The days of gender confusion are over for Hydroides, a large and economically important genus of fouling calcareous tubeworms.

Hydroides, the largest genus of ship-fouling calcareous tubeworms, was given the name in resemblance to the Hydra, a serpent-like snake from the Greek mythology. The paper published in ZooKeys in January 2017 updates all 107 scientific names because of an overlooked change of naming rules that has reinstated the feminine nature of the genus.

Names of animal taxa have a set of rather sophisticated rules governed by the International Code of Zoological Nomenclature. One of such rules in zoological names is the requirement of gender agreement, a heritage of the Latin language that, unlike English, has genders. While generic names are nouns, specific names can be adjectives, meaning that the species name must change its ending according to the gender of the generic name with which it is combined… given that both names are either Latin or Latinized.

Hydroides is a very old name given to a large group of calcareous tubeworms because of supposed resemblance to the Hydra, a nine-headed serpent-like creature with a very unpleasant character. According to the story in Greek mythology, if one Hydra’s head is cut two more grow back, while the middle head breathes fire. Although the genus Hydroides is full of rather humble-looking little (slightly over 1 cm long) marine segmented worms, some of them can be important and troublesome members of fouling communities. The name Hydroides is also misleading because the worms have absolutely no connection to hydroids, the well-known group of colonial animals related to corals.

The paper in question was motivated by an incidental discovery by Geoffrey Read. He noticed that because of an obscure change in the wording of International Code of Zoological Nomenclature from 1 January 2000, the gender of genus Hydroides has reverted to the original feminine. This change was completely overlooked at that time, which in practice meant that starting from about 1992 we all were wrong in treating the gender of Hydroides as masculine!

As well as adjusting the spelling to be in accordance to the zoological code rules, we were also curious about how and why all the species received their names and exactly where in the world the species were discovered. Early taxonomists were often remarkably vague about such details as needed today, so some detective work was often required. Some Hydroides names have descriptive origins that fit how the worms look, such as 'elegantula' and 'longispinosa', others like 'trompi' and 'sanctaecrucis' are named after people and places, but a number of them are much trickier. It turns out that the Hydroides species 'dianthus' really was named after the garden flowers, the species 'euplaeana' and 'stoichadon' have the long forgotten names of tiny Mediterranean islands, and the species 'floridana' actually didn't come from Florida.

This paper provides an important service to taxonomists and ecologists using names in this well-known and species-rich ship-fouling genus and constitutes a step towards a world-wide revision of the group. The original descriptions of the worm species are accessible via the checklist because one third of the 128 total references cited in the checklist are linked to the open access Biodiversity Heritage Library, and only one quarter of citations could not be matched to an online source. Further information on the taxonomy of all Hydroides is available via 110 links to the World Register of Marine Species web pages and the type localities of all species are mapped.

Dr Elena Kupriyanova, Senior Research Scientist, AMRI
Dr Geoffrey Read, National Institute of Water and Atmospheric Research (NIWA), New Zealand

More information:

  • Read, G.B. ten Hove, H.A. Sun, Y., Kupriyanova, E. K. 2017. Hydroides Gunnerus, 1768 (Annelida: Serpulidae) is feminine: a nomenclatural checklist of updated names. Zookeys 642: 1–52
    doi: 10.3897/zookeys.642.10443