Family GNATHIIDAE Leach, 1814

Gnathia campotonotus

© Copyright from Cohen & Poore 1994.

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Introduction

Adult gnathiids are marine benthic isopods but the praniza larva is sometimes ectoparasitic on fishes. The family is cosmopolitan in coastal to deep-sea environments with numerous species (Monod 1926; Camp 1988). Monod (1926) who studied the biology of this most unusual group of isopods recognised six genera but until recently most were treated in the genus Gnathia.

Holdich & Harrison's (1980) review of the Australian fauna was superceded by that of Cohen & Poore (1994) who described 27 new species from Australia. They also presented a phylogenetic analysis which differentiated ten genera. Although the family has long been regarded as belonging to a separate suborder of the Isopoda, Wägele (1989), Brusca & Wilson (1991) and Dreyer & Wägele (2001) concluded that the family is derived from cirolanid- or cymothoid-like ancestors. More recently, Svavarsson & Gísladóttir (2002) published a list of species, one of them new.

Diagnosis

Pereopods 1 modified as flattened pylopods which cover mouth. Pereonite 7 reduced. Pereopods 7 absent. Pleon narrower than pereon. Sexually dimorphic. Male head fused to first 2 pereonites; pereonites 3–6 flattened, parallel-sided; mandible in male large and projecting foward, not so in female. Female and praniza larva with pereonites 4–6 fused, inflated.

General References

Brusca, R.C. & Wilson, G.D.F. 1991. A phylogenetic analysis of the Isopoda with some classificatory recommendations. Memoirs of the Queensland Museum 31: 143-204

Camp, D.K. 1988. Bythognathia yucatensis new genus, new species, from the abyssal depths in the Caribbean Sea, with a list of gnathiid species described since 1926. Journal of Crustacean Biology 8: 668-678

Cohen, B.F. & Poore, G.C.B. 1994. A phylogeny and biogeography of the Gnathiidae (Crustacea: Isopoda) with descriptions of new genera and species, most from south-eastern Australia. Memoirs of Museum Victoria 54: 271-397

Dreyer, H. & Wägele, J.-W. 2001. Parasites of crustaceans (Isopoda: Bopyridae) evolved from fish parasites: molecular and morphological evidence. Zoology (Jena) 103: 157-178

Holdich, D.M. & Harrison, K. 1980. The crustacean isopod genus Gnathia Leach from Queensland waters with descriptions of nine new species. Australian Journal of Marine and Freshwater Research 31: 215-240

Leach, W.E. 1814. Crustaceology. pp. 383-437 in Brewster, D. Sir (ed.). The Edinburgh Encyclopaedia. Edinburgh : John Murray Baldwin & Cradocle Vol. 7 (2).

Monod, T. 1926. Les Gnathiidae. Essai monographique (Morphologie, Biologie, Systématique). Mémoires de la Société des Sciences nat. Physique du Maroc 13: 1-668

Svavarsson, J. & Bruce, N.L. 2012. New and little-known gnathiid isopod crustaceans (Cymothoida) from the northern Great Barrier Reef and the Coral Sea. Zootaxa 3380: 1-33 [3]

Svavarsson, J. & Gísladóttir, E. 2002. Elaphognathia korachaensis sp. nov., a new gnathiid species (Crustacea, Isopoda) from Thailand. Phuket Marine Biological Center Special Publication 23: 157-164

Wägele, J.W. 1989. Evolution und phylogenetisches System der Isopoda. Stand der Forschung und neue Erkenntnisse. Zoologica (Stuttgart) 140: 1-262

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