Leaves of Ipomoea carnea Jacq. subsp. fistulosa (Mart. ex Choisy) D. Austin (Convolvulaceae) with conspicuous, round, yellowish orange leaf spots measuring up to 8 mm in diameter were collected from a garden plant in Cabo Rojo, Miradero, Puerto Rico on 8 December 2004. Uredinia and telia were observed in the symptomatic areas. The uredinia were aecioid, amphigenous but mainly hypophyllous, cupulate, and grouped in the round chlorotic leaf spots. The peridial cells measured 24 to 36 × 18 to 25 μm with walls 4 to 6 μm thick, the outer wall was striate to verrucose and the inner wall was verrucose. Urediniospores were catenulate, globoid to ellipsoid, sometimes narrow at the apex, and measured 28 to 36 × 20 to 30 μm. The urediniospore walls were colorless to yellowish, verrucose, 2 to 3 μm at the sides, and as much as 15 μm at the apex. Telia were epiphyllous, in the same spots as the uredinia, rounded, chestnut brown, and subepidermal, becoming erumpent. Teliospores measured 42 to 57 × 28 to 36 μm and were pale to cinnamon brown when young, becoming chestnut brown at maturity. The teliospores were ellipsoid or oblong, rounded at the top and bottom, with no constriction at the septum, and with walls verrucose, 3 to 4 μm at the sides and 5 to 7 μm at the septum and apex. Each teliospore had a pedicel that was colorless except close to the spore it was pale brown. Pedicels measured as much as 70 μm long and 10 μm thick and were easily broken. The rust was identified as Puccinia puta H.S. Jacks. & Holw. ex F. Kern, Thurst. & Whetzel (2), as compared macroscopically and microscopically with specimens in the U.S. National Fungus Collection (BPI) and also with published descriptions. P. puta has been reported from South America and Mexico on species of Ipomoea (1). I. carnea subsp. fistulosa is cultivated as an ornamental plant and widely distributed mainly in wet areas in the Americas from Argentina to Florida and Texas. To my knowledge this is the first report of P. puta in Puerto Rico. It has not been reported in the continental United States. The voucher specimen has been deposited in the U.S. National Fungus Collection as BPI 872006.
References: (1) D. F. Farr et al. Fungal Databases. Systematic Botany and Mycology Laboratory. On-line publication. ARS, USDA, 2005. (2). F. D. Kern et al. Mycologia 25:448, 1933.
