Chromosome Numbers in Some Cacti of Western North America- VIII Author(s): Marc A Baker, Jon P Rebman, Bruce D Parfitt, Donald J Pinkava, and Allan D Zimmerman Source: Haseltonia, 15:117-134. 2009. Published By: Cactus and Succulent Society of America DOI: http://dx.doi.org/10.2985/026.015.0112 URL: http://www.bioone.org/doi/full/10.2985/026.015.0112 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Haseltonia 15: 117–134. 2009 117 CHROMOSOME NUMBERS IN SOME CACTI OF WESTERN NORTH AMERICA—VIII MARC A BAKER, JON P REBMAN*, BRUCE D PARFITT* DONALD J PINKAVA, AND ALLAN D ZIMMERMAN* School of Life Sciences, Arizona State University Box 87501, Tempe, Arizona 85287–4501 Abstract: Chromosome numbers are determined for 514 individuals belonging to 119 taxa within Cactaceae. Nineteen taxa have chromosome numbers reported for the first time. Based on geographic, morphological, and cytological data, three new nomenclatural com- binations are made: Cylindropuntia ×cardenche (Griffiths) Pinkava & M. A. Baker, Cylin- dropuntia imbricata (Haworth) F. M. Knuth var spinitecta (Griffiths) M. A. Baker, and Echi- nocereus bonkerae Thornber & Bonker ssp apachensis (W. Blum & Rutow) A. D. Zimmerman. Four species are here newly published as interspecific hybrids based, in part, on several char- acter states intermediate of their respective sympatric putative parents: Cylindropuntia ×car- denche (Griffiths) Pinkava & M. A. Baker (pro. sp) comb. nov., Cylindropuntia ×pallida (Rose) F. M. Knuth (pro. sp), Opuntia ×charlestonensis Clokey (pro. sp), and Opuntia streptacantha Lemaire × O. tomentosa Salm-Dyck. The family Cactaceae comprises approximately these early aneuploid chromosome determina- 1800 species (Parfitt and Gibson 2003), the tions may have been in error. Two remaining taxonomy of which is complicated by apomixis, reports of aneuploidy not yet recounted are hybridization, and polyploidy (Pinkava 2002). Echinocactus apricus Arechavaleta (2n = 38) Chromosome numbers in Cactaceae are nearly by Takagi (1938) and Deamia testudo (Kar- always a multiple of eleven. Ploidy levels are winski) Britton & Rose (2n = 24) by Bhat- often correlated with morphological and geo- tacharyya (1970). graphic distribution, and are crucial to the evo- Additional chromosome counts continue lution and systematics of the family. The most to shed light on speciation, geographic mi- important aspect of polyploidy in Cactaceae is grations and distributions, and understand- that it creates a genetic barrier (sexual repro- ing relationships among and within taxa. For ductive isolation) that often leads to speciation taxa having multiple ploidy levels, ecological (Baker 2003, 2006; Baker and Pinkava 1987, or geographic patterns often do not come to 1999; Parfitt 1987, Pinkava and others 2001; light until several to many chromosome de- Powell and Weedin 2001). terminations are made. In this paper, we will Aneuploidy appears to be of little impor- begin to address the geographic distributions tance in cactus evolution considering that of some of these chromosome races. nearly all chromosomes determinations have been euploid. Of the thousands of counts Materials and Methods determined for Cactaceae, only 16 taxa have Flower buds were collected in developmental been reported as aneuploid. Individuals of series from plants growing in native habitats 14 of these taxa have since been reported as or placed in cultivation (mostly at Southwest euploid by other researchers. Nine of the 14 Botanical Research, Chino Valley, Arizona or aneuploid counts were reported in the 1930s Desert Botanical Garden, Phoenix, Arizona). when techniques for determining chromosome The senior author has developed a method numbers may not have been as reliable as they whereby many of the buds were selected by are today. These aneuploid counts have not extracting anthers with fine-tipped forceps been repeated. This information suggests that and previewing meiosis under 100× magni- fication. Closed forceps were gently pushed through the layers of developing tepals, pried * Current addresses: JP Rebman, San Diego Natural History Museum, open, and re-closed over anthers. The proce- PO Box 121390, San Diego, CA 92112–1390; BD Parfitt, Biology Dept, University of Michigan-Flint, Flint MI 48502–1950; AD dure, which was easily done with a field mi- Zimmerman, 13571 N Como Drive, Tortolita, AZ 85755 croscope, allowed for the collection of a min- 118 BAKER AND OTHERS—CACTUS CHROMOSOME NUMBERS Figure 1. Distribution of chromosome determinations for individuals of Cylindropuntia fulgida (Data from Baker and Pinkava 1999; Pinkava and others 1973, 1985, 1992a, 1992b, 1998; Pinkava and Parfitt 1982). imal number of buds and assured a high rate Results of success. Alternatively, severed young buds Chromosome counts are reported for 514 in- were previewed by cutting them in half, and if dividuals representative of 119 taxa from 12 too early, were wrapped in a moist paper towel, genera of native cacti mostly from western placed in a petri dish, and reviewed from time United States and northern Mexico. First-time to time until meiosis was observed. Buds were chromosome counts (Appendix 1) are deter- killed and fixed in chloroform, 95% ethanol, mined for 19 taxa: five species, three infraspe- and glacial acetic acid (3:3:1 or 0:3:1) for at cific taxa, and ten interspecific hybrids. The least 24 hours, transferred to 70% ethanol, chromosome counts for the remaining taxa and refrigerated. In general, best results were are all in agreement with previously pub- obtained from buds transferred to 70% etha- lished reports. nol within 48 hours. Anthers were squashed in First-time counts are reported for the fol- acetocarmine and mounted in Hoyer’s medium lowing: Coryphantha alversonii, Cylindropuntia (Beeks 1955). Most squashes were done using ×cardenche, C. imbricata var spinitecta, C. lep- a metal vise. Voucher specimens (Appendix 1) tocaulis × C. versicolor, C. ×pallida, C. sant- are deposited in ASU unless otherwise stated. amaria, Echinocereus bonkerae ssp apachensis, Most specimens included duplicates that will E. lindsayi, Nopalea guatemalensis, N. hondu- be distributed to various herbaria. rensis, Opuntia aurea × O. phaeacantha, O. au- Morphological measurements, as necessary rea × O. pinkavae, O. aurea × O. polyacantha, for identification and taxonomic review, were O. ×charlestonensis, O. ×columbiana, O. comon- taken from both live and herbarium material. duensis, O. macrorhiza × phaeacantha, O. poly- Herbarium material included specimens from acantha var hystricina, and O. streptacantha × ARIZ, ASC, ASU, BRY, DES, MICH, MO, O. tomentosa. The pentaploid count of one in- NY, NMC, RENO, RM, RSA, SRSC, UNLV, dividual of Opuntia engelmannii var linguifor- UNM, US, UT, and UTEP. mis differs from earlier counts of hexaploid in- HASELTONIA 15, 2009 119 dividuals (Yuasa and others 1973, Weedin and cas, Mexico. The placement ofO . spinitecta Powell 1978, Pinkava and Parfitt 1982). as a variety within C. imbricata is based on their identical chromosome number, degree of Discussion overlap in morphological states, and the occa- In this eight-part series (Pinkava and McLeod sional presence of tuberous roots in C. imbri- 1971; Pinkava and Parfitt 1982; Pinkava and cata. The authors are aware thatC . imbricata others 1973, 1977, 1985, 1992a, 1998, and populations south of the Chihuahuan Desert this paper), chromosome numbers have been possess morphological characteristics that dif- determined for 1632 individuals of 229 taxa fer dramatically from those of populations in (including 35 interspecific hybrids and two in- the Great Plains. Further studies are needed, tergeneric hybrids) in 22 genera of cacti. however, in order to determine where best to Euploidy continues to overwhelmingly dom- determine additional taxonomic lines. inate the karyotype within Cactaceae. No an- Cylindropuntia ×pallida (ROSE) euploid individuals were detected from any of F. M. KNUTH (pro. sp) et status nov. (C. im- the 514 individuals examined (1632 individ- bricata (Haworth) F.M.Knuth × C. tunicata uals for our eight-part series) and, except for (Lehman) F.M.Knuth). Basionym: Opuntia those of odd-polyploids, no aneuploid gam- pallida Rose, Smiths Misc Coll 50: 507. 1908. etes were recorded. Individuals possessing morphological states Cytological, morphological, and geograph- intermediate between those of C. imbricata ical data indicate the need for nomenclatural and C. tunicata are frequent. The frequency of changes for the following: C.×pallida individuals, including those with Cylindropuntia ×cardenche (GRIFFITHS) morphological states favoring one or the other PINKAVA & M. A. BAKER (pro.