Rudgea hostmanniana Bentham (1850: 459) subsp. hostmanniana

Lachenaud, Olivier, Bruniera, Carla P. & Zappi, Daniela C., 2022, The Rudgea hostmanniana complex (Rubiaceae) in the Guiana Shield region, Phytotaxa 561 (3), pp. 219-242 : 231-234

5. Rudgea hostmanniana Bentham (1850: 459) subsp. hostmanniana . Fig. 1D , 2D , 7A–C .

Type: — SURINAME. Without locality, 1843 (fl.), F. W. R. Hostmann 548 (lectotype, first-step designated by Steyermark (1967: 413), second-step K! [ K000579485 ], designated here; isolectotypes BM! [ BM000832001 ], G! [ G00436709 , G00436710 ], GH! [ GH00094434 , 00094435 ], P! [ P04008004 ]) .

Rudgea intercedens Müller Argoviensis (1881: 205) , syn. nov.

Type: — BRAZIL. [Pará]: Without locality, s.d. [1785] (fl.), L. C. M . Richard s.n. (lectotype, P! [ P03985391 ], designated here; isolectotype, G! [ G00436705 ]) .

Much-branched shrub 1–5(–8) m tall; twigs glabrous, 2–4 mm thick, soon covered with a pale buffish-straw bark. Stipules 7–13 × 3–8.5 mm, glabrous, marcescent and soon corky, consisting of a basal sheath 3–5 mm long (usually split at flower-bearing nodes) bearing on each side of the node 1–2 narrowly triangular lateral appendages 2–5 × 0.3–1 mm, and a central keel 5–10 × 1.2–2 mm, much exceeding the latter and divided into 2–8 terminal appendages 2–3 mm long, these often grouped in two phalanges. Leaves opposite; petioles 0.5–2 cm long, glabrous; blades elliptic to slightly oblanceolate, 8.5–20(–22) × 2–7.8(–12) cm, acute or rarely obtuse at base, obtuse to shortly acuminate at apex, very thick, entirely glabrous, drying yellowish-green to olive brown; midrib flat or concave above; secondary veins 8–12 on each side of midrib, rather strongly ascending, forming very inconspicuous loops 1.5–5 mm from the margin; tertiary venation invisible in the fresh state, sometimes prominent but very lax in the dry state; domatia absent. Inflorescences white, terminal, in lax to rather condensed, pyramidal or rarely hemispherical panicles, 5.2–18 cm long, erect, shortly spreading-puberulous, the peduncle often glabrescent; peduncle terete, 3–11 cm long; branched portion 1.7–11 × 2.4–8.5 cm; secondary branches (2–)3–4 per node, 0.5–3 cm long; bracts triangular to lanceolate, 2.5–10 × (0.7–) 1.5–3 mm, entire or the lower ones often dentate at base, acute at apex, glabrous to sparsely pubescent. Flowers sessile, 5-merous, heterostylous. Hypanthium obconical, 0.7 mm long, glabrous. Calyx tube extremely reduced, lobes triangular to semi-circular, 0.7–2 × 0.5–0.8 mm, acute to rounded at apex, glabrous to sparsely pubescent externally, ciliate on the margins. Corolla white, fragrant, hypocrateriform; tube narrowly funnel-shaped, 3–5 mm long, 1–1.2 mm at base, 2–3 mm wide at mouth, glabrous to densely villous outside, densely villous at upper half inside; lobes narrowly triangular, 3–4 × 1.2–1.5 mm, densely villous to sparsely pubescent outside at least near the apex, papillose inside, with hemispherical to conical dorsal cornicula ≤ 0.7 mm long. Stamens included and subsessile in long-styled flowers, or long exserted with filaments 3–4 mm long in short-styled flowers; anthers 1–1.2 x 0.3 mm. Disk shortly cylindrical, 0.6 mm long, glabrous. Style exserted, 5.5–6 mm long in long-styled flowers, or as long as corolla tube, 4.5–5 mm long in short-styled flowers; lobes 0.8–1.5 mm long, stigmatic surface papillose. Fruits obovoid or rarely subglobose, 5.5–10 × 5.5–7.5 mm when dry, green when immature, becoming orange-red later (said to turn black at full maturity), glabrous, sessile, crowned with persistent calyx 1–2 mm in diameter, i.e. not markedly accrescent. Pyrenes plano-convex, hemi-ellipsoid to hemi-obovoid, or rarely hemispherical, 5.5–9 × 4.5–8.5 mm, dorsal side with 3–4 prominent and 2 lateral ridges, smooth between the ridges, ventral side smooth. Seeds with a deep T-shaped ventral furrow.

Distribution and ecology: —Widespread and common in the three Guianas, occurring also locally in eastern Venezuela, and apparently disjunctly in the Brazilian state of Acre ( Fig. 6 ); occurs mostly in riparian forest and in low coastal forest on white sands, occasionally also on granitic outcrops in the interior, from sea level to 850 m in elevation. Another subspecies, R. hostmanniana subsp. freemanii (Sprague & R.O.Williams ex R.O. Williams & Cheesman 1928: 39) Steyermark (1967: 414) is found in similar habitats in Trinidad, Tobago, Grenada, and the coastal cordillera of Venezuela.

Phenology: —Flowering specimens were collected throughout the year; fruiting specimens throughout the year, except December–January, with a peak in August–September.

Notes: —This species is here circumscribed in a narrower sense than previously (e.g., Zappi & Steyermark 2004; Bruniera 2015), and as thus includes only two subspecies, which distributions are discussed above. It is similar to Rudgea billietiae , R. bolivarensis , R. cornigera , R. maypurensis and R. tanaosepala , and has frequently been confused with all of them. Differences between these species are summarised in Table 1 ; especially diagnostic for R. hostmanniana is the shape of the stipules, with the dorsal keel long exceeding the lateral appendages ( Fig. 1D ). An illustration of R. hostmanniana (sensu stricto) may be found in the Flora de Venezuela ( Steyermark 1974, fig. 166) and is quite accurate, although the tertiary leaf veins are usually less apparent than depicted on the figure.

The above species description is based on subsp. hostmanniana . Subspecies freemannii is very similar to subsp. hostmanniana , differing only by the densely puberulous hypanthium and outer surface of the calyx, which is a rather slight but apparently constant character. The length of the peduncle, used as an additional diagnostic character by Steyermark (1967) actually shows much overlap between the two taxa. Not all authors have accepted the distinction of subsp. freemannii , for instance Acevedo-Rodriguez & Strong (2012: 842) considered it a synonym of R. hostmanniana . Zappi & Steyermark (2004) recognized three subspecies, although the third one, subsp. maypurensis (Standley) Zappi (in Zappi & Steyermark 2004: 808), is here reinstated in its original specific rank.

The original description of Rudgea hostmanniana is based on several syntypes: Hostmann 548 from Surinam, Rob. Schomburgk 12 and Rich. Schomburgk 2 from Guyana (or more likely Roraima state, Brazil), and Lockhart s.n. from Trinidad, the latter belonging to subsp. freemannii . The second and third syntype actually represent the same collection ( van Dam 2002: 100 ) since the Schomburgk brothers travelled together and often used separate numbers for the same gathering. Steyermark (1967: 413) cited Hostmann 548 as type, which is to be treated as a first-step lectotypification (Art. 9.10 of the Code) because he did not indicate the herbarium of deposit. The specimen of this collection in K, which is presumably the one studied by Bentham, is here selected as the second-step lectotype.

Müller Argoviensis (1881: 205), in the original description of Rudgea intercedens , did not explicitly cite a type, and he only indicated “Habitat in Brasilia (ex hb. Juss., in hb. Rich., nunc in hb. Franq.)”. A specimen from the Richard herbarium in P, which is annotated R. intercedens probably in Müller’s hand, and bears the indication “Brasiliae – herb. Juss.”, is here selected as lectotype. This specimen matches R. hostmanniana in every detail; the synonymy of the two species, which Zappi (2003: 585) already noted to be strongly similar, was recognized by Bruniera (2015) in her thesis, and is here formally established.

The fruits of Rudgea hostmanniana are usually red or orange; two specimen labels report that they turn black at maturity (Davidse 4110; Tostain et al. 1884) but this indication remains to be confirmed in the field.As far as is known, in all other species of the complex the mature fruits are red.

A collection from Colombia, M.B. Monsalve 741 (GB), cited as Rudgea hostmanniana subsp. hostmanniana by Bruniera (2015: 137) probably represents a new species; its stipules lack the characteristic central keel of R. hostmanniana and its inflorescences have unusually large bracts. No authentic collection of R. hostmanniana from Colombia has been seen by the authors, although the species could be expected in the southeastern region of the country.

Additional Specimens Examined: — BRAZIL. Amazonas: Km 1–5 road Boca do Acre – Rio Branco , 24 September 1966 (fl.), G. T. Prance, B. S. Pena, J. F. Ramos & E. R. Videcki Jr 2534 ( U) .

FRENCH GUIANA. NE foot of Montagne des Pères , 5 km S of Kourou, 5°06’N, 52°36’W, 11 March 1994 (fl. & fr.) , L. Andersson , C. Gustafsson , C. Persson & J. Rova 1954 ( CAY, GB, K); Saut Dalles, Bassin du Sinnamary, 5°27’N, 53°01’W, 24 September 1992 (fl.) , B. Bordenave 236 ( CAY, P, U); Saut l’Autel, Bassin du Sinnamary, 4°42’N 52°58’W, 25 October 1992 (fl. buds) , B. Bordenave 391 ( CAY, P); ibid., 4°45’N, 53°06’W, 10 March 1994 (fl. & fr.) , B. Bordenave 806 ( CAY, P, U); Malmanoury , 5 February 1995 (st.) , L. Cadamuro & F. Solacroup 242 ( CAY); Fusées Sondes , 20 February 1995 (fr.) , L. Cadamuro & F. Solacroup 292 ( CAY); Diamant , 22 February 1995 (st.) , L. Cadamuro & F. Solacroup 340 ( CAY); Kikiwi , 2 March 1995 (st.) , L. Cadamuro & F. Solacroup 349 ( CAY) & 358 ( CAY); Crique Canceler , 5°26’N, 53°02’W, 8 December 1996 (fl.) , G. Cremers , F. Crozier & M. Hoff 14474 ( P, U); Rivière de Kourou , March 1875 (fl. & fr.) , J. Crevaux s.n. ( P); village Boni de Assici , bassin du Maroni, 3°49’N, 54°12’W, 17 March 1989 (fl. & fr.) , M. Fleury 773 ( CAY); Piste de Saint-Elie , 20 February 1985 (fr.) , P.-M. Forget 276 ( CAY); Lieu-dit Maya , route de la Carapa, 4°56’59”N, 52°26’30”W, 1 March 2007 (fr.) , S. Gonzalez 1095 ( CAY); rive du Grand Inini vers Bicade, 21 August 1970 (fr.) , J.-J. de Granville C-31 ( CAY, P, U); îlets du Saut Emérillon sur le Grand Inini , 27 August 1970 (fr.) , J.-J. de Granville C-107 ( CAY, P); bordure du Grand Inini , à Dégrad Nicole, 4 September 1970 (fr.) , J.-J. de Granville B-3657 ( CAY, P); Rivière Petite Ouaqui , entre Saut Macaque et Saut Baille-Nom, 12 July 1973 (fl.) , J.-J. de Granville B-4954 ( CAY, P, U); Rivière Grande Ouaqui , à 8 km de son confluent avec la Petite Ouaqui, 13 July 1973 (st.) , J.-J. de Granville 1814 ( CAY, P); Rivière Petite Ouaqui , “Saut Baille Nom”, 14 July 1973 (st.) , J.-J. de Granville 1829 ( CAY, P, U); Fleuve Mana , Saut Fracas, 23 July 1981 (fl. buds) , J.-J. de Granville 4640 ( CAY, P); Rivière Mana , Gros Saut, 25 July 1981 (fr.) , J.-J. de Granville 4654 ( CAY, P, U); Rivière Grand Inini en aval et en amont de Dégrad Fourmi, 13 September 1985 (fr.) , J.-J. de Granville 8180 ( CAY, P, U); Site Ariane 4 - Crique Karouabo , C. S. G., 11 May 2007 (st.) , J.-J. de Granville 17387 ( CAY); Crique Arouany , 22 August 1962 (fl. & fr.) , F. Hallé 632 ( CAY, K, P); Saut Takari-Tanté, Bassin du Sinnamary, 4°37’N, 52°56’W, 16 November 1989 (fl.) , M. Hoff 5864 ( CAY, U); Saut Aïmara, Bassin du Sinnamary, 16 January 1992 (fl.) , M. Hoff 7576 ( CAY); Rivière Iracoubo , entre roche Hirondelle et Carbet Gendarmerie, 28 December 2010 (fl.) , O. Lachenaud 981 ( BR, CAY, MO); Kourou , Campus du CIRAD, 30 December 2010 (st.) , O. Lachenaud 1011 ( BR, CAY); “ Cayenne ”, no date (fl.) , J.B. Leblond s.n. ( G); without locality, 1859 , F.M.R. Leprieur s.n. ( G); Haute Mana , en amont de Gros Saut, 29 August 1981 (fr.) , C. Moretti 1259 ( CAY, P); entre Saut Vata et Saut Bérard , 22 September 1965 (fr.) , R.A.A. Oldeman 1541 ( CAY, P, U); Fleuve Sinnamary , ca. 4 km en amont sur la Crique Tigre, 4 August 1967 (fr.) , R.A.A. Oldeman B-1153 ( CAY, P); Fleuve Sinnamary , ca. 6 km en amont sur la Rivière Courcibo, 8 August 1967 (fr.) , R.A.A. Oldeman B-1188 ( CAY, P); Rivière Courcibo à ca. 1.5 km en amont su Saut Caouène, 10 August 1967 (fr.) , R.A.A. Oldeman B-1202 ( CAY, P, U); Fleuve Kourou , ca. 700 m en amont du Saut Léodate, 25 September 1967 (fr.) , R.A.A. Oldeman B-1388 ( CAY, P, U); Fleuve Sinnamary , Saut Bois Blanc, 22 April 1969 (fl.) , R.A.A. Oldeman B-2305 ( CAY, P, U); without locality, 1820 (fl.) , G.S. Perrottet s.n. ( G, P); without locality, July 1824 (fl.) , P. A. Poiteau s.n. ( K); Kourou , Campus Silvolab, 5°10’N, 52°39’W, 8 April 2001 (fl.) , M.- F. Prévost & M. Fournier 4151 ( BR, CAY, G, K, P, U); ibid., 16 April 2001 (fr.) , M.-F. Prévost & D. Sabatier 4154 ( CAY, G, K, MO, P); ad montem Macouriae , s.d. (fl.) , L.C.M. Richard s.n. ( P); près de Saut Macaque , rives du Grand Ouaqui, 12–14 September 1961 (fr.) , R. Schnell 12153 ( P); Crique Ouaqui, September 1961 (fr.), Service Forestier ( BAFOG) 7769 ( CAY, P, U), 7807 ( CAY, P, U); Forêt de Maya , route de la Carapa, Macouria, 31 March 2008 (fr.) , O. Tostain , T. Deville & V. Pelletier 1884 ( CAY) .

GUYANA. Towakaima Falls, Barama River, 7°18’N 59°59’W, 3 October 1996 (fr.), T . R. van Andel, E. Samuels, N. George & M.A.J.P. Smeets 1692 ( U); Mabaruma , Aruku River, 11 March 1945 (fl.), D. B . Fanshawe FD 5129 ( K, U); Kaow Island , Essequibo River, 13 July 1943 (fr.), Forest Department 4132 ( K); SE Kanuku Mountains, 3°03’N, 59°25’W, 25 June 1989 (fr.), L. J . Gillespie, D. Gopaul & Peterson 1824 ( K, U); Surama Lake , 4 km NE of Surama Village, 3 May 1992 (fl.), B . Hoffman, D. Allicock & T . Allicock 1567 ( CAY); Kanuku Mts , Moco Moco R ., 3°18’N, 59°39’W, 19 July 1995 (fr.), M. J . Jansen-Jacobs, C . Simmons, A . Jacobs-Brouwer, V . James & R . Andrew 4574 ( CAY, K, P, U); Upper Essequibo Region , Rewa River, Spider Mountains, 3°08’N, 58°32’W, 17 September 1999 (fl.), M. J . Jansen-Jacobs, B. J . H. ter Welle, P.P. Haripersaud, O. Muller & M. van der Zee 5955 ( U); ibid., 20 September 1999 (fl.), M. J . Jansen-Jacobs, B. J . H. ter Welle, P.P. Haripersaud, O. Muller & M. van der Zee 6015 ( CAY, K, P, U); Mazaruni River , September 1880 (fl.), G. S . Jenman 765 ( K); Essequibo River , October 1881 (fl.), G. S . Jenman 1193 ( K); Bartica , November 1888 (fl.), G. S . Jenman 4675 ( K, U); Mazaruni River , August 1889 (fr.), G. S . Jenman 5440 ( K); no locality, 1841 (fl.), Rob. Schomburgk 12 ( BM, K, P); Isorova Hill , June 1912 (fr.), F. A . Stockdale 247 ( K); Cuyuni River , Crab Fall, 30 April 1933 (fl.), T. G . Tutin 16 ( BM, K) .

SURINAME. Without locality, 1841 (fl.), Berthoud-Coulon 197 ( BM), 198 ( BM); in districtu Surinamensi Para, February–April 1844 (fl.), A . Kappler 1455 ( P); ibid., A . Kappler 1485 ( G, P, U); Coppename River, near Raleigh Falls , 13 September 1933 (fr.), J . Lanjouw 814 ( INPA, K, U); along Kort en Duur Creek, tributary of Perica River , 29 November 1953 (fl.), J . C . Lindeman 5117 ( BR, U); Saramacca River Headwaters, Jacob Kondre , 16 June 1944 (fr.), B . Maguire 23833 ( BR, K, P, U); Paramaribo, 23 May 1916 (fr.), J . S . Samuels 317 ( K, L); in sylvis Paraensis prope Onoribo , 8 March 1838 (fl.), F . Splitgerber 665 ( L); fluv. Corantijn, Kaboerie - Winana, 27 October 1916 (fr.), G . Stahel & J . W . Gonggrijp 2985 ( U); Corantyne River, near Mac Claren , 23 January 1963 (fl.), J . G . Wessels Boer 555 ( P, U); Paramaribo, 1851 (fr.), H . R . Wullschlaegel 242 ( BR); “ Para ”, no date (fl.), H . R . Wullschlaegel 995 ( BR) .

VENEZUELA. Miranda: 3 km SW of Araguita , along road between Caucagua and Altigracia de Orituco , 17 November 1973 (fr.), G . Davidse 4110 ( L); Catalina , May 1896 (fl. buds), H . H . Rusby & R . W . Squires 209 ( BM); ibid., May 1896 (fl.), H . H . Rusby & R . W . Squires 444 ( K) .

Figures

FIGURE 1. Stipules in the Rudgea hostmanniana complex.A, R. bolivarensis; B, R. coussareoides; C, R. cornigera; D, R. hostmanniana subsp. hostmanniana; E, R. maypurensis; F, R. tanaosepala. A from Mutchnick 1620 (K), B from Diaz et al. 7727A (K), C from Schulz 7539 (U), D from Lachenaud 1011 (BR), E from Williams 12972 (K), F from Clarke & Hoffman 584 (U). Drawing by O. Lachenaud.

FIGURE 2. Calyx and corolla in the Rudgea hostmanniana complex.A, R. bolivarensis, calyx; B, R.coussareoides, calyx; C, R. cornigera, flower bud; D, R. hostmanniana subsp. hostmanniana, flower bud; E, R. maypurensis, flower bud; F, R. tanaosepala, flower bud. A from Henkel 5675 (U), B from Liesner 24924 (K), C from Procter 4769 (U), D from Lachenaud 981 (BR), E from Plowman 13733 (K), F from Clarke & Hoffman 584 (U). Drawing by O. Lachenaud.

FIGURE 6. Distribution of Rudgea coussareoides (squares), R. hostmanniana subsp. hostmanniana (triangles) and R. maypurensis (circles).

FIGURE 7. A–C, Rudgea hostmanniana. A, inflorescence; B, leaf abaxial side; C, fruits. D–F, Rudgea pungens. D, infructescence, top view; E, infructescence, lateral view; F, stipule. Voucher collections: A–C, plant not collected (Kourou, French Guiana), D–F Lachenaud 1720. A–C Photos by P. Petronelli, D–F photos by O. Lachenaud.