Evolution and systematics

The phylum Phoronida is known to have existed since the Devonian, but there is a poor fossil record of burrows and borings attributed to phoronids. Many scientists now regard the Phoronida as a class within the phylum Lophophorata, along with the Brachiopoda and perhaps the Bryozoa. Phoronida consists of two genera, Phoronis and Phoronopsis, which are characterized by the presence of an epidermal collar fold at the base of the lophophore. The group takes its name from the genus name Phoronis, one of the numerous epithets of the Egyptian goddess Isis.

The phoronid larva, commonly called an actinotroch, retains a separate "generic" name, Actinotrocha, which authorities still consider different from the adult species.

There are 10 well-defined species of phoronid: Phoronis ovalis (creeping larva), P. hippocrepia (larva, Actinotrocha vancouveren-sis), P. ijimai (larva, A. vancouverensis), P. australis (larva, unknown), P. muelleri (larva, A. branchiata), P. psammophila (larva, A. sabatieri), P. pallida (larva, A. pallida), Phoronopsis albbomaculata (larva, unknown), Phoronopsis harmeri (larva, Actinotrocha harmeri), and Phoronopsis californica (larva, unknown). There is no class or order designation in this phylum.

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