The presence of Hacelia attenuata at Berlengas, extends its known northern geographical range in the Atlantic, with literature referring the Azores Islands as its previous northernmost limit (Hansson 1999; Wirtz and Debelius 2003). Rueda et al. (2011) also reported its presence in the Gulf of Cadiz (Spain), although this is an area strongly influenced by the Mediterranean ecosystem (Coll et al. 2014), where it is known to be common (Wirtz and Debelius 2003).
Hacelia attenuata presents a similar reddish coloration and reaches approximately the same diameter as the red seastar Echinaster sepositus but also the purple seastar Ophidiaster ophidianus (Lamarck, 1816) and Hacelia superba H.L. Clark, 1921 which led to some misidentifications in the past (Nobre 1938; Rueda et al.
2011), and may raise doubts on its real distribution.
Unlike Ophidiaster ophidianus and Hacelia superba, which do not occur in this area, the red seastar E. sepositus is relatively common in Berlengas (Rodrigues et al.
2008) - occurs from Roscoff (France) to Ghana, including island groups except Azores and also in the Mediterranean (Wirtz and Debelius 2003) - and one specimen was also found when these underwater records were made. Both species were photographed side by side and differences are notorious (Fig. 1). The coloration of H. attenuata is more yellowish than E. sepositus and, although is not very clear in the photo, the aboral pattern and texture is distinctively different. The presence of H. attenuata in Berlengas represents also the first record of a species of the Ophidiasteridae family for the region.
The Berlengas archipelago is located at the top of the escarpment of the Nazaré Canyon, an important submarine canyon in the transition zone between the Mediterranean and European subregions (Mendes et al. 2011). It is influenced by coastal upwelling (Álvarez-Salgado et al.
2003; Peliz et al.
2002) and characterized by a remarkable productivity and diversity of marine species and habitats (Rodrigues et al.
2008). These factors may lead to the settlement of non-local species that reach the area and manage to thrive (e.g. larvae driven by oceanic currents, ballast waters). Rodrigues (2012) reported various new species records for the area, most of which new northernmost records. Global warming is one possible reason for driving tropical and sub-tropical species to migrate to regions where previous climate was not warm enough (Afonso et al.
2013). However, the same author, recorded new southernmost limits for other species in the same study area, suggesting that this may also reflect the reduced number of underwater surveys when compared to other places worldwide. Surveys from the Mediterranean to Berlengas area would help clarifying the presence of this species in latitudes where it was not known to occur until now.