Refining and defining the genus Psammopyrum (Triticeae, Poaceae): taxonomic evaluation of Ps. fontqueri with implications for the validity of the genus

摘要

Psammopyrum is a small genus of Triticeae (Poaceae) whose taxonomic validity, circumscription, and infra-generic classification remain unclear. In this study, we evaluate the taxonomic status of Ps. fontqueri, the species on which the cytogenetic boundaries of the genus were established. We have analysed its genomic composition by in situ hybridization and compare its lodicule morphology, leaf anatomy, and macro-morphology with those of the remaining species of Psammopyrum represented in the Iberian Peninsula. In addition, for comparative purposes, we consulted lectotypes and materials relevant for the typification of the names of the taxa involved. The in situ hybridization results indicated that Ps. fontqueri has a genomic composition quite similar to that proposed by other authors for Ps. pungens. Although no significant differences relative to lodicule morphology and leaf anatomy were detected among the taxa studied, they clearly differ from the representative species of Elymus s.s., Pauneroa, and Thinopyrum present in the study area. These findings support the contention that Ps. fontqueri has little taxonomic value, either cytogenetically or morphologically, and should be considered a synonym of Ps. pungens subsp. campestre. Since the taxonomic validity of the genus is still far from being established, further investigations are needed regarding its nomenclature, taxonomy, morphology, and cytogenetics, combined with thorough phylogenetic studies.