Phylogenetic relationships in Coryphantha and implications on Pelecyphora and Escobaria (Cacteae, Cactoideae, Cactaceae)

Abstract

The genus Coryphantha includes plants with globose to cylindrical stems bearing furrowed tubercles, flowers arising at the apex, and seeds with flattened testa cells. Coryphantha is the second richest genus in the tribe Cacteae. Nevertheless, the genus lacks a phylogenetic framework. The limits of Coryphantha with its sister genus Escobaria and the infrageneric classification of Coryphantha have not been evaluated in a phylogenetic study. In this study we analyzed five chloroplast regions (matK, rbcL, psbA-trnH, rpl16, and trnL-F) using Bayesian phylogenetic analysis. We included 44 species of Coryphantha and 43 additional species of the tribe Cacteae. Our results support the monophyly of Coryphantha by excluding C. macromeris. Escobaria + Pelecyphora + C. macromeris are corroborated as the sister group of Coryphantha. Within Coryphantha our phylogenetic analyses recovered two main clades containing seven subclades, and we propose to recognize those as two subgenera and seven sections, respectively. Also, a new delimitation of Pelecyphora including C. macromeris and all species previously included in Escobaria is proposed. To accommodate this new delimitation 25 new combinations are proposed. The seven subclades recovered within Coryphantha are morphologically and geographically congruent, and partially agree with the traditional classification of this genus.

Comparative stem anatomy of three species of Coryphantha (Cactoideae-Cactaceae)

“…It is worth mentioning that C. clavata possessed abundant mucilage cells in the cortex, in agreement with the clade O n l i n e f i r s t named mucilaginous by Sánchez et al (2022). Coryphantha cornifera belongs to a species with a characteristic watery cortex.…”

“…In C. clavata prisms and rounded crystals were detected. Crystals in the hypodermis are of high diagnostic value (Terrazas & Arias 2002, De la Rosa-Tilapa et al2020, so the study of the other species of Coryphantha will contribute to support the subclades within the genus according to the recent phylogeny proposed (Sánchez et al 2022).…”

“…oryphantha is the genus with the second highest species richness (only below Mammillaria) in the Cacteae tribe (Vázquez-Benítez et al 2016); it is distributed from the southern United States down to Oaxaca in southern Mexico (Dicht & Lüthy 2005). The species of Coryphantha have predominantly globose, ovoid, cylindrical-ovoid and depressed globose stems (Bravo-Hollis & Sánchez-Mejorada 1991, Vázquez-Sánchez et al 2012, Vázquez-Benítez et al 2016, Sánchez et al 2022. The tubercles exhibit different shapes and vary according to their position on the stem (Dicht & Lüthy 2005, Hunt et al 2006, Vázquez-Benítez et al 2016.…”

“…However, cylindrical growth form prevails; in the youngest and older tubercles, they are conical and medial conical-deltoid (Vázquez-Benítez et al 2016). Recently, a phylogenetic analysis of the recognized species of Coryphantha revealed that the genus is monophyletic, including 43 species recovered in two clades (Sánchez et al 2022). At the anatomical level, it has been reported that the wood of Coryphantha is similar to that of other species of the Cacteae tribe, with solitary vessels embedded in a matrix of wide-band tracheids with little paratracheal parenchyma (Gibson 1973, Mauseth et al 1995, Vázquez-Sánchez & Terrazas 2011.…”

Remarkably rapid, recent diversification of Cochemiea and Mammillaria in the Baja California, Mexico region

“…separate from Pelecyphora (sensu Sánchez et al 2022), is likely to have undergone a significant slowdown in diversification approximately 2.5 Ma, with a median diversification rate of 0.0005, with a 95% confidence interval between 0.0003 and 0.0012, while Pelecyphora s.l. maintained the diversification rate of the Mammilloid clade.…”