Who is not Goniodoridella savignyi Pruvot-Fol, 1933? The challenge of Indo-Pacific Goniodoridella species complex (Nudibranchia, Goniodoridida)

Paz-Sedano S., Gosliner T.M., Pola M.

sofia.paz@uam.es

Goniodoridella Pruvot-Fol, 1933 is a small genus belonging to the family Goniodorididae. The genus was erected from specimens collected in the Red Sea, describing the species Goniodoridella savignyi. Since its original description, this species has been found throughout the Indo-Pacific Ocean. In 2015, Martynov, Sanamyan & Korshunova described the species Goniodoridella borealis. The authors claimed that G. savingyi could include different cryptic species and, in fact, G. borealis was previously confused with G. savingyi. Thus, the specimens identified as G. savingyi reported from the Sea of Japan are Goniodoridella borealis.

In order to study the biodiversity of the genus Goniodoridella and investigate possible cryptic species, specimens collected from Philippines, Australia and Papua New Guinea were studied. Partial gene sequences of Cytochrome Oxidase c subunit I, 16S ribosomal RNA and Histone H3 were included for six specimens. Bayesian Inference and Maximum Likelihood phylogenetic analyses were performed. Moreover, the external morphology of the specimens was studied using photographs of live animals and laboratory observations. The internal anatomy of some specimens was studied by dissections. Photographs of the radulae were taken under the Scanning Electron Microscope.

Specimens were initially identified as Goniodoriella cf. savignyi based on the coloration and external morphology. However, the molecular results differentiate at least four different species. The results obtained shows that i) the lack of information in the original description of the species, ii) the lack of specimens collected from the Red Sea and, iii) the great similarity between the specimens studied, makes Goniodoridella savignyi a species difficult to determine.