Acharagma aguirreanum

Acharagma aguirreanum (Glass & R.A. Foster) Glass, Guía Identif. Cact. Amenazadas México 1: [1] [AC/AG], 1998. Gymnocactus aguirreanus Glass & R.A. Foster, Cact. Succ. J. (Los Angeles) 44: 80 (figs.). 1972. Thelocactus aguirreanus (Glass & R.A. Foster) Bravo, Cact. Suc. Mex. 25: 65, 1980. Escobaria aguirreana (Glass & Foster) N.P. Taylor, Kakteen Sukk. 34: 185, 1983. Type: C. Glass & R. Foster 2206 Cañon Verde eastern slopes of Sierra de la Paila, Coahuila, Mexico, 24 Apr 1970; holotype: POM (jpg 1.7 mb).


Plants usually solitary. Stems deeply seated, the above-ground portion depressed globose (but not flat topped), globose or short cylindroid, soft, medium green to purple, 3-5(-12) cm high, 5-7 cm in diameter. Tubercles arranged in rows (5/8 or 8/13 spirals), well developed, fleshy, somewhat flexible, 10-15 mm wide basally, protruding 5-6 mm, ± 4.5 mm in mid diameter. Central spines 2-5(-6), largest 12-29 mm long, others 20-30 mm long, purplish gray to orange-tan, often difficult to distinguish from upper radials. Radial spines 13-16, often in two series, (7-)8-15 mm long. Flowers yellowish to reddish-yellow, 15-18 mm long, to 20 mm in diameter. Fruits greenish-purple, to 9-12 mm long, 3.5 mm in diameter. Restricted to southeastern and central Coahuila, along the western edge of the Sierra de la Paila, and Sierra San Marcos. Steep mountainsides of igneous rock, in dense scrub; 1350-1550 m elevation.


Seed morphology and seed coat micromorphology: Seed broadly oval, of the Arequipa-type, small, 1.12-1.35 mm long (mean= 1.28 mm), 0.71-0.97 mm dorsal-ventral height (mean= 0.88 mm), 0.68-0.82 mm wide (mean= 0.72 mm), matt, black, boarder expanded around and constricted above the hilum; lacking multicellular sculpture; no distinction of the periphery, i.e., no dorsal crest; cells (jpg 42 kb) uniform, elongate, anitclinal boundaries inconspicuous, generally straight, relief par-concave; micro-relief verrucose; hylem small oblique, superficial, 0.29-0.53 mm long (mean= 0.35 mm), 0.21-0.35 mm wide (mean= 0.29 mm), hylem and micropyle separate or conjunct, the fibrous band separating them 0-0.09 mm (mean= 0.03 mm); hylem-micropylar region 0.41-0.56 mm long (mean= 0.48 mm).

Pollen Morphology: Pollen of Acharagma aguirreanum is spherical to slightly oblate, elongate in the polar axis, 43-47 microns polar diameter, 41-44 microns equatorial diameter, tricolporate (3 apertures, each aperture composed of a colpus, 32-45 microns long, and a pore), exine pertectate, the tectum bearing pores, 0.5-2.5 microns in diameter, and spinule processes, 0.25-0.45 microns high and in diameter.


Spine Micromorphology (jpg 398 kb): At sexual maturity, the radial and central spine differ little in color, but do vary in length and diameter. Cells are elongate in the direction of the long axis of the spine, rectangular, trapezoidal, or rhomboidal. Along the shaft the transverse walls are frequently separated from one another, toward the acute, distal tip, the transverse walls acute and not separated, cells 60-165 microns long, 11-20 microns wide. The cells are smooth, lacking papillae.