Rudgea maypurensis Standley (1930b: 72)

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 : 235-236

6. Rudgea maypurensis Standley (1930b: 72) .

– Rudgea hostmanniana subsp. maypurensis (Standley) Zappi (in Zappi & Steyermark 2004: 808). ( Figs. 1E , 2E )

Type: — VENEZUELA. Amazonas: Maypures, June 1854 (fr.), R. Spruce 3615 (holotype, K! [ K000447196 ]; isotype, P! [ P04008962 ]; fragment, G! [ G00436708 ]) .

R. corocoroensis Steyermark (1988: 349) , syn. nov.

Type: — VENEZUELA. Amazonas, Dpto. Atures, 5–8 km NW of settlement of Yutajé, 3 km W of Rio Coro-Coro, W of Serranía de Yutaje , 5°40’N, 66°09’W, 700–1000 m, 10 March 1987 (fl.), R. Liesner & B. Holst 21827 (holotype MO! [MO-2049858]; isotypes, F! [ N °2030267], NY! [ NY00133209 ], PORT! [ PORT34149 ], U! [ U0006286 ], US! [ US 00153756]) .

Much-branched shrub 1–4 m tall; twigs densely patent-puberulous or more rarely glabrous, 1.5–3 mm thick, soon covered with a pale straw-coloured bark, becoming greyish on older stems. Stipules 3–10 x 3–5.5 mm, densely patentpuberulous to glabrous, marcescent and soon corky, consisting of a basal sheath 1–3 mm long (usually early split) bearing on each side of the node 4–6 erect linear terminal appendages 2–7 mm long, and 4–10 recurved dorsal appendages 1-3 mm long, these often connate at base into a short keel. Leaves opposite; petioles 0.1–0.7 cm long, patent-puberulous to glabrous; blades elliptic, 2.8–12 × 1–8.8 cm, slightly cordate to rounded at base, obtuse to hardly acuminate at apex, very thick, entirely glabrous, drying yellowish-green (or the young leaves blackish-green); midrib flat or concave above; secondary veins 6–11 on each side of midrib, rather strongly ascending, hardly prominent; tertiary venation not or hardly distinct; domatia absent. Inflorescences terminal, in rather condensed pyramidal panicles, 1.8–8.8 cm long, erect, shortly spreading-puberulous or more rarely glabrous; peduncle terete, 1–6.5 cm long; branched portion 0.8–3.5 × 1–3 cm; secondary branches (2–)3–4 per node, 0.4–2.7 cm long; bracts 1.5–5 × 0.7–2 mm, triangular to lanceolate, entire or often dentate at base, acute at apex, glabrous outside, pubescent inside. Flowers sessile, 5- merous, heterostylous. Hypanthium obconical, 0.7 mm long, glabrous. Calyx tube extremely reduced, lobes triangular, 0.5–1.8 × 0.5–0.7 mm, acute or obtuse at apex, densely ciliate. Corolla white (the lobes sometimes pale yellow), hypocrateriform; tube narrowly funnel-shaped, 3–4 mm long, 1–1.2 mm wide at base, 1.7–2 mm wide at mouth, glabrous outside, villose in the upper part inside; lobes narrowly triangular, 2.5 x 1.3 mm, glabrous to puberulous at apex outside, papillose inside, not corniculate dorsally. Stamens included, with subsessile anthers in long-styled flowers, or well-exserted, with filaments 3 mm long, in short-styled flowers; anthers 1.5 x 0.3 mm. Disk cylindrical to slightly conical, 0.5–0.8 mm long, glabrous. Style exserted, 6 mm long in long-styled flowers, or included, ca. 3.5 mm long in short-styled flowers, glabrous or densely pubescent in the distal half; lobes 0.5–1 mm long, stigmatic surface papillose. Fruits obovoid to subglobose, 4.5–6 × 4–5.5 mm when dry, green when immature, orange to red when mature, glabrous, sessile, crowned with persistent calyx 1–1.5 mm in diameter. Pyrenes plano-convex, hemi-obovoid, 5–5.5 × 4.2–5 mm, dorsal side with 2–4 prominent to very weak longitudinal ridges, slightly verrucose, ventral side ± smooth. Seeds with a deep T-shaped ventral furrow.

Distribution and ecology: —Restricted to southeastern Venezuela (Amazonas state) and adjacent northwestern Brazil (Amazonas state), and probably eastern Colombia ( Fig. 6 ); occurs in dry forests bordering granitic rocks (“lajas”) where it is locally abundant, at 85–200 m in elevation.

Phenology: —Specimens with flowers were collected in March–April, with immature fruits in April–May, and with mature fruits in June–August and once in November.

Notes: —This taxon, treated as a subspecies of Rudgea hostmanniana by Zappi & Steyermark (2004), is distinct enough to retain its original species status. It differs from R. hostmanniana by its stipules (compare Fig. 1D & 1E ), its corolla lobes that are not corniculate at apex, and its pyrenes that are dorsally verrucose ( Table 1 ). The leaves are also more coriaceous and shiny than in R. hostmanniana , with an often slightly cordate base and a usually shorter petiole, and the fruits are generally smaller. An illustration of this taxon (as R. hostmanniana subsp. maypurensis ) has been published by Zappi & Steyermark (2004: fig. 618).

The original description of Rudgea maypurensis was published in Standley (1930b: 72), not in Standley (1931: 434) as incorrectly cited by Steyermark (1967: 411). The flowers are here described for the first time; they are mentioned neither in the protologue, nor in any of the subsequent descriptions ( Standley 1930b: 72; Steyermark 1967: 411, 1974: 1070-1071; Zappi & Steyermark 2004: 808–809).

The type specimen of Rudgea corocoroensis was only seen in photograph, which is sufficient to establish that it agrees with R. maypurensis in all essential characters, particularly the diagnostic stipules, although the petioles are longer than usual for the species; the two names are therefore synonymized here. Steyermark (1988: 350) described the stipules of R. corocoroensis as having “5-7 rigid aculeae arising at or just below the sheath summit”, apparently omitting the dorsal appendages that are clearly present, and the calyx tube as 2 mm long, which is instead much smaller. He considered R. corororoensis as related to Rudgea morichensis Steyermark (1967: 424) but the latter is quite different, e.g. in its deeply cupular calyx and prominent tertiary leaf veins, and does not seem to belong to the R. hostmanniana complex.

The types of both Rudgea maypurensis and R. corocoroensis have glabrous twigs, petioles and inflorescences; in all other collections seen these parts are shortly patent-puberulous.

A collection from Brazil, cited below, is a new record for the country; although it is sterile and was only seen on photograph, its identification is without any doubt. A specimen from Colombia, Cuatrecasas 4052, referred to this species with some doubt by Steyermark (1967: 411), has not been seen for this revision.

Additional Specimens Examined: — BRAZIL. Amazonas: vicinity of Pico Rondon, Perimetral Norte Highway km 211, 1°32’N 62°48’W, 2 February 1984 (st.), G. T. Prance , I. L. do Amaral , J. J. Pipoly , A. S. Tavares , C.D.A. da Mora & A. Cress 28731 ( NY) .

VENEZUELA. Amazonas: 8 km S of Puerto Ayacucho , estación de piscicultura, 5°36’N, 67°37’W, 13–15 April 1978 (fl.), G . Davidse & O . Huber 14888 ( K); Raudal d’Atures, 1 August 1887 (fr.), Gaillard 36 ( P); Estación de Piscicultura de Puerto Ayacucho , 5°37’N, 67°37’W, 15 April 1977 (st.), O . Huber 617 ( K); ibid., 15 April 1977 (fl.), O . Huber 617a ( K); ibid., 15 April 1977 (imm. fr.), O . Huber 617b ( K) ; 1–2 km E of Hotel Amazonas, Puerto Ayacucho , 8 November 1953 (fr.), B . Maguire, J. J . Wurdack & G. S . Bunting 36034 ( K) ; 6 km N of Puerto Ayacucho on road to El Burro, 26 April 1984 (fl.), T . Plowman 13733 ( K); ibid., T . Plowman 13742 ( K); Cerro Piapoco, cerca del km 12–13 de la carretera Puerto Ayacucho – Sanariapo, 31 July 1967 (fr.), L . Ruiz-Terán 4444 ( BR, K); Puerto Ayacucho , 18 May 1940 (fr.), L . Williams 12972 ( 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).