Revision of the northeast Atlantic and Mediterranean Stylasteridae (Cnidaria: Hydrozoa). - Zibrowius, H. & S.D. Cairns (Mémoires du Museum national d'Histoire naturelle, Paris, série A, Zoolologie, 1992)
In the northeastern Atlantic, from the Cap Verde Islands to the Mid-Atlantic Ridge at 23 degree 31'N, the Azores, Iceland and northern Scandinavia, 19 species of stylasterids have been recognized, one of which is represented by 3 subspecies. Complementary records extend the study area to Greenland. In addition, 2 species are included from the islands of the Gulf of Guinea, equatorial eastern Atlantic. Of all these species and subspecies, 20 are fully described whereas 3 that are incompletely known, are not yet named. The new taxa are: Pliobothrus gracilis n. sp., Stylaster maroccanus n. sp., S. ibericus n. sp., S. erubescens groenlandicus n. ssp., S. erubescens britannicus n. spp., S. erubescens meteorensis n. ssp., Crypthelia medioatlantica n. sp., and C. vascomarquesi n. sp. Compared with the scleractinian corals present in the same areas, most of the studied stylasterid species appear to have a rather narrow geographical range. Only 3 of the 21 species (15%) recorded from the northeastern and equatorial eastern Atlantic are known in the western Atlantic. Although covering a much wider area, the northeastern Atlantic stylasterid fauna is considerably less diversified than its West Indian counterpart, which comprises about twice as many species in 8 genera. Among the northeastern Atlantic regional faunas, that of the Azores is the richest, with 9 deep-water species. Only one species (Errina aspera) occurs in the southwestern Mediterranean. Although present in the islands of the Gulf of Guinea, shallow-water stylasterids are missing in the northeastern Atlantic and Mediterranean where the shallowest records are from about 100 m. A few records exceed depths of 2000 m. In the study area various symbionts leave characteristic traces on the stylasterid skeleton or cause modifications: the gastropod genus Pedicularia (on 8 species) and polynoid and eunicid polychaetes (each on one species). The reliable record of fossil stylasterids is scarce in Europe and the Mediterranean basin (as it is elsewhere). It ranges from the Lower Paleocene to the Plio-Pleistocene whereas Pedicularia, an obligate symbiont of stylasterids, is known from the Messinian (Upper Miocene) and from the Lower Pleistocene.Descriptors: PLIOBOTHRUS GRACILIS new species; STYLASTER MAROCCANUS new species; STYLASTER IBERICUS new species; STYLASTER ERUBESCENS GROENLANDICUS new subspecies; STYLASTER ERUBESCENS BRITANNICUS new subspecies; STYLASTER ERUBESCENS METEORENSIS new subspecies; CRYPTHELIA MEDIOATLANTICA new species; CRYPTHELIA VASCOMARQUESI new species; ERRINA ASPERA; PEDICULARIAfigs 1-42. (French summary). (20.iii.1992).mediterraneo