A New Species of Oserya (Podostemaceae) from Jalisco, Mexico

Abstract

A new species of Podostemaceae, Oserya longifolia, from Jalisco, Mexico, is described and illustrated. Leaf length is the most prominent feature that distinguishes this species. RESUMEN. Se describe e ilustra una especie nueva de la familia Podostemaceae, Oserya longifolia, del estado de Jalisco, M6xico. La longitud de la hoja es la caracteristica mas prominente que distingue a esta especie. Oserya Tulasne & Weddell is an American genus of six species, most recently monographed by van Royen (1954). Like all Podostemaceae, species of Oserya grow attached to rocks in swift-moving river currents. Five of the six species (O. biceps Tulasne & Weddell, O. flabelifera Tulasne & Weddell, O. minima van Royen, O. perpusilla (Went) van Royen, O. sphaerocarpa Tulasne) occur in northern Brazil and northeastern South America, while O. coulteriana Tulasne occurs in Mexico. Little is known of the geographic distributions of species of Oserya. In fact, four of the South American species are known only from the type collections. At the time of van Royen's monograph, O. coulteriana was known from few collections in the Mexican states of Jalisco and Michoacan. During our recent studies of Mexican Podostemaceae we have found this species to be relatively widespread in Colima, Nayarit, and Guerrero, in addition to Jalisco and Michoacin. A collection from southern Sinaloa is also now known (Novelo & Philbrick, unpublished). While conducting field studies of Mexican Podostemaceae, we made collections that did not correspond to any described species. These collections serve as the basis for the description of a new species, Oserya longifolia Novelo & Philbrick. serya longifolia Novelo & Philbrick, sp. nov. TYPE: Mexico. Estado de Jalisco: municipio de La Huerta, Rio Purificaci6n, 4 km al oeste de La Huerta, 19?30'N, 104?40'W, 300 m, 26 Mar. 1993, Novelo & Philbrick 1166 (holotype, MEXU; isotypes, MO, NY, WCSU). Figure 1. Herbae aquaticae plerumque caulibus stoloniferis applanatis. Folia circinata usque ad 40 cm longa; petiolus laevis; lamina repetite 2-4(-5)-divisa, divisionibus ultimis 0.3-0.6 mm latis, applanatis, apice acutis. Flores hermaphroditi, zygomorphi, pedicellati, axillares, solitarii. Tepala 3, filamentis alternata, uno in furca duorum staminum affixo. Stamina 2, andropodio portata; antherae ellipticae, dorsifixae, per 2 rimas laterales longitudinaliter dehiscentes. Ovarium 2 carpellis, 2 stylis 0.7-1.2 mm longi. Fructus 2 valvis, quaque valva 3-costata. Aquatic herbs usually with stoloniferous and flattened stems 0.8-1.0 mm diam., strongly adhering to rocks. Leaves alternate, circinate, up to 40 cm long, petiole 2-17 cm long, cylindrical, smooth, 0.7-1.6 mm diam., with a broadened base; blade 2-4(-5) divided, the ultimate divisions 0.3-0.6 mm wide, flattened, apex acute. Flowers hermaphroditic, zygomorphic, pedicellate, borne singly, axillary, protected by a spathella; spathella up to 7 mm long, thin clavate. Pedicels 3.5-8.0 mm long, elongating during anthesis, not expanded at capsule base. Tepals 3, alternate with the filaments, free, membranous, subulate, one of them attached in the fork between the two stamens; lateral tepals 0.9-1.2 mm long, medial tepal 0.7-0.9 mm long. Stamens 2, borne by an andropodium, andropodium 0.8-1.3 mm long, elongating during anthesis; filaments 1.01.8 mm long, subulate, flattened, elongating during anthesis, deciduous; anthers 0.4-0.6(-0.8) mm long, elliptic, dorsifixed, 2-celled, dehiscing longitudinally by 2 lateral slits. Ovary superior, 1.7-2.1 mm long, NovoN 5: 54-56. 1995. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 05:39:13 UTC All use subject to http://about.jstor.org/terms Volume 5, Number 1 Novelo & Philbrick 55 1995 Oserya longifolia