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| Agave rosalesii A. Vázquez, Thiede, Etter & Kristen, in Vázquez-García, Thiede, Etter et Kristen, 2022. facebook.com: Santiago Rosales |
Abstract
Background: Agave ellemeetiana (A. sect. Choritepalae) features soft and “spineless” leaves and occurs in two disjunct and ecologically differentiated populations classified as subspecies. An incidental look at the flowers of A. ellemeetiana ssp. subdentata unveiled that these did not match those of A. ellemeetiana s. str. nor those of sect. Choritepalae.
Questions: Do these disjunct populations differ in flower and fruit morphology? Do they belong to the same section within Agave?
Hypotheses: The floral morphology of populations of Agave ellemeetiana ssp. subdentata from western Oaxaca places this species in A. sect. Inermes, and the set of qualitative and quantitative differences is sufficient to recognize it as a distinct species.
Studied species: Agave ellemeetiana, Agave pedunculifera.
Study site and dates: Putla District, western Oaxaca, December 2011 and April 2014.
Methods: We conducted an alpha-taxonomic study of the Agave ellemeetiana species complex, involving two fieldwork expeditions, review of literature, online images, and herbarium specimens.
Results: Differences in flower, fruit and vegetative morphology and habitat support the segregation of the populations (from the Putla District, Oaxaca) from the Agave ellemeetiana complex as a new species, A. rosalesii spec. nov. The presence of an evident corolla tube places the proposed taxon close to A. pedunculifera and within A. sect. Inermes.
Conclusions: The populations from the Putla District are sufficiently distinct in their morphology and ecology to merit recognition as a new species, Agave rosalesii, placed in A. sect. Inermes.
Keywords: Agave ellemeetiana subsp. subdentata, Agave sect. Choritepalae, Agave sect. Inermes, corolla tube, endemic, montane pine-oak forest
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| Agave rosalesii A. Vázquez, Thiede, Etter & Kristen. A. Habit. B. Rosette. C. Leaf margin. D. Terminal spine. E. Capsules. F. Peduncle segment. G. Inflorescence segment. H. Flower bud. I. Fully developed flower. J. Geminate flowering node. K. Dissected flower. Mostly from photographs by Julia Etter & Martin Kristen, except E. from E. Solano w/ R. Ríos 1976 (MEXU). Illustration by Edgar Esau Vázquez-Verdejo. |
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| Agave rosalesii A. Vázquez, Thiede, Etter & Kristen. A. Geminate flowering node with outer and inner floral bracts (bracteoles). B. Dissected flower showing corolla tube and ovary. C. Inflorescence close up. D. Leaf showing a terminal spine. E. Habitat. F. Habit in full bloom. G. Rosettes. H. Leaf margin. Photographs by Julia Etter & Martin Kristen. |
Agave rosalesii A. Vázquez, Thiede, Etter & Kristen, spec. nov.
Agavero salesii is also similar to Agave pedunculifera in having non-offsetting rosettes, a denticulate leaf margin, a distinct corolla tube, a similar tepal lobe size and anther length, but it differs from the latter in having leaves broadly oblanceolate to rarely elliptic vs. mostly ovate-acuminate or lanceolate; leaf size 43.0-60.0 × 14.0-30.0 cm (vs. 80.0-90.0 × 11.0-15.0 cm); leaf length to width ratio 2.6-3.2 (vs. 5.2); terminal spine 2.0-3.0 mm long (vs. 10.0 mm); inflorescence 3.2-3.5 m long (vs. 2.0-3.0 m); pedicels 4.0-5.0 mm long (vs. 20.0-30.0 mm); flower length 3.3-3.5 cm (vs. 3.7-5.2 cm); flower color yellow (vs. pale yellow); tepal lobes reflexed rolled, 19.0-22.0 × 6.5-7.0 mm (vs. erect, 12.0-18.0 × 5.0-6.0 mm); number of flowers per node 2 (vs. 4), filaments 60.0-65.0 mm long (vs. 40.0-55.0 mm); and style 40.0-53 mm long (vs. 20-27 mm) (Table 1).
Distribution and ecology. Agavero salesii is endemic to the Putla District in western Oaxaca, in the municipalities of Santa Cruz Itundujía (paraje Los Monos), Santa María Yucuhiti (Yosonicaje) and Putla Villa de Guerrero (Las Mesas Santo Domingo), inhabiting rocky outcrops of montane pine-oak forest at 2,400-2,600 m in elevation within the Río Verde basin. It grows with A. kavandivi, Echeveria sp., Furcraea sp., Pinguicula sp., Pinus sp., and Sprekelia sp. (Table 2, Figure 1).
Etymology. The species honors Carlos Santiago Rosales Martínez, a young enthusiastic agavologist, explorer, and horticulturist of succulents, who, in collaboration with the first author, unveiled that the Putla populations traditionally treated as belonging to A. sect. Choritepalae, actually belong to A. sect. Inermes due to the presence of a distinct corolla tube.
J. Antonio Vázquez-García, Joachim Thiede, Julia Etter and Martin Kristen. 2022. Agave rosalesii (sect. Inermes, Asparagaceae), segregated from Agave ellemeetiana K. Koch (sect. Choritepalae): A New Species from the Mixteca Alta of western Oaxaca, Mexico. Botanical Sciences. 1(1); DOI: 10.17129/botsci.3044
