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Variation in chromosome number and the basic number of subfamily Epidendroideae Orchidaceae Download Report. Published on Jul View Download A revision of the chromosomenumbers known for the subfamily was also performed, aimed at determining the basic numbers of the genera,subtribes and tribes. The first counts for 31 species and six genera of tribe Sobralieae and subtribe Ponerinae arepresented.

Variation in chromosome number and the basic number of subfamily Epidendroideae (Orchidaceae)

The basic number for each genus was evaluated. Othertribes were more variable. The karyotype variability observed in the subfamily is discussed in light of currentphylogenetic proposals for the family. Studies of chromosomalvariations in Orchidaceae have contributed to thebetter understanding of the taxonomy dws this family atmany hierarchical levels.

Arditti reviewed someof the important aspects of the cytology of the orchidfamily, with emphasis on chromosomal variation.

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Brandham reviewed chromosomal variation ineach genus of Apostasioideae Garay and Cypripedio-ideae Garay, but did not consider the probable basicnumbers of higher taxonomic categories. The basic number corre-sponds to the haploid number encountered in a giventaxon that explains in the most parsimonious mannerthe variation in chromosome numbers seen in that andrelated taxa Guerra, Epidendroideae are highly diversifiedand no morphological synapomorphy is shared by allmembers of the group.

With 5 figures The Linnean Society of London, Botanical Journal of the Linnean Society, Cymbidieae have corms or pseudobulbs and two tofour pollinia bodies Chase et al.

Angioepermas as Psygmorchis pusilla L. Epidendreae are subdivided into two main subtribes: Although themolecular phylogenetics of Epidendroi-deae has been relatively well studied, it has never beencytotaxonomically evaluated.

In the present study, weanalysed 44 Brazilian species of Epidendroideae sensuChase et al. These data were compared with the classificationsystem developed by Dressler and Chase et al.

All of the materialstudied was cultivated at the Federal Rural Univer-sity of Pernambuco, the Federal University of Parabaor the Federal University of Pernambuco, except forsome plants aangiospermas by private collectors. The speciesanalysed, chromosome numbers counted here andprevious counts are listed in Table 1.

Chromosome analyses were undertaken using roottips pretreated with 0. A separate list of chromosome numberswas then prepared, including angiospsrmas data from thepresent analysis see also Appendix 1. In this table,the names evoljo the genera, species and authors arecited as in the Evo,uo Checklist of Monocotyledons Govaerts et al. The data from Appendix 1 were synthesized inTable 2, showing the chromosome number variationin each angiospermqs.


The numbers were ordered from themost to the least frequent, and the probable basicnumber for each genus was underlined, based on thefrequency of each number in the genus and in theclosest related genera.

The chromosome numbersthat were considered questionable as they differedsignificantly from information available in the litera-tureand the occasional case of monosomy andtrisomy were excluded from Appendix 1 and Table 2,and from the discussion, and are presented sepa-rately in Appendix 2. RESULTSThe interphase nucleus structure and the chromo-some number of a total of 44 species belonging to 21genera, seven subtribes and four tribes of Epidendroi-deae angioapermas Chase et al.

Thestructure of the interphase nuclei was quite variableamong the species analysed. According to the classi-fication of interphase nuclei suggested by Tanaka for Orchidaceae, the structural types variedfrom diffuse nuclei in Campylocentrum pernam-bucense Hoehne Angiospetmas. Higgins and Malaxisexcavata Kuntze Fig. Morro do Chapu, BA L.

Taquaritinga do Norte, PE L.

Felix, 40 EANC. Menezes Cultivated, St Cruz Unvouchered c. Hoehne Carmpolis, SE L. Felix, 40 EANE. Williams Bezerros, PE L. Felix, 40 EANP. Van den Berg Cultivated Unvouchered 40 S. Chase Bezerros, PE L. Kuntze Bonito, PE L. Chromosome numbers and probable base numbers underlined of tribes, subtribes and genera of subfamilyEpidendroideae sensu Chase et al.

The proportionof condensed chromatin per chromosome was morevariable in the most asymmetric karyotypes, gener-ally being greater in the largest chromosome pairs, asfor example in E. In tribe Epidendreae, Isochilus linearis Jacq. Numbers connected with a rule have equal frequencies. These species had generally symmetrical karyo-types, with metacentric and submetacentric chromo-somes, and prophase chromosomes with a similarcondensation pattern.

All species investigated of Ajgiospermas R. In the genus Catt-leya Lindl. Angjospermas walkeriana accession Santa Cruz Fig. Meiotic analysis of a sample of E. These chromosomes weregenerally small approximately 0. Prometaphase chromosomes and interphase nuclei of representatives of Sobraliinae, Laeliinae and Angraeci-nae.

A, Eleanthus brasiliensis showing more condensed chromatin in two larger and 10 smaller chromosomes. BC,interphase nuclei of the diffuse angiospedmas in Campylocentrum pernambucense B and the complex chromocentric type inMalaxis excavata C. In subtribe Angiosermas, Acianthera ochreata Lindl.

The latter had a slightly asymmetrickaryotype. In evouo tribe Vandeae, Polys-tachya estrelensis Reichb. In tribe Dendrobieae, Bulbophyllum cribbi-anum Toscano, B. Chromosome complements of subtribes Sobraliinae, Ponerinae, Bletiinae and Laeliinae. Scale bar in O5 mm. Other tribes, such as Sobralieae andNeottieae, are currently insufficiently sampled or havevariable basic numbers among genera.

Previous chromosome counts were con-firmed for Dimerandra emarginata G. Hoehne Guerra,Sophronitis purpurata Lindl. Chase [as Laelia pur-purata Lindl.

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Williams as Schomburgkia crispa Lindl. Chromosome complements of subtribe Laeliinae. Scale bar in I5 mm. Chromosome complements of tribe Malaxideae, subtribes Laeliinae, Pleurothallidinae, Polystachyinae,Angraecinae and Dendrobiinae. Scale bar in P5 mm. There are records of chromosome numbers for fiveof the six recognized genera of tribe Neottieae, but itsbasic number is still unclear.


According to Chase et al. Tribes Sobralieae and Calypsoe are alsoinsufficiently investigated. Tribe Epidendreae, the largest group of subfamilyEpidendroideae Chase et al. Pleurothallisand Stelis display an exceptionally high variation inchromosome numbers, with 13 different numbersamong the 17 species investigated here for thesegenera.

Partial cladogram of subfamily Epidendroideae, based on Chase et al. It seems to represent two indepen-dent examples of intense dysploid reduction ratherthan the ancestral chromosome number of thesegenera Guerra, Small variations around thisnumber have been observed in some species of Veoluo, Epidendrum, Laelia, Scaphyglottis, and Soph-ronitis.

Intraspecific polyploidyoccurred in C. This ploidy change seems to be related angiospermzs variants placed in distinct subspecies,as in C.

In some lithophytic species of Sophronitis, theintraspecific polyploidy observed seems to be relatedto the acquisition of this habit, as has been reportedfor Sophronitis longipes Rchb. Chase Blumenschein, bS.


This tendency was also observed in thepolyploids Epidendrum cinnabarinum, C. Terrestrial species of sub-families Vanilloideae and Cypripedioideae also havegenome sizes notably higher than most epiphyticorchids. As species with large genome sizeusually have large guard cells and a slower responseto water stress, they are better adapted to the terres-trial lifestyle, whereas species with small genome sizeare free to occupy both habits. The only evoluuo analysed here of E.

These data indicate that E. In subtribe Eriinae Benth. The tribe Arethuseae is monophyletic Goldmanet al. The other generaare quite small and insufficiently studied.

At least one of these Liparis species L. The latter isconsidered the sister group of the other subtribes ofVandeae Chase et al. Subtribes Aerangidinae and Angraeci-nae are considered individually to be polyphyletic, buttogether they form the more widely circumscribedmonophyletic clade Angraecinae s. Among the subtribes with undefined taxonomicpositions Chase et al.

Among Dendrobiinae, the two genera largely investi-gated, Bulbophyllum and Dendrobium, showed rela-tively little variation. In contrast, in Collabiinae, thetwo genera with many species investigated, Calantheand Phaius, exhibited a large evolio in chromo-some numbers. A karyotypic aspect observed in four genera andseven species of subfamily Epidendroideae is thepresence of one or more pairs of late-condensing chro-mosomes. Late-condensing chromosomes have also beenobserved in other angiosperms, e.

The data presented here reaffirm the extensivevariation in chromosome numbers encountered insubfamily Epidendroideae. Only five of the genera with chromosome records for more than fivespecies have stable chromosome numbers.