Tapogomea purpurea Aubl., Pl. Guian. 1: 162. pl. 62, fig 3. 1775.
Gamotopea purpurea (Aubl.) Brem., Rec. Trav. Bot. Néerl. 31: 294. 1934.
Callicocca purpurea (Aubl.) Gmel., Syst. Nat. 1: 371. 1791.
Cephaelis purpurea (Aubl.) Willd., Sp. PI. 1: 978. 1798, not Psychotria purpurea Merrill & Perry, Jour. Arnold Arb. 27: 195. 1946.
Uragoga purpurea (Aubl.) O. Kuntze, Rev. Gen. 2: 962. 1891.
Cephaelis surinamensis Standl., Field Mus. Publ. Bot. 4: 335. 1929, not Psychotria surinamensis Brem. 1934.
Gamotopea surinamensis (Standl.) Brem., Rec. Trav. Bot. Néerl. 31: 294. 1934.
The flowering heads of this species are subtended by two larger outermost bracts which surround from 17-28 smaller interior bracts. Eight to seventeen flowers are found within a head. Some of them are subtended on all sides by three bracts or with two bracteoles of equal size and one larger bract or sometimes (Silva 1697) three bracts surround two flowers.
Bremekamp, in restricting his concept of Gamotopea purpurea to plants having “leaves purple beneath, on the upper side usually with a broad gray median band” (Rubiaceae, in Pulle, Fl. Surin. 4,1: 240. 1934), failed to note that the same species varies in the color of the upper surface and that the median gray stripe on the upper surface is by no means constant, nor is the purple color beneath always to be found.
The color of the upper and lower leaf surfaces varies from plain green above and below (Steyermark 59230) to green above with gray stripe in centre and purple below (Steyermark 75223) to silvery-striped above down center with lavender midrib and lavender below (Steyermark 59234). Other collections, likewise indicate a variation on the upper and/or lower surfaces. A. S. Hitchcock 17448 states that the collection is “a variety without the white stripe along the midrib,” Sandwith 8 states “leaves often variegated,” Breteler 4781 mentions “leaves . . . medium green above, paler beneath,” and Steyermark 57950 states “leaves dark green above, gray green below.” Thus, the lack of purple color on the lower side of the leaves is not an unusual condition, nor is the lack of a gray-silvery stripe above.
Standley described Cephaelis surinamensis as having the leaves “subtus ut videtur purpurascens” (Field Mus. Publ. Bot. 4: 335. 1929), but Bremekamp ignores this part of Standley's description, because he places Cephaelis surinamensis in his key to Gamotopea (in Pulle, Fl. Surin. 4(1): 240. 1934) along with those species (Gamotopea alba and G. callithrix) in which the leaves are not purple. The specimen of Samuels 524 from Suriname, referred by Standley to Cephaelis surinamensis, has broadly ovate leaves 1.8-2.5 cm wide, rounded to subcordate at base, and subacute to subobtuse at apex, and is readily matched by collections with similar leaf size and shape, such as Krukoff 7153, Cardona 476, Killip 37393, Silva 1697, and Halle 756. The peduncle length of 15 mm of Cephaelis surinamensis is at the extreme of peduncle length, since the usual range of variation of the peduncle in Psychotria variegata is 4-13.5 mm. Also, the stipular teeth in Psychotria variegata usually vary from 4-5 mm long, whereas those of Cephaelis surinamensis are 2.5-3 mm. However, in other details, the two taxa cannot be separated.
Since both Psychotria purpurea and P. surinamensis already exist as validly published names, it has been necessary to furnish the present taxon with a new name when brought into Psychotria.