Molecular species delimitation
The results for the whole dataset are as follows: i) the GMYC model identified a total of 24 entities (CI = 8-27), 12 of which are represented by singletons and 12 by clusters (CI = 2-13) (likelihood ratio test of the null against the mixed model: 5.4e-05, P < 0.001); ii) the PTP/bPTP method identified a total of 20 entities (CI = 16-25), and iii) the ABGD method, checked at the prior maximal distance (P = 0.001), identified 15 entities.
Regarding the M. lineata complex i) the GMYC model found five entities among the Mediterranean samples and six in the Atlantic; ii) the PTP/bPTP model found a total of seven entities, three from the Mediterranean and four from the Atlantic; iii) the ABGD method found four entities in the Mediterranean and one in the Atlantic, and iv) the K/θ method delimited three and two entities from the Mediterranean and Atlantic, respectively. For details on the species delimitation results, see Fig. 4( and S8, S9, S10, S11.
Fig. 4. Summary of the results obtained by all species delimitation methods applied. The first row refers to the six OTUs obtained in a previous paper (Casu and Curini-Galletti, 2004), here used as null hypothesis. For morphological and karyological datasets, colours and patterns inside the squares correspond to the clusters identified using Gaussian clustering to which specimens have been assigned, respectively. Only those individuals that have been successfully assigned to a cluster above the 95% probability threshold have been reported in the figure. Squares containing different colours or patterns correspond to populations in which individuals were successfully assigned to more than one cluster. Amount of colours or patterns is proportional to the number of individuals assigned to each cluster.