Corallimorphus niwa new species (Cnidaria: Anthozoa), New Zealand members of Corallimorphus, and redefinition of Corallimorphidae and its members

The new species of anthozoan Corallimorphus niwa occurs at depths of 926–1773 m in seas around New Zealand. This new species shares with other members of Corallimorphus stiff and hyaline mesoglea, short column relative to its broad oral disc, and deep-sea habitat. It differs from other members of Corallimorphus in having an equal number of marginal and discal tentacles, the discal tentacles arrayed in multiple circlets. Groups of Corallimorphus are defined by tentacle array; C. niwa n. sp. characterizes the new niwa group. Two of the other five valid species of Corallimorphus (C. profundus and C. pilatus) constitute the profundus group, members of which have about four times as many marginal as discal tentacles, the discal tentacles arrayed in a single circlet; the three members of the rigidus group (C. rigidus, C. denhartogi, and C. ingens) have about twice as many marginal as discal tentacles, the discal tentacles arrayed in multiple circlets. The definition of genus Corallimorphus must be modified to accommodate this species; this also involves synonymizing with one another the other two genera of family Corallimorphidae, Corynactis and Pseudocorynactis. The formal definitions of order Corallimorpharia and family Corallimorphidae are adjusted to be in parallel and hierarchical format