Obituary: William Mark Whitten (1954−2019)

On April 11, 2019, Dr. William Mark Whitten, a prolific neotropical orchid biologist passed away unexpectedly. He leaves an extensive corpus of work focused on (but not limited to) orchid pollination and systematics, and over four thousand beautifully prepared herbarium specimens. Everyone that met Mark can agree that he was a wonderful human being, kind to everyone, incredibly knowledgeable and yet very humble. Always of a calm demeanor, great sense of humor, and willingness to help, Mark was an outstanding and relatable collaborator, and his publications (more than a hundred; see list below) are evidence of a productive and highly collaborative academic career.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Cytogeography of Callisia section Cuthbertia (Commelinaceae)

Determining the distribution of cytotypes across the geographic distribution of polyploid complexes can provide valuable information about the evolution of biodiversity. Here, the phytogeography of cytotypes in section Cuthbertia (Small, 1903) Hunt, 1986 is investigated. A total of 436 voucher specimens was georeferenced; 133 new specimens were collected. Based on flow cytometry data, DNA content of all cytotypes in section Cuthbertia was estimated. Utilizing chromosome counts and flow cytometric analysis, cytotype distribution maps were generated. Two disjunct groups of populations of diploid Callisia graminea (Small, 1903) Tucker, 1989 were discovered; tetraploid C. graminea ranges broadly from the coastal plain of North Carolina through central Florida. One hexaploid C. graminea individual was recorded in South Carolina, and numerous individuals of hexaploid C. graminea were found in central Florida. Diploid C. ornata (Small, 1933) Tucker, 1989 occurs in eastern Florida; previously unknown tetraploid and hexaploid populations of C. ornata were discovered in western and central Florida, respectively. Diploid C. rosea (Ventenat, 1800) Hunt, 1986 occurs in Georgia and the Carolinas, with populations occurring on both sides of the Fall Line. The cytotype and species distributions in Callisia are complex, and these results provide hypotheses, to be tested with morphological and molecular data, about the origins of the polyploid cytotypes