A new tropical species of Aphyllon (Orobanchaceae: Orobancheae) from Chiapas, Mexico

Abstract

Background: Aphyllon is a genus of 25 root-holoparasitic species restricted to the Americas. It has a disjunct distribution, with 21 species distributed in North America and four in South America. Aphyllon is divided into two sections: Aphyllonand Nothaphyllon. All species of the genus  have host-specificity, make it a study model in the evolution of holoparasitic plants. Recently, observations of a putative new species of Aphyllon were detected on iNaturalist. Questions: Are the alluded  iNaturalist observations of Aphyllon supported as a new species? What characters distinguish this taxon from the other species of Aphyllon? Studied species: Taxa of Aphyllon section Nothaphyllon. Study site and dates: Mexico; 2020–2023. Methods: Specimens were collected, dissected, measured, photographed and preserved. Herbarium specimens and literature on Aphyllon were reviewed. Comparisons of the taxon with species of section Nothaphyllon’s were performed. Results: A new species of the holoparasitic Aphyllon (Orobanchaceae) is described and illustrated. It is the second species of tropical  humid vegetation in Mexico, an atypical environment for most of the genus, and it is the only species of the section with racemes with narrowed to nearly closed corolla mouths, and straight, non-revolute lobes of the lower lip. Conclusions: The records in the citizen science platform have been useful to illustrate the morphology and color of the organisms, as well as to propose new species of Aphyllon. The photographs provide information not found in herbarium specimens due to oxidation and discoloration that occurs when drying Orobanchaceae plants.