Sessiline ciliophorans associated with Haliotis species (Mollusca: Archaeogastropoda) from the South Coast of South Afica

[摘要] English: Abalone, locally known as perlemoen, are herbivorous marine gastropods with all speciesin one genus, Haliotis Linneaus, 1758. Abalone have been commercially exploited sinceancient times. Along the southern African coast, the genus Haliotis comprises sixendemic species. Surveys carried out from 1995 to 1999 at the De Hoop NatureReserve along the south coast of South Africa, revealed the presence of scyphidiidperitrichs, of the genus Mantoscyphidia Jankowski, 1980, occurring in abundance on thegills of Haliotis spadicea Donovan, 1808 and H. midae Linnaeus, 1758. These weredescribed as two new species, i.e. M spadiceae sp. nov. and M midae sp. nov. Themantoscyphidians in turn hosted ellobiophryids of the genus Caliperia Laird, 1953,which was also described as a new species, Caliperia perlemoenae sp. nov., occurringon both mantoscyphidian species. During the study a perlemoen aquaculture facility,Danger Point Abalone Farm, was also visited, specimens of H. midae were examined andfound to harbour the same species of scyphidiid peritrich and caliperid than H. midaecollected from the De Hoop Nature Reserve. In the present study, severe infections ofredial, cercarial and metacercarial stages and a few adult specimens of a digeneantrematode were also found in the digestive gland of Haliotis spadicea as well as on thegill filaments. In order to elucidate the symbiont/host associations field experiments andhistopathological examinations were carried out. These led to the conclusions that thehost/scyphidiid peritrich associations are most likely not parasitic. In the case of themantoscyphidianlcaliperid association, no clear evidence was found that the caliperidsare pathogenic to their mantoscyphidian hosts. On the other hand, the trematodes couldbe potential pathogens since they can cause tissue destruction and affect the reproductiveorgans in the host.

[发布机构] University of the Free State