A A. extensa (L. B. Sm.) Grant, cui affinis, sed scapus rubrus, rache inflorescentiae rubra, ramis lateralibus brevioribus, bracteis floriferis irregulariter sulcads, floribus longioribus pallide flavidis et petalis longioribus differt.
PLANT rupicolous, flowering 170-180 cm high;
LEAVES ca. 18 in number, densely rosulate, suberect, forming a broadly crateriform rosette;
SHEATHS broadly elliptic-ovate, 21-23 x 15-16 cm, inconspicuously and minutely brown-lepidote, pale colored;
BLADES linear or nearly so, not narrowed at base, 57-61 x 8.5-10 cm, coriaceous, inconspicously and sparsely white-lepidote abaxially to glabrescent, adaxially green, abaxially green suffused with reddish-wine mainly along the margins and toward the apex, apex acuminate, shortly caudate.
SCAPE stout, 84-90 cm long, ca. 2 cm in diameter, erect, glabrous, red;
SCAPE BRACTS the basal ones subfoliaceous, the upper ones broadly ovate, acuminate-caudate, 9-15 x 6-7 cm, suberect with strongly recurved-recoiled apex, its basal portion enfolding the scape and with distinct waterholding capacity; distinctly exceeding the internodes but not hiding the scape, green except for the sometimes pale reddish base, inconspicuously and sparsely white-lepidote to glabrous, covered by white epicuticular wax.
INFLORESCENCE paniculate, bipinnate, 74-96 cm long (including the terminal branch), 60-75 cm in diameter, erect,
RACHIS stout, red;
PRIMARY BRACTS resembling the upper scape bracts but smaller, shorter than the sterile bases of the branches;
BRANCHES 11 to 13 in number (including the terminal one), the lateral branches 30-36 cm long (basal ones) to 20-26 cm long (upper ones), suberect-spreading, densely flowered in early anthesis to subdensely to laxly flowered afterwards, 5 (upper ones)- to 11 (basal ones)-flowered,
rachis geniculate, subterete to slightly angulose, 1-2 x 0.4-0.7 cm, glabrous, apple green to yellowish-green,
stipes 9-16 x 0.7 cm, terete, reddish to red toward the base, glabrous, bearing 1 to 2 sterile bracts exceeding the internodes and arranged at the apex of the stipes, carinate, the terminal branch resembling the lateral ones, erecto to suberect-recurved, 27-32 cm long, 9- to 11-flowered,
Terminal stipe 9-10 cm long, bearing ca. 2 sterile bracts exceeding the internodes, ecarinate;
FLORAL BRACTS suborbicular, 40-46 x 37-40 mm, pale greenish-yellow toward the apex and the apical margins, pale castaneus-yellowish toward the base and centrally, inconspicuously and sparsely white-lepidote inside, glabrous outside but covered by white epicuticular white wax, almost completely enfolding the sepals and equaling 2/3 to 3/5 of its length, cymbiform and distinctly convex, irregularly longitudinally sulcate at anthesis, ecarinate or the basal ones sometimes obtusely carinate, apex obtuse to subacute, the upper ones densely imbricate in before and at early anthesis.
FLOWERS sub-distichous, divergent, odorless, densely arranged toward the apex in the early anthesis to subdensely or sparsely arranged afterwards, 13.5-15.5 cm long (with petal extended, including the stamens),
PEDICELS stout, 13-15 mm long, ca. 10 mm in diameter at apex, green, glabrous;
SEPALS oblong-elliptic to narrowly obovate, 42-43 x 20-22 mm, inconspicuously and sparsely white-lepidote inside, glabrous outside, free, ecarinate, pale greenish-yellow toward the base and yellowish near the apex, thick-coriaceous near the base, thinly coriaceous toward the apex, apex narrowly obtuse to broadly acute;
PETALS linear or nearly so, apex narrowly obtuse, 125-142 x 9-11 mm, pale yellow, strongly twisted recurved at anthesis with recoiled apex, completely exposing the stamens, becoming pendent-flaccidescent afterwards, bearing at base 2 linear, obtuse to emarginate, entire, 30-38 x 3 mm appendages adnate to the petals for 25-23 mm;
STAMENS exerted at anthesis, shorter than the petals;
FILAMENTS terete, white, the antesepalous ones free, the antepetalous ones shortly adnate to the petals;
ANTHERS linear, 15-18 mm long, base sagittate, apex obtuse, fixed near the base;
STYLE about equaling the petals, white;
STIGMA conduplicate, spreading-contorted, densely papillose, white, blades ca. 3.5 mm long.
This new species is morphologically related to Alcantarea extensa. However, A. lurida differs from it by the red scape and the red rachis of the inflorescence, as well as by the lateral branches distinctly shorter (20-36 cm vs. to 65 cm long), floral bracts irregularly sulcate, flowers longer (13.5-15.5 cm vs. 9-11 cm long) and pale yellow, and the longer petals (12.5-14.2 cm vs. to ca. 8 cm long).
Despite not being closely related, A. lurida can be also compared to A. heloisae J. R. Grant, distinguishing from it by leaf blades not covered by any dense layer of white powdery scales (white epicuticular wax), inflorescence longer and broader (74-96 x 60-75 cm vs. ca.. 41 x 34 cm), primary bracts distinctly shorter than the stipes (vs. about equaling the stipes), branches longer (20 [apical] - 36 [basal] cm vs. 16-20 cm long), stipes distinctly longer (9-16 cm vs. 1.6-3.6 cm long), floral bract suborbicular (vs. broadly elliptic) and larger (40-46 x 37-40 mm vs. 32-35 x 24-26 mm), flowers longer (13.5-15.5 cm vs. 10-10.5 cm), sepals larger (42-43 x 20-22 mm vs. 30-33 x 14-16 mm), petals pale yellow (vs. bright golden yellow), longer (125-142 mm vs. 85-86 mm), and by the longer anthers (15-18 mm vs. 10-11 mm).
Alcantarea lurida was found growing on inclined rock surface along the road from Coronel Fabriciano to Braunas, in Minas Gerais State, in a strongly depleted habitat in the domain of the locally almost extinct Atlantic forest, forming a comparatively small remaining population. Its name came from the Latin "luridus", meaning the pale yellowish color of its floral bracts and flowers.