Polianthes cernua Art.Castro, J.G.González & Aarón Rodr., 2015

Castro-Castro, Arturo, González-Gallegos, Jesús Guadalupe & Rodriguez, Aarón, 2015, A new species of Polianthes subgenus Bravoa (Asparagaceae, Agavoideae) from Jalisco, Mexico, Phytotaxa 201 (2), pp. 140-148 : 143-145

Polianthes cernua Art.Castro, J.G.González & Aarón Rodr. sp. nov. ( Figs. 2 , 3 )

Species P. bicolori et P. geminiflorae var. clivicolae affine sed foliis oblongo-obovatis et plerumque prostratis, nodis floralibus (3–)4– 6(–9), pedicellis per anthesin 1.1–1.7 cm longis et recurvatis, perigoniis tubularibus, nullo modo curvatis, depressis et bicoloribus, perigoniorum lobis per anthesin imbricatis et rectis, et filamentis 1.4–1.6 mm longis ad 1–1.5 mm insertis supra ovaris apicem differt.

Type:— MEXICO. Jalisco: Mixtlán, 5 Km NE de Mixtlán, alrededores del puente Los Tablones de la carretera Ameca-Mascota, brecha a Macuchí, 1918 m, 20º22’8’’N, 104º35’ 58’’ W, 2 August 2011 (fl, fr), A. Castro-Castro, J. G. González-Gallegos, M. Harker & E. A. Suárez-Muro 2495 (holotype IBUG!, isotypes IEB!, MEXU!).

Perennial herb. Corm oblong 0.6–1.9 × 1.1–1.5 cm, with growth buds and thickened contractile and fleshy roots. Bulb ovoid, 2–2.6 × 1.5–1.9 cm, covered by the persistent leaf bases. Leaves (2–)3(–4) in a basal rosette, sometimes with an additional one attached a few cm above the peduncle base, prostrate or slightly elevated from the surface; alternate, oblong-obovate, (6–)8–12 × 0.6–2.2(–4.5) cm, widest at the middle and tapering somewhat abruptly at both ends, semi-succulent, shiny when fresh, acute, margin entire, hyaline, upper and lower surface glabrous. Inflorescence racemose, 45–80 cm long, internodes decreasing in size towards the apex, with (3–)4–6(–10) floral nodes; scape bracts 2–3, primary sterile bract linear-lanceolate, 2.5–4.4 cm × 0.4–0.5 cm, apex acute, base truncate, margin smooth, primary floral bracts lanceolate to triangular, 0.6–1.5 × 0.2–0.3 cm, apex acute, base truncate, margin smooth, becoming scarious. Bracteoles ensiform, 0.2–3 × 0.1–2 mm, entire, acute, truncate. Pedicels 1.1–1.7 cm during anthesis, 1.5–2 cm in fruit, strongly recurved. Flowers geminate, 2–2.5 × 0.3–0.6 cm, bicolor, succulent, odourless; perigone tube 1.6–1.9 × 0.4–0.6 cm at the base of the lobes, tubular, not curved, the first 2/3 orange, the last third and the lobes yellowish green. Lobes broadly ovate, almost equal, 2–4 × 2.5–3 mm, margin hyaline, apex truncate in the internal series to obtuse in the external one and with a tuft of white hairs at the tips, both erect and imbricate. Stamens included, filaments yellow, filiform, 1.4–1.6 cm long from their insertion into the perigone tube, inserted 1–1.5 mm above the ovary apex; anthers linear, 4.5–5 × 1–2 mm, green, in anthesis on the upper portion of the mouth of the tube. Ovary 4.5–5 × 2.5–3 mm; style filiform, 1.6–2 cm, greenish orange, exserted from the tube 2–3 mm in anthesis; stigma trilobed, papillose. Fruit a loculicidal capsule, 0.8–2 × 0.7–1.1 cm, globose to oblong, crowned by the remains of the perigone. Seeds ovate-depressed, 4–6 × 3–5 mm, flat, black to dark brown, opaque ( Figs. 2 , 3 ).

Etymology:—The specific epithet refers to its pendulous flowers; this feature is characteristic of other species of Polianthes subgenus Bravoa , but is very noticeable in P. cernua .

Distribution, habitat and phenology: — Polianthes cernua grows in the upper basin of the Atenguillo River, in western Jalisco. It is endemic to a mountain system known as Sierra Verde, in the municipalities of Atengo and Mixtlán, Jalisco, Mexico ( Fig. 1 ). It inhabits open Quercus L., Juniperus L., and Pinus L. forests. Polianthes cernua is associated with Ageratina Spach sp. , Cosmos intercedens Sherff , C. sessilis Sherff , Dahlia pugana Aarón Rodr. & Art. Castro , Juniperus flaccida Schltdl. , Pinus lumholtzii B.L.Rob. & Fernald , P. oocarpa Schiede ex Schltdl. , Prochnyanthes mexicana (Zucc.) Rose , Quercus castanea Née , Q. resinosa Liebm. , Salvia pugana J.G.González & Art.Castro , Tigridia dugesii S.Watson , and Verbesina L. sp. The plants are found in areas with deep and acid soils at 1700–2120 m elevation. They flower in early August and fruit in September. During numerous fieldwork trips, we noticed hummingbirds visiting P. cernua .

[A. Castro-Castro, J.G. González-Gallegos, M. Harker & E.A. Suárez-Muro 2495 (IBUG, IEB!, MEXU)].

Additional specimens examined (paratypes): — MEXICO. Jalisco: Atengo, Sierra Verde, km 18.5 de la brecha Los Tablones-Soyatlán del Oro-Tenamaxtlán , 2110 m, 20º25’17.8’’N, 104º18’8.1’’W, 5 August 2013 (fl, fr), A. Castro-Castro , J. G. González-Gallegos & J. L. Villa-Vázquez 3269 ( IBUG!). Mixtlán , km 48 carr. Méx. 70 entre Ameca y Mixtlán, puente Los Tablones , 1719 m, 20º 27’44.7’’N, 104º22’45.7’’W, 3 August 2011 (fl, fr), A. Rodríguez, A. Castro-Castro & M. A. García-Martínez 6272 ( ENCB!, IBUG!, IEB!, MEXU!) ; km 47–48 carr. Méx. 70 entre Ameca y Mascota, puente Los Tablones , 1704 m, 20º27’44.8’’N, 104º22’45.5’ W, 17 August 2012 (fl, fr), A. Rodríguez et al. 6727 ( IBUG!, IEB!, MEXU!) ; km 6 de la brecha Los Tablones-Soyatlán del Oro, Sierra Verde , 1918 m, 20º27’1.3’’N, 104º21’44’’W, 5 August 2013 (fl, fr), A. Castro-Castro, J. G. González-Gallegos & J. L. Villa-Vázquez 3260 ( IBUG!, IEB!, MEXU!) ; Sierra Verde, km 17 de la brecha Los Tablones-Soyatlán del Oro, rumbo a Tenamaxtlán , 2052 m, 20º24’26.3’’N, 104º18’41.1’’W, 5 August 2013 (fl, fr), A. Castro-Castro, J. G. González-Gallegos & J. L. Villa-Vázquez 3263 ( IBUG!, IEB, MEXU!) ; puente Los Tablones, km 47–48 carretera Méx. 70 entre Ameca y Mixtlán, 1705 m, 20º27’50’’N, 104º22’38.8’’W, 29 July 2014 (fr), A. Rodríguez & A. Castro-Castro 7138 ( IBUG!, IEB!, MEXU!) .

Taxonomic relationships: — Morphologically, Polianthes cernua falls within P. subgenus Bravoa . It has scentless and geminate flowers at the nodes and the filaments inserted below midportion of the perigone tube. It is characterized by a combination of character-states including: oblong-obovate and generally prostrate leaves, (3–)4–6(–10) floral nodes, pedicels 1.1–1.7 cm long during anthesis and recurved, perigone tubular, not curved, depressed, and bicolor with imbricate and erect lobes in anthesis and filaments 1.4–1.6 mm long, inserted 1–1.5 mm above ovary tip ( Figs. 2 , 3 ). Polianthes cernua shares morphological similarities with P. bicolor and P. geminiflora var. clivicola McVaugh (1989: 252) . Both P. cernua and P. bicolor have bicolor flowers, and P. cernua and P. geminiflora var. clivicola produce depressed flowers. Their differences are highlighted in Table 2.

Figures

FIGURE 1. Diversity and distribution of Polianthes subgenus Bravoa in Nueva Galicia, Mexico.

FIGURE 2. Polianthes cernua Art.Castro, J.G.González & Aarón Rodr. A. Habit. B. Flowers detail. C. Flower dissection showing internal perigone, gynoecium and androecium. D. Fruits. Illustrated by Josue Ortíz-Catedral, based on living plants from the type material

FIGURE 3. Diversity of Polianthes subgenus Bravoa in Mexico. A–E. P. cernua. F. P. bicolor (E. Solano & Ma. del C. López 857, MEXU). G. P. geminiflora var. clivicola (A. Rodríguez & L. Ortiz-Catedral 3210, IBUG).H. P. geminiflora var. geminiflora (A. Rodriguez & D. Szeszko 5617, IBUG). I. P. graminifolia (A. Rodríguez & 5545, IBUG). J. P. howardii (P. Carrillo-Reyes et al. 7401, IBUG). K. P. multicolor (A. Rodríguez 5769, IBUG). L–M. P. zapopanensis (A. Rodríguez et al. 4338, 5120, IBUG). Pictures:A. Castro-Castro (A–E), A. Rodríguez (G–I, K–M), E. Solano (F), and P. Carrillo-Reyes (J).