194 FLABELLIFERA • LIMNORIIDAE 



REMARKS This family includes a number of species that are of considerable 

 economic importance. Given that species of Limnoria are wood borers, 

 wooden structures such as wharf pilings that are immersed in sea water and 

 even in water of reduced salinity are vulnerable to attack by these gribbles. 

 Prolonged exposure can lead to weakening and eventual collapse of these 

 structures (see Ray, 1959). Even creosote-treated wood is not fully protected; 

 Limnoria tuberculata will bore into such wood to where the creosote has not 

 penetrated. 



The isopods rasp at the wood fibres with the rasp and file structures of the 

 mandibles, usually following the grain of the wood. With this boring activity, 

 saprophytic fungi and bacteria invade the wood and assist in the breakdown 

 process. Limnoria lack cellulase-secreting microflora in their gut, but proba- 

 bly secrete a cellulase themselves (Boyle and Mitchell, 1978). It is also prob- 

 able that the fungi and bacteria, the latter often densely aggregated on the 

 setae of the isopod, form part of the animals' diet. In the natural environ- 

 ment, Limnoria perform an important role in the breakdown of dead wood, 

 especially in mangrove areas. 



Sexual dimorphism of the pleotelson does occur in some species. This as- 

 pect of the morphology, however, has hardly been investigated. 



Limnoria Leach, 1814 



DIAGNOSIS Antennular flagellum of four articles. Antennal flagellum of 

 three to five articles. Incisor of right mandible equipped with filelike struc- 

 ture on upper surface; incisor of left mandible with rasplike structure. Rami 

 of pleopod 5 lacking marginal setae. Uropodal exopod much shorter than 

 endopod, bearing terminal claw. Pleotelson smooth, or variously ornamented 

 with tubercles and ridges. 



Limnoria indica Becker and Kampf, 1958 

 Figure 86A,B 



DIAGNOSIS 6 3.0 mm, ovigerous 9 3.0 mm. Pleonite 5 with submedian pair 

 of strong rounded ridges, converging slightly posteriorly. Pleotelson basally 

 with two pairs of submedian tubercles and pair of lateral tubercles. 



RECORDS Cozumel, Mexico; Man o'War Cay, Belize. 

 India; Hong Kong; Philippines; east coast of Australia. 



