Lophocereus
Lophocereus in Contr. U.S. Natl. Herb. 12: 426. 1909 sec. Arias & al. 20121
- ≡Cereus subg. Lophocereus in Rep. (Annual) Missouri Bot. Gard. 16: 62. 1905 syn. sec. Arias & al. 20121
- ≡Pachycereus sect. Lophocereus in Calyx 2: 106. 1992 syn. sec. Arias & al. 20121
- Type: Lophocereus schottii
- =Marginatocereus in Cactaceae (Berlin) 1941(2): 49, 77. 1942 syn. sec. Arias & al. 20122
Content
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-Hollis (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 (Hartmann & 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.A,B,C,D,E,F,G,H,I,J,K,L
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.A,B,C,D,E,F,G,H,I,J,K,L
Taxon standing
Category B. The genus is monophyletic based on phylogenetic studies that support the clade based on a sufficiently dense or even complete sampling, or support a monotypic genus as a distinct lineage, but do not provide a new taxonomic treatment at the species level. In many cases, older classical taxonomic synopses or a monographic treatment exist for these genera providing a reliable assessment of the species included.
Bibliography
A. Arias, S. & Terrazas, T. 2006: Análisis cladístico del género Pachycereus (Cactaceae) con caracteres morfológicos. – Brittonia 58(3): 197-216. http://doi.org/10.1663/0007-196X(2006)58[197:ACDGPC]2.0.CO;2
B. Arias, S. & Terrazas, T. 2009: Taxonomic revision of Pachycereus (Cactaceae). – Systematic Botany 34(1): 68-83
C. Arias, S., Gama López, S., Guzmán Cruz, L. U. & Vázquez-Benítez, B. 2012: Cactaceae. – In: Medina, L. R., Flora del Valle de Tehuacán-Cuicatlán 95. – México D. F.: Instituto de Biología, Universidad Nacional Autónoma de México
D. Arias, S., Terrazas, T. & Cameron, K. 2003: Phylogenetic analysis of Pachycereus (Cactaceae, Pachycereeae) based on chloroplast and nuclear DNA sequences. – Systematic Botany 28(3): 547-557
E. Barthlott, W. & Hunt, D.R. 1993: Cactaceae, pp. 161-197. – In: Kubitzki, K., Rohwer, J.G. & Bittrich, V. (ed.), The Families and Genera of Vascular Plants 2. – Berlin, Heidelberg & New York: Springer
F. Bravo-Hollis, H. 1978: Las Cactáceas de México, ed. 2, 1. – México, D.F.: Universidad Nacional Autónoma de México.
G. Gibson, A.C. & Horak, K.E. 1978: Systematic anatomy and phylogeny of Mexican columnar cacti. – Annals of the Missouri Botanical Garden 65: 999 - 1057
H. Hartmann, S., Nason, J.D. & Bhattacharya, D. 2001: Extensive ribosomal DNA genic variation in the columnar cactus Lophocereus. – Journal of Molecular Evolution 53(2): 124-134
I. Hartmann, S., Nason, J.D. & Bhattacharya, D. 2002: Phylogenetic origins of Lophocereus (Cactaceae) and the senita cactus-senita moth pollination mutualism. – American Journal of Botany 89(7): 1085-1092
J. Hernández-Ledesma, P., Berendsohn, W. G., Borsch, T., von Mering, S., Akhani, H., Arias, S., Castañeda-Noa, I., Eggli, U., Eriksson, R., Flores-Olvera, H., Fuentes-Bazán, S., Kadereit, G., Klak, C., Korotkova, N., Nyffeler, R., Ocampo, G. & Ochoterena, H. 2015: A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales. – Willdenowia 45(3): 281-383. http://doi.org/10.3372/wi.45.45301