Abstract
We describe Phoronis emigi sp. n. as the eighth member of the genus based on specimens collected from a sandy bottom at 33.2 m depth in Tomioka Bay, Amakusa, Japan. The new species is morphologically similar to P. psammophila Cori, 1889, but can be distinguished from the latter by the number of longitudinal muscle bundles in the body wall (56–72 vs. 25–50 in P. psammophila) and the position of the nephridiopores (situated level with the anus vs. lower than the anus in P. psammophila). Using sequences of the nuclear 18S and 28S rRNA genes and the mitochondrial cytochrome c oxidase subunit I (COI) gene, we inferred the relationship of P. emigi to other phoronids by the maximum likelihood method and Bayesian analysis. The analyses showed that P. emigi is closely related to P. hippocrepia Wright, 1856 and P. psammophila Cori, 1889. We describe the morphology of the topotypes and additional material for P. ijimai Oka, 1897. Neither our morphological observations of P. ijimai, nor the phylogenetic analyses based on 18S and COI sequences, contradicts that P. vancouverensis Pixell, 1912 is conspecific with P. ijimai, a synonymy that has long been disputed.
Highlights
Phoronids, or horseshoe worms, are exclusively marine, sedentary, vermiform animals with a crown of ciliated tentacles, the lophophore, used in suspension feeding
More recently described nominal species have been regarded as invalid, junior synonyms of older names based on morphological concordance: Phoronis svetlanae Temereva & Malakov, 1999 as synonymous with P. ijimai Oka, 1897 (Emig 2007), and Phoronopsis malakhovi Temereva, 2000 with Phoronopsis harmeri Pixell, 1912 (Emig 2003)
Since DNA sequence data have been obtained for almost all valid species in the phylum (e.g., Santagata and Cohen 2009, and references therein), sequences from Phoronis svetlanae and Phoronopsis malakhovi would have helped either to discriminate these species from congeners or to corroborate the proposed synonymies
Summary
Horseshoe worms, are exclusively marine, sedentary, vermiform animals with a crown of ciliated tentacles, the lophophore, used in suspension feeding They comprise the small phylum Phoronida, which currently contains two genera, Phoronis Wright, 1856 and Phoronopsis Gilchrist, 1907, with seven and three species, respectively (Emig 2007). Phoronid species are morphologically well defined, primarily on the basis of the arrangement and pattern of the body-wall musculature, nephridia, and lophophore in adults (e.g., Emig 1974, 1979, 1982). No sequence data have been reported for P. ijimai, either from its type locality or a reasonably close locality in the northwestern Pacific This has in part contributed to the continuing dispute over synonymy. We 1) describe a new phoronid species from Japan, which differs from all the previously known species in adult morphology; 2) reconstruct the phylogeny of representative phoronids, including the new species, based on DNA sequences of the nuclear 18S and 28S rRNA genes (hereafter, 18S and 28S, respectively), and the mitochondrial cytochrome c oxidase subunit I gene (COI); 3) describe topotypes of P. ijimai from Misaki, Sagami Bay, and discuss the synonymy with P. vancouverensis in the context of adult morphology and the molecular phylogeny; and 4) provide a key to the Japanese phoronid species
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
