A new deep-sea cumacean species (Crustacea: Peracarida) from Argentina, and the taxonomic status of platytyphlops orbicularis (Calman, 1905)

Abstract

Calman (1905) described the cumacean Platyaspis orbicularis (currently in the genus Platytyphlops) based on an immature specimen collected on West Ireland at 699 m depth, which lacks the abdomen and most of the thoracic segments. A few years later, Calman (1912) reported four specimens of P. orbicularis from the east coast of USA (613-1015 m) and published a full description of the female. Lastly, this species was cited from Faroe Islands (810 m) and Biscay Bay (470-1739 m). Herein, a new species of Platytyphlops is reported from off the coast of Buenos Aires Province at 1011-1712 m depth, based on material collected by the Atlantis II 60 survey (1971) and the Talud I Argentine expedition (2012). Specimens of P. orbicularis from off the coast of Ireland and Biscay Bay were also examined. The new species reported here differs from the specimens from Ireland/Biscay Bay (characters between parentheses) as follows: (1) carapace without submedian carinae (with submedian carinae); (2) pereopod 5 as long as pereonite 5 in adults (much shorter than pereonite 5); (3) antennule main flagellum with 5-6 articles plus a minute distal one in adult males (with 4 articles plus a minute distal one); (4) adult total length ~17 mm (~10 mm). In addition, the specimens from Argentina herein reported correspond quite well with Calman's 1912 description. This fact suggests that the specimens reported by Calman from USA probably do not belong to P. orbicularis.