Karyology of the genusEpidendrum(Orchidaceae: Laeliinae) with emphasis on subgenusAmphiglottiumand chromosome number variability inEpidendrum secundum

Abstract

Epidendrum is one of the largest Neotropical genera of Orchidaceae and comprises approximately 1500 species. Only 2.8% of these species have been studied cytologically, demonstrating chromosome numbers ranging from n = 12 in E. fulgens to n = 120 in E. cinnabarinum. The present work evaluated the evolution of the karyotypes of Epidendrum spp. based on data gathered from the literature and from analyses of the karyotypes of 16 Brazilian species (nine previously unpublished). The appearance of one karyotype with n = 12 with one larger chromosome pair in subgenus Amphiglottium appears to have occurred at the beginning of the divergence of this lineage, and x = 12 probably represents the basic number of this subgenus. Epidendrum secundum exhibits wide variation in chromosome numbers, with ten different cytotypes found in 22 Brazilian populations, seven of which were new counts: 2n = 30, 42, 50, 54, 56, 58 and 84. Most lineages of Epidendrum seem to have been secondarily derived from one ancestral stock with x = 20, as is seen in the majority of the present‐day representatives of the genus. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172, 329–344.

Intra- and interspecific karyotypic variations of the genus Senna Mill. (Fabaceae, Caesalpinioideae)

“…Additionally, polysomy and aneusomy (intra-individual variations in somatic chromosome numbers caused by polyploidy or aneuploidy respectively [Nirmala & Rao 1996;Rodrigues et al 2009]) have likely occurred in certain species of Senna (Chaulagain & Sakya 2002;Matos et al 2011), contributing to chromosome number variability in the genus. Intraspecific variations in chromosome numbers are quite common in other plant groups, such as Epidendrum secundum (Orchidaceae) (Assis et al 2013), Rutidosis leptorrhynchoides (Asteraceae) (Murray & Young 2001) and Zephyranthes sylvatica (Amaryllidaceae) (Felix et al 2008). In those cases, intraspecific variations could be related to factors such as distance or geographic isolation, together with hybridization in natural populations.…”

Research Article Chromosome variations and diversity of Epidendrum ibaguense Lindl. (Orchidaceae) on the Tepequém's Tepuy, Roraima, Brazil.

“…Epidendrum is one of the few genera that present variation in chromosome number, including at the intraspecific level [e.g., E. ciliare L., E. denticulatum, E. radicans, E. xanthinum, and in the complex E. secundum (Tanaka and Kamemoto, 1984;Pinheiro et al, 2009;Felix and Guerra, 2010;Assis et al, 2013) and E. ibaguense (this study)].…”

“…Rodr.,2n = 40,57,60,62,64,70;and E. xanthinum Lindl.,2n = 28,30,40,60,ca. 80) (Pinheiro et al, 2009;Felix and Guerra, 2010;Assis et al, 2013). The largest number of cytotypes is currently known for E. secundum Jacq., with 2n = 28, 40, 48, 52, 68, and 80 (Pinheiro et al, 2009) or 2n = 30, 42, 50, 54, 56, 58, and84 (Assis et al, 2013).…”

“…The largest number of cytotypes is currently known for E. secundum Jacq., with 2n = 28, 40, 48, 52, 68, and 80 (Pinheiro et al, 2009) or 2n = 30, 42, 50, 54, 56, 58, and84 (Assis et al, 2013). Additionally, in E. secundum the chromosomes also vary in size, revealing a strong karyotypic asymmetry and bimodality (Assis et al, 2013).…”

Chromosomal evolution in Pleurothallidinae (Orchidaceae: Epidendroideae) with an emphasis on the genusAcianthera: chromosome numbers and heterochromatin

“…Frequently, species involved in taxonomic complexes show chromosome number variation, as observed, for example, in the Epidendrum secundum Jacq. complex (2 n = 30 to 2 n = 84; Pinheiro et al ., ; Assis et al ., ). However, considering chromosome data for species from both taxonomic complexes, each species showed a characteristic chromosome number (inside each complex) suggesting that, at least among these species, chromosome data can differentiate between species, and the discordance between our data and those published previously is most likely to be a consequence of problems with taxonomic identification.…”