Rudgea pungens (Steyermark) 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 : 236-237

7. Rudgea pungens (Steyermark) C.M. Taylor, Bruniera & Zappi (2015: 45 , p. 4).

– Psychotria pungens Steyermark (1972: 677) . ( Fig. 7 D–F ).

Type: — FRENCH GUIANA. Without locality, s.d., F. M. R. Leprieur 118 (holotype, P! [ P00837150 ]; probable isotype (unnumbered collection), G! [ G00418599 , G00418600 ]) .

Shrub 0.3–2 m tall, with nearly horizontal branches; twigs glabrous, 1–1.5 mm thick, soon covered with a pale strawcoloured bark. Stipules 8–16(–20) × 1–7 mm, glabrous, marcescent and soon corky, consisting of a narrow tubular sheath 5–9(–12) mm long (usually split at flower-bearing nodes) bearing 8–15 terminal linear appendages 3–8 mm long, and 5–7 dorsal linear appendages 0.5-3 mm long, forming a very short decurrent keel inserted 1–3 mm above the base of the stipule. Leaves opposite; petioles 0.2–0.6 cm long, glabrous; blades elliptic, 6.5–14.5(–16) × 1.8–4.5(–5.5) cm, acute or obtuse at base, gradually long-acuminate at apex, very thick, entirely glabrous, drying olive green to olive brown; midrib concave above; secondary veins 5–10 on each side of midrib, strongly ascending, forming an angle of 45–60° with the midrib; tertiary veins invisible in fresh leaves, sometimes slightly prominent when dry; domatia absent. Inflorescences terminal, subcapitate and involucrate, ca. 8-flowered, patent to sub-erect, glabrous, sessile or pedunculate; peduncle (when present) terete, to 1 cm long; flower-bearing portion 1.3–2.2 × 1.4–3.5 cm, secondary branches apparently absent or extremely reduced in flower, to 2 mm long in fruit; bracts pale green, numerous and imbricate in several rows, 10–20 × 2–7 mm, lanceolate, entire, acute at apex, glabrous or shortly ciliate, erect or patent, persistent in fruit. Flowers sessile, 5-merous, heterostylous. Hypanthium obovoid, 1.5 mm long, glabrous, Calyx tube 0.5–1 mm long, glabrous; lobes linear to narrowly triangular, 1.2–3.5 × 0.5–1 mm, glabrous or ciliate. Corolla white, tube narrow and almost cylindrical, 13 mm long, 1 mm wide at base, 1.5–2.5 mm wide at mouth, glabrous outside (inside not seen); lobes narrowly triangular, 2.5 × 1 mm, glabrous, with short, obtuse dorsal appendage 0.5 mm long. Stamens included in long-styled flowers, or exserted with filaments exceeding corolla throat by 1 mm in short-styled flowers; anthers 2.3 × 0.3 mm. Disk shortly cylindrical, 0.5 mm long, glabrous. Style exserted, exceeding corolla mouth by 1.5 mm in long-styled flowers, or included in short-styled flowers. Fruits ovoid with truncate apex, 11 × 7–8 mm when fresh, 7–10 × 5–7 mm when dry, dark red-brown and hard when immature, cherry red when mature, glabrous, sessile, crowned with persistent calyx 2.5–4 mm in diameter. Pyrenes plano-convex, hemi-obovoid to hemi-ellipsoid, 9 × 6.5 mm, dorsal side smooth, ventral side smooth. Seeds with a deep T-shaped ventral furrow.

Distribution and ecology: —This species is only known from French Guiana ( Fig. 5 ), where it occurs on the main summits of the central Inini-Camopi chain (Mts Atachi Bacca to Mts Bakra) and disjunctly at low altitudes in the northeast; it should be expected in adjacent parts of Suriname and Brazil. It is apparently restricted to relatively low forests on rocky substrates, 5-800 m in elevation, and is locally abundant.

Phenology: —Flowering collections were made in January, May and August; fruiting collections in January, March–April (full-sized, but still hard) and August (mature fruits). As in the similar Rudgea billietiae , the fruits probably take several months to mature.

Notes: —This species, originally described in Psychotria ( Steyermark 1972) , was recently transferred to Rudgea ( Taylor et al. 2015) but its affinities within the genus were still unclear. Taylor and Bruniera (2018) mentioned its similarity to the R. bracteata J.H. Kirkbride (1981: 97) group, especially because of the well-developed bracts, but members of that group have larger fruits, and stipules with a prominent dorsal keel and without marginal appendages. The involucrate inflorescences and narrowly tubular stipules of R. pungens are unusual characters in Rudgea , but the discovery of R. billietiae , with similar stipules and lax inflorescences, links it to R. cornigera , R. hostmanniana and R. tanaosepala , which have lax inflorescences and shorter stipular sheaths. The differences between these species are summarised in Table 1 .

The original description of the species was based on a single specimen without fruits or corollas, and is therefore incomplete on several points. The species is now known from additional complete material, which allows to present here a full description; only the interior of the corolla tube cannot be described, because the flowers are too few for a dissection to be made. The dimensions in brackets refer to a vegetative collection (Granville 4002) from Mount Bakra, French Guiana, which has slightly larger leaves and stipules; though it almost certainly belongs to this species, confirmation with reproductive material from the same area would be reassuring.

Specimens Examined: — FRENCH GUIANA. Crique Kapiri – RN2, bassin de l’Approuague, 4°07’N, 52°05’W, 11 January 1991 (fallen fl.), G . Cremers 11474 ( CAY); savane-roche [inselberg] Virginie , 4°11’N, 52°08’W, 18 February 2009 (fallen fl.), C . Delnatte, F . Billiet, J.- J . de Granville & B . Jadin 1682 ( CAY); Fleuve Sinnamary , rive droite, layon ONF (n°7) direction Sud, à 7 km du fleuve, 1 May 1969 (fl.), J.- J . de Granville 128 ( CAY); sommet des Monts Atachi Bacca , 4 March 1971 (fr.), J.- J . de Granville 765 ( CAY, P); Monts Galbao , 10 km WSW Saül, 14 March 1973 (imm. fr.), J.- J . de Granville 1534 ( CAY, P); Monts Bakra , versant Sud, 5 km WSW du pic Coudreau, 28 September 1980 (st.), J.- J . de Granville 4002 ( CAY, P); Montagne Bellevue de l’Inini , zone centrale, 23 August 1985 (fl. & imm. fr.), J.- J . de Granville, L . Allorge, G . Cremers, A. R. A . Görts-van Rijn & J. F . Kodjoed 7770 ( BR, CAY, P); Crique Gabaret , bassin de l’Oyapock, Saut Mérignan, 13 April 1988 (fallen fl.), J.- J . de Granville 10275 ( CAY); Monts Atachi Bacca , versant Nord, 9 km au SE de Gobaya Soula, 3°33’N, 53°55’W, 12 January 1989 (fl.), J.- J . de Granville, G . Cremers, J. I . Hagemann, B. E . Leuenberger, R. W . Sanders & M . Sangrey 10616 ( CAY, P); Monts Atachi Bacca , est du plateau sommital, 3°33’N, 53°55’W, 22 January 1989 (fr.), J.- J . de Granville, G . Cremers, J. I . Hagemann, B. E . Leuenberger, R. W . Sanders & M . Sangrey 10861 ( CAY, P); layon Régina – Kaw , 4°21’W – 52°08’W, 7 August 1997 (fallen fl.), V . Hequet 688 ( CAY); Route Régina – Saint Georges , piste de la savane-roche [inselberg] Virginie, 4°11’05”N, 52°08’13”W, 6 April 2014 (fr.), O . Lachenaud 1720 (BR, CAY, L, MO, P); without locality, s.d. (fl.), L.C.M. Richard s.n. ( P [ P04008549 ], mixed with R. billietiae ); sommet nord du Mont Galbao, 29 January 1978 (fallen fl.), Tay 91 ( MPU) .

Figures

FIGURE 5. Distribution of Rudgea billietiae (black triangles), R; bolivarensis (grey circles), R. cornigera (black squares), R. pungens (grey squares) and R. tanaosepala (grey triangles).

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.