Lophocereus

Lophocereus

Content

Synonymy

Lophocereus (A.Berger) Britton & Rose in Contr. U.S. Natl. Herb. 12: 426. 1909 sec. Arias & al. (2012)
  • Cereus subg. Lophocereus A.Berger in Rep. (Annual) Missouri Bot. Gard. 16: 62. 1905 syn. sec. Arias & al. (2012)
  • Pachycereus sect. Lophocereus (A.Berger) P.V.Heath in Calyx 2: 106. 1992 syn. sec. Arias & al. (2012)
  • =Marginatocereus (Backeb.) Backeb. in Cactaceae (Berlin) 1941(2): 49, 77. 1942 syn. sec. Arias & al. (2012)

Notes

Lophocereus (including L. gates and L. schottii) was strongly recognized as a separate genus, restricted to the Sonoran Desert, by e.g. Lindsay (1963) and Bravo-Holis (1978). Comparative studies carried out by Gibson & Horak (1978) showed that those species share morphological and anatomical characteristics with Pachycereus marginatus. However, other taxonomists preferred to include this genus and others (e.g. Backebergia, Lemaireocereus, Marginatocereus, Mitrocereus, Pterocereus) in a broader genus Pachycereus (Barthlott & Hunt 1993; Hunt 2006). Phylogenetic studies based on structural (anatomy + morphology) and molecular data confirm that Lophocereus is monophyletic including three species (L. marginatus as sister to the remaining species). The genus represents a lineage within the subtribe Pachycereinae but is not directly related to Pachycereus s.str. or Backebergia (see there; Hartmann S. & al. 2001, 2002; Arias & al. 2003; Arias & Terrazas 2006). A proposal to recognize this genus newly circumscribed (now going also beyond the Sonoran Desert) was conducted by Arias & al. (2012).
Lophocereus now includes taxa characterized by cylindrical stems with basal branching, an apical fertile zone with areoles, and spines larger than those of the sterile zone, and two or more flowers per areole. The flowering zone is conspicuously modified in all three species, although in L. gatesii and L. schottii internodes are shorter and spines are longer (Arias & Terrazas 2009; Arias & al. 2012). Structural changes in the fertile zone exist between several genera of Pachycereinae, including cephalium (e.g. Backebergia, Cephalocereus spp.), pseudocephalium (e.g. Lophocereus, Neobuxbaumia spp.) and intermediate forms. However, those structures are highly homoplastic and occur within several genera.