Appunia morindoides Delprete, C. M. Taylor & T. McDowell, comb. nov.

Appunia morindoides (A. Rich.) Delprete, C.M. Taylor & T. McDowell, comb. nov. (Fig. 3).

≡ Ronabea morindoides A. Rich. in DC., Prodr. 4: 504. 1830. ≡ Psychotria morindoides (A. Rich.) Lemée, Fl. Guyane Franç. 3: 564. 1954 [nom. illeg., non Hutch. 1916].

Lectotypus (designated here): FRENCH GUIANA: sine loco, s.d. [1781–1785], L.C.M. Richard s.n. (P [P00837122, excl. the small branch at the top of the sheet] image!) (Fig. 1, branches labeled B and C).

= Patabea tenuiflora DC., Prodr. 4: 538. 1830. ≡ Cephaelis tenuiflora (DC.) D. Dietr., Syn. Pl. 1: 774. 1839. ≡ Ixora tenuiflora (DC.) Lemée, Fl. Guyane Franç. 3: 536. 1954 [non Appunia tenuiflora (Benth.) Jacks. & Hook. f. 1893], syn. nov. Holotypus: FRENCH GUIANA: “ Cayenne ”, IX.1785, Patris s.n. (G-DC [G00667064]!) (Fig. 2).

= Bellynkxia brachycalyx Bremek. in Recueil Trav. Bot. Néerl. 31: 277. 1934. ≡ Appunia brachycalyx (Bremek.) Steyerm. in Mem. New York Bot. Gard. 17: 359. 1967. ≡ Morinda brachycalyx (Bremek.) Steyerm. in Mem. New York Bot. Gard. 23: 385. 1972, syn. nov. Holotypus: SURINAME: Emma Range, 15.III.1922, Gonggrijp & Stael 5679 (U [U0006082]!).

= Bellynkxia surinamensis Bremek. in Rec. Trav. Bot. Neerl. 31: 276. 1934. ≡ Appunia surinamensis (Bremek.) Steyerm. in Mem. New York Bot. Gard. 17: 359. 1967. ≡ Morinda surinamensis (Bremek.) Steyerm. in Mem. New York Bot. Gard. 23: 386. 1972, syn. nov. Holotypus: SURINAME: Para, II–IV.1844, Kappler 1453 (U [U0006085]!; iso-: MO-124295!, P [P04579957]!, S-S05-1569!).

Habitat and Distribution. – This species is mostly found in the Guianas, northeastern South America, in primary and secondary moist forests, on lateritic and brown sand soils, at 50–700 m elevation. It is also known by a few collections in Amazonian Brazil, in the states of Amapá, Pará, Mato Grosso, and Acre.

Notes. – A full description, habitat, and range of this species will be presented in the forthcoming Appunia treatment (McDowell, in prep.) of the Flora of the Guianas Rubiaceae (Delprete et al., in prep.). Selected additional information about Ronabea and Appunia is available in the RUBIACEAE PROJECT (2020).

Appunia morindoides is recognized by its inflorescences that are leaf-opposed, which develop on distal nodes with one opposed leaf, or with three leaves forming a false whorl due to the extremely reduced final internode (Fig. 3A). The inflorescences may also appear to be axillary (Fig. 3A), due to reiteration of the corresponding axillary branch of the same node, and are often present at alternate nodes, resulting in branches with 2–6(–10) peduncles present at the distal nodes. Each peduncle bears a head of (2–)5–9(–12) flowers, and may have one (occasionally two) sessile or subsessile flower at the base (Fig. 3C–D). Sessile flowers at the base of the peduncle may also rarely occur in A. tenuiflora (Benth.) Jacks. & Hook. f. and other Appunia species occurring in the Guianas.

The stipules of Appunia morindoides are 2 –7(– 10) mm long, usually longer than in most other species of the genus, puberulent, and entire (Fig. 3B) or bifid at apex. Its leaf blades are often relatively large, (5–)10–15(–30) × (1.5–)3–7(–10) cm, and membranaceous to chartaceous (Fig. 3A), while blades are usually smaller, and papyraceous to subcoriaceous in most other species of the genus. Appunia morindoides is similar to A. calycina (Benth.) Sandwith, but the latter can easily be differentiated by its conspicuously larger calyx, which is funnelform to broadly cupular with the free portion of the tube 3–6 mm long and the 5 rounded lobes about 2 mm long; also its calyx is pubescent outside with sparse, stiff hairs (vs. a very short calyx tube, 0.2 mm long that is entire or sometimes denticulate and minutely puberulent or glabrous outside in A. morindoides). In A. calycina the funnelform calyx continues to expand after anthesis and forms a conspicuous crown above the fruit, which is lacking in A. morindoides.