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Tiputinia foetida, a new mycoheterotrophic genus of Thismiaceae from Amazonian Ecuador, and a likely case of deceit pollination

Abstract:

Tiputinia foetida is described here as a new genus of flowering plants in the Thismiaceae. A single individual of this achlorophyllous mycoheterotroph was found flowering in leaf litter at the Tiputini Biodiversity Station in Amazonian Ecuador. This new taxon is placed in Thismiaceae based on its pyramidal stigma, lack of septal nectaries, and other floral and vegetative features consistent with the other four genera known in the family. It differs from Thismia, the only other genus of the family present in the Neotropics, by its placentae parietally attached to the apex of the ovary; its identical, strap-shaped tepals that are blunt-tipped and horizontally spreading; and its stamens with highly ornamented filaments that are basally broad and erect, then curve inwards to partially obstruct the mouth of the floral tube. Some of these same characters, however, occur in African genera of Thismiaceae such as Afrothismia, Haplothismia, and Oxygyne. The closest relative of Tiputinia may actually be Oxygyne, which differs in having three (vs. six) stamens and less ornamented filaments. At anthesis, the flower of Tiputinia emits a foetid odor that attracts carrion flies and other insects that could function as pollinators. We hypothesize that Tiputinia evolved its scent and unusual floral morphology as a deceit pollination mechanism to attract flies or other pollinators down into the floral tube, where they would first contact the stigma, lay eggs on the inner, horizontal ridges of the tube, and finally contact the latrorse anthers as the insects emerge from the flower. Since foetid odors are capable of attracting pollinators from long distances in other carrion insect-pollinated plants, this pollination system may be particularly effective in rare, ephemeral, and otherwise inconspicuous forest herbs such as Thismiaceae.