DOI: 10.5061/dryad.xgxd254vp
title: Data from: Elucidating a morphological and taxonomic continuum in <em>Pappophorum</em> (Poaceae: Chloridoideae)

description: Pappophorum Schreb. is a genus of perennial grasses included in
 Chloridoideae, found in arid and semiarid grasslands of the Americas. The
 genus is monophyletic, a sister group to Tridens Roem. & Schult.,
 and the clade formed by these two is sister to Neesiochloa Pilg. Some
 taxonomic treatments in Pappophorum have repositioned taxa and indicated
 synonymizations based on morphological attributes. One of the classic
 examples of delimitation proposals in the genus concerns the morphological
 boundaries between P. subbulbosum and P. mucronulatum in the Southern
 Hemisphere, as well as between P. vaginatum in the Northern Hemisphere.
 This complex species serves as a valuable biological model, demonstrating
 that comparing delimitation proposals with phenotypic data can be
 sufficient for discussing and clarifying taxonomic issues. In this study,
 we tested species circumscription proposals as taxonomic hypotheses using
 a statistical framework that assesses the possibility of classifying all
 variation in the samples as a single species. This statistical routine
 integrates univariate, multivariate, simple Bayesian classification, and
 morphological classification models to answer: (i) what is the diagnostic
 potential of morphological characters between taxa; (ii) which
 classification proposal better accommodates the morphological variation of
 the species; and (iii) what level of morphological overlap can exist in
 recently diverged groups. The MCluster analysis indicated that the
 unsupervised classification of three species was the best taxonomic model.
 Six characters were statistically significant for distinguishing at least
 one species in the complex. Our results indicate that P. subbulbosum
 should be recognized as an accepted species, warranting its reinstatement
 and suggesting complementary descriptions for P. mucronulatum and P.
 vaginatum.
description: # Data from: Elucidating a morphological and taxonomic continuum in
 *Pappophorum* (Poaceae: Chloridoideae) ## 1. Overview This repository
 contains the morphological dataset used in the manuscript: **Elucidating a
 morphological and taxonomic continuum in** ***Pappophorum*** **(Poaceae:
 Chloridoideae)**. The dataset includes continuous and categorical
 characters collected from the herbarium and digitized specimens of
 *Pappophorum* species. The matrix supports all statistical analyses
 performed in the study. --- ## 2. File Description ### **1.**
 **`Couceiro_et_al._2026_Pappophorum_specimens.zip`** CSV file containing
 supp_matrix_metadata_YC.csv and supp_matrix_legend_YC.csv: * Morphological
 characters measured for all specimens. * Continuous variables (e.g., awn
 length, lemma measurements). * Categorical variables (e.g., panicle type,
 presence/absence of glands). * Specimen metadata (collector, character
 values). * NA-coded values for non-evaluated characters. * Commas are used
 as a decimal delimiter. ### **2.** **`README.md`** This document,
 describing dataset structure, coding, and metadata. --- ## 3. Data
 Structure and Coding ### **Specimen Identification** Each row corresponds
 to a unique specimen. Fields include: * Species name (sp) * Collector
 (col) * Character and codes (char01, char02...) ### **Morphological
 Characters** Characters follow the coding described in **Supplemental
 Table S1** of the manuscript. * **Continuous characters:** numeric
 measurements (mm/cm) * **Categorical characters:** integers representing
 discrete states\ Example:\ **Char13 (Panicle type)** * 1 = sub-spiciform *
 2 = lax * 3 = spiciform ### **Missing Data** * `NA` indicates characters
 that could not be evaluated in the specimen. --- ## 4. Methodological
 Notes * Data were used for PCA, species delimitation analyses (Mcluster
 and Naive Bayes classification), and morphological comparisons
 (Bray-Curtis distance matrix, Pearson chi-square test, and Kruskal-Wallis
 analysis). ---