Floral Ontogeny ofTelipogonspp. (Orchidaceae) and Insights on the Perianth Symmetry in the Family

Telipogon s.l. (i.e., including Hofmeisterella and Stellilabium) is a Neotropical epidendroid genus that has some species with an unusual tendency to develop an actinomorphic perianth; most species have the typical monosymmetric orchid perianth. The genus is nested in a clade that includes Pachyphyllum, Fernandezia, and Trichoceros, all of which consistently exhibit a monosymmetric perianth. The study of floral ontogeny in Telipogon shows that early and mid‐development is similar to that found in other orchids with monosymmetric perianth and that the acquisition of an actinomorphic perianth occurs late in development. On the basis of optimization of the mature polysymmetric perianth onto the phylogenetic analysis available for Telipogon, it has arisen independently several times within the genus; however, the polysymmetric perianth of Telipogon andicola and Telipogon nervosus (representing distant clades within the genus) is the result of the same developmental pathway. Conversely, a further comparison of floral development in other Telipogon spp., as well as in the closely related Fernandezia lanceolata and other distantly related orchids, indicates that the sequence of organ initiation is highly variable and that different ontogenetic pathways can lead to a monosymmetric perianth. Heterochrony during the development of the perianth has been proposed as one of the pivotal evolutionary processes that has enhanced a high‐specific radiation in the family. Our results in Telipogon agree with this statement.