Reconstruction of the Leaves of Two New Species ofPseudosmodingium(Anacardiaceae) from Oligocene Strata of Puebla, Mexico

Leaves of two new plants are reconstructed from their isolated leaflets collected from the Oligocene Los Ahuehuetes locality near Tepexi de Rodríguez in Puebla, Mexico. The leaves ofPseudosmodingium mirandaeRamírez‐Garduño et al. are compound imparipinnate with leaflets of variable morphology. The l...

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Published inInternational journal of plant sciences Vol. 161; no. 3; pp. 509 - 519
Main Authors Ramírez, José L., Cevallos‐Ferriz, Sergio R. S., Silva‐Pineda, Alicia
Format Journal Article
LanguageEnglish
Published The University of Chicago Press 01.05.2000
Subjects
Fossil plants
Fossils
Geology
Leaves
Numerical analysis
Paratypes
Plants
Taxa
Trichomes
Vegetation
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Summary:Leaves of two new plants are reconstructed from their isolated leaflets collected from the Oligocene Los Ahuehuetes locality near Tepexi de Rodríguez in Puebla, Mexico. The leaves ofPseudosmodingium mirandaeRamírez‐Garduño et al. are compound imparipinnate with leaflets of variable morphology. The leaflets of five leaf morphotypes vary from narrow elliptic to lanceolate or lorate; they are symmetrical to slightly asymmetrical, with acute to attenuate apex, acute to cuneate base, and entire to serrate margin. Venation is simple pinnate craspedodromous, with secondary veins slightly curved near their base; secondary veins may dichotomize near the margin to become tertiary veins, and intersecondary veins are small and oblique to the secondary veins. A small number of leaflets assigned toPseudosmodingium terrazasiaeRamírez‐Garduño et al. are distinguished fromP. mirandaeby the leaflet shape, length:width ratio, base shape, and apex angle. Morphological comparison of the fossil leaves with leaves of extant species of Anacardiaceae based on numerical analyses indicates a close similarity betweenP. mirandaeandPseudosmodingium multifoliumRose, whileP. terrazasiaeis more similar toPseudosmodingium perniciosum(HBK) Engl. The presence of fossil species with extant relatives that are endemic to Mexico, along with previous reports, indicates that by the Oligocene, some lineages were already in place, although today they form part of the more xeric communities in southern North America.
ISSN:1058-5893
1537-5315
DOI:10.1086/314261