LEAVES pendent; petioles 14-45 cm long, ca. 6 mm diam., terete: geniculum to 1.5 cm long; blades oblong, moderately coriaceous, abruptly to gradually short-acuminate at apex, acute to weakly attenuate at base, 32-68 cm long, 6-10.3 cm wide, broadest near the middle, the midrib raised above and below; the primary lateral veins 13-15 per side, departing midrib at 55° angle, sunken above, prominulous below; collective vein arising from the base, 2-5 mm from the margin, sunken above, raised below.

INFLORESCENCE erect or pendent, shorter than the leaves; peduncle (10)28-43 cm long, 4-5 mm diam., terete, shorter or longer than petioles; spathe moderately thick, medium green sometimes tinged reddish at anthesis, ovate to ovate-elliptic, 5.5-8.5 cm long, 3.5-5.5 cm wide, broadest from 1 cm above the base to about the middle, acute to rounded and apiculate at apex, cordate and somewhat clasping at base, inserted at 25°-40° angle on peduncle, ± erect and held close to spadix or at ca. 45° angle to peduncle; spadix sessile or subsessilc, green, reddish-brown to red-violet, 7-8 cm long, to 8 mm diam., at base, to 6 mm diam. at apex; flowers square to weakly 4-lobed, 1.7-2.5 mm long in both directions; 6-10 flowers visible in the principal spiral, 6-9 flowers visible in the alternate spiral; the lateral tepals to 1.2 mm wide, the inner margin concave, pistil green scarcely emergent, the stigma oblong, 0.5-0.6 mm long; stamens emerging rapidly throughout, lateral stamens first, quickly followed by alternate stamens, exserted on short, translucent filaments, retracting to hold anthers just above the margins of the tepals; anthers orange, ca. 0.6 mm long, 0.8 mm wide; thecae ovate-ellipsoid, slightly divaricate; pollen orange, faintly spicy scented at anthesis.

INFRUCTESCENCE spreading to pendent, the spathe usually withered, the spadix to 9 cm long, 2 cm diam.; berries exserted ca. 1 mm, before maturity, obovoid, flattened, orange (B & K Yellow-red 7/5), 9-11 mm long, 5-7.5 mm diam., rounded at apex; mesocarp juicy with sparse, thick raphide cells; seeds 2 (rarely 1), tan, 3-4.5 mm long, 2.2-3 mm wide, 1.8-2.2 mm thick, enveloped in almost translucent (tinged orange) casing, ca. 10 mm long and as wide as the seed. Figs. 20, 21, and 27.

Anthurium brenesii is presently known only from the Cordillera Central in the Province of Alajuela between San Ramon and Quesada at 1,000 to 1,560 m elevation. The species is related to A. protensum with which it shares similar leaf texture and cataphylls, and similar altitudinal range. It differs from that species, however, by its abruptly acuminate leaf blades, its short, broad spathe, which is subcordate at the base, and its shorter, broader spadix. It is also similar, especially vegetatively, to A. prolatum, but differs in having much shorter, broader leaves. It is placed in section Pachyneurium.

Map of Mesoamerican specimens with coordinates

Costa Rica : Rincón de la Vieja, 1000 m,, 1984, Baker R20 (BM). Costa Rica Alajuela: 1000 m, 10.12.10N 84.36.10W, 21 Feb. 1991, Herrera et al. 4936 (MO, CR).
Costa Rica Alajuela: Reserva Forestal San Ramón, 800-1000 m, 10.12.53N 84.36.28W, 3 Nov 1986, Herrera & Mora 180 (MO).
Costa Rica Alajuela:, , Brenes 5738 (F). Costa Rica Alajuela: Cordillera Central,, , Williams et al. 29034 (F).
Costa Rica Alajuela:, , Thomas B. Croat 46923 (COL,CR,DUKE,F,GH,K,MEXU,MO,NY,P,PMA,RSA,SEL,U,US,VEN).
Costa Rica Alajuela: 900-950 m, 10.17N 84.45W, 20 Jul 1985, B. Hammel, C. Kremen & J. Trainer 14231 (MO).
Costa Rica Alajuela: R.F. San Ramón, 1100 m,, 27 Apr 1993, Reyes, M. & C. Plantas 121 (INB).
Costa Rica Guanacaste: Parque Nacional Ríncon de la Vieja, 900-1200 m, 10.47N 85.18W, 27-28 Jan 1983, Davidse et al. 23448 (CR, K, MO).
Costa Rica Guanacaste: 1100 m, 10.55.45N 85.28.15W, 21 November 1990, Roberto Espinoza 35 (MO).
Costa Rica Guanacaste: 1100 m, 10.56N 85.28W, 14 Mar. 1989, Grayum et al. 9323 (MO).
Costa Rica Puntarenas: 1700 m,, 24 August 1985, William A. Haber 2413 (MO).
Costa Rica Puntarenas: 1000-1200 m, 10.16N 84.48W, 18 Jun 1985, B. Hammel & W. Haber 13906 (MO).
Costa Rica Puntarenas: 1000-1200 m, 10.16N 84.48W, 18 Jun 1985, B. Hammel & W. Haber 13905 (MO).
Costa Rica Puntarenas: R.B. Monteverde; Cordillera de Tilarán, 1300 m, 10.16N 84.22W, 4 May 1991, Erick Bello, Eladio & Roy Cruz 2723 (CR).