Arachnothryx aspera (Standl.) Borhidi

Rondeletia aspera Standley, sp. nov
Branches stout, brown, pilose when young with short ascending hairs; stipules linear to oblong-lanceolate, 6-9 mm. long, erect, subpersistent, thin, brown, strigose outside; leaves opposite, the petioles stout, 5-10 mm. long, densely short-pilose, the blades oblong-elliptic to lance-oblong, 6-10 cm. long, 2-4.2 cm. wide, acute or acuminate at the base, acute or acutely short-acuminate at the apex, membranaceous, green above, very scabrous with short slender hairs, beneath densely white-tomentose when young, the tomentum deciduous in age, the lower surface then short-pilose, the venation prominent, the lateral veins 8 or 9 on each side, subarcuate, ascending at an acute angle; inflorescence terminal, cymose-paniculate, many-flowered, very dense, hemispheric, 3-4 cm. broad, pedunculate, the flowers sessile or nearly so; bracts and bractlets small; hypanthium densely pilose with short whitish appressed hairs; calyxlobes 4, oval to ovate-deltoid, obtuse or rounded, 1-2 mm. long, erect; corolla arachnoidtomentose outside the tube stout, 8-9 mm. long, the throat naked, the 4 lobes rounded, about 3 mm. long; anthers included.
Type collected at Pont du Rodeo, below Pacaca, Costa Rica. January, 1891, //. Pittier 3243 (U. S. Nat. Herb. no. 94140S).

Arachnothryx aspera là một loài thực vật có hoa trong họ Thiến thảo. Loài này được (Standl.) Borhidi mô tả khoa học đầu tiên năm 1982.