Dipterocladia arabiensis sp. nov. (Dasyaceae, Rhodophyta) from the Sultanate of Oman

Dipterocladia arabiensis sp. nov. is described on the basis of specimens collected from the Dhofar and Al Wusta regions of southern Oman. Observations are made on cystocarpic and tetrasporangiate specimens occurring from the shallow sublittoral to a depth of 17m. The new species differs from the two previously known species of Dipterocladia by themuchmore robust size of the thalli, the higher order of branching, and the relatively smaller sizes of both the pseudolaterals and the tetrasporangia. In the new species all of the polysiphonous sympodial axes are indeterminate, unlike D. pulchella, in which there is a distinction between determinate and indeterminate sympodial axes, whereasD. pinnatifolia is intermediate with respect to this feature. Prior collections of this alga from Oman have been cited as ‘Rhodoptilum plumosum ?’.