Mytilidae

The Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, Limnoperna, even inhabits freshwater environments. Mytilidae, which contains some 52 genera, is the only extant family within the order Mytilida.^[1]

Mytilidae
Two shells of Mytilus edulis washed up on a beach
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Mytilida
Superfamily:	Mytiloidea
Family:	Mytilidae Rafinesque, 1815
Genera
32, See text

Species in the family Mytilidae are found worldwide, but they are more abundant in colder seas, where they often form uninterrupted beds on rocky shores in the intertidal zone and the shallow subtidal. The subfamily Bathymodiolinae is found in deep-sea habitats.

Mytilids include the well-known, edible sea mussels.

A common feature of the shells of mussels is an asymmetrical shell, which has a thick, adherent periostracum. The animals attach themselves to a solid substrate using a byssus.

A 2020 study of the phylogeny of the Mytilidae recovered two main clades derived from an epifaunal ancestor, with subsequent lineages shifting to other lifestyles, and correlating convergent evolution of siphon traits.^[2]

Subfamilies and genera

A bed of the edible California mussel, Mytilus californianus

Mussels and attached barnacles on the Cornish coast near Newquay

Mytilus (Falcimytilus) jurensis from the Middle Jurassic (Callovian) Matmor Formation of southern Israel

As of March 2025^[update], the World Register of Marine Species accepts 32 genera split into eight subfamilies.^[1]

Subfamily Brachidontinae

• Brachidontes Swainson, 1840
• Geukensia Van de Poel, 1959
• Ischadium Jukes-Browne, 1905
• Mytilaster Monterosato, 1883

Subfamily Crenellinae

• †Arcoperna Conrad, 1865
• Arcuatula Jousseaume, 1919
• Arvella Scarlato, 1960
• Choromytilus T. Soot-Ryen, 1952
• Crenella T. Brown, 1827
• Exosiperna Iredale, 1929
• Musculus Röding, 1798
• Mytella T. Soot-Ryen, 1955
• Parabrachidontes K. S. Tan, S. H. M. Tan, Sanpanich, Duangdee & Ambarwati, 2024
• Perna Philipsson, 1788
• Rhomboidella Monterosato, 1884
• †Semimodiola Cossmann, 1887
• Solamen Iredale, 1924
• Vilasina Scarlato, 1960

Subfamily Dacrydiinae

• Dacrydium Torell, 1859

Subfamily Lithophaginae

• Lithophaga Röding, 1798

Subfamily Mytilinae

• Adula H. Adams & A. Adams, 1857
• Crenomytilus T. Soot-Ryen, 1955
• Dentimodiolus Iredale, 1939
• Gregariella Monterosato, 1883
• Mytilus Linnaeus, 1758
• †Praemytilus F. W. Anderson & L. R. Cox, 1948
• Trichomya Ihering, 1900

Subfamily Mytiliseptinae

• Austromytilus Laseron, 1956
• Mytilisepta T. Habe, 1951
• Perumytilus Olsson, 1961
• Semimytilus T. Soot-Ryen, 1955

Subfamily Septiferinae

• Septifer Récluz, 1848

†Subfamily Xenomytilinae

• †Lycettia L. R. Cox, 1937
• †Xenomytilus Squires & Saul, 2006

Incertae sedis

• †Admytilus Berezovsky, 2015
• Amygdalum Megerle von Mühlfeld, 1811
• †Arcomytilus Agassiz, 1842
• †Assytilus Berezovsky, 2015
• Aulacomya Mörch, 1853
• †Cuneolus Stephenson, 1941
• †Inoperna Conrad, 1873
• †Limnolycettia C. M. Kolesnikov, 1980
• †Mauricia G. D. Harris, 1919
• †Mysidioptera Salomon, 1895
• †Mytilosootus Stilwell & Zinsmeister, 1992
• †Paramusculus Kadolsky, 1989
• †Promytilus Newell, 1942
• †Regulifer Fürsich & Werner, 1988
• †Rhynchomytilus Rollier, 1914
• †Samiolus Kiel & Taviani, 2017
• Urumella Hayami & Kase, 1993
• †Volsellina Newell, 1942