A new species of horseshoe worm discovered in Japan after a 62 year gap

April 4, 2014
This is Phoronis emigi, preserved in formalin. Credit: Dr. Masato Hirose

The horseshoe worm is a worm-like marine invertebrate inhabiting both hard and soft substrates such as rock, bivalve shells, and sandy bottom. The name "horseshoe" refers to the U-shaped crown of tentacles which is called "lophophore." Horseshoe worms comprise a small phylum Phoronida, which contains only ten species decorating the bottom of the oceans.

The new species Phoronis emigi, the eleventh member of the group described in the open access journal ZooKeys, comes after a long 62 year gap of new discoveries in the phylum. It is unique in the number and arrangement of body-wall muscle bundles and the position of the nephridia which is the excretory organ of some invertebrates. The new species is morphologically similar to sand-dwelling species Phoronis psammophila and it is also closely related to Phoronis hippocrepia, which inhabits hard substrate.

The morphology of the topotypes for Phoronis ijimai is also described in this study after 117 years since its original description. The combination of a detailed observation of the internal morphologies and the molecular phylogenetic analyses including the topotypes ensure a synonymy between P. ijimai and the northeastern pacific species Phoronis vancouverensis that has long been disputed.

This is a living Phoronis ijimai, extending its lophophore. Credit: Dr. Masato Hirose.

"It is necessary to use both internal anatomy and molecular data for reveal the global diversity of horseshoe worm. The known phoronid diversity still remains low, with all specimens reported from limited habitats and the localities by the limited reports. Investigations at new localities or habitats may yield additional in the future", explains Dr Masato Hirose, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan.

Explore further: Climate change affects horseshoe crab numbers

More information: Hirose M, Fukiage R, Katoh T, Kajihara H (2014) Description and molecular phylogeny of a new species of Phoronis (Phoronida) from Japan, with a redescription of topotypes of P. ijimai Oka, 1897. ZooKeys 398: 1. DOI: 10.3897/zookeys.398.5176

Related Stories

Climate change affects horseshoe crab numbers

October 4, 2010

Having survived for more than 400 million years, the horseshoe crab is now under threat – primarily due to overharvest and habitat destruction. However, climatic changes may also play a role. Researchers from the University ...

Horseshoe crabs are one of nature's great survivors

January 24, 2012

It may look like something out of a science fiction movie, but the horseshoe crab is definitely real. In fact it is one of nature’s great survivors, lasting through 3 of the Earth’s major extinction events.

Evolution is not a one-way road towards complexity

October 18, 2013

There are still a lot of unanswered questions about mollusks, e.g. snails, slugs and mussels. The research group of Andreas Wanninger, Head of the Department of Integrative Zoology of the University of Vienna, took a detailed ...

Recommended for you

Study suggests fish can experience 'emotional fever'

November 25, 2015

(Phys.org)—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

New gene map reveals cancer's Achilles heel

November 25, 2015

Scientists have mapped out the genes that keep our cells alive, creating a long-awaited foothold for understanding how our genome works and which genes are crucial in disease like cancer.

Insect DNA extracted, sequenced from black widow spider web

November 25, 2015

Scientists extracted DNA from spider webs to identify the web's spider architect and the prey that crossed it, according to this proof-of-concept study published November 25, 2015 in the open-access journal PLOS ONE by Charles ...

How cells in the developing ear 'practice' hearing

November 25, 2015

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.