During botanical investigations within the framework of a German-Bolivian project of technical cooperation (PROSANA) in the Bolivian province of Arque (Ibisch, 1992), a new dwarf species of Puya was found that shows the remarkable growth habit of a cushion plant. Within the bromeliad family this growth habit is well known from Abromeitiella. It is interesting to note that Puya raimondii Harms, the biggest bromeliad, and some dwarf puyas occur in the Bolivian flora. Rauh (1983) described Puya hromadnikii, from the south of Bolivia, which is related to Puya minima L.B. Smith and Puya tuberosa Mez.
Puya prosanae grows among rocks on rocky slopes and on degraded stony soil at an altitude of 3500-3700 m. The mean annual temperature is about 11 ° C. The precipitation of 650 to 700 mm is restricted to the humid season of October to April.
Puya prosanae is found within an open, scrubby vegetation of Baccharis polycephala Wedd., Satureja boliviana (Benth.) Briq., Baccharis dracunculifolia DC., and others
with a grass-stratum, which is generally dominated by Stipa ichu (R. & P.) Kunth. The historical vegetation of the area is believed to be a forest of Polylepis besseri Hieron., of which numerous relicts are found. Specimens of Alnus acuminata H.B.K. can be observed near small rivers and along brooks. The vegetation is heavily influenced by the land use of the quechua-farmers: the collecting of firewood and livestock grazing are the main components of degradation. Like other members of the genus, Puya prosanae is eaten by the animals.
Puya prosanae is distributed in the northeast of Arque. Within the area of occurrence, the species is not rare. Other puyas were found in the same region, namely Puya cardenasii L.B. Smith (2700-3750 m), Puya glabrescens L.B. Smith (ca. 3750 m) and Puya mirabilis L.B. Smith (ca. 2900 m).
Above Chapi-Chapi, Prov. Arque, Dept. Cochabamba, Bolivia, near the crossroads Cochabamba-Oruro (km 82), 3500-3700 m elev. Further observations in the area of the type locality in the northeast of Arque, not rare. —SeeIbisch & Gross 1993p. 43(5): 211-215