Petronymphe decora Moore (1951: 258)

Gutiérrez, Jorge, Terrazas, Teresa & Solano, Eloy, 2016, Petronymphe rara a new species of Oaxaca, Mexico and the rediscovery of P. decora (Asparagaceae: Brodiaeoideae), Phytotaxa 269 (2), pp. 113-119 : 116-118

Petronymphe decora Moore (1951: 258)

Type:— MEXICO. Guerrero: Km 337‒338, outside Acahuizotla in the highway to Acapulco, 13 September 1949, H. E. Moore 5105 (holotype BH!).

Perennial herbs, up to 50‒60 cm high. Corm 1.5‒2.2 × 1.5‒2.5 cm, subglobose, slightly compressed, covered by grey, membranous leaves bases, covering up to 2.5 cm of the lower base; roots fibrous, some fleshy. Leaves 4‒6, light green, obtriangular in transversal section, 45‒75 × 0.3‒0.5 cm, linear, with hyaline prominences on the parallel veins and acute apex. Inflorescence stem 45‒60 × 0.3‒0.4 cm, terete, glabrous. Bracts triangular 3‒4, 7.5‒8.0 × 2.2‒2.5 mm, 3- nerved; bracteole one per flower, 6.0 × 1.5 mm. Inflorescence an umbel with 3‒14 flowers, pedicels 5.5‒8.5 cm long, with a conspicuous joint with flowers. Flowers tubular, descendent and nodding, 6-merous; perigone yellow-green, perigone tube 4.0‒ 5.5 cm long, with three depressions in the base; tepals lobes imbricated, biseriate, shorter than the tube, entire, papillose, with a green middle line; outer lobes 11‒13 × 3.5‒4.0 mm, narrowly elliptic, with acute apex; inner lobes 11‒13 × 4.0‒5.0 mm, elliptical, with obtuse apex. Stamens 6, filaments adnate to the tube and arising at the mouth of the tube, free portion of filaments filiform, flared towards the base, white, 3.5‒6.5 mm long; anthers blue, (2.0‒)3.5‒4.5 × 0.6‒0.8 mm, sagittate, dorsifixed. Gynophore 10‒15 mm long, radially adnate to the perigone tube, developing three cavities. Ovary superior, ovoid, 7.0‒9.0 × 2.5‒3.0 mm, adnate along ¼ of its length to the tube; style 35‒42 mm long, filiform; stigma 3-lobed, papillose. Fruit a capsule, erect, loculicidal, ovoid, 15‒17 × 10 mm, brown, glabrous, enclosed by the persistent remnants of the perigone and erect. Seeds 6.0 × 3.0 mm, irregularly ellipsoid, laterally compressed, black, shiny, reticulated ( Fig. 2b ).

Habitat:— Petronymphe decora inhabits semi-deciduous forests at an elevation of ca. 700 m.

Distribution:— It is distributed in the Sierra Madre del Sur, in the state of Guerrero.

Phenology:— Petronymphe decora blooms from August to September and fruits appear from September to October.

Other specimens examined:― MÉXICO. Guerrero: Municipality Chilpancingo de Los Bravo, km 337‒338, beyond Acahuizotla on highway to Acapulco , cultivated at Ithaca , 2 August 1952, H. E. Moore 6468 (2262319, US!) ; Ibidem, cultivated at Ithaca , 14 October 1958, H. E. Moore 6937 bis (2262319, US!) ; Guerrero: Municipality Chilpancingo de Los Bravo, 1 km after the highway junction Acapulco-México, along the road to Acahuizotla , 18°05´01´´N, 99°04´54´´W, 19 August 2012, 721 m elevation, J. Gutiérrez & R. Ríos 1350 ( MEXU!) .

Conservation status:— The species is only known from the vicinity of Acahuizotla. A single population is known that does not exceed 30 individuals covering ca. 100 m 2. The Acahuizotla region is part of the priority area for the conservation of Mexican dry forests ecoregions in the dry forests of the Mexican Pacific ( Ceballos et al. 2010). Based on these data the species can be assigned to the Critical Risk IUCN category. However, a demographic study is needed.

Figures

FIGURE 2. Some diagnostic traits of Petronymphe species.a–c. P.decora (J. Gutiérrez & R. Ríos 1350), a. Flower, b. Testa ornamentation. c. Leaf in transversal section. d–f. P. rara (J. Gutiérrez & R. Ríos 1410). d. Flower, e. Testa ornamentation, f. Leaf in transversal section. Scales: b, e: 200 μm; c, f: 300 μm.