Monograph of Carex section Schiedeanae (Cyperaceae): Unexpected taxonomic and ecological diversity in a Mexican sedge clade

• Published in: Journal of systematics and evolution : JSE 2021-07, Vol.59 (4), p.698-725
• Main Authors: Reznicek, Anton A., González‐Elizondo, María del Socorro, Hahn, Marlene, Garner, Mira, Hipp, Andrew L.
• Format: Article
• Language: English
• Subjects: Biodiversity; Carex; Carex muriculata; Cyperaceae; DNA sequencing; endemism; Mexico; Morphology; new species; Papillae; Phylogeny; Sierra Madre; Species; systematics; taxonomy
• ISSN: 1674-4918; 1759-6831
• DOI: 10.1111/jse.12741

Carex section Schiedeanae (subg. Euthyceras) has long been thought to comprise at most five species of Mexican sedges. Our morphological studies in the field and herbarium, however, supported by more recent DNA sequencing work, demonstrate that the section is, in fact, three times as species‐rich, making it one of the largest sections in Mexico. Its 15 species range from Chihuahua to Tamaulipas south to Veracruz and Oaxaca; a single species, Carex muriculata, extends into the United States. The section has unusual inflorescences with simple (except in Carex complexa), uniformly androgynous, sessile spikes, utriculiform cladoprophylls, and perigynia with a unique combination of pubescence types composed of papillae; unicellular, simple hairs; and (in many species) multicellular tubercles. We recognize five previously described species (C. muriculata, Carex perstricta, Carex schiedeana, Carex stellata, and Carex vizarronensis) and describe 10 additional species (Carex angustilepis, Carex cabralii, Carex complexa, Carex dentata, Carex gypsophila, Carex mesophila, Carex paneroi, Carex planilamina, Carex revoluta, and Carex tehuacana). We have expanded the morphological features used in the section to include particularly anther, staminate scale, and style features, and more detailed micromorphology of the perigynia, especially indumentum. In total, 13 of the 15 species recognized herein, with a total of 32 individuals, were examined for ETS and ITS for phylogenetic reconstruction. Phylogenetically, the xeric species (plus C. paneroi) form a grade leading to a clade of the more mesophytic species adapted to forest understories, plus the unique cliff dwelling C. complexa. Carex section Schiedeanae (subg. Euthyceras) is revised to consist of 15 species, including 10 species described here. They range from one species reaching into the southeastern United States to southern Mexico. All species essentially occur in calcareous soils (including one gypsum endemic) and many occur in very dry habitats and display local endemism.