The not-so-cosmopolitan bloodworm

The bloodworm, Marphysa sanguinea, originally described from the UK was once thought to be found around the world. New evidence reveals this is not the case, it has a much narrower distribution and there are many more species of bloodworm than previously thought. It is critical that worms are correctly identified using relevant literature for the region in question, and that specimens are ideally examined using both morphological and molecular techniques. It is important that specimens are deposited in a museum as vouchers and that all sequences lodged in GenBank have registered vouchers associated with them. These measured will ensure proper documentation of biodiversity and biogeography are correctly reported.

This large worm was described in 1813 (1815 volume) in Devon, UK, from intertidal rocky shores by the Reverend Montagu, who called it Marphysa sanguinea. 'Sanguinea' referring to the brightly coloured red branchiae all along its body, red because of the haemoglobin dissolved in the blood and hence the common name used by many – “the bloodworm”. He illustrated his description with a lovely painting which is, however, too basic to give any useful characteristics of this species, something not surprising given the knowledge of worms back in 1813. This probably explains why this species has been subsequently reported from around the world, without any consideration of the habitat in which it was collected. For example, M. sanguinea was reported from the seagrass beds in Moreton Bay, Queensland, where water temperatures are at least 10-15°C warmer than in Devon, UK where supposedly the same animals live in rock crevices. This should have set off alarm bells but no, not until recently. In Australia these worms are commercially harvested and highly prized as a fishing bait and a kilo of worms costs more than a kilo of best fillet steak!

It became apparent that we urgently needed to properly describe the species present in Devon both using a high powered scanning electron microscope to illustrate bristles on the worm’s body and to use molecular techniques to sequence the worm's DNA. We found that the distribution of the original species that is M. sanguinea is restricted to both sides of the English Channel. Nevertheless, the name M. sanguinea has been reported and is widespread in the ecological literature around the world. The animals are widely used in physiological experiments and even have been reported as eating polystyrene! Not surprisingly, DNA sequences on the international online molecular database, GenBank, labelled as M. sanguinea do not even belong to the genus Marphysa, let alone this species. With regards to the ecological literature, typically no reference specimens are deposited in an institution so it is impossible to determine what species was actually collected. Recently a Chinese student working in our lab and brought over a batch of worms from bait collectors in northern China, working together we were able to identify them as five undescribed species of Marphysa which we later described. Many records of M. sanguinea occur in the Chinese ecological literature and who knows whether any or all refer to those five newly described species.

Recently additional new species of the genus Marphysa have been recorded from the Philippines and Hong Kong and it is becoming apparent that each species has a very specific habitat, such as seagrass beds, muddy substrates or rocky substrates, so even within one location several species may co-occur. For example, in Moreton Bay we are aware that three species occur, only one of which is described, while we have recently collected the second one and will shortly describe it, the third species still remains elusive.

Our recent paper (Lavesque et al. 2019) highlights the importance of correct identification because each species has specific ecological and reproductive characteristics. One must use appropriate literature for the area to identify species and to check morphological characters carefully, we suggest that many more species still remain undescribed. It is therefore critical to deposit a reference collection to allow taxonomists to be able to confirm identifications. Finally, we suggest that all species of Marphysa have very restricted distributions, which is also true for many other so called "widespread species", especially in areas where there are no active polychaete researchers.

Dr Pat Hutchings, AMRI Senior Fellow

Dr Laetitia Gunton, Chadwick Biodiversity Fellow

Dr Elena Kupriyanova, Senior Research Scientist, AMRI

More Information

• Lavesque N., Daffe G., Grall J., Zanol J., Gouillieux B., Hutchings P. (2019). Guess who? On the importance of using appropriate name: case study of Marphysa sanguinea (Montagu, 1813). ZooKeys 2019 (859):1-15. DOI: 10.3897/zookeys.859.34117