Pelagodoxa (Arecaceae, Arecoideae, Areceae) is a Pacific genus of uncertain geographic origin. Two species have been described. The type species, Pelagodoxa henryana, from the Marquesas Islands, has large fruits, 8.5 cm in diameter, while a species with smaller fruits (6 cm in diameter) was described as P. mesocarpa and later considered as a synonym of P. henryana. The smaller-fruited entity is known from the Melanesian archipelagos of the southwest Pacific, but the type of P. mesocarpa is of doubtful origin. No truly wild population of any Pelagodoxa is known either in the Marquesas or in the southwest Pacific. The structure and histology of the pericarp and seed of the two fruit morphs were investigated and proved to be similar, except for a color change after ripening in the mesocarp of the smaller fruit morph. Distinctive anatomical features of the fruit of Pelagodoxa include an outer layer of cork tissue, an expanded soft parenchymatous mesocarp lacking raphides and sclereids, numerous vascular bundles with thick fibrous sheaths running radially through the pericarp, conspicuous stegmata on the surface of bundle fibers, an endocarp consisting of a thickened locular epidermis, with conspicuous crystalline structures located at the distal end of each radially elongated cell, and an additional layer of sclerenchyma derived from the seed coat. These features suggest a possible relationship with Sommieria within the subtribe Iguanurinae, in which Pelagodoxa is currently included, but they are also reminiscent of the pericarp of Orania (Oraniinae). A distinct operculum on the endocarp, which characterizes most genera of Iguanurinae, is lacking in Pelagodoxa.
Communicating Editor: Kathleen A. Kron