Parasite biodiversity in a coral reef fish: twelve species of monogeneans on the gills of the grouper Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia, with a description of eight new species of Pseudorhabdosynochus (Monogenea: Diplectanidae)

Abstract

Coral reefs are known for their high level of biodiversity, but parasite biodiversity has not been evaluated. Cases such as Epinephelus maculatus, described here, show that the numerical estimation of parasite biodiversity in coral reefs could reach more than ten times the number of fish species; consequently, the extinction of certain fish species from endangered coral reefs would result in the co-extinction of at least ten times the number of parasite species. E. maculatus is a grouper of intermediate size (1-2 kg) and common in the coral reefs of New Caledonia, South Pacific. Based on the examination of more than 800 monogenean specimens, 12 species of monogeneans (ten diplectanids and two ancyrocephalids) were differentiated on the gills. These species of diplectanids have not been found in other epinephelines in the same area and thus are considered as specific to this host. In addition, three species of copepods, and isopod larvae, are present on the gills; E. maculatus thus has a total of 16 species of gill ectoparasites, which can be found together on a single individual fish. Diplectanids include Laticola dae Journo & Justine, 2006, which is the most abundant species representing about 50% of the specimens, and nine species which are rare, each representing 2-7% of the specimens: Diplectanum uitoe n. sp. and eight species of Pseudorhabdosynochus Yamaguti, 1958. D. uitoe, provisionally attributed to Diplectanum Diesing, 1858, is characterised by a small conical penis with internal walls. Pseudorhabdosynochus auitoe n. sp., P. buitoe n. sp., P. cuitoe n. sp., P. duitoe n. sp., P. euitoe n. sp. and P. fuitoe n. sp. are differentiated on the basis of the morphology of the sclerotised vagina, but are very similar in other characteristics; P. guitoe n. sp. is characterised by a quadriloculate organ with very thick walls and a very small sclerotised vagina; and P. huitoe n. sp. is characterised by its sclerotised vagina and by very long ventral and dorsal haptoral bars. Two rare (2-3% of specimens) ancyrocephalids, Haliotrema epinepheli Young, 1969 and Haliotrema sp., are briefly described in relation to the male copulatory organs and haptoral bars; H. epinepheli is apparently a generalist species found in various epinephelines and other fish species. A table of the 50 species of diplectanids (Pseudorhabdosynochus, Laticola Yang et al., 2006, Echinoplectanum Justine & Euzet, 2006 and Diplectanum) from serranids is provided.

Pseudorhabdosynochus inversus sp. nov. (Monogenea, Diplectanidae) from the halfmoon grouper Epinephelus rivulatus (Perciformes, Serranidae) off New Caledonia

“…The fish was 344 mm in length and 654 g in weight. Preparation of monogeneans, measurement methods, nomenclature for the sclerotised vagina, and conventions for the description of the squamodisc were those routinely used (Justine 2005(Justine , 2007(Justine , 2008a(Justine , 2008b in press; Hinsinger and Justine 2006b). All measurements are in µm.…”

Resolution of the discrepant host-specificity of Pseudorhabdosynochus species (Monogenea, Diplectanidae) from serranid fishes in the tropical Indo-Pacific

“…The type-host of H. epinepheli is E. fasciatus; curiously, this parasite was never found in E. fasciatus in New Caledonia, but was instead found in Variola louti and E. maculatus (Justine 2005a(Justine , 2007. In addition, this parasite was not found in E. fasciatus from Moorea (present results).…”

“…The ancyrocephalid Haliotrema epinepheli has a variety of hosts (see list in Justine 2005bin Justine , 2007 but E. merra is now excluded from this list and E. quoyanus in Australia is added. The type-host of H. epinepheli is E. fasciatus; curiously, this parasite was never found in E. fasciatus in New Caledonia, but was instead found in Variola louti and E. maculatus (Justine 2005a(Justine , 2007.…”

“…In these cases, publication of a drawing of the host (example: Marie and Justine 2005), or, more efficiently, deposition of the host in a Museum collection together with a host DNA sample (examples : Justine 2005a: Justine , 2007, is the only guarantee that the host will be adequately identified in the future, allowing comparative studies with other hosts and localities. A simple method is to take only the right gills of a host and deposit the specimen in an ichthyological collection.…”

Diplectanum parvus sp. nov. (Monogenea, Diplectanidae) from Cephalopholis urodeta (Perciformes, Serranidae) of New Caledonia

“…Drawings were scanned and redrawn on a computer with Adobe Illustrator. Methods of measurement of haptoral hardparts are as in Justine (2005Justine ( , 2007a; measurements of the right-hand haptoral hard-parts and left-hand equivalents were pooled. All measurements are given in micrometres.…”