THE NEW GENUS AND SPECIES OSSIELLA-PACIFICA (GRIFFITHSIEAE, RHODOPHYTA) FROM HAWAII AND NORFOLK-ISLAND, PACIFIC-OCEAN

Ossiella pacifica gen. et sp. nov, is described from subtidal habitats (5-19 m) in the central (Hawaiian Islands) and southwestern (Norfolk Island) Pacific Ocean. Plants consist of limited prostrate axes that r apidly become erect and form ecorticate, subdichotomously branched axe s bearing up to seven (mostly six) di-/to trichotomously branched, pig mented, determinate, quickly caducous whorled laterals from subapical axial cells. Two to five tetrasporangia are borne directly on the infl ated basal cells of pigmented determinate laterals. One to two spermat angial fascicles are similarly placed in male plants. Subapical procar ps are borne on a three-celled fertile axis, which occupies the same p osition as an indeterminate branch, being itself displaced laterally b y the continued growth of the indeterminate axis. Procarps are bicarpo gonial, the sterile cell normally associated with the supporting cell in procarps of the Griffith-sieae being converted into a functional fo ur-celled carpogonial branch. Ossiella is compared with the other memb ers of the tribe, and a dichotomous key to the genera is offered. On m orphological grounds, Ossiella seemingly forms a perfect intermediary link along the phylogenetic lineage between the eastern Australian gen us Baldockia A. Millar, the eastern American genus Calliclavula C. W. Schneid, and the widespread Anotrichium Nageli.