Hesperelaea

Hesperelaea is a plant genus with only one species, probably now extinct. Hesperelaea palmeri was found only on Guadalupe Island, a small island in the Pacific Ocean, part of the Mexican state of Baja California, about 400 km (250 mi) southwest of Ensenada. The last collection of the plant on the island was in 1875, so the species and the genus must now be presumed extinct.[2] An intensive search for the plant in 2000 was unsuccessful.[3]

Hesperelaea
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Lamiales
Family: Oleaceae
Tribe: Oleeae
Subtribe: Oleinae
Genus: Hesperelaea
A.Gray
Species:
†H. palmeri
Binomial name
†Hesperelaea palmeri

At the time of the collection of the type material in 1875, Hesperelaea palmeri was found only in a single canyon on the east side of the island. It was a shrub with broadly lanceolate leaves up to 5 cm long. Flowers were pale yellow, the petals over 10 mm long. The species was unusual in the family in having fully distinct petals.[4][5]

Phylogenetic analyses based on DNA from the nuclear genome as well as mitochondrial and chloroplast DNA suggest that H. palmeri is closely related to the genera Forestiera and Priogymnanthus in tribe Oleeae, and perhaps the sister lineage of Forestiera.[6][7] A molecular clock analysis estimated its divergence from its closest relatives in the Early Miocene, likely pre-dating the age of Guadalupe Island. This suggests that H. palmeri is a paleoendemic that was once more widespread and then retreated to Guadalupe Island following environmental change.[6]

References
  1. Fuentes, A.C.D.; Martínez Salas, E.; Samain, M.-S. (2020). "Hesperelaea palmeri". IUCN Red List of Threatened Species. 2020: e.T126608606A126609708. doi:10.2305/IUCN.UK.2020-3.RLTS.T126608606A126609708.en. Retrieved 20 November 2021.
  2. Govaerts, R. (2017). "Hesperelaea palmeri A.Gray, Proc. Amer. Acad. Arts 11: 83 (1876)". Royal Botanic Gardens, Kew. Retrieved 2017-08-06.
  3. Rebman, J.P.; Oberbauer, T.A.; Léon de la Luz, J.L. (2005). "La flora de Isla Guadalupe y sus islotes adyacentes". In Santos del Prado, K.; Peters, E. (eds.). Isla Guadalupe: restauración y conservación (PDF) (in Spanish). México: Instituto Nacional de Ecología. pp. 67–81. ISBN 968-817-725-3.
  4. Gray, A. (1876). Miscellaneous Botanical Contributions. Proceedings of the American Academy of Arts and Sciences. Vol. 11. p. 83.
  5. Shreve, F.; Wiggins, I.R. (1964). Vegetation and Flora of the Sonoran Desert. Vol. 2. Stanford: Stanford University Press.
  6. Zedane, L.; Hong-Wa, C.; Murienne, J.; Jeziorski, C.; Baldwin, B.G.; Besnard, G. (2016). "Museomics illuminate the history of an extinct, paleoendemic plant lineage (Hesperelaea, Oleaceae) known from an 1875 collection from Guadalupe Island, Mexico" (PDF). Biological Journal of the Linnean Society. 117 (1): 44–57. doi:10.1111/bij.12509. ISSN 0024-4066. open access
  7. Van de Paer, C.; Hong-Wa, C.; Jeziorski, C.; Besnard, G. (2016). "Mitogenomics of Hesperelaea, an extinct genus of Oleaceae". Gene. 594 (2): 197–202. doi:10.1016/j.gene.2016.09.007. ISSN 0378-1119. PMID 27601255.

Photographs of isotype herbarium specimens at Missouri Botanical Garden:

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