A New Species of Villarsia (Menyanthaceae) from the Porongurup Range, Western Australia

Villarsia marchantii, known from a single population growing in a shaded woodland of the Porongurup Range in southwestern Western Australia, is newly described. It is closely related to V. calthifolia, another endemic of this group of mountains, which occurs in exposed situations at or above timberline. In addition to differences in habitat, vegetative, floral, and fruit characters, seed size, flowering time, duration of seed maturation, and susceptibility to Septoria infection, V. marchantii has strongly distylous flowers and is self-incompatible, whereas V. calthifolia has weakly distylous flowers, is fully self-compatible, and shows some degree of autogamy. Artificial interspe- cific hybrids exhibited reduced pollen stainabilities. Villarsia Vent. is a genus of ca. 16 species oc- curring in southeastern Asia, Australia, and South Africa (Aston 1969). Nine species occur in southwestern Western Australia, where the genus exhibits its greatest degree of morpho- logical and ecological diversity (Ornduff and Chuang 1988). In 1983 I spent several months in Western Australia studying features of the breeding systems of Villarsia, most of which are distylous (Ornduff 1986). In the course of mak- ing field observations and collections, I sampled populations of V. calthifolia F. Muell., an en- demic of the small (3 x 12 km) granitic Poron- gurup Range. Subsequent study of cultivated plants attributed to this species and of material obtained on a second visit to the range late in 1988 indicates that there are two closely related species of Villarsia occurring there that differ in