Integrative taxonomy of Mexican cycads: biogeography, morphology and DNA barcoding corroborate a new sympatric species in Ceratozamia (Zamiaceae)

Abstract

A new species, from the montane region of Los Tuxtlas (state of Veracruz, Mexico), Ceratozamia subroseophylla, is proposed in accordance with the integrative taxonomy framework and through application of the taxonomic circle rationale. Our identification of this new species is the result of a thorough re-evaluation of four formerly described Ceratozamia species, namely: (1) C. miqueliana, with which it overlaps geographically; (2) C. mexicana; (3) C. robusta, which has also been previously seen as morphologically similar to C. miqueliana; and (4) C. brevifrons, which was at the center of a controversy concerning the morphological and geographic limits when compared to C. mexicana. Even though there are morphometric affinities of C. subroseophylla with this set of species, there are apomorphies in qualitative morphological characters and diagnostic nucleotidic variants established through character-based DNA barcoding to allow the recognition of this new species. The implications that our integrative taxonomy-based assessment of systematic diversity in Ceratozamia species from Veracruz have for evaluating the overall taxonomic status of the genus are discussed.

Qualitative and quantitative morphological evidence for recognition of a new species within Ceratozamia (Zamiaceae) from Mexico

“…Taxonomically, Ceratozamia species are notoriously difficult to identify because of the high morphological species variability, coupled with their very similar morphology , Martínez-Domínguez et al 2016. Hence, field studies of all species of the genus in local populations are useful in furthering the understanding of this variation.…”

“…Hence, field studies of all species of the genus in local populations are useful in furthering the understanding of this variation. Recent research has suggested the importance of reproductive characters (Martínez-Domínguez et al 2016). Considering descriptions of this characters based only on herbarium specimens may, therefore, be incomplete, ambiguous, and/or distorted, particularly for large strobili.…”

“…We evaluated 20 adult specimens in each population, from which a set of quantitative and qualitative morphological characters were recorded. Qualitative morphological characters: 1) Stem type, 2) Stem habit, 3) Prickles in petiole, 4) Prickles in rachis, 5) Type of prickles, 6) Leaf color at emergence, 7) Leaf insertion on stem, 8) Leaflet insertion on rachis, 9) Leaflets arrangement on rachis, 10) Arrangement of the petiole; 11) Arrangement of the rachis, 12) Leaflet form, 13) Leaflet shape, 14) Leaflet lamina symmetry For character selection, we utilized criteria reflected in previous taxonomic work , Vovides et al 2004b, Martínez-Domínguez et al 2016.…”

A novelty in Ceratozamia (Zamiaceae, Cycadales) from the Sierra Madre del Sur, Mexico: biogeographic and morphological patterns, DNA barcoding and phenology

“…The latter region was amplified in Ceratozamia subroseophylla (an ITS region sequence was previously available) and included in the molecular matrix. Choice of markers followed previous publications where they performed best in terms of number of diagnostic sites (Martínez-Domínguez et al 2016, 2017. Amplification products were visualized in 1% ethidium bromide-stained, agarose gels.…”

Taxonomic review of Ceratozamia (Zamiaceae) in the Sierra Madre Oriental, Mexico

“…However, other contemporary studies have shown that these characters can be highly variable between and amongst populations, which limits species diagnosis (Martínez-Domínguez et al 2016; 2017a, b, c). Other characters commonly used are the direction, form and texture of leaflets and the formation of prickles (Pérez-Farrera et al 2001; Vovides et al 2003).…”