6 - Sphaeromatidae::“Cute As Buttons”

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.