Description originale
Lachenaud, O., Bruniera, C. & Zappi, D. 2022. Six new and a little-known species of Rudgea (Rubiaceae—Palicoureeae) from the Guianas. Phytotaxa, 531(3): 154-174.

 

Statut pour la Guyane française
Lachenaud, O., Bruniera, C. & Zappi, D. 2022. Six new and a little-known species of Rudgea (Rubiaceae—Palicoureeae) from the Guianas. Phytotaxa, 531(3): 154-174. [GF = S]

 

Date de publication : Phytotaxa, 531(3): 163-166, fig. 2, 5. 2022 [21/01/2022].

Distribution : Endémique du nord de la Guyane française et du Suriname, inféodée aux forêts basses de lisière d'inselbergs où elle peut être abondante, connue d'une poignée de localités dispersées: massif des Emerillons, Nouragues, la Trinité, Voltaire, monts Bakhuis. Deux données anciennes non localisées suggèrent une dispersion plus importante et peut-être aussi une écologie plus large.

Taxonomie : D'après Lachenaud et al. (Phytotaxa, 531(3): 163-165. 21/01/2022): "This species has previously been confused with the more widespread and rather similar Rudgea crassiloba. Both have relatively small and coriaceous leaves, minutely puberulous twigs, very short stipules with a dorsal keel bearing terminal appendages, usually paniculate inflorescences (sometimes glomerulate in R. graniticola), a short corolla tube, orange to red ellipsoid fruits, and dorsally costate pyrenes. Both are also commonly associated with granitic rocks (hence the specific name of R. graniticola) although R. crassiloba may also be found on other substrates. They differ by the characters given in the diagnosis.
Rudgea graniticola also resembles R. ayangannensis (see above) in vegetative and inflorescence characters. Differences between the three species are summarised in Table 3. The distribution of R. graniticola is separate from both R. ayangannensis, which is endemic to Guyana, and R. crassiloba, which is mostly found in the Amazon/Orinoco basin and only reaches the southern part of Suriname and French Guiana.
According to Bruniera (2015), Rudgea crassiloba belongs to the informal “lanceifolia clade”, being closely related to R. reticulata Bentham (1850: 458). In view of its morphology, R. graniticola probably also belongs to this clade.
The inflorescences are very variable in this species. Collections from the Nouragues inselberg (including the type specimen) have lax and many-flowered panicles, while those from Chutes Voltaire and Massif des Emerillons have few-flowered glomerules. Specimens from Bakhuis Mountains and La Trinité are intermediate, and since no other differences have been found, we recognize only one variable taxon.
The oldest collection of this species (Collector unknown in A.P. de Candolle & C.L. L’Héritier s.n.) is labelled “Cayenne”, which at that time often referred to the whole of French Guiana. In view of its habitat, the species is unlikely to occur in the close vicinity of Cayenne. Neither Candolle nor L’Héritier ever visited French Guiana, so they must have obtained this material from another, unknown collector."

Type : Guyane française, montagne des Nouragues, 4°03’N, 53°42’W, formation arbustive basse au sommet de l'inselberg, 390 m, 10/1989, fleurs. Très fréquent dans ce milieu. Arbuste. Ligneux à tronc souvent très penché dans ces formations. Feuilles opposées coriaces. Inflorescences terminales. Boutons floraux tubulaires blancs. Fleurs: 4 pétales blancs, campanulés à la base, ouverts à l'apex, 4 petits sépales vert à la base, 4 étamines. D. Larpin 722 (HT: CAY078936 [Rudgea crassiloba (Benth.) B.L.Rob. 1910, det. F. Crozier, 1999]; IT: P04008509 [R. crassiloba, det. D. Zappi, 01/1997]).
Guyane française, "Cayenne" (see notes), no date [c.1800], fruits. Collector unknown in A.-P. de Candolle & C.L. L’Héritier s.n. (PT: G).
Guyane française, without locality, 1842, fruits. E. Mélinon s.n. (PT: P04008508 [R. crassiloba, det. D. Zappi, 01/1997]).
Guyane française, massif des Emerillons, zone nord, savane roche au sommet d’une colline sur la gauche de la Haute Approuague, 29/09/1980, fleurs tombées. J.J. de Granville 3949 (PT: CAY078933, CAY078934 [R. crassiloba, det. F. Crozier, 1999], P06800578 [R. crassiloba, det. F. Crozier, 1999], L.2067862, L.2067863 [R. crassiloba, det. F. Crozier, 1999]).

Type : Guyane française, station des Nouragues, 4°03’N, 52°42’W, 22/02/1991, fruits. J.J. de Granville 11164 (PT: CAY003770 [R. crassiloba, det. F. Crozier, 1999], MO, NY, P04008572 [Rudgea sp.], U.1580820 [R. crassiloba, det. D. Zappi, 2009]).
Guyane française, montagne des Nouragues, 4°03’N, 52°42’W, 04/1989, fruits. D. Larpin 496 (PT: CAY078935 [R. crassiloba, det. F. Crozier, 1999], P04008505 [R. crassiloba, det. D. Zappi, 01/1997]).
Guyane française, Nouragues Field Station, 4°05.289’N, 52°40.774’W, 16/02/2002, fruits. S.A. Mori, F. Blanchard & T.A. Lobova 25381 (PT: CAY022728 [Rudgea sp. det. P.G. Delprete, 2003], NY).
Guyane française, réserve des Nouragues, Station de recherches, 4°03’N, 52°42’W, 14/03/2004, fleurs et fruits. O. Poncy, L. Barrabé, P. Petronelli, J.Y. Serein & J.G. Jourget 1878 (PT: CAY059276 [Rudgea sp., det. P.G. Delprete 2008], NY, P00429266 [Rudgea sp., det. C.M. Taylor 2008]).
Guyane française, montagne des Nouragues, 4°03’N, 52°42’W, 17/04/1988, fruits. C. Sarthou 275 (PT: CAY078937, CAY078938 [R. crassiloba, det. F. Crozier, 1999], P00916518 [R. crassiloba, det. C. Sarthou, 1988]).
Guyane française, station des Nouragues, 13/03/1996, fruits. P. Solano K331 (PT: CAY035760 [cf. Psychotria marginata Jacq., det. P. Solano, 1996]).
Guyane française, station des Nouragues, 14/03/1996, fruits. P. Solano K394 (PT: CAY023596 [Rudgea sp., det. P.G. Delprete, 2008]).

Type : Guyane française, montagnes de la Trinité, sommet nord, 12/01/1984, jeunes fruits, J.J. de Granville, C.C. Berg, M.J. Jansen-Jacobs & J. van Setten 5909 (PT: BR, CAY003766 [R. crassiloba, det. F. Crozier, 2000], G, K000005092 [R. crassiloba], MG, MO, P05058672 [Rudgea sp., det. C.M. Taylor 2008], U.1580819 [R. crassiloba, det. D. Zappi, 01-02/2009]).
Guyane française, montagnes de la Trinité, sommet nord, 12/01/1984, jeunes fruits, J.J. de Granville, C.C. Berg, M.J. Jansen-Jacobs & J. van Setten 5938 (PT: BR, CAY003767 [R. crassiloba, det. F. Crozier, 2000], G, K000005093 [R. crassiloba], MO, P06591610 [Rudgea sp., det. C.M. Taylor 2008], U.1580818 [R. crassiloba, det. D. Zappi, 01-02/2009]).
Guyane française, montagnes de la Trinité, inselberg Nord-Ouest, 16/01/1984, fleurs tombées. J.J. de Granville, C.C. Berg, M.J. Jansen-Jacobs & J. van Setten 6016 (PT: CAY003002 [R. aff. crassiloba, det. J.A. Steyermark, 1984], MO, P04008503 [R. crassiloba], U.1580828 [R. crassiloba, det. D. Zappi, 2009]).
Guyane française, inselberg Trinité, 4°35’N, 53°21’W, 09/05/1998, stérile. J.F. Villiers & C. Sarthou 6294 ["6293"] (PT: CAY012798 ["6293" par interversion des étiquettes; Rudgea sp., det. F. Crozier, 2003], P05058460 [R. crassiloba]).
Guyane française, inselberg des Chutes Voltaire, 20/12/2015, fleurs tombées. O. Lachenaud 2166 (PT: BR, CAY).
Suriname, Bakhuis Mountains, concession BMS, zone 22, centre, 4°29’45”N, 57°00’59”W, 05/04/2006, fruits. B. Bordenave, S. Dourga, F. van Troon, I. van Troon & J. James 8365 (PT: BBS, CAY073478 [R. crassiloba, det. J.-J. de Granville, 2006], MO, P).