Page 74 - Invasive_Species_2013

Mediterranean invasive species factsheet

MOLLUSCS

Reproduction Fine concentric lines Interior iridescent blue
Common name: Black pygmy mussel

identification

Scientific Name:
Limnoperna (Xenostrobus) securis
Picture

Key identifying features
Brief history
The thin, elongated shell, almost triangular in shape,
is formed of two valves of similar shape and size.
The shell is shiny and smooth, with a sculpture of fine
concentric lines. Young individuals are yellowish
brown, while the adults are dark brown or black, up to
2–3 cm in length. The interior of the shell is iridescent
blue. individuals per square metre attaching themselves to
the substrate with strong threads.
Field identification signs and habitat
Adults can survive several days out of the water;
The black pygmy mussel is found exclusively in
they are tolerant of wide ranges of salinity, oxygen
estuaries and lagoons, often together with the mussel
concentration and temperature. The species is not
Mytilus galloprovincialis, on any kind of submerged or
found in the sea or in the downstream parts of
partially emergent hard substratum or oyster shells
estuaries where salinity is constantly high.
and occasionally also on sandy and muddy bottoms
in crevices and holes. It is a filter-feeder of Reproduction
microscopic plankton and organic particles. These
The facility with which the pygmy mussel reproduces
small mussels form dense clumps of up to 50,000
partially explains its success as an invader. It is a
fast-growing species with a short life span, living on
average for only 1 year or occasionally 2–3 years.
Fertilization takes place in the water column and free
swimming larvae disperse on water currents, helping
to colonize new habitats.

Xenostrobus securis. Photo: Guido and P. Poppe Xenostrobus securis. Photo: M. Taru

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 71