Specialized fly pollination in Apoballis mutata (Araceae): high reproductive success in the absence of a trap system

Background and aims – While some plants achieve reproductive success through wind or deceptive pollination strategies, many animal-pollinated species depend on mutualistic interactions with pollinators, supported by floral cues, rewards, and microstructural adaptations. Despite the diversity within Araceae, pollination ecology remains poorly characterized for most species. Material and methods – To address this gap, this study investigates the flowering biology and pollination dynamics of Apoballis mutata, with particular focus on pistillate, transitional, and staminate phases of anthesis, followed by infructescence development and seed dispersal. Seeds germination trials were conducted on cotton wool in sealed Petri dishes, and fruit set was quantified from pistillate flower and berry counts. Scanning Electron Microscopy (SEM) was used to examine staminate floral structures and pollen distribution on pollinators. Key results – Three legitimate pollinators were identified, Colocasiomyia sp. 2 aff. bogneri, C. sp. 34 aff. bogneri, and C. sp. 17 aff. bogneri, along with two non-pollinating insect visitors, forming a co-occurring assemblage. Echinate pollen consistently adhered to the bodies of Colocasiomyia flies, confirming their role as effective pollinators. Unlike trapping system observed in some aroids, spathe movements in A. mutata regulated pollinator behaviour, allowing repeated visits and efficient pollen transfer. Pollinator diversity declined from the pistillate to staminate phases, with C. sp. 2 aff. bogneri remaining dominant, particularly in creamy green-spathed inflorescences. Overall fruit set exceeded 90%, with creamy melon-red spathes achieving 77.90% and creamy green spathes surpassing 100%. Conclusion – These findings reveal a specialized, non-trapping pollination system in A. mutata, enhancing understanding of its mutualistic relationship with Colocasiomyia flies and contributing new insights into the pollination ecology of Araceae.