Monographs Details: Psychotria mapourioides var. opaca (Bremek.) Steyerm.
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Rubiaceae
Description:Distribution and Ecology - Distribution. Guianas. FRENCH GUIANA. 1838, Le Prieur s n; 1840, Le Prieur s n; Maroni, 1864, Melinon s n; 1863, Melinon s n; Barbier s n; 1862, Melinon 345, 371, 404, 438, 480; Maroni, 1876, Melinon 64; Cayenne, Martin 94; Martin s n; Leschenault 292; 1877, Melinon 431; 1863, Melinon s n. SURINAME. Nassau Mountains, Marowijne River, Plateau B, Line 25 north of Expedition Line, alt 525 m, 3 Mar 1955, Maguire 40738; Kayser airstrip aan de Zuid Rivier, 56° 30' W, 3° 12' N, 22 Feb 1961, Kramer & Hekking 2985; Brownsberg, 3 Apr 1925, Bot. Mus. 6805; on bauxite, Adjoema Kondre Hill no. 1, trail to Adjoema Kondre village, vicinity of Moengo, Cottica River, 27 Dec 1954, Cowan 39010; Bosch Reserve (forest reserve) Seihe 0, 24 Feb 1916, Bot. Mus. 1641; Coppename River near Raleigh Falls, 16 Sep 1933, Lanjouw 848; Nassau Mountains, Marowijne River, on laterite-ferrite, Plateau A, Line 12, alt 525 m, 28 Feb 1955, Maguire 40712; in montibus Nassau, Km 12.9, 23 Mar 1949, Lanjouw & Lindeman 2874. BRITISH GUIANA. Schomburgk 823; Mazaruni Station, 20 Mar 1943, Fanshawe 1235; upper Rupununi River, near Dadanawa, lat 2° 45' N, 31 May 1922, De la Cruz 1423.

Discussion:

Mapouria opaca Brem., Rec. Trav. Bot. Neerl. 31: 289. 1934.

Type (Syntype). Sectie 0, Suriname, 19 Aug 1918, Bot. Mus. 3971; Sectie 0, Suriname, 8 Nov 1915, Bot. Mus. 1369.

In this taxon the leaves tend to be narrower and relatively more elongated with an oblanceolate to lance-elliptic shape up to nearly four times as long as broad, and usually few-nerved (6-8 each side) with the nerves slender and only slightly elevated or impressed. But, while the corolla is usually rather densely puberulent (furfuraceous-tomentellose) externally, it may vary to only papillate or sparsely puberulent (De la Cruz 2137 from British Guiana), but even on the same specimen, as in Lanjouw 848 from Suriname, the pubescence varies from sparsely to more densely tomentellose-puberulent.

One of the characters used by Bremekamp in separating Mapouria opaca from M. chionantha is that the stipules are “hairy in the axil” in M. chionantha, but “not hairy in the axil” for M. opaca. An examination of a large series of specimens does not bear this out. The specimen of Bot. Mus. 6805 from Brownsberg, determined by Bremekamp as M. opaca and cited by him under that species, shows a minute ferruginous pubescent zone on at least one of the stipule scars. Other specimens determined by Bremekamp as M. opaca (Lanjouw & Lindeman 2874, Cowan 39010, Kramer & Hekking 2985) show ferruginous hairs at the stipular axils. The hairs at the base of these stipular axils are usually manifest on the uppermost stipular bases on usually the node just below the uppermost, but eventually the hairs become deciduous on the lower portion of the stem, dropping off and leaving bare scars.

On the other hand, in M. chionantha (= Psychotria mapourioides var chionantha) the hairs at the base of the stipular axils are usually longer and more in evidence as ferruginous zones, due perhaps to the generally broader-based and longer stipules. However, it is not possible to differentiate the two taxa by referring to the presence or absence of these ferruginous hairs, as was attempted by Bremekamp.

Distribution:French Guiana South America| Suriname South America| Guyana South America|