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A new species of Weltrichia (Williamsoniaceae: Bennettitales) is described from the Middle Jurassic of Oaxaca. The specimens come from the Tecomazuchil Formation in the Ayuquila region, at the border between the Oaxaca and Puebla states. Fossils are preserved as impressions and compressions, in a fine-grained sublitharenite sequence deposited in a fluvial environment. Preserved diagnostic characters include: large size; a cup-shaped receptacle showing seven radially arranged and basically fused microsporophylls bearing synangia. Microsporophylls are ornamented with longitudinal striations and fine brittled hairs on the edge of their wide base, and taper into a narrow distal tip. In the adaxial part of the microsporophylls seven to nine synangia are observed. These characters differentiate the new species Weltrichia mixtequensis from all previously recorded species from Mexico or elsewhere. The presence of this new species in the Middle Jurassic strata of the Ayuquila region add to the scarce fossil record of microsporangiate structures in the Jurassic flora of Mexico. |
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