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| Megastigma acarrilloi Pío-León, in Pío-León, 2024. |
Abstract
Background and Aims: The genus Megastigma has six described species of shrubs distributed from Colima, Mexico, to Nicaragua. Through a routine review of the iNaturalistMX platform in 2023, a record of an individual of the Megastigma genus was observed, although in a very disjunct locality with respect to known species. The collection and subsequent review of the specimens allowed us to determine that it was a new species for science.
Methods: Botanical explorations and collections were carried out during 2023 and 2024 in the Sierra de Barobampo, municipality of Ahome, Sinaloa, Mexico. The identity of the species was determined by the review of specialized literature. A map with the distribution of each species of the genus was elaborated using the available data in digital repositories and specimens in the MEXU herbarium. The conservation status of the new species was evaluated and proposed according to the IUCN criteria. An identification key is provided for all species of the genus Megastigma.
Results: Megastigma acarrilloi is endemic to northern Sinaloa, Mexico, and has the northernmost distribution of the genus. The species with the closest morphological affinity is M. morenoi, which is endemic to Colima, from which M. acarrilloi differs because it is glabrous and has fewer leaflets per leaf. During the explorations, Lepidopteran larvae of the genus Papilio were observed feeding on its leaves. It is recommended to include M. acarrilloi as a Vulnerable species (VU) on the IUCN Red List.
Conclusions: With the new species, the genus Megastigma is now integrated by seven species, all present in Mexico, and of which six are endemic to the country. Megastigma acarrilloi also represents the first record of the genus for Sinaloa and north of the Trans-Mexican Volcanic Belt.
Keywords: Barobampo mountains, endemism, iNaturalist, iNaturalistMX, Megastigma morenoi, Megastigma skinnerii
Juan Fernando Pío-León. 2024. Megastigma acarrilloi (Rutaceae), A New Species from Sinaloa, Mexico, with the northernmost distribution of the genus. Acta Botanica Mexicana. 131; DOI: doi.org/10.21829/abm131.2024.2406