An inclusion of Melastomataceae leaf from the Miocene amber of Simojovel de Allende, Chiapas, México

Abstract

Melastomataceae Jussis a family well represented in tropical biomes and is characterized by a distinctive venation pattern in its leaves. The worldwide fossil record consists mainly of leaves that date back to the Palaeocene. However, this family is poorly represented in the fossil record in Mexico. Here, we show a new finding of a Melastomataceae leaf preserved as inclusion in amber outcrops in Chiapas that preserves evidence of the complex Miocene ecosystem through well-preserved fossil organisms. The morphological characteristics described were based on shape and venation patterns and compared with extant or fossil organisms with similar patterns, allowing us to assign individuals to one of the species hypotheses or name them as a new species. The fossil leaf has ovate to elliptical lamina, nanophyll size, long petiole, and basal acrodromous venation, with one pair of secondaries emerging from the petiole and merging at the leaf apex and opposite percurrent epimedial tertiary veins. This combination of characteristics are typical of Miconia Ruiz & Pavón and have not been observed together in any leaf recordings for this family, proposing a new fossil species. This discovery confirms the presence of Melastomataceae in Southern Mexico during the Miocene, which was once part of the tropical rainforest of the Simojovel Formation of Chiapas, Mexico.