Hiding in Plain Sight: Novel Observations of Plant Crypsis in a Well-Known Symbiotic System of a Hyperdiverse Tropical Forest

Devils gardens are among the most striking ant-plant mutualisms in Amazonian forests. In this system, the tree Duroia hirsuta is associated with the ant Myrmelachista schumanni, which actively removes neighboring vegetation and maintains nearly monodominant patches of the host plant. Despite the apparent efficiency of this system, repeated field observations at the Tiputini Biodiversity Station, Yasuni Biosphere Reserve, revealed that individuals of Palicourea alba recurrently occur within active devils gardens. Palicourea alba closely resembles dead plant material, exhibiting leaf morphology and coloration that strongly mimic the surrounding litter layer, and appears to be uncommon outside these gardens. To our knowledge, this "dead-leaf" masquerade has not been previously documented in this intensively studied system, making it a particularly striking and unexpected observation. To evaluate whether this masquerade facilitates persistence within devils gardens, we surveyed 35 gardens and recorded P. alba in 19 (52.8%). When present, P. alba covered on average 27% of plot area, while mean herbivory across sampled leaves remained low (8.6%). Generalized linear mixed models showed that P. alba cover decreased significantly with increasing herbivory (F = 8.09, p = 0.0159), whereas herbivory increased with leaf-litter cover (F = 8.73, p = 0.0120). Field observations further revealed that many individuals are nearly indistinguishable from dry leaf litter, suggesting a role for visual crypsis or masquerade. Together, these results indicate initially, that the persistence of P. alba within devils gardens is mediated by a multi-layered ecological filtering process. First, masquerade likely reduces detection by M. schumanni, allowing seedlings to escape ant-mediated removal. Second, low herbivory suggests either enemy avoidance or reduced apparency to herbivores within the simplified understory. Third, spatial heterogeneity in leaf-litter cover may create microhabitats where both ant activity and herbivore pressure are modulated, reinforcing establishment success. This system thus represents a previously undocumented mechanism in which plant-litter resemblance enables persistence within a highly structured, biotically filtered habitat, highlighting how subtle trait-mediated interactions may modulate outcomes in otherwise strongly deterministic mutualisms.