Mytilopsis leucophaeata - the False Dark Mussel

 

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Mytilopis leucophaeata is another biofouling mussel species similar in appearance to the zebra mussel. It typically inhabits more brackish water habits.

 

Superfamily: Dreissenacea

 

Family: Dreissenidae

 

Genus: Mytilopsis

 

Species: leucophaeata

 

Common Name: False dark mussel

 

Native Dreissenacea: Native to North America.

 

Habitat: Attached to hard substrates (epifaunal) in brackish habitats (salinities >5 ppt)

 

Size: Small, shell length ranges between <1and 2 cm, with an average length of 1 cm

 

Life span: Short-lived (3-5 years)

 

Reproductive Cycles:

 Dioecious (i.e., seperate sexes) with external fertilization.

 Larvae are planktonic, much like those of Dreissena spp.

 Larvae settle out of the plankton and attach to hard substrates with byssal threads as described for D. polymorpha (See Life History section).

 

Distinguishing Characteristics:

 

Internal

 Myophore plate (shelf) present anteriorly.

 Apophysis (tooth) present on the anterior myophore plate.

 

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All three dreissenid mussels have a shell or myophore plate located anteriorly on the internal portion of the shell. Only Mytilopis leucophaeata has an apophysis or projection on the lateral margin of its myophore plate (as indicated by the arrow). This protrusion, used for mussel attachment, is absent in both zebra and quagga mussels. It can be observed using a hard lens or dissecting microscope.

 

External

      Dorsally tapered shell valves.

      Epifaunal, attached to hard substrate.

      Umbone located anteriorly.

      Byssal threads present ventrally.

      Bottom of organism convex and lacking an acute angle.

 

Included Groups or Species

Zebra Mussel Identification