2.1. Study Site

The Los Tuxtlas Biosphere Reserve (LTBR) is located in the southeastern part of Veracruz state, Mexico (18°05′–18°43′ N, 94°35′–95°25′ W). This region is the northernmost distributional limit of the evergreen tropical rainforest in the Americas, characterized by a complex topography with elevations from 0 to 1600 m asl, approximately [45,46]. Sampling was conducted at three sites of different elevations. The lowest site, “Biological Station of Tropical Biology Los Tuxtlas and surroundings” (BSLT), is found at 100–300 m asl characterized by climate subtype Am warm-humid with a summer rainy season and winter rainfall of between 5–10%, annual rainfall of 4001–5000 mm and an average temperature of 24.1–25 °C. The middle site “La Perla” is located at 500–700 m asl, with climate subtype Af (m) warm-humid, featuring rains throughout the year, winter precipitation of <18% and an average temperature of 23.1–24 °C with annual rainfall of between 4001–5000 mm. The highest site “Calería” is located at 1000–1200 m asl, with climate subtype (A)C (fm) semi-warm, with a temperature in the coldest month (January) of <18 °C and an average temperature of 22.1–23 °C [47,48].

Based on floristic studies [49,50], the natural vegetation at BSLT is a “tropical rainforest”, characterized by canopies of over 30 m in height, featuring elements such as Ficus spp., Ceiba pentandra, Poulsenia armata, Nectandra ambigens, Brosimum alicastrum, among others, while the understory is dominated by palms, especially Astrocaryum mexicanum and Chamaedorea species. At “La Perla”, the canopies do not exceed 20 m in height, and present a floral composition similar to that of the lower site (BSLT). The upper site of our study (Calería) is characterized by a transition zone, known as “Cloud Forest” (sensu Rzedowski [51]), with typical tree species such as Liquidambar styraciflua, Alfaroa mexicana, Juglans olanchana, Ulmus mexicana, among others. In the region of Los Tuxtlas, aroids are an important element of the native vegetation, represented by 34 species of nine genera, distributed from 0 to 1600 m asl, at the top of the San Martin volcano. The best-represented genera in terms of the highest number of species are Philodendron, Anthurium, Monstera and Syngonium [52].