The genus Hybocodon (Cnidaria, Hydrozoa) in the southwestern Atlantic Ocean, with a revision of the species recorded from the area

Abstract

The genus Hybocodon includes seven species, two of which (H. prolifer and H. unicus) have been recorded in the southwestern Atlantic. These reports were based on the medusa stage and only a few diagnostic characters were described, rendering some of these records rather doubtful. Additionally, H. prolifer has a boreal distribution, suggesting that the reports of this species from the southern hemisphere could correspond to other Hybocodon species. Recently, we sampled benthic and planktonic specimens of Hybocodon in the southwestern Atlantic and two species were identified: polyps and medusae of Hybocodon chilensis Hartlaub, 1905, and medusae of Hybocodon unicus (Browne, 1902). These samples allowed us to review and discuss the geographical distribution and validity of previous records of Hybocodon species for this area. We conclude that H. chilensis and H. unicus are the only Hybocodon species presently known for the southwestern Atlantic Ocean.