MUSSELpdb
Taxonomy
Species & Genus Richness of
freshwater mussels
by Taxonomy
Species & Genus Richness of
freshwater bivalves
by Family
Geography
Species Richness & Endemism of
freshwater mussels
by Geography
Data last updated
Thu 22 January 2026
Class BIVALVIA
For each taxon, information is provided regarding habitat, horizon (Recent unless otherwise listed), and diversity. We are actively working on the Recent freshwater mussels, and those are the taxa for which the data are most complete. For other Recent freshwater bivalves, the information largely builds on Graf (2013). For other taxa (e.g., marine, fossil), the content is provided to put the Recent, freshwater bivalves in context.
Included Taxa
PALAEOHETERODONTA
order UNIONIDA: 1005 Recent freshwater species.
These are the freshwater mussels. There are six modern families, restricted entirely to fresh waters. In addition, there are several fossil families.
order TRIGONIIDA: no Recent freshwater species in the MUSSELpdb.
Trigoniids are the marine sister-group to freshwater mussels.
IMPARIDENTIA
order ADAPEDONTA: 6 Recent freshwater species.
Although mostly marine, the ADAPEDONTA includes the genus Novaculina in the family PHARIDAE.
order CARDIIDA: 10 Recent freshwater species.
Cardiids are mostly marine, with a minor radition into freshened waters.
superfamily CYAMIOIDEA Sars, 1878: no Recent freshwater species in the MUSSELpdb.
synonymy (2 nomina) | 2 families
order GALEOMMATIDA: 1 Recent freshwater species.
order GASTROCHAENIDA: no Recent freshwater species in the MUSSELpdb.
order LUCINIDA: no Recent freshwater species in the MUSSELpdb.
order MYIDA: 23 Recent freshwater species.
Myids are primarily marine bivalves, but there are freshwater species as well, including species of the family DREISSENIDAE.
order SPHAERIIDA: 278 Recent freshwater species.
The family Sphaeriidae is the second-most species-rich radition of bivalves into inland habitats.
order VENERIDA: 96 Recent freshwater species.
The family Cyrenidae represents the most significant radition of venerids into fresh waters, but there are also a number of freshwater species in primarily marine families.
order MODIOMORPHIDA: fossil only.
ANOMALODESMATA
order ANOMALODESMATA: no Recent freshwater species in the MUSSELpdb.
ARCHIHETERODONTA
order CARDITIDA: no Recent freshwater species in the MUSSELpdb.
order ACTINODONTIDA: fossil only.
PTERIOMORPHIA
order ARCIDA: 5 Recent freshwater species.
Arcids are primarily marine. However, the genus Scaphula in the family ARCIDAE occurs in fresh waters.
order LIMIDA: no Recent freshwater species in the MUSSELpdb.
order MYTILIDA: 9 Recent freshwater species.
There are a few secondarily freshwater species in this order, but otherwise mytilids are primarily marine.
order OSTREIDA: no Recent freshwater species in the MUSSELpdb.
order PECTINIDA: no Recent freshwater species in the MUSSELpdb.
An order of bivalves that has freshwater species or at least species attributed to freshwater clades.
order MYALINIDA: fossil only.
PROTOBRANCHIA
order MANZANELLIDA: no Recent freshwater species in the MUSSELpdb.
order NUCULANIDA: no Recent freshwater species in the MUSSELpdb.
order NUCULIDA: no Recent freshwater species in the MUSSELpdb.
order SOLEMYIDA: no Recent freshwater species in the MUSSELpdb.
