Basic Literatur

Agave rzedowskiana, a new species in subgenus Littaea (Agavaceae) from western Mexico

Pablo Carrillo-Reyes, Rito Vega Aviña, and Raymundo Ramírez-Delgadillo

Carrillo-R., Pablo (Jardín Botánico y Herbario, Universidad Autónoma de Guadalajara, Apartado postal 1-440, 44100 Guadalajara, Jalisco, México. pcarrilloreyes@yahoo.com.mx), Rito Vega-A., (Facultad de Agronomía, Universidad Autónoma de Sinaloa, Apartado postal 726, 80000 Culiacán, Sinaloa, México. rito29@prodigy.net.mx), & Raymundo Ramírez-D. (Departamento de Botánica y Zoología, CUCBA, Universidad de Guadalajara, Apartado postal 1-139, 45101 Zapopan, Jalisco, México. rramirez@udgserv.cencar.udg.mx). Agave rzedowskiana, a new species in subgenus Littaea (Agavaceae) from western Mexico. Brittonia 55: 240-244. 2003.- Agave rzedowskiana is described and illustrated from the states of Sinaloa and Jalisco, Mexico. This species is a member of subgenus Littaea (Tagliabue) Baker "group Striatae" of Baker. It is compared with A. petrophila García-Mend. & E. Martínez and A. dasylirioides Jacobi & Bouché.

Key words: Agave rzedowskiana, Agavaceae, Littaea, Mexico, Jalisco, Sinaloa.

Carrillo-R., Pablo (Jardín Botánico y Herbario, Universidad Autónoma de Guadalajara, Apartado postal 1-440, 44100 Guadalajara, Jalisco, México. pcarrilloreyes@yahoo.com.mx), Rito Vega-A., (Facultad de Agronomía, Universidad Autónoma de Sinaloa, Apartado postal 726, 80000 Culiacán, Sinaloa, México. rito29@prodigy.net.mx), & Raymundo Ramírez-D. (Departamento de Botánica y Zoología, CUCBA, Universidad de Guadalajara, Apartado postal 1-139, 45101 Zapopan, Jalisco, México. rramirez@udgserv.cencar.udg.mx). Agave rzedowskiana, a new species in subgenus Littaea (Agavaceae) from western Mexico. Brittonia 55: 240-244. 2003.-Se describe e ilustra Agave rzedowskiana de los estados de Sinaloa y Jalisco, México. La especie pertenece al subgénero Littaea (Tagliabue) Baker "Grupo Striatae" de Baker. Se le compara con A. petrophila García-Mend. & E. Martínez z A. dasylirioides Jacobi & Bouché.

During recent botanical exploration in western Mexico, we found a species of Agave, that had not previously been described; we describe it here:

Agave rzedowskiana P. Carrillo, R. Vega & R. Delgad, sp. nov. (Fig. 1)

FIG.1. Agave rzedowskiana. A. Habit. B. Leaf. C. Leaf margin, detail. D. Peduncle bract. E. Flower. F. Flower, in longitudinal section. G. Fruits. H. Seed (From Carrillo-Reyes & Cabrera 1503, IBUG, Holotype).

TYPE: MEXICO. Jalisco: Mun. San Cristóbal de la Barranca, La Mesa de los Caballos, 1680 m, 27 Feb 2001, P. Carrillo-Reyes & D. Cabrera 1503 (HOLOTYPE: IBUG; ISOTYPES: GUADA, MEXU, NY).

Planta perennis, caespitosa, rosula densa; folia viridi-glauca, lineari-triangularis vel falcata, recta vel arcuata, acuminata, striata, marginibus hyalinis subtiliter denticulatis, (11-)20-35(-50) cm longis, (0.7)0.8- 1.2(1.4) cm latis, spina terminali rigida (8-)10-19(- 23) mm longa; inflorescentia (42-)70-170 cm longa (pedunculo incluso), in spicam densa; flores geminatio, infundibuliformes, (20-)22-23(-24) mm longo, ovario viridi, cylindrico, 7-9 mm longo, 3-3.5(-4) mm lato, tubo 7-7.5(-10) mm longo, perianthii segmentis 4-6(- 8) mm longis, 2-4(-6) mm latis, ovato-ellipticis, incurvatis; filamenta (22-)28-38(-45) mm longa; capsulae subsphaericae, 7-13 mm longae, 6-9 mm latae.

FIG. 2. Distribution of Agave rzedowskiana, A. dasylirioides and A. petrophila.

Plant perennial, cespitose. Stem repent to 50 cm long. Rosette hemispheric, compact, 25-45(-65) cm diam., 20-40 cm tall, grayish green. Leaves 100-260 in each rosette, linear-triangular, straight or falcate, rigid, acuminate, striate on both surfaces, glaucous or green, (11-)20-35(-50) ? (0.7-)0.8- 1.2(-1.4) cm (width in the middle; leaf widest at base, to 2.1 cm); margins hyaline, mi-nutely serrulate with 17-30 teeth per cm; spines (8-)10-19(-23) mm long, rigid, reddish brown. In?orescence including the peduncle, (42-)70-170 cm long, inclined to decumbent, occasionally sinuous; fertile portion to 10-32(-53) cm long, densely spicate, located in the upper 1/8-1/3 portion of the scape; bracts of the peduncle 2.5-9 X 0.5-0.7 cm, widest near the base, narrowed upward, acicular, pale yellow, base pale pink or pale purple, terminal spine reddish brown; floral bracts triangular, 4.2-0.7 cm long, the upper ones shorter, apex caudate, 1.9-3.5 X 0.6-0.7 cm, pale yellow, base purple, persistent, longer than the flowers. Flowers 50-200 pairs per spike, funnelform, greenish purple, (20-)22-23(-24) mm long; pedicels less than 1 mm long at anthesis, to 2 mm in fruit. Ovary 7-9 X 3- 3.5(-4) mm, cylindric to fusiform, gla-brous, slightly protruding from the perianth tube; perianth tube 7-7.5(-10) ? 9-10 mm. Tepals incurved, the inner tepals slightly narrower than the outer ones, ovate-elliptic, 4-6(-8) X 2-4(-6) mm, with a tuft of microscopic hairs at apex. Anther filaments (22-)28-38(-45) mm long, inserted at the middle of the tube; anthers centric, arched, oblong, rounded at both extremes, 8-10(- 12.5) mm long, yellow or brownish. Style filiform, sinuate when young, straight at anthesis 40-48(-51) mm. Capsules erect or appressed, nearly deltoid in cross section, subspheric, 7-13 X 6-9 mm, smooth or verrucose, dehiscence apical; the perianth occasionally persistent. Seeds 2.4-3.1 X 1.2-2.1 mm, hemispheric, triangular in cross section, black.

TABLE I Comparison between A. rzedowskiana and its more similar species. Data of Agave dasylirioides were taken from Gentry, 1982 and García-Mendoza & Martínez, 1998A. Data on A. petrophila were taken from García-Mendoza & Martínez, 1998A

Additional specimens examined: MEXICO. Jalisco: Mun. San Cristóbal de la Barranca, La Mesa de los Caballos, 1680 m, 3 Sep 2000 (fr), Carrillo-Reyes & Barba 1255 (IBUG); 18 Mar 2001 (fl), Carrillo-Reyes & Ramírez-Delgadillo 1540, (IBUG, IEB); [anomalous inflorescence], Carrillo-Reyes & Ramírez-Delgadillo 1541 (GUADA, IBUG, MEXU). Sinaloa: Mun. Concordia, La Petaca, 1600-1700 m, 19 Mar 1999 (fr), Vega-Aviña & Gutiérrez-García 10000 (MEXU, UAS); 12 Feb 2000 (fl), Vega-Aviña & Gutiérrez-García 10567 (MEXU, UAS).

Distribution and ecology. Agave rzedowskiana occurs in the southern Sierra Madre Occidental, with disjunct populations in the states of Sinaloa and Jalisco, Mexico. It might also occur in the state of Nayarit, between these two states (Fig. 2).

Agave rzedowskiana grows on igneous rocky slopes and cliffs at 1600-1700 m, in oak or oak-pine forests. In Sinaloa it occurs in oak-pine forest of Quercus subspathulata Trel. and Pinus oocarpa Scheid., associated with Trachypogon stenophyllus Hitch., Tristachya avenacea (J. Presl.) Scribn. & Merr., Muhlenbergia scoparia Vasey, Muhlenbergia alamosae Vasey, Muhlenbergia distichophylla Kunth, Cuphea hookeriana Walp., Agave pedunculifera Trel., Cheilanthes angustifolia Kunth, Dalea versicolor Zucc., Oxypappus scaber Benth., Asclepias linaria Cav., Befaria mexicana Benth., Gaultheria cordata M. Martens & Galeotti, Oncidium sp., and Encyclia sp. In the state of Jalisco, it occurs in a forest of Quercus resinosa Liebm., Quercus praineana Trel., and Pinus oocarpa Scheid., with Comarostaphylis glaucescens (H.B.K.) Zucc. et Klotz., Agarista mexicana (Hemsl.) Judd var. pinetorum (Standl. et Wms.) Judd, Acacia pennatula (Schltdl. et Cham.) Benth., Dodonaea viscosa Jacq., Clethra rosei Britton, Opuntia sp., Vernonia steetzii Sch.Bip. var. aristifera (Blake) McVaugh, Ximenia parviflora Benth., Agave guadalajarana Trel., Agave schidigera Lem., Muhlenbergia sp., Tripsacum sp., and often Epidendrum sp., Mammillaria scrippsiana (Britton et Rose) Orcutt, Hechtia sp., and Selaginella sp.

Phenology. Flowering in February-March; fruiting in May-September.

Agave rzedowskiana belongs to "group Striatae" of Baker (1888), of subgen. Littaea (Tagliabue) Baker, characterized by narrow, striate, "hard and thick but firmly fleshed" leaves, with scabrous serrulate borders, and flowers without necks and the ovary slightly protruding from the tube (Gentry, 1982).

Although the leaves of the new species resemble those of A. striata Zucc. ssp. falcata (Engelm.) Gentry, the floral morphology of the new species seems to be more similar to A. petrophila A. García-Mend. & E. Martínez and A. dasylirioides Jacobi & Bouché, with which it shares a short floral tube about as long as the tepals. However it differs from those species by its shorter and often falcate leaves and other floral characteristics: Agave rzedowskiana can be distinguished from A. dasylirioides by its habit (caespitose vs. single rosette), narrower leaves ((0.7-)0.8-1.2(-1.4) cm vs. 2-3.8 cm), and shorter flowers (22-23(-24) mm vs. (25-)30-35(-39) mm). On the other hand the new species, shares the caespitose habit with A. petrophila, but differs in its wider leaves ((0.7-)0.8-1.2(-1.4) vs. 0.4- 0.9 cm), longer floral tube (7-7.5(-10) mm vs. 3-4 mm) and shorter tepals (4-6(-8) mm vs. 9-11 mm). In addition Agave rzedowskiana has a western distribution (Sierra Madre Occidental) and it is known at 1600-1700 m elevation (vs. 1900-2500 m in A. dasylirioides and 850-1300 m in A. petrophila) (Table I).

Etymology. This species is named to honor Dr. Jerzy Rzedowski Rotter (b. 1926), of Instituto de Ecología, A. C., an untiring collector of herbarium specimens and student of the Mexican flora, who has made substantial contributions to the knowledge of the ?ora and vegetation of Mexico.

Acknowledgments

We are grateful to Abisai García-Mendoza for reviewing this manuscript and valuable advice; Mollie Harker and Eduardo Sahagún-Godínez for reviewing the English translation; Roberto González-Tamayo for the Latin description; Eugenia María Barba Robert, Dánae Cabrera-Toledo, Erika R. M. Guevara, J. Antonio Gutiérrez-García, and Luis Ortiz-Catedral for their valuable assistance and companionship during fieldwork. Thanks are given to María del Refugio Vázquez-Velasco for the illustration. We are indebted to the curators of GUADA, IBUG, IEB, MEXU, NY, and UAS for permission to examine their herbarium collections.

Literature Cited

Baker, John G. 1888. Handbook of the Amaryllidaceae. George Bell & Sons, London.

García-Mendoza, A & E. Martínez S. 1998a. Una nueva especie de Agave, subgénero Littaea (Agavaceae) de Guerrero y Oaxaca, México. Sida 18: 227-230.

---& ---. 1998b. Agave petrophila García-Mend. & E. Martínez, nom. nov. (Agavaceae). Sida 18: 627.

Gentry, H. S. 1982. Agaves of continental North America. University of Arizona Press, Tucson, Arizona.