POLLINATION OF PHILODENDRON PROPINQUUM SCHOTT (ARACEAE): A NEW PATTERN IN THE LINEAGE PHILODENDRON

Premise of research. Philodendron subg. Pteromischum has different floral traits and smaller inflorescence size than other species from the Philodendron lineage (genus Thaumatophyllum and P. subgenus Philodendron). We examined the flowering cycle, thermogenesis, and effective pollinators of Philodendron propinquum (P. subgenus Pteromischum) and compared them with the pattern described for Thaumatophyllum and P. subgenus Philodendron. Methodology. A population of P. propinquum was monitored at Reserva Biológica do Tinguá in southeastern Brazil. Through both instantaneous and continuous observations, we recorded spadix temperature dynamics and opening and closing, as well as flower visitors. Visitors were collected for identification and analysis of pollen loads. To detect whether spontaneous self-fertilization occurs, inflorescences were bagged before spathe opening. Flower consumption by pollinators was also recorded. Pivotal results. The flowering cycle in P. propinquum lasted 2 d, during which the small spathe remained permanently open; no noticeable thermogenesis was recorded. Two individuals of Erioscelis sp. with pollen grains of P. propinquum adhered to the body were observed visiting the inflorescences and feeding on the sterile units. Visits lasted about 15 min, and the sterile units were massively consumed. No spontaneous self-fertilization occurred in P. propinquum. Conclusions. Despite the insufficient shelter and absence of floral heating, as well as smaller availability of feeding resources compared with other species from the Philodendron lineage, inflorescences of P. propinquum are pollinated by Erioscelis beetles, similarly to those belonging to the above lineage.