They discover a new species of hermit crabs

From morphological and DNA analysis, it was discovered that there are at least three different species of hermit crab of the genus Diogenes, one of which is new, previously considered one species.

The research was conducted by an international team that includes scientists from the Supreme Council for Scientific Research (CSIC) in Spain.

This discovery was made possible thanks to the study of samples from the coasts of Andalusia in Spain.

With this new species, the number of hermit crabs found in the waters of the Iberian Peninsula increases to 46, and since the study is still ongoing, more descriptions of the new species are expected based on preliminary data from other samples.

This discovery is part of a broader study of hermit crabs in the Iberian Peninsula, and is part of the doctoral thesis of Bruno Almon, first author of the work, from the CSIC Vigo Oceanographic Center (IEO) attached to the CSIC; Together with José Antonio Cuesta, of CSIC’s Institute of Marine Sciences (ICMAN) of Andalusia, and in collaboration with researchers from the University of Malaga in Spain and the University of Regensburg in Germany.

Morphological and DNA studies of several specimens previously considered to belong to the species Diogenes pugilator, revealed the presence of at least three different species listed under the same name. Jose Antonio Cuesta of the research team notes that “the role of molecular techniques has been fundamental to the discovery of new species, and to the confirmation of validity and relationship between other species of the genus.” As a result of this study, it was possible to clarify the true identity of the Diogenes pugilator species, re-describe their morphology, and thus avoid future confusion.

A specimen of Diogenes curvimanus. (Photo: Bruno Almon)

One of the forms previously included under the same name turned out to be the new species of the flag, described as Diogenes armatus, in reference to the spines that appear in the forceps. A third species corresponds to one previously described in 1874 by Clément, Diogenes curvimanus, considered in his day to be the same as D. pugilator, and which is re-described in this work and considered a valid species. Bruno Almon explains that “detailed study of the morphology of the molecularly selected samples, as well as their in vivo staining, resulted in a set of characters that facilitate the distinction between the three species.” The combined use of morphology and DNA made it possible not only to discover a new species, but also to be able to validate another that in its day was considered, based only on morphology, to be equal to the existing species, which in taxonomy is called a synonym.

The three species described in this work live in shallow waters, indicating a preference for soft sandy bottoms with empty shells available to occupy and replacing older ones as animals grow. According to the data available so far, at least two of them used to bury themselves in the sand and remain camouflaged, a behavior that has not been documented so far. The three species have distribution ranges that overlap at some points such as the Andalusian coast, however Diogenes pugilator of Mediterranean convergence and Diogenes curvimanus typical of Atlantic. In the case of the new species Diogenes armatus, it is known so far only from specimens mainly coming from the Cádiz region and southern Portugal, with isolated records in different regions of the Mediterranean such as Corsica and the Tunisian coast.

El estudio se titula “Re-description of the hermit crab Diogenes pugilator (Decapoda: Anomura) reveals a group of species in the Atlantic-Mediterranean transition, leading to the revival of D. curvimanus and the description of a new species.” Y se ha publicado en la revista académica Zoological Journal of the Linnean Society.

This line of research for Iberian hermit crabs is ongoing, and it is expected that there will be more descriptions of new types of primary data from other specimens. (Source: CSIC Andalucía)