Rudgea coussareoides (Standley) C.M. Taylor, Bruniera & Zappi (2015: 45

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 : 229-231

4. Rudgea coussareoides (Standley) C.M. Taylor, Bruniera & Zappi (2015: 45 , p. 4 [E-publication]).

– Psychotria coussareoides Standley (1931: 441) . – Palicourea coussareoides (Standley) Delprete & J.H. Kirkbride (2016: 417) . Fig. 1B , 2B .

Type: — VENEZUELA. Amazonas, slopes of Mount Duida, Agüita , 4000 ft [ca. 1220 m], 1928–29 (fl. buds), G. H. H. Tate 919 (holotype, NY! [ NY00132650 ]) .

Rudgea tillettii Steyermark (1967: 416) .

Type: — GUYANA. Porkknocker Camp 2 on Partang River, about 19 miles from mouth, Merume Mountains, 625 m, 28 June 1960 (fl. buds), S. S. Tillett , C. L. Tillett & R. Boyan 43934 (holotype, NY! [2 sheets, NY00133238 , NY00133239 ], isotypes K! [ K000005080 ], VEN! [ VEN 64649]) .

Psychotria coussareoides var. ciliata Steyermark (1972: 496) .

Type: — VENEZUELA. Bolivar: Cerro Venamo (parte SO), 950–1000 m, 10 January 1964 (fl. buds), J. A. Steyermark , G. C. K. Dunsterville & E. Dunsterville 92929 (holotype, VEN! [ VEN 62981], isotype, NY! [ NY00132651 ]) .

Shrub or tree 1.5–7 m tall; twigs glabrous, 1.5–3 mm thick, soon covered with a brown corky bark. Stipules 2.5–7 × 4.5–10 mm, glabrous, marcescent but soon damaged, consisting of a truncate sheath bearing 6 groups (2 between every pair of leaves) of ca. 10 thick aculeiform dorsal appendages 0.5–1 mm long, shorter than the sheath and inserted between 2/3 and 3/4 of its length from the base. Leaves ternate; petioles 0.8–2.5 cm long, glabrous; blades elliptic, 6.2–21 × 1.2–7 cm, decurrent on petiole at base, acuminate at apex, coriaceous with slightly recurved margin, entirely glabrous, drying olive brown to dark brown; midrib slightly prominent above; secondary veins 8–11 on each side of midrib, weakly to moderately ascending, forming irregular loops 0.5–2 mm from the margin; tertiary venation prominently reticulate (at least in the dry state) and concolorous below, the veins 1–2 mm apart; domatia absent. Inflorescences terminal, pale green to purplish (at least in the fruiting stage), in pyramidal panicles, 5.7–13.5 cm long, erect, minutely spreading-puberulous; peduncle terete, 2.2–4.2 cm long; branched portion 3.5–10.5 × 3–8 cm; secondary branches (2–)3–4 per node, 1.2–2 cm long; bracts of basal node resembling small leaves, 8–27 × 1–5.5 mm, narrowly elliptic, glabrous, the other bracts minutely triangular, 1–2.5 × 0.5–2 mm, entire or dentate, glabrous to puberulous. Flowers sessile, 5-merous, fragrant. Hypanthium cylindrical, 0.8–1 mm long, glabrous. Calyx shortly cupuliform, glabrous to puberulous; tube 0.3–0.7 mm long; lobes triangular, 0.2–0.3 mm long. Corolla white, hypocrateriform; tube funnelshaped, 2–2.5 × 1.2–1.8 mm, glabrous to papillose outside, densely villose inside except towards the base; lobes narrowly triangular, 2.5–3 × 1–1.5 mm, acute at apex, glabrous outside, papillose inside. Stamens mostly included with only the tips exserted, anthers 1 × 0.5 mm. Disk cylindrical, 0.3–0.7 mm long, glabrous. Style exserted, 4.5–5.5 mm long, bilobed, glabrous. Fruits ellipsoid to subglobose, 5.5–8 × 4–5.5 mm when dry, green or greyish-blue when immature, dark purple when mature, glabrous, sessile or with pedicel <2 mm long, calyx not markedly enlarged, 1.3–2.5 mm wide. Pyrenes plano-convex, hemi-ellipsoid, 7–7.5 × 5–5.5 mm; dorsal side faintly and irregularly ridged, slightly granulose, ventral side smooth. Seeds with a deep T-shaped ventral furrow.

Distribution and ecology: —Occurring in western Guyana, eastern Venezuela, and northern Brazil (Amazonas) and apparently in disjunct populations in Amazonian Peru ( Fig. 6 ); in tepui slope forests, sometimes on riverbanks, mostly 700–1500 m but as low as 300 m altitude in Peru.

Phenology: —Flowers in October (buds), January-February, and June; fruits in January, April and October-November.

Notes: —The systematic position of this species, which has only recently been transferred to Rudgea from Psychotria ( Taylor et al. 2015) has long been unclear. It appears that it is part of the R. hostmanniana complex, and in particular closely resembles R. bolivarensis in stipule morphology. It is easily separated from the latter – and from all species of Rudgea in the Guiana Shield region – by its ternate, rather than opposite, leaves. Furthermore, its stipules bear two separate groups of appendages between every leaf pairs (as opposed to one in R. bolivarensis ) and its inflorescences are also more slender than in R. bolivarensis .

It is unclear whether the flowers of this species are heterostylous; only two specimens with open flowers have been seen, and both seem to pertain to the long-styled form.

A specimen from Brazil, cited below, represents a new record for the country; though it was seen in photograph only, this identification is without any doubt. A previous record of this species from French Guiana ( Funk et al. 2007, as Psychotria coussareoides ) is presumably based on the specimen R.A.A. Oldeman & C. Sastre 88 (CAY), which is Coussarea sp. No authentic material of R. coussareoides from French Guiana has been seen by the authors.

Additional Specimens Examined: — BRAZIL. Amazonas: Manacapuru, margen do lago grande, operação Radam , ponto 4, 9 October 1976 (fl. buds), T. R. Bahia 219 ( F n.v., NY, photo K) .

GUYANA. Upper Mazaruni River region , Karowtipu Mountain, 5°45’N, 60°35’W, 1000 m, 25 April 1987 (fr.), B . M . Boom & D. Gopaul 7728 ( MO); Pakaraima Mountains , Mount Wokomung , Wusupubaru Creek, 2 km from juncture with Suruwubaru Creek, 5°03’N, 59°53’W, 975–1125 m, 13 February 1993 (fl.), T . M . Henkel, M . Chin & W . Ryan 1326 ( MO); Pakaraima Mountains , Mount Wokomung, headwaters of Wusupubaru Creek, 5°03’N, 59°53’W, 975–1125 m, 15 February 1993 (fl.), T. M. Henkel, M. Chin & W. Ryan 1385 ( NY) .

PERU. Amazonas: Distrito Imaza, comunidad Aguaruna Putuim, Anexo de Yamayakat , 700–750 m, 21 January 1996 (fr.), C. Díaz S., H. Osores, H. Díaz & D. Díaz 7727 A ( K) .

VENEZUELA. Amazonas: Distrito Atabapo, Cerro Marahuaca , 3°43’N, 65°30’W, 1200 m, 16 October 1988 (fr.), R . Liesner 24924 ( K); Distrito Atabapo, Cerro Huachamacari , 3°49’N, 65°43’W, 800–1300 m, 5 November 1988 (fr.), R. Liesner 25881 ( 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).