Family CYMOTHOIDAE Leach, 1814

Renocila quadrata

© Copyright from Bruce 1991.

Museums

Regional Maps

Introduction

Cymothoids are ectosymbionts or parasites of marine, freshwater and brackish-water fishes. Most attach epidermally, externally or the buccal region, and in the gill chamber (Brusca 1981). The family is cosmopolitan with numerous species in more than 40 genera.

Brusca's excellent work was based very largely on East Pacific species and therefore was based on a rather small data set. The three lineages mentioned reflect the continued influence of the point of attachment of the parasite on the host; they do not reflect phylogeny. Position on the host can determine body shape, and this has long had an overriding influence on interpreting cymothoid relationships. As Bruce (1986, 1987a, 1990) demonstrated these lineages do not hold up, and genera of the 'Anilocrinae' which are largely externally attaching also occur on the gills and in the mouth. Species of Mothocya attach to gill arches with the exception of one species which is in the mouth and that species has a body shape similar to Cymothoa and Ceratothoa. There has been considerable confusion over the cymothoid genera and no recent key is available.

The world fauna (up to about 1990) was catalogued by Trilles (1994), but his taxonomy is not always followed here. The Australian fauna has been reviewed by Bruce (1986, 1987b, 1987c, 1990, 1991) who provided keys to species of several genera and to the genera of the Anilocrinae and gill- or branchial-attaching genera. That work resolved the complex taxonomy of some of the major genera and species and detailed the ecology of each. The large genera Ceratothoa and Cymothoa remain unrevised with many nominal species of doubtful or unclear identity. Many cymothoid species have been referred to the genus Livoneca Leach or its misspelling Lironeca (International Commission on Zoological Nomenclature 1996); this genus does not occur in Australia.

Smit et al. (2014) give a review of the history of discovery of the Cymothoidae, discuss current classification and summarise current knowledge on the ecology of the Cymothoidae.

Excluded Taxa

Misidentifications

CYMOTHOIDAE: Ceratothoa trigonocephala (Leach, 1818) — Martin, M.B., Bruce, N.L. & Novak, B.F. 2015. Review of the fish-parasitic genus Ceratothoa Dana, 1852 (Crustacea: Isopoda: Cymothoidae) from Australia, with description of two new species. Zootaxa 3963(3): 251–294 [283]

CYMOTHOIDAE: Mothocya lineata (Miers, 1876) — Martin, M.B., Bruce, N.L. & Novak, B.F. 2015. Review of the fish-parasitic genus Ceratothoa Dana, 1852 (Crustacea: Isopoda: Cymothoidae) from Australia, with description of two new species. Zootaxa 3963(3): 251–294 [285]

Diagnosis

Body with dorsum weakly to strongly vaulted, unornamented. Eyes lateral when present. Pleonites 1-5 free. Antennae 1 and 2 with flagellum not distinct from peduncle. Frontal lamina absent. Mouthparts forming a buccal cone. Mandible incisor simple, conical; lacinia mobilis and spine row absent, molar present; palp of 3 articles. Maxilla 1 styliform, with terminal robust setae. Maxilla 2 with small medial lobe and lateral lobe; each lobe with 2 or more robust setae. Maxilliped 3-articled, article 3 with robust setae. All pereopods prehensile. Pleopods without marginal setae, lamellar or with fleshy folds. Uropods biramous, freely articulating, situated at anterolateral angles of pleotelson. All appendages largely or totally devoid of setae and (except mouthparts) of robust setae.

General References

Bruce, N.L. 1986. Revision of the isopod crustacean genus Mothocya Costa, in Hope, 1851 (Cymothoidae: Flabellifera), parasitic on marine fishes. Journal of Natural History 20: 1089-1192

Bruce, N.L. 1987a. Australian Renocila Miers, 1880 (Isopoda: Cymothoidae), crustacean parasites of marine fishes. Records of the Australian Museum 39: 169-182

Bruce, N.L. 1987b. Australian species of Nerocila Leach, 1818, and Creniola n. gen. (Isopoda: Cymothoidae), crustacean parasites of marine fishes. Records of the Australian Museum 39: 355-412

Bruce, N.L. 1987c. Australian Pleopodias Richardson, 1910 and Anilocra Leach, 1818 (Isopoda: Cymothoidae), crustacean parasites of marine fishes. Records of the Australian Museum 39: 85-130

Bruce, N.L. 1990. The genera Catoessa, Elthusa, Enispa, Ichthyoxenus, Idusa, Livoneca and Norileca n. gen. (Isopoda, Cymothoidae), crustacean parasites of marine fishes, with descriptions of eastern Australian species. Records of the Australian Museum 42: 247-300

Bruce, N.L. 1991. Two new species of Renocila from off the tropical Australian coasts (Isopoda: Cymothoidae), crustacean parasites of marine fishes. The Beagle, Records of the Museums and Art Galleries of the Northern Territory 8: 159-168

Brusca, R.C. 1981. A monograph on the Isopoda Cymothoidae (Crustacea) of the eastern Pacific. Journal of the Linnean Society of London, Zoology 73: 117-199

International Commission on Zoological Nomenclature 1996. Opinion 1849. Livoneca Leach, 1818 (Crustacea, Isopoda): the original spelling confirmed as correct, and the spelling of Lironeca rejected. Bulletin of Zoological Nomenclature 53: 210-212

Ketmaier, V., Joyce, D.A., Horton, J.T. & Mariani, S. 2008. A molecular phylogenetic framework for the evolution of parasitic strategies in cymothoid isopods (Crustacea). Journal of Zoological Systematics and Evolutionary Research 46: 19-23

Smit, N.J., Bruce, N.L. & Hadfield, K.-A. 2014. Global diversity of fish parasitic isopod crustaceans of the family Cymothoidae. International Journal for Parasitology: Parasites and Wildlife [early view]

Trilles, J.P. 1994. Les Cymothoidae (Crustacea: Isopoda) du monde. Podrome pour une faune. Studia Marina Sinica 21/22: 1-288

History of changes