A new species, Alstroemeria marticorenae (Alstroemericaceae), from central Chile is described and illustrated. Diagnostic morphological characters that allow the distinction of A. marticorenae from similar taxa are presented. It differs from these in its flower shape, size, and color. The plants are small, reaching up to 35 cm tall, the flowers are pink, the upper inner tepals are rhomboidal and narrow, with a yellow stripe and a pattern of purple lines in the two upper tepals, varying from yellow to white in the basal portion; the anthers are yellow. It grows in hard, reddish soils, never in dunes. It is endemic to the Valparaíso Region of central Chile. A comparative cytological analysis of other sympatric species of Alstroemeria was conducted. The most important karyotypic characteristic for A. marticorenae is the presence of a submetacentric chromosome 3.