A new extinct member of the resin producer group of the Mexican amber: Hymenaeaphyllum mirandae n. gen. n. sp. (Detarioideae-Leguminosae)

Abstract

One of the most important amber deposits with bioinclusion outcrops in Chiapas, southern Mexico, dated ca. 23–15 Ma (early–middle Miocene). Angiosperms (flowering plants) are the most frequently recorded group, with ca. 16 families based principally on fossil flowers and occasional leaves, including members of Leguminosae. This study reports new bifoliolate-compound leaves preserved in Mexican amber, represented by a pair of leaflets marginally attached to a short petiole. Each leaflet is ovate to oblong with an entire margin and has an acuminate apex with a pinnate primary vein. Their characteristics are comparable with bifoliate compound leaves of extant members of Cercidoideae, Caesalpinioideae, and Detarioideae subfamilies. Their asymmetrical base, brochidodromous secondary veins, and abundant translucid glands allow establishment of a new extinct resin-producing member of the Hymenaea clade (Detarieae, Detarioideae), Hymenaeaphyllum mirandae n. gen. n. sp. Hymenaea clade includes Guibourtia, Hymenaea, and Peltogyne, all with similar foliar architecture and other plant characteristics, including reproductive structures. The connection of Hymenaeaphyllum mirandae with extinct members of resin-producing plants recognized previously is uncertain. The discovery of Hymenaeaphyllum mirandae in the Mexican amber suggests that the Boreotropical Flora extended to low latitudes of North America during the Miocene.