Petronymphe rara J. Gut., 2016

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 : 114-116

Petronymphe rara J. Gut. sp. nov. ( Figs. 1 , 2d‒f ).

Perennial herb; leaves terete; flowers nodding, tubular, red-orange; perigone tube 1.0‒2.0 cm long; free portion of tepals ovate and three ribbed; anthers 2.0 × 0.7 mm; fruit 10 × 6‒8 mm; and seeds 3.0 × 2.0 mm.

Type:— MÉXICO. Oaxaca: District Huajuapan, municipality Santo Domingo Tonalá, 2 km S of Santo Domingo Tonalá , on the highway Santo Domingo Tonalá-Juxtlahuaca , 17°38´35´´N, 97°52´21´´W, 1423 m elevation, 9 September 2012, J. Gutiérrez & R. Ríos 1410 (holotype, MEXU!; isotypes, FEZA!, IEB!, UAMIZ!, NY!) .

Perennial herbs, up to 60 cm high. Corm 1.5‒2.5 × 1.5‒2.0 cm, subglobose, slightly compressed, covered by grey, membranous leaf bases which extend about 4 cm up the inflorescence stem below the leaves rosette; roots fibrous, somewhat fleshy. Leaves dark green, semiterete in transversal section, 3–4 per rosette, 34‒60 × 0.1‒0.2 cm, linear, rough with prominent parallel veins and acute apex. Inflorescence stem 33‒65 × 0.15 cm, terete, glabrous or scaberulous at its base. Bracts narrowly triangular, 4, located at the base of the umbel, (3.5‒)5‒6 × (0.5‒)2.0‒ 2.5 mm, 3-nerved; bracteole one per flower, 5.0 × 1.5 mm. Inflorescence an umbel with 3‒25 flowers, pedicels 2.0‒ 4.5 cm long, spreading to suberect with a conspicuous geniculate joint. Flowers tubular, descendent and nodding, 6-merous; perigone reddish-orange with a yellow tinge and purple margins in the lobes, perigone tube 1.0‒2.0 cm long, with three depressions at the base; tepals lobes imbricated, biseriate, shorter than the tube, entire, acute, papillose, reddish with purple margin and a greenish-yellow middle line; outer lobes 4.5‒6.5 × 1.5‒2.5 mm, ovate; inner lobes 4‒6 × 2.0‒ 2.7 mm, obovate. Stamens 6, adnate to the perigone and arising at the mouth of the perigone tube; free portion of filaments white, 1.0‒ 1.5 mm long, filiform, wider towards the base; anthers blue, 2.0 × 0.7 mm, lanceolate, dorsifixed. Gynophore (6.5‒)10.0‒ 15.0 mm, radially adnate to perigone tube, developing three cavities. Ovary superior, ovoid, 3‒4 × (1.0‒) 1.8 mm, adnate for ¼ of its length to the tube; style 4.5‒7.5 mm long, filiform; stigma 3-lobed, papillose. Fruit a capsule, erect, loculicidal, ovoid, 10.0 × 6.0‒8.0 mm, brown, glabrous, enclosed by the persistent remnants of the perigone. Seeds 3.0 × 2.0 mm, irregularly ellipsoid, laterally compressed, black, shiny, reticulated ( Fig. 2a‒c ).

Habitat:— Petronymphe rara inhabits tropical deciduous forest on gypsum soils.

Distribution:— It is distributed in the Sierra Madre del Sur, in the state of Oaxaca in elevations between 1400 and 1500 m.

Etymology:— The specific epithet of the new species ‘rara’ is derived from the Latin word rare, meaning “rare” because its distribution is limited to a small geographical area.

Phenology:— Petronymphe rara blooms from July to August and fruits appear from August to September.

Paratypes:— MÉXICO. Oaxaca, District Huajuapan, municipality Santo Domingo Tonalá. Tropical deciduous forest, on the hills, 27 August 2008, A. Torres-Hernández & L. Hernández 194 (MEXU!, SERO!). Culebra hill on the top, 13 September 2008, A. Torres-Hernández & L. Hernández 294 (1260399, MEXU!, SERO!). De la Cuchara gully, 7 October 2008, L. Hernández & A. Torres-Hernández 444 (1281904, MEXU!, SERO!). 2 km south of Santo Domingo Tonalá, adjacent to the gypsum mine, along the highway Huajuapan-Juxtlahuaca. 28 July 2012, J. Gutiérrez et al. 1272 (MEXU!, FEZA!, JES!, IEB!, UAMIZ!, NY!).

Conservation status:— The new species is only known from Santo Domingo Tonalá and its surroundings. Its populations are abundant but localized. In addition, the area where it is distributed has been decreed recently as Flora and Wildlife Boquerón de Tonalá Protected Area by the Mexican government ( CONANP 2013). It is urgent to generate the required information to be able to assign this species to one of the IUCN categories.

Figures

FIGURE 1. Petronymphe rara. a. Plant; b. Leaf in transversal section; c. Inflorescence; d. Flower; e. Free portion of outer tepal; f. Free portion of inner tepal; g. Outer tepal apex; h. Dissected flower; i. Stamen; j. In transversal section: 1. Ovary, 2. Ovary base, 3. Floral tube and gynophore, 4. Pedicel; k. Fruit; l. Seed.

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.