Agave mayo A.Vázquez & Rosales, 2023

Vázquez-García, J. Antonio, Rojas-Aguilar, E. Itzel, Gónzalez-Bernal, Marco A., Carrillo-García, Jesús Alfredo & Rosales-Martínez, C. Santiago, 2023, Agave mayo (sect. Littaea, Asparagaceae), a new species from northern Sinaloa, Mexico, Phytotaxa 616 (1), pp. 99-106 : 101-104

Agave mayo A.Vázquez & Rosales , sp. nov. ( Figs. 2 and 3 )

Type: — MEXICO. Sinaloa: ca. 8 miles north of Río Fuerte in Cerros del Fuerte , on volcanic rock and cliffs, elev. 200–300’ [61–91 m], 9 December 1966 (transplant flowered in Desert Botanical Garden, Phoenix, spring 1975), Gentry & Arguelles 22289 (holotype: ASU!; isotypes: BRY!, DES!, MEXU!, NLU!, SBBG!, US!).

Diagnosis: — Agave mayo is similar to A. schidigera by having open rosettes with filiferous leaves of similar length, but it differs from the latter in the curvature of the leaves (often falcate vs. mostly straight), inflorescence shape (inclined vs. erect), total flower length (43.0–46.0 vs. 30.0–33.0 mm), flower color (reddish to green-purplish vs. yellowish), ovary length (18.0–20.0 vs. 10.0–13.0 mm), tube size (9.0–11.0 × 11.0–12.0 vs. 6.0–8.0 × 4.0–6.0 mm), tepal lobes size (17.0–19.0 × 6.0–7.0 vs. 12.0–13.0 × 3.0–4.0 wide), filament insertion (in the middle of the tube vs. at the rim of the tube), fruit length (29.0–33.0 vs. 17.0–20.0 mm), and fruit shape (obpyriform vs. oblongoid).

Description: —Plants perennial, monocarpic, solitary, acaulescent; rosettes 70.0–110.0 cm in diameter, 45.0–60.0 cm high, openly spreading, hemispherical, green. Leaves less than 70 per rosette, 35.0–60.0 × 1.2–2.0 cm, long linear, narrowing to the apex, often falcate, flexible, flattish ventrally, concave dorsally, smooth on both surfaces, green to dark green, sometimes reddish under stress, with white linear markings by leaf bud impression on both; margin straight, filiferous; threads 5–9 per side, usually 5.0–9.0 cm long, white to brownish white, variously curved; terminal spine 4.0–8.0 × 1.0–2.0 mm at the base, shortly conical, channeled at the base ventrally, rounded dorsally, firm, brown-reddish to grayish with age. Inflorescence spiciform, 2.0–3.0 m long, inclined, with greenish peduncle; bracts numerous, up to 15.0 cm or more, filiform, deltoid at the base, greenish-purple at first buy drying fast; fertile part in the upper 3/5 of the inflorescence, dense, tapering to the apex. Flowers 43.0–46.0 mm long, geminate; pedicels 8.0–10.0 mm long, greenish; neck short, constricted; corolla tube 9.0–11.0 × 11.0–12.0 mm, broadly funnel-shaped; tepal lobes subequal, 17.0–19.0 × 6.0–7.0 mm, elliptic, erect, reddish to green-purplish, sometimes with small macules, the inner ones keeled on the back; filaments 36.0–39.0 mm long, inserted in the middle of the tube, purplish; anthers 17.0–19.0 mm long, centric, more or less curved, and rounded at both ends, reddish, yellow during dehiscence; ovary inferior, 18.0–20.0 mm long, fusiform, angled, smooth, greenish; style filiform, stout, thickened distally, straight, reddish; stigma trilobate. Fruits 29.0–33.0 × 12.0–15.0 mm at the widest part, obpyriform, trigonous, shortly apiculate. Seeds ca. 4.0 mm wide, crescent-shaped, flattened, black, somewhat rugose, shiny.

Distribution, habitat and phenology: —It is endemic to the Sierra de Barobampo, Ahome municipality, northern Sinaloa, at the junction of the Pacific Lowlands and Sonoran provinces. It grows abundantly in tropical deciduous forests and thorn forests at elevations between 20–350 m, especially on calcareous outcrops of mountains near the sea, which are the result of the elevation of the seabed by volcanic activity. It shares habitat with Agave aktites , Bursera fagaroides , Echinocereus bristolii , Ficus petiolaris , Graptopetalum rusbyi , Hechtia montana , Lysiloma divaricatum , Opuntia sp. , Stenocereus thurberi , Tillandsia sp. , among other species.

Etymology: —The specific epithet honors the Mayo people (“people of the riverside”), a mexican ethnic group that lives in the Río Fuerte and Río Mayo valleys in northern Sinaloa and in southern Sonora.

Conservation status: —The species grows abundantly on rocky outcrops; however, its distribution is restricted to a few locations. Using 2 km cell width in GeoCAT (Bachman et al. 2011), A. mayo has an Extent of Occurrence (EOO) of 464.6 km 2 and an Area of Occupancy (AOO) of 28.0 km 2. Following the IUCN (2022) categories and criteria, the species is Endangered under B1ab(v).

Additional specimens examined:— MEXICO. Sinaloa: Cerro 15–20 miles north of Los Mochis , north exposure of volcanic cliffs, elev. 300–500’ [91–152 m], 31 March 1953, Gentry 12561 (MEXU!, US!).

Figures

FIGURE 2. Agave mayo in the Sierra de Barobampo, municipality of Ahome, Sinaloa.A–C. Rosettes growing on calcareous outcrops; D. Cliffs where the species grows; E. Rosette in detail; F. Flowering specimen. Photographs: A. by Iztel Rojas & Marco González, B–E. by J. Alfredo Carrillo and F. by Oscar Cuitláhuac Romero.

FIGURE 3. Reproductive traits of Agave mayo. A. Dissected flower; B. Flowers; C. Stamens; D. Scape with flowers and buds; E. Flowering rosette. Photographs: Iztel Rojas & Marco González.