Spathacanthus magdalenae Castillo-Campos, Nordic J. Bot. 31: 449. 2013.

Burgos-Hernandez, Mireya & Castillo-Campos, Gonzalo, 2020, Taxonomic revision of the Mesoamerican genus Spathacanthus (Justicieae, Acanthoideae, Acanthaceae), PhytoKeys 144, pp. 31-55 : 31

Spathacanthus magdalenae Castillo-Campos, Nordic J. Bot. 31: 449. 2013. Figs 6 , 7

Type.

Mexico. Veracruz: San Andrés Tlalnelhuayocan (previously Coatepec as a publication error), Piedras Blancas, eastern slopes of the volcano Cofre de Perote, riparian vegetation, 1666 m a.s.l., 7 Mar 2012. G. Castillo-Campos et al. 27235 (holotype XAL!; isotypes ENCB!, MEXU!).

Description.

Small trees or shrubs, up to 12 m height, highly branched, internodes glabrous. Stems quadrate to flattened when young, glabrous or pubescent at nodes with eglandular trichomes. Leaves with petioles 10-50 mm long, blade elliptic to obovate-elliptic, 110-280 mm × 42-129 mm, apically acute to acuminate, basally acute, margin undulate, tomentose when very young along veins, then glabrous on both surfaces. Inflorescences terminal, rarely axillary, rachis glabrous; bracts triangular to subulate, 7 mm × 1 mm, abaxial surface tomentose; bracteoles triangular to subulate, 3.5 mm long, abaxial surface tomentose. Flowers subsessile to short pedicellate, pedicels to 6 mm long, glabrous; calyx yellowish before fruiting, turning green in ripe fruit, 18-25 mm × 13 mm, equally divided into 2 prominent elliptic to ovate segments; anterior segment bilobed, the posterior segment trilobed; lobes triangular, 15 mm long, apically acute to apiculate; corolla white, 58-100 mm long × 38-44 mm wide, externally glabrous and internally pubescent, throat 10-12 mm long × 3-6 mm in diameter near midpoint, upper lip bilobed, oblong, lower lip trilobed, both lobes 10-17 mm long, glabrous. Stamens whitish, longer pair about 16 mm long from the base to the apex of the thecae, shorter pair about 10 mm long; anthers monothecate, 3.5 mm long; style glabrous, 26 mm long, stigma lobes 0.3-0.7 mm long. Capsule 65-89 mm long; stipe 35-49 mm long, head 30-40 mm long. Seeds subcircular to subcordate, 8 mm × 9 mm long, surface roughened.

Distribution, habitat and phenology.

Spathacanthus magdalenae is endemic to southern Mexico where it is restricted to the riparian vegetation of central Veracruz (Fig. 1B ). It is frequent near rivers or humid canyons in cloud forests and oak forests in tropical to temperate zones, at 1300 to 1700 m a.s.l. Flowering takes place from November to March; mature fruits can be found from January to March.

Specimens examined.

Mexico. Veracruz: Mpio. San Andrés Tlalnelhuayocan, Piedras Blancas, Eastern slope of the volcano Cofre de Perote, 1666 m a.s.l., 7 Mar 2012, G. Castillo-Campos et al. 27189 (XAL, MEXU, ENCB); Piedras Blancas, Eastern slope of the volcano Cofre de Perote, 1666 m a.s.l., 30 Apr 2012, G. Castillo-Campos et al. 27377 (XAL, MEXU, ENCB); San Antonio, 1350 m a.s.l., 06 Feb 1982, F. Ventura A. 19361 (ENCB, IEB, XAL); Mpio. Jacomulco, barranca de Actopan, road to Buena Vista, 1 km after Jalcomulco, 646 m a.s.l., 12 Jun 1991, G. Castillo-Campos et al. 8206 (XAL).

Figures

Figure 1. Distribution of the Mesoamerican genus Spathacanthus Baillon. A Distribution of S. hahnianus and S. hoffmannii B distribution of S. magdalenae and S. parviflorus.

Figure 6. Spathacanthus magdalenae Castillo-Campos. G. Castillo-Campos 27235 (XAL), Mexico: Veracruz, San Andres Tlalnelhuayocan.

Figure 7. Spathacanthus magdalenae Castillo-Campos. Image and legend modified from Castillo-Campos et al. (2013), page 450. a Branch showing insertion of the leaves and position on the branch, inflorescences with flowers and buds b flowers, c calyx d open flower with stamens and style e stamen f style g branch with open capsules h open capsule with retinacula subtending seeds in both valves of fruit i interior of half of a capsule j seeds k retinacula removed from the capsules. Illustration: E. Saavedra.