Monographs Details: Psychotria iodotricha Müll.Arg. subsp. iodotricha
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Discussion:

Psychotria iodotricha M.-Arg., Mart. Fl. Bras. 6(5): 375. 1881.

I am taking as lectotype the specimen of Spruce 3274 at K, which is the first one cited by Müller-Argoviensis. The Spruce 3397 specimen, from the Pacimoni, is similar to the Spruce 3274 lectotype, except that the stems are not as densely hirsute. It is curious that, despite numerous collections of other botanists in the Territory Federal Amazonas of Venezuela, only one collection of P. iodotricha subsp iodotricha has been collected since Spruce’s time in the Amazonas of Venezuela. All the other specimens recorded from Venezuela come from the eastern part of the Guayana of Venezuela and from British and French Guiana.

The Spruce 3274 type represents the variation with small heads (in anthesis) having five flowers, according to Müller-Argoviensis. Although the number of pairs of lateral nerves is given in the type description as “circ. 10,” there may be 11-12, as counted on the type specimen at K. The type specimen has dense spreading to subdeflexed hairs up to 1-2 mm long. On the upper leaf surface the hairs are abundant, about 1 mm long, substrumose or tuberculate at the base, and are found conspicuously along the margins, which are ciliate with hairs reaching 1.5 mm in length. The lower leaf surface is similarly pubescent with the hairs about 1 mm long, but those on the lower midrib and lateral nerves are longer, attaining 1.5-2 mm long, and spreading.

Psychotria iodotricha, in its typical form, has small sessile heads 6-10 mm long (high) by 4-12 mm broad, containing relatively few (4-9) flowers. The outer involucral bract is generally deeply lobate with 6-9 broader segments and shorter and narrower intermediate and lateral lobes. Generally two-four entire narrow, linear-lanceolate, inner bracts, free to their base are present, about equal in length the lobed outer bract.

In placing this species in the Series D. Schizolobariae of Sect. 11. Tapogomea, and noting that it is “Analogae Trichocephaelis sectionis Cephaelis,” Müller-Argoviensis (Mart. Fl. Bras. 6(5): 375. 1881) unnecessarily established an unnatural division between taxa, such as P. iodotricha and the group pertaining to his Trichocephaleae of section Cephaelis, which included species closely related to P. iodotricha, not only in general aspect and habit, but in details of involucre and flowers. Müller-Argoviensis split Psychotria into twelve sections, Cephaelis and Tapogomea being separated by him on the basis of the degree of union of the involucral bracts, namely, in section Cephaelis the bracts are free at the base or only shortly connate, whereas in Tapogomea the bracts are united into a tube or unit which is either entire or 2-4-fid or lobed. Since P. iodotricha has the bract united for at least 4-6 mm, it was placed by Müller-Argoviensis in Tapogomea, but in a special series, Schizolobarieae, based on its many-lobed involucre to differentiate it from other species of the Tapogomea having two-lobed or four-fid involucres.

As is evident from an examination and study of related species, entirely too much intergradation in the degree and extent of fusion or union of the involucral bracts exists to maintain Tapogomea as a section distinct from Cephaelis, or to isolate within Tapogomea a species, such as P. iodotricha, as separate from various other species within Cephaelis.

Considerable variation exists within P. iodotricha, for which the following variations have been recognized.