Extrafloral nectaries in Nephelium lappaceum (Sapindaceae)

Background: There is no previous evidence in the literature that documents the presence of extrafloral nectaries (EFNs) or the exomorphology of domatia in Nephelium lappaceum (rambutan), a fruit tree native to Malaysia introduced in various American countries. Question: It is the presence of EFNs responsible for the frequent visit of ants to young leaves of Nephelium lappaceum? Study site and dates: This study was conducted in a commercial rambutan orchard in the town of Francisco I. Madero, municipality of Frontera Hidalgo (Chiapas, Mexico) during the period September 2020-February 2021. Methods: External morphology of EFNs and domatia were studied using scanning electron microscopy. Nectar sugar concentration produced by EFNs was determined by refractometry. EFNs location on the plant and the frequency of visiting ants were quantified by visual counting. Results: A description of the external morphology of EFNs and domatia, as well as their location on rambutan leaflets are presented. A volume of 0.3 ± 0.2 µL/EFN of a nectar (9.3 ± 0.6 °Bx) was collected each day. Ten species of ants feeding on the nectar excreted by the EFNs were identified. Conclusion: Evidence of the presence of NEFs on rambutan leaflets is presented, which have an external morphology and location different from that observed in domatia, producing a sweet nectar used as food by a large community of ants.