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Notes
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This species can be recognized by its obovate to broadly elliptic, rather thin-textured leaves that are glabrous adaxially; its hirtellous, bilobed, caducous stipules that expose a fringe of persistent ferrugineous colleters when they fall; its corymbiform, pedunculate, terminal inflorescences wtih the flowers shortly pedicellate; short calyx limb; short yellow corolla; and distinctive subglobose to rather didymous fruits that are borne on red pedicels, which become markedly thickened and longer, up to 15 mm, as the fruits mature. The fruits apparently are white when young and then become black. This species is deciduous with the flowers apparently flushing with the leaves, and the leaves and petioles then enlarge markedly and the leaf blades change from rather elliptic to obovate as flowering proceeds (e.g., De Block et al. 1220). This species has been documented frequently from limestone substrates, including tsingy. The color and form of the mature fruits of Psychotria rubropedicellata is characteristic of Chassalia, however the pubescent stipules with the lobes closely set and the persistent fringe of colleters the stipules leave behind on the stem when they fall indicate that this species belongs to Psychotria. This species is similar to several species of Apomuria, in habit and range as well as general aspect, but the thickened, enlongated, red fruiting pedicels and black fruits are not reported in Apomuria (though perhaps found in some species such as Apomuria perrieri) or otherwise in Psychotria in Madagascar. This species was originally described based on one fruiting specimen from Namoroka in Mahajanga, which has generally narrower leaves than the other material included in the circumscription of Psychotria rubropedicellata here, which is all from Antsiranana. However the variation in leaf size and shape between the type and the other specimens is not discontinuous, and the other specimens are all from the same substrate and share the distinctive combination of stipule and fruit form. Possibly there are two species included here but the material available, in particular the type material, is not yet adequate to resolve this.
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