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

Plastic in 99 percent of seabirds by 2050

August 31, 2015

Researchers from CSIRO and Imperial College London have assessed how widespread the threat of plastic is for the world's seabirds, including albatrosses, shearwaters and penguins, and found the majority of seabird species ...

Researchers unveil DNA-guided 3-D printing of human tissue

August 31, 2015

A UCSF-led team has developed a technique to build tiny models of human tissues, called organoids, more precisely than ever before using a process that turns human cells into a biological equivalent of LEGO bricks. These ...

Study shows female frogs susceptible to 'decoy effect'

August 28, 2015

(Phys.org)—A pair of researchers has found that female túngaras, frogs that live in parts of Mexico and Central and South America, appear to be susceptible to the "decoy effect." In their paper published in the journal ...

0 comments

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.