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| a and b Nichima magalloniae c and d N. gonzalez-medranoi L.Hern., Cevallos-Ferriz et Hernández-Damián, in Hernández-Sandoval, Cevallos-Ferriz et Hernández-Damián, 2023. |
Abstract
Premise of the study:
Alismataceae, a sub-cosmopolitan 28 family with ca. 17 genera 29 and 113 species, is a large group of aquatic plants. Compression/impressions and bio-inclusions in amber support the documentation of the lineage in low-latitude North America. In Mexico, fossil aquatic plants have been infrequently documented. The new flowers recognize a group mainly known through fruits and seeds.
Material and Method:
Impression/compression reproductive structures from the Oligocene Los Ahuehuetes locality, Puebla, and bio-inclusions from the Miocene amber of Simojovel de Allende, Chiapas, Mexico, known through 150 samples. They are described and compared with extinct and extant taxa. A parsimony analysis based on 29 floral characters of 17 extant genera of the Alismataceae evaluates the relationship between the fossil material and their potential living relatives.
Results:
Nichima gen. nov. is a perfect, actinomorphic flower with an expanded receptacle, three persistent sepals with multi-vasculature, delicate and caducous petals, six stamens, and gynoecium composed of three to more superior carpels, maturing into achenes. These characteristics resemble flowers of Alismataceae. Nichima represents an extinct member of the family, with two new species, Nichima magalloniae L. Hern., Cevallos-Ferriz et Hernández-Damián sp. nov. and Nichima gonzalez-medranoi L. Hern., Cevallos-Ferriz et Hernández-Damián, sp. nov. Their phylogenetic position suggests affinity with a clade that includes Baldiella, Echinodorus, and Alisma.
Conclusions:
Reproductive structures from the Cenozoic of Mexico support the identification of a new extinct genus, Nichima, evidencing Alismataceae's extensive history in North America's low latitudes and suggests a southern extension of the Boreotropical Flora.
Keywords: Botreotropical Flora, Cenozoic, Fossil, aquatic plant, Nichima, Statzia
Genus⎼ Nichima L.Hern., Cevallos-Ferriz et Hernández-Damián, gen. nov.
Etymology⎼ The generic name refers to the word flower in Tzotzil, a Maya language spoken by the indigenous Tzotzil Maya people in the Mexican state of Chiapas.
Generic diagnosis⎼ Bisexual trimerous flowers, extended receptacle; calyx aposepalous, three persistent sepals; corolla apopetalous, three, narrow to unguiculate at the base, caducous petals; stamens 6, filaments flat, widened and connate at the base, anthers latrorse, ovate; carpels 3-6, fused at the apex, but separated at maturity; style very short or wanting, terminal; stigma punctuate.
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| Fossil flowers reconstructions with an inflorescence organization proposal. Only isolated flowers have been recollected; inflorescences are based on comparison with extant ones of closely related plants. a and b Nichima magalloniae L.Hern., Cevallos-Ferriz et Hernández-Damián; c and d N. gonzalez-medranoi L.Hern., Cevallos-Ferriz et Hernández-Damián. |
Luis Hernández-Sandoval, Sergio R. S. Cevallos-Ferriz and Ana L. Hernández-Damián. 2023. Nichima gen. nov. (Alismataceae) based on Reproductive Structures from the Oligocene-Miocene of Mexico. American Journal of Botany. DOI: 10.1002/ajb2.16231
