Molluscs are invertebrates that make up one of the most numerous groups in the animal kingdom. They are everywhere, from great heights of over 3,000m above sea level to ocean profundities of over 5,000m deep, in polar and tropical waters and they tend to be common elements on coastlines around the world. Within this animal group are found the nudibranchs, characterized among other things, for not having shells and being brightly coloured. This colouring alerts their predators to their toxicity. Within this group, in turn, we can find the Aeolidiidae family.
This family has been the centre of a study by the researcher from the University of Cádiz, Leila Carmona; a project which has been principally based on reviewing, from a molecular and morphological point of view, all of the known species that make it up. This group of invertebrates "is one of the biggest with regard to the number of genera that make it up and, although it has been known for a long time, not a lot is known about it", explains the researcher.
So, Doctor Carmona started a project whose primary objective was to draw up a list of the greatest possible number of these animals and in order to do this, together with one of her thesis directors, the UCA professor Juan Lucas Cervera, she requested material from museums, research institutes, universities, diving associations or any individual familiar with and residing in the areas where specific species of Aeolidiidae could be found. In this way, the University of Cadiz, gradually built up an important collection of these molluscs, 52 species, which were studied by Leila Carmona.
"Once we started acquiring the species, the molecular analysis began. For this, their DNA was extracted and a series of analyses known as "phylogenetic analyses" was carried out, the aim of which was to determine the degree of relatedness between species and genera. In this way, a list of results was gradually compiled and we could decide which genera were valid and which were not, in order to define the difference between genera and which characteristics determined each of them", in the words of the researcher. Of the 52 species studied, 18 of them were new, that is to say, "they were not previously known to science". Therefore, "at this moment I am drawing up descriptions of these newly discovered species".
Among the new species discovered by Leila Carmona there is one species, Anteaeolidiella indica, which has brought her many surprises. "A priori, it was a species that was supposedly spread throughout the world, and after molecular analysis it was observed to be not one species, but eight different ones. Of these, three are new and the ironic thing is that the species described initially and which corresponds to this denomination, does not appear, or at least, we have not managed to find it. With the data that we currently have, extracted from these species and with the original description dating from the 19th Century, we have not managed to find that animal. Therefore it would appear that we have been using an incorrect name since the 19th Century for eight different species and we do not know with precision which mollusc corresponds to the name we have been using", determines the doctor.
Another striking case is that of the Spurilla onubensis. "From the work carried out using modern Molecular Biology and Scanning Electron Microscope techniques, we realized that a series of examples of this found in Huelva corresponded to a species new to scientists, in spite of having been identified as Spurilla neapolitana for years".
All of this work is included in Leila Carmona's thesis, a study tutored by Doctor Juan Lucas Cervera; Doctor Marta Pola, of the Autonomous University of Madrid; and the prestigious researcher Terrence M. Gosliner, of the California Academy of Sciences of San Francisco (USA) and carried out within the investigative guidelines set out in the Campus of International Excellence of the Sea (CEI.Mar).