''Ptychobranchus subtentum'', also known as the fluted kidneyshell, is a species of freshwater mussel, an aquatic

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk in the family Unionidae, the river mussels. This species is endemic to the drainages of the

Cumberland River The Cumberland River is a major waterway of the Southern United States. The U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed June 8, 2011 river drains almost of southern Kentucky and ...

and the Tennessee River in the United States.

Reproduction

All Unionidae are known to use the gills, fins, or skin of a host fish for nutrients during the larval glochidia stage. ''Ptychobranchus subtentum'' enclose their larvae in a membranous capsule that resembles the pupae of

black flies A black fly or blackfly (sometimes called a buffalo gnat, turkey gnat, or white socks) is any member of the family Simuliidae of the Culicomorpha infraorder. It is related to the Ceratopogonidae, Chironomidae, and Thaumaleidae. Over 2,200 speci ...

. When a fish bites the capsule bait, the ''Ptychobranchus subtentum'' larvae are forced out through the mimic capsule's "eyes" and then attach to the gills of the host fish.

References

subtentum Endemic molluscs of the United States ESA endangered species Taxa named by Thomas Say Bivalves described in 1825 Taxonomy articles created by Polbot {{Unionidae-stub