite interrelationships, along with host-parasite co-speciation ( Beer et al, 2019 ), and relevant niche expertise ( Zaragoza-Tapia et al, 2020a ).…”

“…Gathering information on the molecular phylogeny could prove if species presenting testes located in this region might in fact comprise their own monophyletic clade ( Fyler and Caira, 2010 ), along with possible effects caused by regional geographical influences (i.e. the Eastern South Atlantic Ocean vs. the Indo-Pacific Ocean), given that adult species of Acanthobothrium are restricted to the same geographical limits portrayed by their hosts ( Zaragoza-Tapia et al, 2020a ).…”

“…These apex marine predators are heavily affected by anthropogenic impacts, most notably through overfishing and by-catch, and habitat degradation (amongst others) that caused a drastic decline in populations in recent years ( Siskey et al, 2019 ; Sousa et al, 2019 ). What makes it even more alarming is that elasmobranchs host a variety of affiliate species within and on their bodies, that make up a large proportion of the marine biodiversity ( Caira and Healy, 2004 ; Zaragoza-Tapia et al, 2020a ).…”

“…Unfortunately, concurrent with their elasmobranch hosts, research on cestodes and their unique interrelationships with their definitive hosts are ignored and not taken into consideration by conservation agencies. This leaves most of these taxa and their unique ecological services they may provide unknown to science, and render them even more vulnerable to extinction ( Poulin and Presswell, 2016 ; Zaragoza-Tapia et al, 2020a ). Acknowledging this research necessity, two specimens of the endangered white skate, Rostroraja alba (Lacépède), were screened for cestodes as part of a larger study on elasmobranch affiliates in the understudied ocean basins surrounding southern Africa.…”