2021 Volume 26 Issue 1 Pages 101-110
Hirsutocrinus duplex, a new genus and new species of the Bathycrinidae, collected from Okinawa, Japan at a depth of 596–606 m, is described. The main diagnostic characters of the new genus are the presence of side plates in pinnules and of knobby processes on Brs 1–2. Knobby processes on secundibrachials are found for the first time. Monachocrinus A. H. Clark, 1913 shares side plates with Hirsutocrinus. It differs from the new genus in having knobby processes on IBrs 1, parallel ridges on the articular surface of knobby processes, proximal and distal arm pattern a b+c d+e f, saccules, in lacking knobby processes on IBrs 2 and Brs 1–2, pinnule on every second Br, x-shaped tube-feet plates, needle-like spines on external surface of IBrs and Brs. The cover and side plates are similar to each other in Monachocrinus, and quite different in Hirsutocrinus. Hirsutocrinus duplex is the shallowest species in the abyssal family Bathycrinidae usually known from 1100 to 9735 m. Other than H. duplex, only three among 25 nominal bathycrinid species are known from depths less than 1000 m.