Rapicactus

Rapicactus
Rapicactus zaragosae
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Caryophyllales
Family:	Cactaceae
Subfamily:	Cactoideae
Tribe:	Cacteae
Genus:	Rapicactus Buxb. & Oehme
Type species
Rapicactus subterraneus
Species
See text.

Rapicactus is a genus of cactus in the tribe Cacteae, subfamily Cactoideae. It has been synonymized with Turbinicarpus but molecular phylogenetic studies have supported its monophyly and separation from that genus.[1]

Taxonomy

The genus Rapicactus was proposed in 1942 by Buxbaum and Oehme.[2] It was characterized by having thick roots with a constriction above forming a neck. However, most subsequent treatments sank the genus into a broadly circumscribed genus Turbinicarpus. The circumscription of Turbinicarpus has been described as "remarkably unstable", with species regularly transferred to other genera.[1] The broad circumscription of Turbinicarpus was recognized as polyphyletic by Hunt in 2016.[3] A phylogenetic study published in 2019 showed that a monophyletic Rapicactus was sister to Acharagma, separated from a monophyletic Turbinicarpus:[1]

	Three species of other genera Acharagma Rapicactus Species of other genera Species of other genera Kadenicarpus Ariocarpus Turbinicarpus s.s.

Species

As of May 2024^[update], Plants of the World Online accepted four species:[4]

Image	Scientific name	Distribution
	Rapicactus beguinii (N.P.Taylor) Lüthy	NE. Mexico
	Rapicactus booleanus (G.S.Hinton) D.Donati	Mexico (Nuevo León)
	Rapicactus mandragora (Fric ex A.Berger) Buxb. & Oehme	Mexico (Durango, Coahuila, Nuevo León)
	Rapicactus subterraneus (Backeb.) Buxb. & Oehme	Mexico (Nuevo León, Tamaulipas, San Luis Potosí)
	Rapicactus zaragosae (Glass & R.A.Foster) D.Donati	Mexico (Nuevo León, Tamaulipas)

References

1. Vázquez-sánchez, Monserrat; Sánchez, Daniel; Terrazas, Teresa; De La Rosa-Tilapa, Alejandro & Arias, Salvador (2019), "Polyphyly of the iconic cactus genus Turbinicarpus (Cactaceae) and its generic circumscription", Botanical Journal of the Linnean Society, 190 (4): 405–420, doi:10.1093/botlinnean/boz027
2. "Rapicactus Buxb. & Oehme", International Plant Names Index (IPNI), Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens, retrieved 2022-03-05
3. Hunt, D.R. (2016), CITES Cactaceae checklist (3rd ed.), Kew: Royal Botanic Gardens and D. Hunt, ISBN 978-0-9933113-2-1
4. "Rapicactus Buxb. & Oehme", Plants of the World Online, Royal Botanic Gardens, Kew, retrieved 2022-03-07