Variability among Mediterranean populations of Sabella pavonina (Annelida: Sabellidae)

Sabella pavonina Savigny, 1920 is a species common to sheltered areas of northwest Europe and reported also in several Mediterranean sites. However, most Mediterranean records refer to faunistic lists with only few papers reporting morphological descriptions supported by drawings or photographs, most of which are short and out-dated. Moreover, no analysis of intraspecific variations among Mediterranean populations is available. In the present paper we provide the descriptions of individuals identified as S. pavonina belonging to four different Mediterranean populations and deposited at the Laboratory of Zoology of the Salento University. We analyzed the species morphological variation within the Mediterranean area compared to the deposited neotype and some other specimens collected from the type locality (Plymouth) and from Portsmouth (English Channel). The examined specimens from the four Mediterranean localities all differ from the English Channel Plymouth specimens with respect to a higher crown/body length ratio and smaller body size. Among them, individuals from Taranto and Gela resemble the morphology of the neotype specimens from Plymouth more closely than the others, with only a few differences, mostly involving the branchial crown features. Statistical analysis shows the occurrence of two different groups, one formed by specimens collected in sites located at deeper depths (100–130 m), separated by another containing specimens collected at shallower depths (5–10 m). Based on these considerations, it could be hypothesized that the specimens collected from greater depths do not actually belong to the S. pavonina species. However, the poor condition of the material does not yet allow the establishment of a new taxon. Only the examination of additional material coupled with further data including genetic analysis, will clarify the status of the taxon S. pavonina within the Mediterranean area.