Lernaeodiscidae is a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 of parasitic

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

 barnacle

Barnacle

A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...

s. They belong to the bizarre and highly apomorphic

Synapomorphy

In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...

 superorder Rhizocephala

Rhizocephala

Rhizocephala are derived barnacles that parasitise decapod crustaceans. Their bauplan is uniquely reduced in an extreme adaptation to their parasitic lifestyle, and makes their relationship to other barnacles unrecognisable in the adult form...

, and therein to the less diverse of the two orders

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

, the Kentrogonida. The Lernaeodiscidae are one of the smallish families of Rhizocephala, though the only one among the Kentrogonida (which otherwise contain the two larger rhizocephalan families). The family contains three genera: Lernaeodiscus Müller, 1862, Septodiscus Van Baal, 1937 and Triangulus Smith, 1906.