Pollen morphology of Cactaceae in Northern Chile

Chile is habitat to over 140 species of cactus of which 45% are endemic and most of them grow in the arid northernmost part of the country between 18°-32°S. As the Cactaceae family plants are quite well adapted to arid environments, their fossil pollen may serve as a tool to reconstruct past environmental dynamics as well as to trace some issues regarding the family evolution or even some autoecological aspects. Aiming to create a reference atlas to be applied to some of these purposes, the pollen morphology of the following 14 different species of the Cactaceae family from Northern Chile was studied under optical microscopy: Cumulopuntia sphaerica, Maihueniopsis camachoi, Tunilla soehrensii, Echinopsis atacamensis, Echinopsis coquimbana, Haageocereus chilensis, Oreocereus hempelianus, Oreocereus leucotrichus, Copiapoa coquimbana, Eriosyce aurata, Eriosyce subgibbosa, Eulychnia breviflora, Browningia candelaris and Corryocactus brevistylus. Pollen grains of species of the subfamily Opuntioideae are spheroidal, apolar and periporate whereas grains of the subfamily Cactoideae are subspheroidal, bipolar and tricolpate and can be taxonomically differentiated between tribes. The results show that it is possible to identify pollen from the Cactaceae family at the genus level but pollen taxonomic resolution may be complicated to identify up to a specific level. A wider reference collection considering more characters than those included in the present study could improve this aspect in the near future.