Unraveling the extreme morphological variation in the neotropical Ficus aurea complex (subg. Spherosuke, sect. Americanae, Moraceae)

Abstract

AbstractFicus (Moraceae) is one of the most diverse genera of tree species in the world. The subgenus Spherosuke, section Americanae, comprises several species complexes because its diagnostic structures are extremely variable. Currently, neither there is a phylogenetic hypothesis that can help solve the delimitation problems within these complexes nor has an integrative taxonomic approach been developed. In the present study, morphometric methods were applied to solve the taxonomic problems in the Ficus aurea complex. Morphometric variation of syconia and leaves was analyzed to find differences between four previously recognized forms (fo. aurea, fo. cookii, fo. isophlebia, and fo. tuerckheimii). Syconium characters were analyzed using traditional morphometrics, while leaf shape was evaluated with geometric morphometrics, encompassing 20 populations along two‐thirds of the distribution range of the complex. Data sets from syconia and leaves were tested for possible associations with geographic and rainfall variables. There are significant differences between the four forms in syconium characters and leaf shape. Geography and rainfall variables show significant covariation related to the morphometric variation of syconia but not to leaf shape. Consequently, we propose that the four forms should be repositioned into the specific rank. Besides, F. tecolutensis is also recognized as a separated species from form aurea considering Principal Component Analysis, field observations, and herbarium specimens. An identification key, descriptions, as well as taxonomic comments of the species are provided.